Science.gov

Sample records for aeolian sandy soil

  1. [Nutrient contents and microbial populations of aeolian sandy soil in Sanjiangyuan region of Qinghai Province].

    PubMed

    Lin, Chao-feng; Chen, Zhan-quan; Xue, Quan-hong; Lai, Hang-xian; Chen, Lai-sheng; Zhang, Deng-shan

    2007-01-01

    Sanjiangyuan region (the headstream of three rivers) in Qinghai Province of China is the highest and largest inland alpine wetland in the world. The study on the nutrient contents and microbial populations of aeolian sandy soils in this region showed that soil organic matter content increased with the evolution of aeolian sand dunes from un-stabilized to stabilized state, being 5.9 and 3.8 times higher in stabilized sand dune than in mobile and semi-stabilized sand dunes, respectively. Soil nitrogen and phosphorus contents increased in line with the amount of organic matter, while potassium content and pH value varied slightly. The microbial populations changed markedly with the development of vegetation, fixing of mobile sand, and increase of soil nutrients. The quantities of soil bacteria, fungi and actinomycetes were 4.0 and 2.8 times, 19.6 and 6.3 times, and 12.4 and 2.6 times higher in stabilized and semi-stabilized sand dunes than in mobile sand dune, respectively, indicating that soil microbial bio-diversity was increased with the evolution of aeolian sand dunes from mobile to stabilized state. In addition, the quantities of soil microbes were closely correlated with the contents of soil organic matter, total nitrogen, and available nitrogen and phosphorus, but not correlated with soil total phosphorus, total and available potassium, or pH value. PMID:17396507

  2. Aeolian desertification from the mid-1970s to 2005 in Otindag Sandy Land, Northern China

    NASA Astrophysics Data System (ADS)

    Liu, Shulin; Wang, Tao

    2007-01-01

    Aeolian desertification in Otindag Sandy Land has expanded dramatically during the past 50 years. This research explored processes and causes of aeolian desertification in the study area. The results showed that aeolian desertification development in Zhenglan Qi of typical region located at the center in the study area can be divided into three stages including rapid occurrence before 1987, parts of rehabilitation and most of deterioration from 1987 to 2000 and little rapid rehabilitation occurrence from 2000 to 2005, according to remote sensing images and field investigations. Gradually declining MI indicated that climate change was not the major cause of aeolian desertification development during the last 40 years, while increasing population should be the underlying cause of local aeolian desertification. Irrational human activities mainly including unsuitable reclamation in the 1960s and lasting over-grazing after 1980 are direct causes contributing to local aeolian desertification, especially over-grazing, while climate change often played a revealer of irrational human activities mainly through drought events. Over-grazing and undesirable climate have different functions during the whole aeolian desertification process. Over-grazing gradually changed grasslands to slight aeolian desertified lands at the initial stage, while climate with windy days or droughts often accelerated formation of serious aeolian desertified lands. Aeolian desertification in the study area both possesses occurrence possibility and great rehabilitative potential. At present, more integrated countermeasures combating local aeolian desertification still are expected.

  3. Atmospheric significance of aeolian salts in the sandy deserts of northwestern China

    NASA Astrophysics Data System (ADS)

    Zhu, B.-Q.

    2015-12-01

    Large sandy deserts in the middle latitudes of northwestern China were investigated for soluble salt variations in modern and ancient aeolian sediments, aiming to explore the environmental significance of "aeolian salts". Results revealed that aeolian salt variations have a clear relationship with the changing meridional and zonal gradients of the desert locations and the aeolian differentiation effect, but are weakly linked to local geological conditions. It suggests that the natural system of aeolian salts is hydrologically open and the chemistry of the parent brines are different from that predicted for hydrologically closed systems. Atmospheric depositions of water-soluble chemical species are an important process/source contributing to aeolian salt. Sequential variations of soluble salts in sedimentary profiles interbedded with aeolian and non-aeolian deposits and their palaeoenvironmental implications in the hinterland areas of these deserts were further evaluated, based on the constraints of OSL dating and radiocarbon dating data. The results indicate that the inorganic salts may be a latent geoproxy in revealing regional palaeoclimatic changes in desert areas for the sediments deposited under onefold depositional environment, but the interpretation should be more careful for the sediments deposited under diverse depositional conditions. This study presents the evidence of atmospheric origin of aeolian salt in sandy deserts, with limited climatic significance in palaeoenvironmental reconstruction.

  4. Atmospheric significance of aeolian salts in the sandy deserts of northwestern China

    NASA Astrophysics Data System (ADS)

    Zhu, B.-Q.

    2016-02-01

    Large sandy deserts in the middle latitudes of northwestern China were investigated for soluble salt variations in modern and ancient aeolian sediments, aiming to explore the environmental significance of "aeolian salts". Results revealed that aeolian salt variations have a clear relationship with the changing meridional and zonal gradients of the desert locations and the aeolian differentiation effect, but are weakly linked to local geological conditions. Atmospheric depositions of water-soluble chemical species are an important process/source contributing to aeolian salt. Sequential variations of soluble salts in sedimentary profiles interbedded with aeolian and non-aeolian deposits and their palaeoenvironmental implications in the hinterland areas of these deserts were further evaluated, based on the constraints of OSL dating and radiocarbon dating data. The results indicate that inorganic salts may be a latent geoproxy in revealing regional palaeoclimatic changes in desert areas for sediments deposited under a single depositional environment, but the interpretation should be more cautious for sediments deposited under diverse depositional conditions. This study presents evidence of the atmospheric origin of aeolian salt in sandy deserts, with limited climatic significance in palaeoenvironmental reconstruction.

  5. Aeolian cliff-top deposits and buried soils in the White River Badlands, South Dakota, USA

    USGS Publications Warehouse

    Rawling, J. E., III; Fredlund, G.G.; Mahan, S.

    2003-01-01

    Aeolian deposits in the North American Great Plains are important sources of Holocene palaeo-environmental records. Although there are extensive studies on loess and dune records in the region, little is known about records in aeolian cliff-top deposits. These are common on table (mesa) edges in the White River Badlands. These sediments typically have loam and sandy-loam textures with dominantly very fine sand, 0.5-1% organic carbon and 0.5-5% CaCO3. Some of these aeolian deposits are atypically coarse and contain granules and fine pebbles. Buried soils within these deposits are weakly developed with A-C and A-AC-C profiles. Beneath these are buried soils with varying degrees of pedogenic development formed in fluvial, aeolian or colluvial deposits. Thickness and number of buried soils vary. However, late-Holocene soils from several localities have ages of approximately 1300, 2500 and 3700 14C yrs BP. The 1300 14C yr BP soil is cumulic, with a thicker and lighter A horizon. Soils beneath the cliff-top deposits are early-Holocene (typically 7900 but as old as 10000 14C yrs BP) at higher elevation (???950 m) tables, and late-Holocene (2900 14C yrs BP) at lower (???830 m) tables. These age estimates are based on total organic matter 14C ages from the top 5 cm of buried soils, and agreement is good between an infrared stimulated luminescence age and bracketing 14C ages. Our studies show that cliff-top aeolian deposits have a history similar to that of other aeolian deposits on the Great Plains, and they are another source of palaeoenvironmental data.

  6. Aeolian dust in Colorado Plateau soils: Nutrient inputs and recent change in source

    PubMed Central

    Reynolds, Richard; Belnap, Jayne; Reheis, Marith; Lamothe, Paul; Luiszer, Fred

    2001-01-01

    Aeolian dust (windblown silt and clay) is an important component in arid-land ecosystems because it may contribute to soil formation and furnish essential nutrients. Few geologic surfaces, however, have been characterized with respect to dust-accumulation history and resultant nutrient enrichment. We have developed a combination of methods to identify the presence of aeolian dust in arid regions and to evaluate the roles of this dust in ecosystem processes. Unconsolidated sandy sediment on isolated surfaces in the Canyonlands region of the Colorado Plateau differs greatly in mineralogical and chemical composition from associated bedrock, mainly aeolian sandstone. Detrital magnetite in the surficial deposits produces moderately high values of magnetic susceptibility, but magnetite is absent in nearby bedrock. A component of the surficial deposits must be aeolian to account for the abundance of magnetite, which formed originally in far-distant igneous rocks. Particle-size analysis suggests that the aeolian dust component is typically as much as 20–30%. Dust inputs have enriched the sediments in many elements, including P, Mg, Na, K, and Mo, as well as Ca, at sites where bedrock lacks calcite cement. Soil-surface biologic crusts are effective dust traps that apparently record a change in dust sources over the past several decades. Some of the recently fallen dust may result from human disturbance of land surfaces that are far from the Canyonlands, such as the Mojave Desert. Some land-use practices in the study area have the potential to deplete soil fertility by means of wind-erosion removal of aeolian silt. PMID:11390965

  7. Aeolian dust in Colorado Plateau soils: Nutrient inputs and recent change in source

    USGS Publications Warehouse

    Reynolds, R.; Belnap, Jayne; Lamothe, Paul; Luiszer, Fred

    2001-01-01

    Aeolian dust (windblown silt and clay) is an important component in arid-land ecosystems because it may contribute to soil formation and furnish essential nutrients. Few geologic surfaces, however, have been characterized with respect to dust-accumulation history and resultant nutrient enrichment. We have developed a combination of methods to identify the presence of aeolian dust in arid regions and to evaluate the roles of this dust in ecosystem processes. Unconsolidated sandy sediment on isolated surfaces in the Canyonlands region of the Colorado Plateau differs greatly in mineralogical and chemical composition from associated bedrock, mainly aeolian sandstone. Detrital magnetite in the surficial deposits produces moderately high values of magnetic susceptibility, but magnetite is absent in nearby bedrock. A component of the surficial deposits must be aeolian to account for the abundance of magnetite, which formed originally in far-distant igneous rocks. Particle-size analysis suggests that the aeolian dust component is typically as much as 20a??30%. Dust inputs have enriched the sediments in many elements, including P, Mg, Na, K, and Mo, as well as Ca, at sites where bedrock lacks calcite cement. Soil-surface biologic crusts are effective dust traps that apparently record a change in dust sources over the past several decades. Some of the recently fallen dust may result from human disturbance of land surfaces that are far from the Canyonlands, such as the Mojave Desert. Some land-use practices in the study area have the potential to deplete soil fertility by means of wind-erosion removal of aeolian silt.

  8. Mechanics of aeolian processes: Soil erosion and dust production

    NASA Technical Reports Server (NTRS)

    Mehrabadi, M. M.

    1989-01-01

    Aeolian (wind) processes occur as a result of atmosphere/land-surface system interactions. A thorough understanding of these processes and their physical/mechanical characterization on a global scale is essential to monitoring global change and, hence, is imperative to the fundamental goal of the Earth observing system (Eos) program. Soil erosion and dust production by wind are of consequence mainly in arid and semi arid regions which cover 36 percent of the Earth's land surface. Some recent models of dust production due to wind erosion of agricultural soils and the mechanics of wind erosion in deserts are reviewed and the difficulties of modeling the aeolian transport are discussed.

  9. Aeolian vertical mass flux profiles above a dry and moist sandy beach

    NASA Astrophysics Data System (ADS)

    Rotnicka, Joanna

    2013-04-01

    The vertical distribution of aeolian mass flux was investigated in a natural beach environment. Field experiments conducted on the beach of the Łeba Barrier, southern Baltic coast, Poland, measured the sand transport rate and the vertical mass flux distribution above dry rippled sand and a moist flat sandy surface. The experiments were intended to show the changes in the vertical distribution of sand with changing wind speed. All the data represent maximum flux conditions achieved during alongshore winds. Sand transport was measured using 0.5 m-high vertically segmented sand traps, the wind speed and direction were monitored at 1 m elevation. The obtained dataset comprises 65 measurements on dry surfaces and 51 measurements on moist sandy surfaces. The sand transport rate above the moist surface was higher than above the dry surface, but higher velocities gave smaller differences between the surfaces. The saltation layer was thicker above the moist surface than above the dry surface. All the vertical sand flux profiles are best described by exponential decay functions. Analysis of the normalised flux profiles grouped by wind velocity shows that the fitted curves are less inclined for moist surfaces than dry surfaces.The regression coefficients depict a marked trend in which the intercept decreases and the slope increases with increasing wind speed; this indicates that more sand is transported at higher elevations above the bed and less at lower elevations. The proportion of total transport seems to be independent of wind speed at elevations of approximately 35 mm and 50 mm above the dry and moist surfaces, respectively. Differences between the measured- and exponential-fit values of mass flux are particularly distinct close to the bed, where the exponential fit either over- or under-predicts the measured values. Over-predictions occur in weaker winds, whereas under-predictions become more pronounced as the wind becomes stronger and when the layer in which the

  10. Soil Response to Aeolian Disturbance in West Greenland

    NASA Astrophysics Data System (ADS)

    Heindel, R. C.; Culler, L. E.; Chipman, J. W.; Virginia, R. A.

    2015-12-01

    Arctic soils are a critical ecological resource, yet are increasingly vulnerable to global change. In the Kangerlussuaq region of West Greenland, aeolian disturbance is the greatest threat to soil stability, with strong katabatic winds eroding vegetation and soil down to the underlying glacial till or bedrock. Little is known about what controls the distribution and rate of the aeolian erosion, which initially results in a state change from tundra to a deflated and nearly unvegetated ground. It is unclear if vegetation can eventually reestablish after erosion occurs, potentially aided by the biological soil crust (BSC) that develops within the eroded areas, or if this soil loss is an irreversible change in vegetation and soil carbon (C) and nitrogen (N) cycling. Our analysis of high-resolution satellite imagery shows that across the entire study region, deflated ground covers 22% of the terrestrial landscape. Aeolian erosion occurs more frequently closer to the Greenland Ice Sheet and on S-facing slopes. Using lichenometry, we estimate that erosional fronts move across the landscape at rates of 2.5 cm yr-1, leaving unproductive ground in their wake. The onset of widespread aeolian erosion occurred roughly 700-1000 years ago, pointing toward regional cooling and aridity as the drivers behind erosion. Finally, we consider whether the BSCs can improve soil quality enough to allow for full vegetation regrowth. Preliminary results show that while the BSCs fix atmospheric N and increase C storage, the rate of soil quality recovery is extremely slow. Understanding the thresholds between vegetated tundra and eroded ground is critical for predicting how the Kangerlussuaq landscape will respond to anticipated changes in climate and ice sheet dynamics.

  11. Geochemical provenance of soils in Kerman urban areas, Iran: Implications for the influx of aeolian dust

    NASA Astrophysics Data System (ADS)

    Dehbandi, Reza; Aftabi, Alijan

    2016-06-01

    The investigation of the interaction of aeolian dust with residual soils has not been fully explored in the Kerman urban areas, Iran. To assess the geochemical influence of aeolian dust on the residual soils of the Kerman urban areas of Iran, 27 samples were studied petrogeochemically. The arid-semi-arid climate of the area together with the southwest-northeast prevailing wind, have deposited aeolian sands over the residual soils. Residual soils reflect similar mineral compositions to that of the underlying bedrock and include mostly calcite and quartz. However, the minor occurrences of pyroxene, amphibole, olivine, plagioclase and volcanic clasts in urban soils and aeolian dust are attributed to volcanogenic inputs transported by aeolian dust. Urban soils and aeolian dust show different geochemical signatures from the local carbonate rocks. All samples contain trace element concentrations that are higher than the carbonate bedrock. Discrimination diagrams indicate that immobile trace elements have geochemical affinity to the detrital ferromagnesian dust inputs and are different from the local carbonate bedrock. Based on the elemental bivariate and ternary diagrams, the soils and aeolian dust are derived from the interaction of carbonate and volcanic rocks. This highlights that the urban soils in the Kerman urban areas have been formed by interactions of the aeolian dust with the primitive residual soils.

  12. BACTERIOPHAGE TRANSPORT IN SANDY SOIL AND FRACTURED TUFF

    EPA Science Inventory

    Bacteriophage transport was investigated in laboratory column experiments using sandy soil, a controlled field study in a sandy wash, and laboratory experiments using fractured rock. In the soil columns, the phage MS-2 exhibited significant dispersion and was excluded from 35 to ...

  13. Responses of soil fungal community to the sandy grassland restoration in Horqin Sandy Land, northern China.

    PubMed

    Wang, Shao-Kun; Zuo, Xiao-An; Zhao, Xue-Yong; Li, Yu-Qiang; Zhou, Xin; Lv, Peng; Luo, Yong-Qing; Yun, Jian-Ying

    2016-01-01

    Sandy grassland restoration is a vital process including re-structure of soils, restoration of vegetation, and soil functioning in arid and semi-arid regions. Soil fungal community is a complex and critical component of soil functioning and ecological balance due to its roles in organic matter decomposition and nutrient cycling following sandy grassland restoration. In this study, soil fungal community and its relationship with environmental factors were examined along a habitat gradient of sandy grassland restoration: mobile dunes (MD), semi-fixed dunes (SFD), fixed dunes (FD), and grassland (G). It was found that species abundance, richness, and diversity of fungal community increased along with the sandy grassland restoration. The sequences analysis suggested that most of the fungal species (68.4 %) belonged to the phylum of Ascomycota. The three predominant fungal species were Pleospora herbarum, Wickerhamomyces anomalus, and Deconica Montana, accounting for more than one fourth of all the 38 species. Geranomyces variabilis was the subdominant species in MD, Pseudogymnoascus destructans and Mortierella alpine were the subdominant species in SFD, and P. destructans and Fungi incertae sedis were the dominant species in FD and G. The result from redundancy analysis (RDA) and stepwise regression analysis indicated that the vegetation characteristics and soil properties explain a significant proportion of the variation in the fungal community, and aboveground biomass and C:N ratio are the key factors to determine soil fungal community composition during sandy grassland restoration. It was suggested that the restoration of sandy grassland combined with vegetation and soil properties improved the soil fungal diversity. Also, the dominant species was found to be alternative following the restoration of sandy grassland ecosystems. PMID:26661957

  14. Changes in soil aggregation and dust emission potential in response to aeolian processes

    NASA Astrophysics Data System (ADS)

    swet, Nitzan; Katra, Itzhak

    2016-04-01

    Aeolian (wind) dust emission has high environmental and socioeconomic significances due to loss of natural soil and air pollution. Dust emission involves complex interactions between the airflow and the soil surface. The soil aggregates were dust particles are held determine the topsoil erodibility in aeolian erosion. Although the key role of soil aggregation in dust emission mechanisms, information on changes in soil aggregate size distribution (ASD) due to aeolian erosion is lucking. This study is focused on quantitative ASD analyses before and after aeolian processes (saltation). Aeolian experiments and soil analyses were conducted on semiarid loess topsoils with different initial conditions of aggregation. The results show that saltation rates and PM emissions depend on the initial ASD and shear velocity. In all initial soil conditions, the content of aggregates at saltator-sized 63-250 μm was increased by 10-34 % following erosion of macro-aggregates > 500 μm. It revealed that the aggregate-saltator production increases with the shear velocity (up to 0.61 m s-1) for soils with available macro-aggregates. The findings highlight the dynamics in soil aggregation in response to aeolian transport and therefore its significance for determining the mechanisms of dust emission from soil aggregates.

  15. ANAEROBIC SOIL DISINFESTATION IN MICROCOSMS OF TWO SANDY SOILS.

    PubMed

    Stremińska, M A; Runia, W T; Termorshuizen, A J; Feil, H; Van Der Wurff, A W G

    2014-01-01

    In recent years, anaerobic soil disinfestation (ASD) has been proposed as an alternative control method of soil-borne plant pathogens. It involves adding a labile carbon source, irrigating the soil to stimulate decomposition of organic material and then covering the soil with air-tight plastic to limit gas exchange. During the ASD process, soil microorganisms switch from aerobic to anaerobic metabolism. As a result, by-products of anaerobic metabolism are released into the soil environment such as various organic acids and gases. These by-products are reported to have a negative effect on survival of soil-borne plant pathogens. However, the efficacy of ASD to reduce soil-borne pathogens in practice may vary significantly. Therefore, we studied the efficacy of the ASD process in two different soils. In addition, it was investigated whether a pre-treatment with an anaerobic bacterial inoculum prior to ASD affected the efficacy of the process. Two sandy soils (dune sand and glacial sand) were inoculated in 2 L soil microcosms. We tested the efficacy of ASD treatment against the potato cyst nematode Globodera pallida. For each soil, three treatments were used: control treatment (no Herbie addition, aerobic incubation), ASD 1 (organic substrate addition, anaerobic incubation) and ASD 2 (organic substrate and anaerobic bacterial inoculum addition, anaerobic incubation). Soil microcosms were incubated in the dark at 20°C for two weeks. We observed that anaerobic soil disinfestation treatments were highly effective against Potato Cyst Nematode (PCN), with pathogen being eradicated totally in all but one ASD treatment (glacial sand ASD2) within two weeks. The relative abundance of Firmicutes (spore-forming bacteria, often fermentative) in total bacteria increased significantly in ASD treated soils. Numbers of these bacteria correlated positively with increased concentrations of acetic and butyric acids in soil water phase in ASD treatments. PMID:26084078

  16. Switchgrass and pecan biochar amendments to a sandy coastal soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sandy soils of the wet, warm SE Coastal Plain have poor physical characteristics and low carbon contents. To improve soil properties, we added switchgrass (Panicum virgatum) and non-activated pecan (Carya illinoinensis) biochar. Switchgrass was ground to a fine powder and added to soil at rates of 0...

  17. Acidic sandy soil improvement with biochar - A microcosm study.

    PubMed

    Molnár, Mónika; Vaszita, Emese; Farkas, Éva; Ujaczki, Éva; Fekete-Kertész, Ildikó; Tolner, Mária; Klebercz, Orsolya; Kirchkeszner, Csaba; Gruiz, Katalin; Uzinger, Nikolett; Feigl, Viktória

    2016-09-01

    Biochar produced from a wide range of organic materials by pyrolysis has been reported as a means to improve soil physical properties, fertility and crop productivity. However, there is a lack of studies on the complex effects of biochar both on the degraded sandy soil physico-chemical properties and the soil biota as well as on toxicity, particularly in combined application with fertilizer and compost. A 7-week microcosm experiment was conducted to improve the quality of an acidic sandy soil combining variations in biochar types and amounts, compost and fertilizer application rates. The applied biochars were produced from different feedstocks such as grain husks, paper fibre sludge and wood screenings. The main purpose of the microcosm experiment was to assess the efficiency and applicability of different biochars as soil amendment prior to field trials and to choose the most efficient biochar to improve the fertility, biological activity and physical properties of acidic sandy soils. We complemented the methodology with ecotoxicity assessment to evaluate the possible risks to the soil as habitat for microbes, plants and animals. There was clear evidence of biochar-soil interactions positively affecting both the physico-chemical properties of the tested acidic sandy soil and the soil biota. Our results suggest that the grain husk and the paper fibre sludge biochars applied to the tested soil at 1% and 0.5 w/w% rate mixed with compost, respectively can supply a more liveable habitat for plants and soil living animals than the acidic sandy soil without treatment. PMID:26850860

  18. Microfungi diversity isolation from sandy soil of Acapulco touristic beaches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microscopic fungi diversity in marine sandy soil habitats is associated with key functions of beach ecosystems. There are few reports on their presence in Mexican beaches. Although standard methods to obtain the fungi from soil samples are established, the aim of this pilot study was to test the pla...

  19. Adding Clays to Sandy Soils to Increase Carbon Storage

    NASA Astrophysics Data System (ADS)

    Harper, R. J.; Sochacki, S. J.

    2011-12-01

    Soil carbon storage is often related to clay content and mineralogy. For example, in a dryland farming area (300 mm/year annual rainfall) of Western Australia, carbon storage increased systematically with increasing clay content. Carbon storage in the surface 0.1 m was 42.5 Mg CO2-e/ha in soils with 1.7% clay compared to 99.1 Mg CO2-e/ha for soils with 9.1% clay. Similar results are evident in other data-sets, with carbon storage being related to site water balance, clay content and soil chemical fertility. We thus investigated whether soil carbon storage could be manipulated in sandy soils by adding clay. Clays are often added to farmed sandy soils to overcome water repellency and to reduce nutrient losses by leaching, but are not considered as a carbon management tool. The combined effects can improve plant productivity and thus carbon inputs to soil carbon pools. Bauxite processing residue (10% clay) had been applied in 1982 to sandy soils at different rates in an area with 760 mm/year annual rainfall. Application of 25 Mg clay/ha resulted in an increase in soil carbon content of 47.7 Mg CO2-e/ha. Soils were sampled to a depth of 0.3 m, with most (65%) of the increase being in the surface 0.1 m. Globally, there are large areas of sandy soils occurring across several soil taxonomic orders. In this presentation we describe the implications of clay amendments for increasing the carbon storage in such soils, and suggest areas of further investigation.

  20. FIELD SAMPLING OF RESIDUAL AVIATION GASOLINE IN SANDY SOIL

    EPA Science Inventory

    Two complimentary field sampling methods for the determination of residual aviation gasoline content in the contaminated capillary fringe of a fine, uniform, sandy soil were investigated. The first method featured filed extrusion of core barrels into pint size Mason jars, while ...

  1. Southern Highbush Establishment Cultural Studies on Sandy Loam Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cultural practices to establish southern highbush blueberries were initiated in 2002 and 2003 in Stone County research plots of hte Thad Cochran Southern Horticultural Laboratory. Studies were initiated to examine different cultural practices on sandy loam soils. Southern highbush plants preferred...

  2. Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients

    USGS Publications Warehouse

    Reynolds, R.; Neff, J.; Reheis, M.; Lamothe, P.

    2006-01-01

    Rock-derived nutrients in soils originate from both local bedrock and atmospheric dust, including dust from far-distant sources. Distinction between fine particles derived from local bedrock and from dust provides better understanding of the landscape-scale distribution and abundance of soil nutrients. Sandy surficial deposits over dominantly sandstone substrates, covering vast upland areas of the central Colorado Plateau, typically contain 5-40% silt plus clay, depending on geomorphic setting and slope (excluding drainages and depressions). Aeolian dust in these deposits is indicated by the presence of titanium-bearing magnetite grains that are absent in the sedimentary rocks of the region. Thus, contents of far-traveled aeolian dust can be estimated from magnetic properties that primarily reflect magnetite content, such as isothermal remanent magnetization (IRM). Isothermal remanent magnetization was measured on bulk sediment samples taken along two transects in surficial sediment down gentle slopes away from sandstone headwalls. One transect was in undisturbed surficial sediment, the other in a setting that was grazed by domestic livestock until 1974. Calculation of far-traveled dust contents of the surficial deposits is based on measurements of the magnetic properties of rock, surficial deposits, and modern dust using a binary mixing model. At the undisturbed site, IRM-based calculations show a systematic down-slope increase in aeolian dust (ranging from 2% to 18% of the surface soil mass), similar to the down-slope increase in total fines (18-39% of surface soil mass). A combination of winnowing by wind during the past and down-slope movement of sediment likely accounts for the modern distribution of aeolian dust and associated nutrients. At the previously grazed site, dust also increases down slope (5-11%) in sediment with corresponding abundances of 13-25% fines. Estimates of the contributions of aeolian dust to the total soil nutrients range widely

  3. Aeolian nutrient fluxes following wildfire in sagebrush steppe: Implications for soil carbon storage

    USGS Publications Warehouse

    Hasselquist, N.J.; Germino, M.J.; Sankey, J.B.; Ingram, L.J.; Glenn, N.F.

    2011-01-01

    Pulses of aeolian transport following fire can profoundly affect the biogeochemical cycling of nutrients in semi-arid and arid ecosystems. Our objective was to determine horizontal nutrient fluxes during an episodic pulse of aeolian transport that occurred following a wildfire in a semi-arid sagebrush steppe ecosystem in southern Idaho, USA. We also examined how temporal trends in nutrient fluxes were affected by changes in particle sizes of eroded mass as well as nutrient concentrations associated with different particle size classes. In the burned area, total carbon (C) and nitrogen (N) fluxes were as high as 235 g C m????'1 d????'1 and 19 g N m????'1 d????'1 during the first few months following fire, whereas C and N fluxes were negligible in an adjacent unburned area throughout the study. Temporal variation in C and N fluxes following fire was largely attributable to the redistribution of saltation-sized particles. Total N and organic C concentrations in the soil surface were significantly lower in the burned relative to the unburned area one year after fire. Our results show how an episodic pulse of aeolian transport following fire can affect the spatial distribution of soil C and N, which, in turn, can have important implications for soil C storage. These findings demonstrate how an ecological disturbance can exacerbate a geomorphic process and highlight the need for further research to better understand the role aeolian transport plays in the biogeochemical cycling of C and N in recently burned landscapes. ?? 2011 Author(s).

  4. Origin of basaltic soils at Gusev crater, Mars, by aeolian modification of impact-generated sediment

    NASA Astrophysics Data System (ADS)

    McGlynn, Ian O.; Fedo, Christopher M.; McSween, Harry Y., Jr.

    2011-04-01

    Textural properties of soils including grain size, sorting, modality, skewness, shape (quantified as sphericity and qualified as form), roundness, and grain size distribution, have been measured and calculated from Microscopic Imager (MI) high-resolution images from the Mars Exploration Rover (MER) Spirit in Gusev crater. Soil targets were classified by grain size into five groups: fine to medium sand dark soil, medium sand to very fine pebble bed form armor, and very fine to medium pebble lithic fragments, a bimodal mixed soil, and an excavated soil trench. The abundance of submature, very poorly sorted, bimodal mixed soils indicates incomplete sorting by soil type. Probability distributions of excavated subsurface soil match crushed sediment analogs, indicating impact comminution, while all other soils show no direct evidence of an impact origin. If soils were produced primarily by impacts, then the evidence from probability distributions, angular shapes, and agglutinates have been reworked by postimpact surface activity. Soils in Gusev crater are continuously modified, reworked, and sandblasted. Textures of surface sediments are disconnected from subsurface textures and only reflect modern surficial aeolian processes. Models to reconstruct physical and chemical soil formation properties should not assume a static three-dimensional structure. A three-step model, initiated by the formation of basaltic crust and its alteration, followed by bolide impact, and finally modification by aeolian reworking is envisioned for the formation of soils. Such a scenario accounts for the potential that surface sediments may be compositionally and texturally distinct from the subsurface.

  5. Deep Compaction Control of Sandy Soils

    NASA Astrophysics Data System (ADS)

    Bałachowski, Lech; Kurek, Norbert

    2015-02-01

    Vibroflotation, vibratory compaction, micro-blasting or heavy tamping are typical improvement methods for the cohesionless deposits of high thickness. The complex mechanism of deep soil compaction is related to void ratio decrease with grain rearrangements, lateral stress increase, prestressing effect of certain number of load cycles, water pressure dissipation, aging and other effects. Calibration chamber based interpretation of CPTU/DMT can be used to take into account vertical and horizontal stress and void ratio effects. Some examples of interpretation of soundings in pre-treated and compacted sands are given. Some acceptance criteria for compaction control are discussed. The improvement factors are analysed including the normalised approach based on the soil behaviour type index.

  6. Mitigation of Liquefaction in Sandy Soils Using Stone Columns

    NASA Astrophysics Data System (ADS)

    Selcuk, Levent; Kayabalı, Kamil

    2010-05-01

    Soil liquefaction is one of the leading causes of earthquake-induced damage to structures. Soil improvement methods provide effective solutions to reduce the risk of soil liquefaction. Thus, soil ground treatments are applied using various techniques. However, except for a few ground treatment methods, they generally require a high cost and a lot of time. Especially in order to prevent the risk of soil liquefaction, stone columns conctructed by vibro-systems (vibro-compaction, vibro-replacement) are one of the traditional geotechnical methods. The construction of stone columns not only enhances the ability of clean sand to drain excess pore water during an earthquake, but also increases the relative density of the soil. Thus, this application prevents the development of the excess pore water pressure in sand during earthquakes and keeps the pore pressure ratio below a certain value. This paper presents the stone column methods used against soil liquefaction in detail. At this stage, (a) the performances of the stone columns were investigated in different spacing and diameters of columns during past earthquakes, (b) recent studies about design and field applications of stone columns were presented, and (c) a new design method considering the relative density of soil and the capacity of drenage of columns were explained in sandy soil. Furthermore, with this new method, earthquake performances of the stone columns constructed at different areas were investigated before the 1989 Loma Prieta and the 1994 Northbridge earthquakes, as case histories of field applications, and design charts were compiled for suitable spacing and diameters of stone columns with consideration to the different sandy soil parameters and earhquake conditions. Key Words: Soil improvement, stone column, excess pore water pressure

  7. The evolution of sandy soils under the influence of vegetation succession and anthropogenic activities - case study from Błędów Desert

    NASA Astrophysics Data System (ADS)

    Gus, Magdalena; Drewnik, Marek

    2016-04-01

    Sandy areas are an important source of research about early stages of the soils formation process and their further development. The rate of succession is reflecting the influence of vegetation on chemical and physical properties of soils which as the time goes undergo the evolution process caused by other environmental factors. The Błędów Desert (Poland, Central Europe) is an example of this kind of area, where sandy soils evolved into Podzols, but as a result of human activities conducted since Middle Ages soil cover has been destroyed to bedrock. Currently progressing vegetation succession occurred in two ways: primary, which took place in areas covered by loose sand and secondary, in the areas with fossil soils. Presently the Błędów Desert is a suitable example to study soil changes in both cases mentioned above. The main aim of the study was to present diversity and characteristics of soils in The Błędów Desert in relation to their development stages and vegetation succession. During field studies soil profiles were described and selected for the detailed studies and soils samples were taken for laboratory analysis, including a determination of basic physical and chemical analysis as well as for micromorphological analysis (selected profiles). Podzols located near the boundary of the study area was selected as a reference soils. The results proved the complexity of the soil process formation, which strongly depends on the vegetation succession and human activities including human-induced aeolian processes. Results confirmed the presence of buried soils, which together with the contemporary soils formed a soil sequence. Moreover, research shows that the dominant soil-forming processes at the Błędów Desert are humus accumulation and podzolization. To summarize, The Błędów Desert is a dynamic environment undergoing rapid changes of soil cover under the influence of the interaction of vegetation, anthropopression and aeolian processes.

  8. Effects of leachate on geotechnical characteristics of sandy clay soil

    NASA Astrophysics Data System (ADS)

    Harun, N. S.; Ali, Z. Rahman; Rahim, A. S.; Lihan, T.; Idris, R. M. W.

    2013-11-01

    Leachate is a hazardous liquid that poses negative impacts if leaks out into environments such as soil and ground water systems. The impact of leachate on the downgraded quality in terms of chemical characteristic is more concern rather than the physical or mechanical aspect. The effect of leachate on mechanical behaviour of contaminated soil is not well established and should be investigated. This paper presents the preliminary results of the effects of leachate on the Atterberg limit, compaction and shear strength of leachate-contaminated soil. The contaminated soil samples were prepared by mixing the leachate at ratiosbetween 0% and 20% leachate contents with soil samples. Base soil used was residual soil originated from granitic rock and classified as sandy clay soil (CS). Its specific gravity ranged between 2.5 and 2.64 with clay minerals of kaolinite, muscovite and quartz. The field strength of the studied soil ranged between 156 and 207 kN/m2. The effects of leachate on the Atterberg limit clearly indicated by the decrease in liquid and plastic limit values with the increase in the leachate content. Compaction tests on leachate-contaminated soil caused the dropped in maximum dry density, ρdry and increased in optimum moisture content, wopt when the amount of leachate was increased between 0% and 20%. The results suggested that leachate contamination capable to modify some geotechnical properties of the studied residual soils.

  9. Sandy inland braidplain deposition with local aeolian sedimentation in the lower and middle parts of the buntsandstein and sandy coastal braidplain deposition in the topmost zechstein in the sudetes (Lower Silesia, Poland)

    NASA Astrophysics Data System (ADS)

    Mroczkowski, Jerzy; Mader, Detlef

    The lower and middle parts of the Buntsandstein between Röt and Zechstein in the Sudetes (Lower Silesia, Poland) crop out in the marginal seams of the North Sudetic Trough and the Intra Sudetic Trough. The continental red beds originate in predominantly sandy braided river systems of an extensive inland alluvial plain in almost arid climate. The sediments are laid down in channels and floodplains of a moderately- to highly-braided, sandy to pebbly stream complex consisting of narrowly- to moderately-spaced low-sinuosity watercourses and narrow to wide overbank plains between the channels. Rapid aggradation and abandonment, quick lateral migration or high avulsion rates of the considerably mobile streams result in effective combing of the interchannel areas. Persistent high-energy overspilling of watercourse banks and invasion of bed-load-saturated flood surges into the overbank areas often lead to primary restriction or even suppression of formation of topstratum suspension fines. Secondarily, the silty-clayey and fine sandy overbank sediments which could occasionally originate in remote or sheltered lakes and ponds are frequently completely reworked by considerable lateral and vertical erosion during sidewards displacement of the rivers. As a result of both primary-depositional restriction and secondary-erosional removal of floodplain fines, the channel sediments are commonly stacked upon each other to multistorey stream sand complexes. Emergence and desiccation of parts of the alluvial plain sometimes give rise to aeolian deflation and accumulation of the winnowed sand to small dunelets and wind ripple trains. The aeolian depositional environment representing a more peripheral erg facies with sheet sand interdune milieu could not be fully ascertained due to poor outcrop conditions, but is likely to occur locally in view of comparative interpretation with other mixed dune and river sand sequences in the Mid-European Buntsandstein. Variations of fluvial style are

  10. Aeolian nutrient fluxes following wildfire in sagebrush steppe: Implications for soil carbon storage

    USGS Publications Warehouse

    Hasselquist, N.J.; Germino, M.J.; Sankey, J.B.; Ingram, L.J.; Glenn, N.F.

    2011-01-01

    Pulses of aeolian transport following fire can profoundly affect the biogeochemical cycling of nutrients in semi-arid and arid ecosystems. Our objective was to determine horizontal nutrient fluxes occurring in the saltation zone during an episodic pulse of aeolian transport that occurred following a wildfire in a semi-arid sagebrush steppe ecosystem in southern Idaho, USA. We also examined how temporal trends in nutrient fluxes were affected by changes in particle sizes of eroded mass as well as nutrient concentrations associated with different particle size classes. In the burned area, total carbon (C) and nitrogen (N) fluxes were as high as 235 g C m????'1 d????'1 and 19 g N m????'1 d????'1 during the first few months following fire, whereas C and N fluxes were negligible in an adjacent unburned area throughout the study. Temporal variation in C and N fluxes following fire was largely attributable to the redistribution of saltation-sized particles. Total N and organic C concentrations in the soil surface were significantly lower in the burned relative to the unburned area one year after fire. Our results show how an episodic pulse of aeolian transport following fire can affect the spatial distribution of soil C and N, which, in turn, can have important implications for soil C storage. These findings demonstrate how an ecological disturbance can exacerbate a geomorphic process and highlight the need for further research to better understand the role aeolian transport plays in the biogeochemical cycling of C and N in recently burned landscapes. ?? Author(s) 2011. CC Attribution 3.0 License.

  11. Sugarcane yields and soil chemical properties due to mill mud application to a sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mill mud is a potentially beneficial by-product from the sugar milling process. An experiment was conducted to assess sugarcane yield and nutrient movement into subs after mill mud application in sandy soil. Treatments consisted of fertilizer (low fertilizer (LF) and adequate fertilizer (AF)), and m...

  12. Phosphorus leaching from biosolids-amended sandy soils.

    PubMed

    Elliott, H A; O'Connor, G A; Brinton, S

    2002-01-01

    Increasing emphasis on phosphorus (P)-based nutrient management underscores the need to understand P behavior in soils amended with biosolids and manures. Laboratory and greenhouse column studies characterized P forms and leachability of eight biosolids products, chicken manure (CM), and commercial fertilizer (triple superphosphate, TSP). Bahiagrass (Paspalum notatum Flugge) was grown for 4 mo on two acid, P-deficient Florida sands, representing both moderate (Candler series: hyperthermic, uncoated Typic Quartzipsamments) and very low (Immokalee series: sandy, siliceous, hyperthermic Arenic Alaquods) P-sorbing capacities. Amendments were applied at 56 and 224 kg P(T) ha(-1), simulating P-based and N-based nutrient loadings, respectively. Column leachate P was dominantly inorganic and lower for biosolids P sources than TSP. For Candler soil, only TSP at the high P rate exhibited P leaching statistically greater (alpha = 0.05) than control (soil-only) columns. For the high P rate and low P-sorbing Immokalee soil, TSP and CM leached 21 and 3.0% of applied P, respectively. Leachate P for six biosolids was <1.0% of applied P and not statistically different from controls. Largo biosolids, generated from a biological P removal process, exhibited significantly greater leachate P in both cake and pelletized forms (11 and 2.5% of applied P, respectively) than other biosolids. Biosolids P leaching was correlated to the phosphorus saturation index (PSI = [Pox]/[Al(ox) + Fe(ox)]) based on oxalate extraction of the pre-applied biosolids. For hiosolids with PSI < or = approximately 1.1, no appreciable leaching occurred. Only Largo cake (PSI = 1.4) and pellets (PSI = 1.3) exhibited P leaching losses statistically greater than controls. The biosolids PSI appears useful for identifying biosolids with potential to enrich drainage P when applied to low P-sorbing soils. PMID:11931462

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

    PubMed

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

    2009-08-01

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

  14. The accretion of aeolian dust in soils of the San Juan Mountains, Colorado, USA

    NASA Astrophysics Data System (ADS)

    Lawrence, Corey R.; Neff, Jason C.; Farmer, G. Lang

    2011-06-01

    Recent observations suggest a contemporary aeolian dust flux of at least 5-10 g m-2 yr-1 to high-elevation ecosystems of the San Juan Mountains of southwestern Colorado. To better quantify the influence of dust on San Juan soil geochemistry, we used Sr and Nd isotopic mixing models to estimate the total mass of accreted dust in soils of two alpine basins underlain by bedrocks of different geochemical composition. In order to minimize the potentially confounding effects caused by transient soil pools of Sr and Nd, we implemented a sequential leaching procedure that isolates the residual mineral fraction of soils and their putative parent materials, including local saprolite and exogenous dust inputs. Using this approach, we calculated masses of accreted dust in soils, which were similar across the two isotopic tracers and differing local geologies. Long-term rates of dust accretion were estimated to be slightly higher than contemporary rates of dust deposition. We conclude that dust inputs comprise from 10% to 40% of the total soil mass in these ecosystems. Our observations suggest that dust inputs have exerted a primary control on soil development in the San Juan Mountains and have likely influenced the physical and chemical characteristics of soils in this region.

  15. Morphology of Rain Water Channeling in Systematically Varied Model Sandy Soils

    NASA Astrophysics Data System (ADS)

    Wei, Yuli; Cejas, Cesare M.; Barrois, Rémi; Dreyfus, Rémi; Durian, Douglas J.

    2014-10-01

    We visualize the formation of fingered flow in dry model sandy soils under different rain conditions using a quasi-2D experimental setup and systematically determine the impact of the soil grain diameter and surface wetting properties on the water channeling phenomenon. The model sandy soils we use are random closely packed glass beads with varied diameters and surface treatments. For hydrophilic sandy soils, our experiments show that rain water infiltrates a shallow top layer of soil and creates a horizontal water wetting front that grows downward homogeneously until instabilities occur to form fingered flows. For hydrophobic sandy soils, in contrast, we observe that rain water ponds on the top of the soil surface until the hydraulic pressure is strong enough to overcome the capillary repellency of soil and create narrow water channels that penetrate the soil packing. Varying the raindrop impinging speed has little influence on water channel formation. However, varying the rain rate causes significant changes in the water infiltration depth, water channel width, and water channel separation. At a fixed rain condition, we combine the effects of the grain diameter and surface hydrophobicity into a single parameter and determine its influence on the water infiltration depth, water channel width, and water channel separation. We also demonstrate the efficiency of several soil water improvement methods that relate to the rain water channeling phenomenon, including prewetting sandy soils at different levels before rainfall, modifying soil surface flatness, and applying superabsorbent hydrogel particles as soil modifiers.

  16. Effect of hydrocarbon pollution on the microbial properties of a sandy and a clay soil.

    PubMed

    Labud, Valeria; Garcia, Carlos; Hernandez, Teresa

    2007-01-01

    The aim of this work was to ascertain the effects of different types of hydrocarbon pollution on soil microbial properties and the influence of a soil's characteristics on these effects. For this, toxicity bioassays and microbiological and biochemical parameters were studied in two soils (one sandy and one clayey) contaminated at a loading rate of 5% and 10% with three types of hydrocarbon (diesel oil, gasoline and crude petroleum) differing in their volatilisation potential and toxic substance content. Soils were maintained under controlled conditions (50-70% water holding capacity, and room temperature) for six months and several microbiological and toxicity parameters were monitored 1, 60, 120 and 180 days after contamination. The toxic effects of hydrocarbon contamination were greater in the sandy soil. Hydrocarbons inhibited microbial biomass, the greatest negative effect being observed in the gasoline-polluted sandy soil. In both soils crude petroleum and diesel oil contamination increased microbial respiration, while gasoline had little effect on this parameter, especially in the sandy soil. In general, gasoline had the highest inhibitory effect on the hydrolase activities involved in N, P or C cycles in both soils. All contaminants inhibited hydrolase activities in the sandy soil, while in the clayey soil diesel oil stimulated enzyme activity, particularly at the higher concentration. In both soils, a phytotoxic effect on barley and ryegrass seed germination was observed in the contaminated soils, particularly in those contaminated with diesel or petroleum. PMID:17083964

  17. Modification of sandy soil hydrophysical environment through bagasse additive under laboratory experiment

    NASA Astrophysics Data System (ADS)

    Abd El-Halim, A. A.; Kumlung, Arunsiri

    2015-01-01

    Until now sandy soils can be considered as one roup having common hydrophysical problems. Therefore, a laboratory experiment was conducted to evaluate the influence of bagasse as an amendment to improve hydrophysical properties of sandy soil, through the determination of bulk density, aggregatesize distribution, total porosity, hydraulic conductivity, pore-space structure and water retention. To fulfil this objective, sandy soils were amended with bagasse at the rate of 0, 0.5, 1, 2, 3 and 4% on the dry weight basis. The study results demonstrated that the addition of bagasse to sandy soils in between 3 to 4% on the dry weight basis led to a significant decrease in bulk density, hydraulic conductivity, and rapid-drainable pores, and increase in the total porosity, water-holding pores, fine capillary pores, water retained at field capacity, wilting point, and soil available water as compared with the control treatment

  18. Effects of Pisha sandstone content on solute transport in a sandy soil.

    PubMed

    Zhen, Qing; Zheng, Jiyong; He, Honghua; Han, Fengpeng; Zhang, Xingchang

    2016-02-01

    In sandy soil, water, nutrients and even pollutants are easily leaching to deeper layers. The objective of this study was to assess the effects of Pisha sandstone on soil solute transport in a sandy soil. The miscible displacement technique was used to obtain breakthrough curves (BTCs) of Br(-) as an inert non-adsorbed tracer and Na(+) as an adsorbed tracer. The incorporation of Pisha sandstone into sandy soil was able to prevent the early breakthrough of both tracers by decreasing the saturated hydraulic conductivity compared to the controlled sandy soil column, and the impeding effects increased with Pisha sandstone content. The BTCs of Br(-) were accurately described by both the convection-dispersion equation (CDE) and the two-region model (T-R), and the T-R model fitted the experimental data slightly better than the CDE. The two-site nonequilibrium model (T-S) accurately fit the Na(+) transport data. Pisha sandstone impeded the breakthrough of Na(+) not only by decreasing the saturated hydraulic conductivity but also by increasing the adsorption capacity of the soil. The measured CEC values of Pisha sandstone were up to 11 times larger than those of the sandy soil. The retardation factors (R) determined by the T-S model increased with increasing Pisha sandstone content, and the partition coefficient (K(d)) showed a similar trend to R. According to the results of this study, Pisha sandstone can successfully impede solute transport in a sandy soil column. PMID:26598989

  19. Relationships between hydric soil indicators and wetland hydrology for sandy soils in Florida. Final report

    SciTech Connect

    Segal, D.S.; Sprecher, S.W.; Watts, F.C.

    1995-02-01

    Several alternative lists of hydric soil indicators have been proposed for use in delineating jurisdictional wetlands in the sandy landscapes of the southeast coastal plain. Because the issue is so recent, very little quantitative research has been conducted to test the validity of these alternative lists. Presence of various hydric soil indicators from four different hydric soil lists was compared with 3 to 5 years of shallow water well data along 14 wetland transects in peninsular Florida. Lists of indicators recently proposed by the USDA Soil Conservation Service were an improvement to the list of hydric soil indicators currently mandated in the Corps of Engineers 1987 and 1989 Wetlands Delineation Manuals. Wetland hydrology and morphological indicators of sandy hydric soils were compared at 58 sites along 14 transects in Florida. The best correspondence between hydrology and soil morphology was found for accumulation of muck on the soil surface and sulfur smell. Poorest correspondence was found for subsoil mineral horizon features such as organic accretions, thick dark A horizon, wet spodosol, and vertical streaking.

  20. Trade-offs between soil hydrology and plant disease effects after biochar amendment in sandy soil

    NASA Astrophysics Data System (ADS)

    Verheijen, Frank; Silva, Flavio; Amaro, Antonio; Pinto, Gloria; Mesquita, Raquel; Jesus, Claudia; Alves, Artur; Keizer, Jacob

    2015-04-01

    Biochar can affect multiple soil-based ecosystem services to varying extents, leading to trade-offs. Improvements in plant-available water have predominantly been found at high biochar application rates in sandy soils. Reductions in plant diseases after biochar application have been found in various horticultural plants, and trees such as maple and oak, mostly at relatively low biochar application rates. Serious damage to Eucalyptus globulus has been reported since 1999 when frequent and severe defoliation of young trees was observed, and eucalypts are the major tree species in commercial forestry plantations of Portugal, forming an important economic activity. Here we investigated simultaneous effects on plant available water and on disease suppression of eucalypt, in a completely randomised full factorial greenhouse pot experiment, using a range of woody feedstock biochar concentrations in sandy soil. Treatments included plant inoculation with the fungus Neofusicoccum kwambonambiense and cycles of acute drought stress. Preliminary results showed delayed wilting for plants treated with 3-6% biochar, but also increased stem lesion length. These results suggest a trade-off between effects on water availability and disease for Eucalyptus globulus plants in the selected sandy soil amended with this specific biochar, at the selected application rates.

  1. Photolysis degradation of polyaromatic hydrocarbons (PAHs) on surface sandy soil.

    PubMed

    El-Saeid, Mohamed H; Al-Turki, Ali M; Nadeem, Mahmoud E A; Hassanin, Ashraf S; Al-Wabel, Mohamed I

    2015-07-01

    Polycyclic aromatic hydrocarbons (PAHs) are potent environmental pollutants, and some of them have been identified as carcinogenic and mutagenic. To advance the knowledge of the environmental fate of PAHs, we systematically investigated the influence of different UV wavelengths irradiation on photolysis of PAHs on sandy soil under tow wavelengths (254 and 306 nm) UV irradiation for six PAHs. In addition, kinetic model and influence of several parameters on PAHs photolysis have been studied. The results obtained indicated that UV radiation with a wavelength of 306 nm was more efficient in the photolysis of the polycyclic aromatic hydrocarbons. Our results showed that fluoranthene (Flt) was the fastest in decomposition, has the greatest value for the coefficient of photolysis (7.4 × 10(-3) h(-1)), and has less half-life, reaching 94 h when using a wavelength of 254 nm. The results indicated that the pyrene (Pyr) was more resistant to photolysis in comparison with indeno(1,2,3-cd) pyrene (IP) and fluoranthene (Flt). The results indicate that photolysis is a successful way to remediate the six studied PAHs compounds. PMID:25586619

  2. Sugarcane response to mill mud, fertilizer, and soybean nutrient sources on a sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improving soil organic matter and soil fertility are important factors in the sustainability of sugarcane (Saccharum spp.) production. A 3-year field trial was established in 2004 on a sandy soil in Florida to compare the effect of organic and inorganic nutrient sources on sugarcane production. Th...

  3. Effect of increasing biochar application rate on soil hydraulic properties of an artificial sandy soil

    NASA Astrophysics Data System (ADS)

    Lopez, V.; Ghezzehei, T. A.

    2013-12-01

    Biochar, a product of the pyrolysis of biomass, has become an increasingly studied subject of interest as an agricultural soil amendment to address issues of carbon emission, population density, and food scarcity. Biochar has been reported to increase content and retention of nutrients, pH, cation-exchange capacity, vegetative growth, microbial community, and carbon sequestration. A number of studies addressing the usefulness of biochar as a soil amendment have focused on chemical and biological properties, disregarding the effects on soil physical properties of amended soil. Aside from biochar, lime (calcium carbonate) addition to soils has also been utilized in agricultural practices, typically to raise the pH value of acidic soils, increase microbial activity, and enhance soil stability and productivity as a result. Both biochar and lime amendments may be beneficial in increasing the soil physical properties, particularly through the formation of aggregates. In previous studies an increase in soil particle aggregates resulted in higher rates of biological activity, infiltration rates, pore space, and aeration, all of which are a measure of soil quality. While the effectiveness of biochar and lime as soil amendments has been independently documented, their combined effectiveness on soil physical properties is less understood. This study aims to provide a further understanding on the effect of increasing biochar application rate on soil particle aggregation and hydraulic properties of a low reactive pre-limed artificial sandy soil with and without microbial communities. Microbial communities are known to increase soil aggregates by acting as cementing agents. Understanding the impact of biochar addition on soil physical properties will have implications in the development of sustainable agricultural practices, especially in systems undergoing climate stress and intensive agriculture.

  4. Microbial community composition as affected by dryland cropping systems and tillage in a semiarid sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated microbial communities of soil (0-10 cm) as affected by dryland cropping systems under different tillage practices after 5 years. The soil is an Olton sandy loam (Fine, mixed, superactive, thermic Aridic Paleustolls) with an average of 16.4% clay, 67.6% sand and 0.65 g kg-1 of O...

  5. Organic amendment effects on the transformation and fractionation of aluminum in acidic sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was attempted to evaluate the transformation of aluminum (Al) in an acidic sandy soil amended with composts (yard waste, yard + municipal waste, GreenEdge®, and synthetic humic acid), based on soil Al fractionation by single and sequential extraction. The compost amendment significantly i...

  6. Responses of Enzyme Activities in Sandy Soils to Cropping System Changes in a Semiarid Region

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sandy soils in the semi-arid Southern High Plains of the United States are inherently low organic matter, and when agricultural practices such as intensively tilled, low-residue cropping (e.g., monoculture cotton) are practiced, soil of organic matter becomes further depleted. Although alternative ...

  7. Aeolian sands and buried soils in the Mecklenburg Lake District, NE Germany: Holocene land-use history and pedo-geomorphic response

    NASA Astrophysics Data System (ADS)

    Küster, Mathias; Fülling, Alexander; Kaiser, Knut; Ulrich, Jens

    2014-04-01

    The present study is a pedo-geomorphic approach to reconstructing Holocene aeolian sand dynamics in the Mecklenburg Lake District (NE Germany). Stratigraphical, sedimentological and soil research supplemented by morphogenetic interpretations of the genesis of dunes and aeolian sands are discussed. A complex Late Holocene aeolian stratigraphy within a drift sand area was developed at the shore of Lake Müritz. The results were confirmed using palynological records, archaeological data and regional history. Accelerated aeolian activity was triggered by the intensification of settlement and land-use activities during the 13th and in the 15th to 16th century AD. After a period of stability beginning with population decline during the ‘Thirty Years War' and continuing through the 18th century, a final aeolian phase due to the establishment of glassworks was identified during the 19th century AD. We assume a direct link between Holocene aeolian dynamics and human activities. Prehistoric Holocene drift sands on terrestrial sites have not been documented in the Mecklenburg Lake District so far. This might be explained either by erosion and incorporation of older aeolian sediments during younger aeolian phases and/or a lower regional land-use intensity in older periods of the Holocene. The investigated drift sands are stratigraphically and sedimentologically characterised by a high degree of heterogeneity, reflecting the spatial and temporal variability of Holocene human impact.

  8. Effect of Plant-derived Hydrophobic Compounds on Soil Water Repellency in Dutch Sandy Soils

    NASA Astrophysics Data System (ADS)

    Mao, Jiefei; Dekker, Stefan C.; Nierop, Klaas G. J.

    2013-04-01

    Soil water repellency or hydrophobicity is a common and important soil property, which may diminish plant growth and promotes soil erosion leading to environmentally undesired situations. Hydrophobic organic compounds in the soil are derived from vegetation (leaves, roots, mosses) or microorganisms (fungi, bacteria), and these compounds induce soil water repellency (SWR) and can be called SWR-biomarkers. As common hydrophobic constituents of organic matter, plant lipids are mainly from wax layers of leaves and roots, whereas cutins and suberins as aliphatic biopolyesters occur in leaves and roots, respectively. Their unique compositions in soil can indicate the original vegetation sources. To investigate the individual or combined effects of the hydrophobic compounds on SWR and their possible associations with each other, we conducted experiments to analyse the organic composition of Dutch coastal dune sandy soils in relation to SWR. DCM/MeOH solvent is used to remove solvent soluble lipids. BF3-methanol is utilized to depolymerize cutins and suberins from isopropanol/NH3 extractable organic matter. Total organic carbon (TOC) has a positive linear relation with SWR only for those soils containing low TOC (

  9. Effects of sodium polyacrylate on water retention and infiltration capacity of a sandy soil.

    PubMed

    Zhuang, Wenhua; Li, Longguo; Liu, Chao

    2013-01-01

    Based on the laboratory study, the effects of sodium polyacrylate (SP) was investigated at 5 rates of 0, 0.08, 0.2, 0.5, and 1%, on water retention, saturated hydraulic conductivity(Ks), infiltration characteristic and water distribution profiles of a sandy soil. The results showed that water retention and available water capacity effectively increased with increasing SP rate. The Ks and the rate of wetting front advance and infiltration under certain pond infiltration was significantly reduced by increasing SP rate, which effectively reduced water in a sandy soil leaking to a deeper layer under the plough layer. The effect of SP on water distribution was obviously to the up layer and very little to the following deeper layers. Considering both the effects on water retention and infiltration capacity, it is suggested that SP be used to the sandy soil at concentrations ranging from 0.2 to 0.5%. PMID:24701379

  10. [Monitoring of water and salt transport in silt and sandy soil during the leaching process].

    PubMed

    Fu, Teng-Fei; Jia, Yong-Gang; Guo, Lei; Liu, Xiao-Lei

    2012-11-01

    Water and salt transport in soil and its mechanism is the key point of the saline soil research. The dynamic rule of water and transport in soil during the leaching process is the theoretical basis of formation, flush, drainage and improvement of saline soil. In this study, a vertical infiltration experiment was conducted to monitor the variation in the resistivity of silt and sandy soil during the leaching process by the self-designed automatic monitoring device. The experimental results showed that the peaks in the resistivity of the two soils went down and faded away in the course of leaching. It took about 30 minutes for sandy soil to reach the water-salt balance, whereas the silt took about 70 minutes. With the increasing leaching times, the desalination depth remained basically the same, being 35 cm for sandy soil and 10 cm for the silt from the top to bottom of soil column. Therefore, 3 and 7 leaching processes were required respectively for the complete desalination of the soil column. The temporal and spatial resolution of this monitoring device can be adjusted according to the practical demand. This device can not only achieve the remote, in situ and dynamic monitoring data of water and salt transport, but also provide an effective method in monitoring, assessment and early warning of salinization. PMID:23323426

  11. 26Al/10Be dating of an aeolian dust mantle soil in western New South Wales, Australia

    NASA Astrophysics Data System (ADS)

    Fisher, Adrian; Fink, David; Chappell, John; Melville, Michael

    2014-08-01

    Aeolian dust mantle soils are an important element of many landscapes in south-eastern Australia, though the age of these aeolian deposits has not been radiometrically determined. At Fowlers Gap in western New South Wales, surface cobbles of silcrete and quartz overlie a stone-free, aeolian dust mantle soil, which has a thickness of about 1.6 m. The clay-rich aeolian dust deposit in turn lies upon a buried silcrete and quartz stone layer. Modelling in-situ cosmogenic 26Al and 10Be concentrations measured in both the surface quartz stones and in the buried quartz layer of rocks, reveals that each has experienced a complex exposure-burial history. Due to the absence of quartz stones or sand at intermediate depths, our cosmogenic 26Al and 10Be modelling was not able to determine a definitive mechanism of stone pavement formation and stone burial. Various scenarios of stone formation, transport, burial and exhumation were tested that constrain the age of the deposit to range from 0.9 ± 0.2 Ma to 1.8 ± 0.2 Ma, based largely on different assumptions taken for the time-dependency of the net sedimentation rate. This corresponds with the initiation of the Simpson Desert dune fields and the deflation of lakes in central Australia, which probably responded to the shift to longer-wavelength, larger-amplitude Quaternary glacial cycles at around 1 Ma. Sensitivity analyses were carried out to identify those parameters which better constrained model outputs. Within model errors, which largely are the result of analytical errors in measured 26Al and 10Be concentrations, all three competing theories of colluvial wash, upward displacement of stones, and cumulic pedogenesis are possible mechanisms for the formation of the surface stone pavement.

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    Coastal dune landscapes are very dynamic. The present distribution of vegetation and soil is the result of over 2000 years of natural processes and human management. The initial soil development was controlled by an increase of the organic matter content, which consisted mainly of decomposed roots of grasses (rhizomull), and a decrease of the soil pH to 3-4 by decalcification. This stage was followed by the development of a deciduous forest, which was dominated by Quercus robur. Since 1600 AD, a large part of the deciduous forest that dominated the east side of the coastal dune landscape transferred in expensive residential areas and urbanizations. Nevertheless some parts of the oak forest belt remained. The present forest soils are acid and the controlling soil processes are leaching of sesquioxides and storage of organic matter in mormoder humus forms. The sustainability of ecosystems is closely related to the quality of the humus form, controlling nutrient cycling and water supply. Therefore, improve of knowledge of humus form development and properties is important. We applied soil micromorphology and pyrolysis-gas chromatography/mass spectrometry (GC/MS) to investigate more details of humus form development at two locations (Duivendrift and Hoek van Klaas) in the coastal dune area of the Amsterdamse Waterleidingduinen (near Haarlem, the Netherlands). However, to understand forest soil development, including the organic matter composition in the humus form, the age of the substrate and the forest is required. Therefore, we used tradition techniques as pollen analysis and radiocarbon dating but also the recently introduced optical stimulated luminescence (OSL) dating technique. OSL dating works excellent for aeolian sandy deposits with a high percentage of quartz grains. The OSL age is defined as the time after the last bleaching by solar radiation of mineral grains. Or in other words, the start of a stable period without sand drifting. In the Ah horizons we

  13. SOIL AND HYDROLOGY OF A WET-SANDY CATENA IN EAST-CENTRAL MINNESOTA

    EPA Science Inventory

    Sail properties are strongly related to the retention and movement of water within the soil system. The purposes of this study were to document the near-surface hydrology of a wetland-upland hillslope on a sandy glacial outwash plain in east-central Minnesota and to describe the ...

  14. Yield and growth characteristics for cotton under various irrigation regimes on sandy soil.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An irrigation experiment was set up to apply water to cotton at six different rates ranging from 33% to 144% of normal, with hopes of identifying the regime that produces maximum yield. Two cultivars, Acala Maxxa and Acala PhytoGen-72 were planted on sandy soil and irrigated daily with a highly effi...

  15. Effect of soil coarseness on soil base cations and available micronutrients in a semi-arid sandy grassland

    NASA Astrophysics Data System (ADS)

    Lü, Linyou; Wang, Ruzhen; Liu, Heyong; Yin, Jinfei; Xiao, Jiangtao; Wang, Zhengwen; Zhao, Yan; Yu, Guoqing; Han, Xingguo; Jiang, Yong

    2016-04-01

    Soil coarseness is the main process decreasing soil organic matter and threatening the productivity of sandy grasslands. Previous studies demonstrated negative effect of soil coarseness on soil carbon storage, but less is known about how soil base cations (exchangeable Ca, Mg, K, and Na) and available micronutrients (available Fe, Mn, Cu, and Zn) response to soil coarseness. In a semi-arid grassland of Northern China, a field experiment was initiated in 2011 to mimic the effect of soil coarseness on soil base cations and available micronutrients by mixing soil with different mass proportions of sand: 0 % coarse elements (C0), 10 % (C10), 30 % (C30), 50 % (C50), and 70 % (C70). Soil coarseness significantly increased soil pH in three soil depths of 0-10, 10-20 and 20-40 cm with the highest pH values detected in C50 and C70 treatments. Soil fine particles (smaller than 0.25 mm) significantly decreased with the degree of soil coarseness. Exchangeable Ca and Mg concentrations significantly decreased with soil coarseness degree by up to 29.8 % (in C70) and 47.5 % (in C70), respectively, across three soil depths. Soil available Fe, Mn, and Cu significantly decreased with soil coarseness degree by 62.5, 45.4, and 44.4 %, respectively. As affected by soil coarseness, the increase of soil pH, decrease of soil fine particles (including clay), and decline in soil organic matter were the main driving factors for the decrease of exchangeable base cations (except K) and available micronutrients (except Zn) through soil profile. Developed under soil coarseness, the loss and redistribution of base cations and available micronutrients along soil depths might pose a threat to ecosystem productivity of this sandy grassland.

  16. Temporal stability of electrical conductivity in a sandy soil

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Understanding of soil spatial variability is needed to delimit areas for precision agriculture. Electromagnetic induction sensors which measure the soil apparent electrical conductivity reflect soil spatial variability. The objectives of this work were to see if a temporally stable component could be found in electrical conductivity, and to see if temporal stability information acquired from several electrical conductivity surveys could be used to better interpret the results of concurrent surveys of electrical conductivity and soil water content. The experimental work was performed in a commercial rainfed olive grove of 6.7 ha in the `La Manga' catchment in SW Spain. Several soil surveys provided gravimetric soil water content and electrical conductivity data. Soil electrical conductivity values were used to spatially delimit three areas in the grove, based on the first principal component, which represented the time-stable dominant spatial electrical conductivity pattern and explained 86% of the total electrical conductivity variance. Significant differences in clay, stone and soil water contents were detected between the three areas. Relationships between electrical conductivity and soil water content were modelled with an exponential model. Parameters from the model showed a strong effect of the first principal component on the relationship between soil water content and electrical conductivity. Overall temporal stability of electrical conductivity reflects soil properties and manifests itself in spatial patterns of soil water content.

  17. Biochar and Mill Ash Use as Soil Amendments to Grow Sugarcane in Sandy Soils of South Florida

    NASA Astrophysics Data System (ADS)

    Alvarez-Campos, O.; Lang, T. A.; Bhadha, J. H.; McCray, M.; Gao, B.; Glaz, B.; Daroub, S. H.

    2015-12-01

    The use of agricultural and urban organic residues as amendments provides an option to improve sugarcane production in sandy soils located northwest of the Everglades Agricultural Area, while reducing waste. This study was conducted to determine the effect of mill ash and three biochars on sugarcane yield and sandy soil properties. Mill ash and biochars produced from hardwood yard waste (HY), barn shavings with horse manure (HM), and rice hulls (RH) were incorporated at 1% and 2% (by weight) to sandy soils in a lysimeter experiment. A control without amendment and an often-used commercial practice of mill ash applied at 6% (AS6) were also included. Results showed that RH2 and AS6 produced greater biomass and sucrose yield compared with the control. According to critical nutrient level analysis, RH and AS amendments also resulted in the highest silicon content, which had a positive correlation with increasing sugarcane yield. In addition, RH2 and AS6 increased total phosphorus, Mehlich-3 phosphorus, and cation exchange capacity (CEC) compared with the control. While CEC remained constant with AS2 and AS6 applications, CEC significantly increased over time with RH2. Moreover, higher amendment applications increased soil organic matter compared with the control and did not decrease over time, which suggests a positive influence for long term carbon sustainability and nutrient cycling in sandy soils. Overall, RH2 and AS6 have the most potential to be used as amendments in sandy soils of South Florida due to their positive effects on soil properties, which improved sugarcane yield. However, no negative consequences were found with the application of any other amendment in terms of sugarcane growth and soil quality. Future research should focus on the use of RH and AS amendments on long-term field-scale studies, and the economic feasibility of a single year application on plant and ratoon cane yields.

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

    NASA Astrophysics Data System (ADS)

    Mabilde, Lisa

    2016-04-01

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

  19. Soil erosion rates by wind-driven rain from a sandy soil in Denmark

    NASA Astrophysics Data System (ADS)

    Fister, W.; Kuhn, N. J.; Itin, N.; Tesch, S.; Heckrath, G.; Ries, J. B.

    2012-04-01

    Soil erosion by wind and water is able to cause severe soil loss from agricultural fields. Laboratory studies in recent years have shown that wind most probably has an increasing effect on soil erosion rates by water. However, field studies have so far not been able to quantify and proof this assumption explicitly. Especially the differentiation between the influence of windless and wind-driven erosion seems to be the major issue. The objectives of this study were, therefore, to explicitly investigate the importance of wind-driven rain in relation to erosion rates without the effect of wind by applying a newly developed Portable Wind and Rainfall Simulator (PWRS) that is able to simulate the processes both separately and simultaneously. The PWRS was used on bare sandy soil near Viborg, Denmark. Prior to simulation the soil was ploughed and after consolidation harrowed to create surface structures and roughness representing typical conditions after seed bed preparation. To facilitate the separation of specific influences by wind-driven rain and to avoid systematic errors a defined order of four consecutive test runs was established: 0) single wind test run for 10 min, 1) single rainfall test run on dry soil, 2) single rainfall test run on moist soil, 3) simultaneous wind and rainfall test run (wind-driven rainfall). Each rainfall simulation lasted for 30 minutes with a 30 min break in between to allow for initial drainage of the soil and for remounting sediment catchers. By utilizing a gutter in combination with wedge-shaped sediment traps it was possible to separate between splash and runoff erosion from the 2.2 m2 plot. The results show a wide range of soil detachment raging from zero up to more than 500 g m-2 in 30 minutes. Five out of nine test sequences support the theory that wind-driven rain causes more erosion than windless rain. The relation between the two processes is therefore not as clear as expected and seems to be dominated by the natural variability

  20. Diversity of Microfungi in Sandy Beach Soil of Teluk Aling, Pulau Pinang

    PubMed Central

    Zakaria, Latiffah; Yee, Teh Li; Zakaria, Maziah; Salleh, Baharuddin

    2011-01-01

    A total of 82 isolates of microfungi were isolated from 6 sandy soil samples collected from Teluk Aling beach, Pulau Pinang. The soil microfungi were isolated by using direct isolation, debris isolation and soil dilution techniques. Based on morphological characteristics, seven genera of microfungi were identified namely, Fusarium (42%), Aspergillus (24%), Trichoderma (13%), Curvularia (9%), Colletotrichum (6%), Helminthosporium (4%) and Penicillium (2%). The most common species isolated was Fusarium solani followed by Fusarium semitecum, Aspergillus niger, Trichoderma viride, Curvularia clavata, Curvularia lunata, Helminthosporium velutinum, Colletotrichum sp. and Penicillium chrysogenum. From the present study, it appears that the sandy beach contains a microfungi reservoir comprising of a variety of genera which contributes significantly to the ecological functioning of a marine ecosystem. PMID:24575210

  1. Changes in physical properties of sandy soil after long-term compost treatment

    NASA Astrophysics Data System (ADS)

    Aranyos, József Tibor; Tomócsik, Attila; Makádi, Marianna; Mészáros, József; Blaskó, Lajos

    2016-07-01

    Studying the long-term effect of composted sewage sludge application on chemical, physical and biological properties of soil, an experiment was established in 2003 at the Research Institute of Nyíregyháza in Hungary. The applied compost was prepared from sewage sludge (40%), straw (25%), bentonite (5%) and rhyolite (30%). The compost was ploughed into the 0-25 cm soil layer every 3rd year in the following amounts: 0, 9, 18 and 27 Mg ha-1 of dry matter. As expected, the compost application improved the structure of sandy soil, which is related with an increase in the organic matter content of soil. The infiltration into soil was improved significantly, reducing the water erosion under simulated high intensity rainfall. The soil compaction level was reduced in the first year after compost re-treatment. In accordance with the decrease in bulk density, the air permeability of soil increased tendentially. However, in the second year the positive effects of compost application were observed only in the plots treated with the highest compost dose because of quick degradation of the organic matter. According to the results, the sewage sludge compost seems to be an effective soil improving material for acidic sandy soils, but the beneficial effect of application lasts only for two years.

  2. Investigation of the degradation of pentachlorophenol in sandy soil via low-temperature pyrolysis.

    PubMed

    Thuan, Ngo Thi; Chang, Moo Been

    2012-08-30

    Thermal treatments are the primary technologies used to simultaneously remove high-concentrations of pentachlorophenol (PCP) and polychlorinated dibenzo dioxins/furans (PCDD/Fs) from contaminated soils such as the An-Shun soil, Taiwan. However, the high cost of energy required and the potential formation of dioxins during the incineration/combustion of PCP have limited their applications. In this study, an investigation of PCP pyrolysis in sandy soil at a relatively low temperature range (200-400°C) was conducted. Temperature and heating time required to achieve the maximum removal efficiency of PCP and its byproducts from soil were investigated. Additionally, primary pathways leading to PCP removal from sandy soil were studied. The experimental results showed that a significant portion of PCP (>90%) and its byproducts were removed from the soil at 350°C with a treatment time of 40 min. The PCP decay rate constant increased exponentially from 0.20 min(-1) to 1.98 min(-1) as the operating temperature was increased from 200°C to 400°C. While pyrolysis and desorption are the main degradation pathways, detection of lower chlorinated phenols in the gas/soil indicates that dechlorination of PCP occurs during the degradation process. Low levels of PCDD/Fs were detected in the soil/gas during the pyrolysis of PCP-contaminated soils. PMID:22770752

  3. Late Pleistocene to early Holocene aeolian and flash-flood sedimentation and soil formation in a small hilly catchment in SW-Germany (Palatinate forest)

    NASA Astrophysics Data System (ADS)

    Dotterweich, M.; Kühn, P.; Tolksdorf, J. F.; Müller, S.; Nelle, O.

    2012-04-01

    This paper focuses on the dynamics of sedimentation processes and soil development in a steep slope 0-order catchment in the sandy Lower Bunter of the south-western mid-range mountains in Germany during the transition period from the late Glacial to the early Holocene. Italso discusses how late Palaeolithic gatherers and hunters may have influenced these processes by sedentary land occupation. The investigated dry valley covers an area of around 16.6 ha and is characterized by short and steep slopes of 30° to 60°. A significant amount of the sediments from the adjacent slopes had been captured along the wide and rather flat valley bottom and at the small outlet. Several exposures, pits, and percussion liner drillings revealed a weak to highly weathered reddish sandy material at the base and eight subsequent layers of incoherent sandy and charcoal (from pines) enriched sediments with different colours ranging from olive-brown to dull reddish brown. By stratigraphical means, the lowermost sediment can be ascribed to the early Lateglacial when the deposition of aeolian sands under cold conditions with scarce vegetation cover was a widespread phenomenon. The subsequent layer contains a higher amount of silt and dates into the Allerød as suggested by radiocarbon dating. This is corroborated by the occurrence of LST that indicate that these sediments have been near to the surface around 12,900 yr BP. It shows characteristics of a palaeosol with Bwb and BwAhb horizons (Brunic Arenosols dystric) and with greyish Ahb and Eb horizons (Albic Arenosols dystric) similar to the Usselo/Finow soils in north-eastern Germany. In the material above, many remnants of roots and organic particles and rounded bone fragments were revealed by micromorphological analyses. Then, an alternation of reddish brown coarse to fine sands and small, partly rounded stones with some small intercalate aggregations of humic material rich in charcoal which dates to around 10,000 yr BP were deposited

  4. Aeolian Coastal Landscapes in changes (a study from Tahkuna, Estonia)

    NASA Astrophysics Data System (ADS)

    Anderson, A.

    2012-04-01

    The openness of the coast to the winds and storm waves has an important part in changing aeolian coastal landscapes as well as anthropogenic factor. The aeolian coastal landscapes are probably the most dynamic areas. Occurrence of aeolian coastal landscapes in Estonia is limited. They consist of sandy beaches, sandy beach ridges and dunes. The coastal ecosystems are strongly affected by their topography, based on the character of deposits and moisture conditions. The majority of their ecosystems are quite close to the specific natural habitat. These ecosystems are represented in the list of the European Union Habitats (Natura 2000). In recent decades human influence has changed the landscape over time in different activities (recreation, trampling, off-road driving) and their intensities, which has led to destruction or degradation of various habitats. Previously coastal landscapes were used for forestry and pasture. Nowadays one of the most serious threats to open landscape is afforestation. This study examines the relationships between landscape components during last decades. Trying to find out how much aeolian coastal landscapes are influenced by natural processes or human activities. The results are based on cartographic analysis, fieldwork data. The method of landscape complex profile was used. The profiles show a cross-sections of landforms and interrelationships between landscape components, most frequently describing the relations between soils and vegetation. In each sample point the mechanical composition of sediments, vegetation cover and soil is determined. Results show that changes in landscapes are induced by their own development as well as changes in environmental factors and human activities. Larger changes are due to increase of coastal processes activity. These processes can be observed in sandy beaches, which are easily transformed by waves. Higher sea levels during storm surges are reaching older beach formation, causing erosion and creating

  5. Methane emissions from MSW landfill with sandy soil covers under leachate recirculation and subsurface irrigation

    NASA Astrophysics Data System (ADS)

    Zhang, Houhu; He, Pinjing; Shao, Liming

    CH 4 emissions and leachate disposal are recognized as the two major concerns in municipal solid waste (MSW) landfills. Recently, leachate recirculation was attempted to accelerate land-filled waste biodegradation and thus enhanced landfill gas generation. Leachate irrigation was also conducted for volume reduction effectively. Nevertheless, the impacts of leachate recirculation and irrigation on landfill CH 4 emissions have not been previously reported. A field investigation of landfill CH 4 emissions was conducted on selected sandy soil cover with leachate recirculation and subsurface irrigation based on whole year around measurement. The average CH 4 fluxes were 311±903, 207±516, and 565±1460 CH 4 m -2 h -1 from site A without leachate recirculation and subsurface irrigation, lift B2 with leachate subsurface irrigation, and lift B1 with both leachate recirculation and subsurface irrigation, respectively. Both gas recovery and cover soil oxidation minimized CH 4 emissions efficiently, while the later might be more pronounced when the location was more than 5 m away from gas recovery well. After covered by additional clay soil layer, CH 4 fluxes dropped by approximately 35 times in the following three seasons compared to the previous three seasons in lift B2. The diurnal peaks of CH 4 fluxes occurred mostly followed with air or soil temperature in the daytimes. The measured CH 4 fluxes were much lower than those of documented data from the landfills, indicating that the influences of leachate recirculation and subsurface irrigation on landfill CH 4 emissions might be minimized with the help of a well-designed sandy soil cover. Landfill cover composed of two soil layers (clay soil underneath and sandy soil above) is suggested as a low-cost and effective alternative to minimize CH 4 emissions.

  6. Nitrogen limitation and nitrogen fixation during alkane biodegradation in a sandy soil.

    PubMed Central

    Toccalino, P L; Johnson, R L; Boone, D R

    1993-01-01

    We investigated nutrient limitations during hydrocarbon degradation in a sandy soil and found that fixed nitrogen was initially a limiting nutrient but that N limitation could sometimes be overcome by N2 fixation. Hydrocarbon biodegradation was examined in an unsaturated sandy soil incubated aerobically at 20 degrees C with propane or butane and various added nutrients. Propane and butane degradation proceeded similarly during the first 3 months of incubation. That is, bacteria in soil amended with N oxidized these hydrocarbons more rapidly than in controls without nutrient additions or in soil with added phosphate or trace minerals. Both propane- and butane-amended soil apparently became N limited after the initial available inorganic N was utilized, as indicated by a decrease in the rates of hydrocarbon degradation. After 3 months, propane and butane degradation proceeded differently. Bacteria in propane-degrading soil apparently remained N limited because propane degradation rates stayed low unless more N was added. In contrast, bacteria in butane-degrading soil appeared to overcome their N limitation because butane degradation rates later increased regardless of whether more N was added. Analyses of total N and acetylene reduction assays supported this apparent surplus of N in butane-amended soil. Total N was significantly (P < 0.01) higher in soil incubated with butane and no N amendments than in soil incubated with propane, even when the latter was amended with N. Acetylene reduction occurred only in butane-amended soil. These results indicate that N2 fixation occurred in butane-amended soil but not in propane-amended soil. PMID:8215369

  7. Fine dust emissions in sandy and silty agricultural soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dust emissions from strong winds are common in arid and semi-arid regions and occur under both natural and managed land systems. A portable field wind tunnel has been developed to allow measurements of dust emissions from soil surfaces to test the premise that dust concentrations are highly correlat...

  8. Nitrogen limiation and nitrogen fixation during alkane biodegradation in a sandy soil

    SciTech Connect

    Toccalino, P.L.; Johnson, R.L.; Boone, D.R. )

    1993-09-01

    Leaking underground storage tanks are a significant source of petroleum hydrocarbon contamination in soils and ground water. Hydrocarbon biodegradation studies have been conducted in both ground water and topsoil regions, but few studies have been done on the unsaturated zone between these two. This study examines the effects of Nitrogen on propane and butane biodegradiations in an unsaturated sandy soil. Results indicate that nitrogen additions initially stimulated both propane and butane oxidizing organisms in the soil, but that propane-amended soil became N limited whereas butane-amended soil eventually overcame its N limitations by fixing Nitrogen and that nitrogen fixing organisms grew in butane amended but not in propane amended soil. 27 refs., 6 figs.

  9. Distribution of transformed organic matter in structural units of loamy sandy soddy-podzolic soil

    NASA Astrophysics Data System (ADS)

    Kogut, B. M.; Yashin, M. A.; Semenov, V. M.; Avdeeva, T. N.; Markina, L. G.; Lukin, S. M.; Tarasov, S. I.

    2016-01-01

    The effect of land use types and fertilizing systems on the structural and aggregate composition of loamy sandy soddy-podzolic soil and the quantitative parameters of soil organic matter has been studied. The contribution of soil aggregates 2-1 mm in size to the total Corg reserve in the humus horizon is higher than the contributions of other aggregates by 1.3-4.2 times. Reliable correlations have been revealed between the contents of total (Corg), labile (Clab), and active (C0) organic matter in the soil. The proportion of C0 is 44-70% of Clab extractable by neutral sodium pyrophosphate solution. The contributions of each of the 2-1, 0.5-0.25, and <0.25 mm fractions to the total C0 reserve are 14-21%; the contributions of each of the other fractions are 4-12%. The chemically labile and biologically active components of humic substances reflect the quality changes of soil organic matter under agrogenic impacts. A conceptual scheme has been proposed for the subdivision of soil organic matter into the active, slow (intermediate), and passive pools. In the humus horizon of loamy sandy soddy-podzolic soil, the active, slow, and passive pools contain 6-11, 34-65, and 26-94% of the total Corg, respectively.

  10. Character and provenance of aeolian sediments in northeast Thailand

    NASA Astrophysics Data System (ADS)

    Nichol, Janet E.; Nichol, Douglas W.

    2015-12-01

    Aeolian activity is not generally associated with the humid tropics, and although reports of loess-like soils in various locations in southeast Asia exist, these mainly lack the detailed analysis to set them in meaningful spatial or historical context. This paper examines the red and yellow sandy sediments of the Khorat Plateau in northeast Thailand which have been variously referred to as 'cover sands', 'loessial soils' or 'loess'. The sediments are referred to as having alluvial, biological as well as aeolian origin, and a date of 9-35 ka is reported. The study compares the Khorat sediments physically and geochemically with loess and aeolian sediments from other regions, as well as with other sites in southeast Asia which are reported here. The moderate degree of particle sorting and unimodal sizes of the sediments along with a sub-spherical sub-rounded form, supports previous diagnoses of an aeolian origin. Geochemical analysis of the Khorat sediments indicates severe depletion in both mobile and immobile elements, which are even more depleted than other southeast Asian loessic soils examined. This depletion, along with the only moderate particle sorting, suggests the source of the sediments to be the local weathered sandstones outcropping around the edge of the Khorat Plateau. The dissimilarity of the Khorat sediments from Upper Continental Crust (UCC) elemental values supports this, as homogenisation would occur if diverse source areas were involved. The study suggests that aeolian sediments of humid tropical regions warrant more attention as climate proxy markers, due to the dissimilarity between the present climate and conditions required for their formation.

  11. Uranium partitioning under acidic conditions in a sandy soil aquifer

    SciTech Connect

    Johnson, W.H. |; Serkiz, S.M.; Johnson, L.M.

    1995-07-01

    The partitioning of uranium in an aquifer down gradient of two large mixed waste sites was examined with respect to the solution and soil chemistry (e.g., pH redox potential and contaminant concentration) and aqueous-phase chemical speciation. This involved generation of field-derived, batch sorption, and reactive mineral surface sorption data. Field-derived distribution coefficients for uranium at these waste sites were found to vary between 0.40 and 15,000. Based on thermodynamic speciation modeling and a comparison of field and laboratory data, gibbsite is a potential reactive mineral surface present in modified soils at the sites. Uranium partitioning data are presented from field samples and laboratory studies of background soil and the mineral surface gibbsite. Mechanistic and empirical sorption models fit to the field-derived uranium partitioning data show an improvement of over two orders of magnitude, as measured by the normalized sum of errors squared, when compared with the single K{sub d} model used in previous risk work. Models fit to batch sorption data provided a better fit of sorbed uranium than do models fit to the field-derived data.

  12. Effects of vegetable oil residue after soil extraction on physical-chemical properties of sandy soil and plant growth.

    PubMed

    Gong, Zongqiang; Li, Peijun; Wilke, B M; Alef, Kassem

    2008-01-01

    Vegetable oil has the ability to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sandy soil for a remediation purpose, with some of the oil remaining in the soil. Although most of the PAHs were removed, the risk of residue oil in the soil was not known. The objective of this study was to evaluate the effects of the vegetable oil residue on higher plant growth and sandy soil properties after soil extraction for a better understanding of the soil remediation. Addition of sunflower oil and column experiment were performed on a PAH contaminated soil and/or a control soil, respectively. Soils were incubated for 90 d, and soil pH was measured during the soil incubation. Higher plant growth bioassays with Avena sativa L. (oat) and Brassica rapa L. (turnip) were performed after the incubation, and then soil organic carbon contents were measured. The results show that both the nutrient amendment and the sunflower oil degradation resulted in the decrease of soil pH. When these two process worked together, their effects were counteracted due to the consumption of the nutrients and oil removal, resulting in different pH profiles. Growth of A. sativa was adversely affected by the sunflower oil, and the nutrient amendments stimulated the A. sativa growth significantly. B. rapa was more sensitive to the sunflower oil than A. sativa. Only 1% sunflower oil addition plus nutrient amendment stimulated B. rapa growth. All the other treatments on B. rapa inhibited its growth significantly. The degradation of the sunflower oil in the soils was proved by the soil organic carbon content. PMID:19209632

  13. Alum amendment effects on phosphorus release and distribution in poultry litter-amended sandy soils

    USGS Publications Warehouse

    Staats, K.E.; Arai, Y.; Sparks, D.L.

    2004-01-01

    Increased poultry production has contributed to excess nutrient problems in Atlantic Coastal Plain soils due to land application of poultry litter (PL). Aluminum sulfate [alum, Al2(SO4)3?? 14H2O] amendment of PL effectively reduces soluble phosphorus (P) in the PL; however, the effects of these litters when added to acidic, sandy soils are not well understood. The objective of this study was to investigate the efficacy of alum-amended poultry litter in reducing P release from three Delaware Coastal Plain soils: Evesboro loamy sand (Ev; excessively drained, mesic, coated Typic Quartzipsamments), Rumford loamy sand (Ru; well drained, coarse-loamy, siliceous, subactive, thermic Typic Hapludults), and Pocomoke sandy loam (Pm; very poorly drained, coarse-loamy, siliceous, active, thermic Typic Umbraquults). Long-term (25 d) and short-term (24 h) desorption studies were conducted, in addition to chemical extractions and kinetic modeling, to observe the changes that alum-amended versus unamended PL caused in the soils. The Ev, Ru, and Pm soils were incubated with 9 Mg ha-1 of alum-amended or unamended PL. Long-term desorption (25 d) of the incubated material resulted in approximately 13.5% (Ev), 12.7% (Ru), and 13.3% (Pm) reductions in cumulative P desorbed when comparing soil treated with unamended and alum-amended PL. In addition, the P release from the soil treated with alum-amended litter was not significantly different from the control (soil alone). Short-term desorption (24 h) showed 7.3% (Ev), 15.4% (Ru), and 20% (Pm) reductions. The overall implication from this study is that the use of alum as a PL amendment is useful in coarse-textured soils of the Coastal Plain. With increased application of alum-amended PL, more significant decreases may be possible with little or no effect on soil quality.

  14. Imidacloprid sorption kinetics, equilibria, and degradation in sandy soils of Florida.

    PubMed

    Leiva, Jorge A; Nkedi-Kizza, Peter; Morgan, Kelly T; Qureshi, Jawwad A

    2015-05-27

    Imidacloprid (IMD) is a neonicotinoid insecticide soil-drenched on sandy soils of southwest Florida for the control of Diaphorina citri Kuwayama or Asian citrus psyllid (ACP). The ACP vectors causal pathogens of a devastating citrus disease called citrus greening. Understanding the behavior of IMD in these soils and plants is critical to its performance against target pests. Samples from Immokalee fine sand (IFS) were used for sorption kinetics and equilibria experiments. IMD kinetics data were described by the one-site mass transfer (OSMT) model and reached equilibrium between 6 and 12 h. Batch equilibrium and degradation studies revealed that IMD was weakly sorbed (K(OC) = 163-230) and persistent, with a half-life of 1.0-2.6 years. Consequently, IMD has the potential to leach below the citrus root zone after the soil-drench applications. PMID:25938475

  15. Transfer of cadmium from a sandy acidic soil to man: A population study

    SciTech Connect

    Staessen, J.A.; Celis, H.G.; Fagard, R.H.; Lijnen, P.J.; Thijs, L.B.; Amery, A.K. ); Vyncke, G. ); Lauwerys, R.R.; Roels, H.A. ); Claeys, F. ); Dondeyne, F. ); Ide, G. ); Rondia, D.; Sartor, F. )

    1992-06-01

    This population study included 230 subjects (age range 20-83 years) who consumed vegetables grown in kitchen gardens on a sandy acidic soil (mean pH {approximately}6.3). The study investigated the association between the Cd (cadmium) levels in blood and urine and the Cd concentration in the soil (range 0.2-44 ppm). Seventy-six subjects were current smokers and 122 participants lived in a district with known Cd pollution. Urinary Cd in the 230 subjects averaged 8.7 nmole/24 hr, (range 1.3 to 47 nmole/24 hr) after age adjustment positively correlated with the Cd level in the soil; a twofold increase of the Cd concentration in the soil was accompanied by a 7% rise in urinary Cd in men and by a 4% rise in women. Blood Cd averaged 11.5 nmole/liter (range 1.8-41 nmole/liter) and was negatively associated with the Cd level in the soil. After adjustment for significant covariates (smoking and serum {gamma}-glutamyl transpeptidase in both sexes, and age and serum ferritin in women), a twofold increase in the Cd concentration in the soil was accompanied by a 6% decrease in blood Cd in men and by a 10% decrease in women. In conclusion, in a rural population, consuming vegetables grown on a sandy acidic soil, 2 to 4% of the variance of urinary Cd was directly related to the Cd level in the soil. The negative correlation with blood Cd, a measure of more recent exposure, was biased by the implementation of preventive measures in the polluted district.

  16. Hydrological indications of aeolian salts in mid-latitude deserts of northwestern China

    NASA Astrophysics Data System (ADS)

    Zhu, Bing-Qi

    2016-06-01

    Large sandy deserts in middle latitude of northwestern China were studied on salt variations in modern and ancient aeolian sediments, aiming to explore their hydrological indications at the present and past. Globally, sulphate is rich in arid to semi-arid deserts, including the aeolian loess sediments in China and soils in low-latitude deserts, but is less common in the aeolian sediments from the mid-latitude deserts in this study. The compositional differences between aeolian salts and local natural waters is evident, indicating the chemistry of aeolian salts and the associated parent brines may be significantly different than that predicted for hydrologically closed systems. The formation of aeolian salts in the studied deserts is strongly controlled by earth surface processes in a large scale but not in a local scale. Vertical changes in facies and salinities are abrupt in the studied palaeo-aeolian sediment samples, which were interbedded by lacustrine/fluvial sediments with OSL and 14C ages ranging between 40 and 2 ka BP, reflecting rapid high-amplitude changes in hydrological settings during late Pleistocene to later Holocene in these ancient playa systems. A great difference in salt composition between aeolian and lacustrine sediments suggests that the inorganic salt is a latent geoproxy in revealing local hydrological variations and climate change in the desert areas. But the environmental indications could be amphibolous for the sedimentary sequences with dual/multiple depositional end-members; under this situation an increase in sequence salinity does not always represent an enhanced environmental aridity. Ancient playas are arid or humid at the same time based on several sporadic records is not a valid approach to correlation of salt deposits in adjacent saline playa basin in the studied areas. Effects of earth surface processes including erosion, deposition and other processes on sediment properties will bias the hydrological implications of sediment

  17. Biochar pyrolyzed at two temperatures affects Escherichia coli transport through a sandy soil.

    PubMed

    Bolster, Carl H; Abit, Sergio M

    2012-01-01

    The incorporation of biochar into soils has been proposed as a means to sequester carbon from the atmosphere. An added environmental benefit is that biochar has also been shown to increase soil retention of nutrients, heavy metals, and pesticides. The goal of this study was to evaluate whether biochar amendments affect the transport of Escherichia coli through a water-saturated soil. We looked at the transport of three E. coli isolates through 10-cm columns packed with a fine sandy soil amended with 2 or 10% (w/w) poultry litter biochar pyrolyzed at 350 or 700°C. For all three isolates, mixing the high-temperature biochar at a rate of 2% into the soil had no impact on transport behavior. When added at a rate of 10%, a reduction of five orders of magnitude in the amount of E. coli transported through the soil was observed for two of the isolates, and a 60% reduction was observed for the third isolate. Mixing the low-temperature biochar into the soil resulted in enhanced transport through the soil for two of the isolates, whereas no significant differences in transport behavior were observed between the low-temperature and high-temperature biochar amendments for one isolate. Our results show that the addition of biochar can affect the retention and transport behavior of E. coli and that biochar application rate, biochar pyrolysis temperature, and bacterial surface characteristics were important factors determining the transport of E. coli through our test soil. PMID:22218181

  18. Carbon mineralization and nutrient availability in calcareous sandy soils amended with woody waste biochar.

    PubMed

    El-Naggar, Ahmed H; Usman, Adel R A; Al-Omran, Abdulrasoul; Ok, Yong Sik; Ahmad, Mahtab; Al-Wabel, Mohammad I

    2015-11-01

    Many studies have reported the positive effect of biochar on soil carbon sequestration and soil fertility improvement in acidic soils. However, biochar may have different impacts on calcareous sandy soils. A 90-day incubation experiment was conducted to quantify the effects of woody waste biochar (10 g kg(-1)) on CO2-C emissions, K2SO4-extractable C and macro-(N, P and K) and micro-(Fe, Mn, Zn and Cu) nutrient availability in the presence or absence of poultry manure (5 g kg(-1) soil). The following six treatments were applied: (1) conocarpus (Conocarpus erectus L.) waste (CW), (2) conocarpus biochar (BC), (3) poultry manure (PM), (4) PM+CW, (5) PM+BC and (6) untreated soil (CK). Poultry manure increased CO2-C emissions and K2SO4-extractable C, and the highest increases in CO2-C emission rate and cumulative CO2-C and K2SO4-extractable C were observed for the PM+CW treatment. On the contrary, treatments with BC halted the CO2-C emission rate, indicating that the contribution of BC to CO2-C emissions is negligible compared with the soils amended with CW and PM. Furthermore, the combined addition of PM+BC increased available N, P and K compared with the PM or BC treatments. Overall, the incorporation of biochar into calcareous soils might have benefits in carbon sequestration and soil fertility improvement. PMID:26037818

  19. Soil heterogeneity of an East and West facing ridge above timberline due to differences in snow and aeolian deposition

    NASA Astrophysics Data System (ADS)

    Traver, E.

    2015-12-01

    Hans Jenny's soil forming factors—time, parent material, climate, topography, and organisms—represent the major components of his system to describe and quantify soil development. In almost all situations, it is difficult to hold even one of these factors constant while focusing on another factor; however, in our study site—the East and West side of a narrow North-South running ridge, above timberline in SE Wyoming—we can hold three factors nearly constant (time, parent material, and climate) and focus on how topography, in particular, has influenced the soil differences on the two sides. The East side is the leeside of prevailing and strong westerly winds and receives a large snow pack while the West is consistently snow-free during winter creating a very different moisture and soil temperature regime. The East receives aeolian dust deposition while the West loses surface material from wind scour. A standard chemical and physical analysis found that while the two sides are nearly identical textually, with a similar pH and low electrical conductivity, the East side is richer in minerals. During the short growing season, soil moisture results show that the West side is holding more water than the East side; however, the East side has a higher percentage of organic matter and is more shrub and forb rich. An isotope analysis shows that the C:N ratios are very similar on the two sides. Microbial biomass and functional groups will be analyzed in the soil samples as well as a seismic study conducted to quantity depth of soil to bedrock. Using all these results will help quantify the differences on the two sides of this narrow ridge and add to our understanding of fine-scale soil heterogeneity and its relationship to watershed hydrology.

  20. Toluene Removal from Sandy Soils via In Situ Technologies with an Emphasis on Factors Influencing Soil Vapor Extraction

    PubMed Central

    Amin, Mohammad Mehdi; Hatamipour, Mohammad Sadegh; Nourmoradi, Heshmatollah; Farhadkhani, Marzieh; Mohammadi-Moghadam, Fazel

    2014-01-01

    The integration of bioventing (BV) and soil vapor extraction (SVE) appears to be an effective combination method for soil decontamination. This paper serves two main purposes: it evaluates the effects of soil water content (SWC) and air flow rate on SVE and it investigates the transition regime between BV and SVE for toluene removal from sandy soils. 96 hours after air injection, more than 97% removal efficiency was achieved in all five experiments (carried out for SVE) including 5, 10, and 15% for SWC and 250 and 500 mL/min for air flow rate on SVE. The highest removal efficiency (>99.5%) of toluene was obtained by the combination of BV and SVE (AIBV: Air Injection Bioventing) after 96 h of air injection at a constant flow rate of 250 mL/min. It was found that AIBV has the highest efficiency for toluene removal from sandy soils and can remediate the vadose zone effectively to meet the soil guideline values for protection of groundwater. PMID:24587723

  1. Evidence for Differential Comminution/Aeolian Sorting and Chemical Weathering of Martian Soils Preserved in Mars Meteorite EET79001

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; McKay, David S.

    2004-01-01

    Impact-melt glasses containing Martian atmospheric gases in Mars meteorite EET79001 are formed from Martian soil fines that had undergone meteoroid-comminution and aeolian sorting accompanied by chemical weathering near Mars surface. Using SiO2 and SO3 as proxy for silicates and salts respectively in Mars soils, we find that SiO2 and SO3 correlate negatively with FeO and MgO and positively with Al2O3 and CaO in these glasses, indicating that the mafic and felsic components are depleted and enriched relative to the bulk host (Lith A/B) respectively as in the case of Moon soils. Though the overall pattern of mineral fractionation is similar between the soil fines on Mars and Moon, the magnitudes of the enrichments/depletions differ between these sample-suites because of pervasive aeolian activity on Mars. In addition to this mechanical processing, the Martian soil fines, prior to impact-melting, have undergone acid-sulfate dissolution under oxidizing/reducing conditions. The S03 content in EET79001,507 (Lith B) glass is approx.18% compared to < 2% in EET79001, 506 (Lith A). SiO2 and SO3 negatively correlate with each other in ,507 glasses similar to Pathfinder soils. The positive correlation found between FeO and SO3 in ,507 glasses as well as Pathfinder rocks and soils is consistent with the deposition of ferric-hydroxysulfate on regolith grains in an oxidizing environment. As in the case of Pathfinder soils, the Al 2O3 vs SiO2 positive correlation and FeO VS S102 negative correlation observed in ,507 glasses indicate that SiO2 from the regolith is mobilized as soluble silicic acid at low pH. The large off-set in the end-member FeO abundance ( SO3=0) between Pathfinder soil-free rock and sulfur-free rock in ,507 glass precursors suggests that the soils comprising the ,507 glasses contain much larger proportion of fine-grained Martian soil fraction that registers strong mafic depletion relative to Lith B. This inference is strongly supported by the Al2O3 - SO3

  2. Does thermal carbonization (Biochar) of organic material increase more merits for their amendments of sandy soil?

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Xu, G.; Sun, J. N.; Shao, H. B.

    2014-02-01

    Organic materials (e.g. furfural residue) are generally believed to improve the physical and chemical properties of the soils with low fertility. Recently, biochar have been received more attention as a possible measure to improve the carbon balance and improve soil quality in some degraded soils. However, little is known about their different amelioration of a sandy saline soil. In this study, 56d incubation experiment was conducted to evaluate the influence of furfural and its biochar on the properties of saline soil. The results showed that both furfural and biochar greatly reduced pH, increased soil organic carbon (SOC) content and cation exchange capacity (CEC), and enhanced the available phosphorus (P) in the soil. Furfural is more efficient than biochar in reducing pH: 5% furfural lowered the soil pH by 0.5-0.8 (soil pH: 8.3-8.6), while 5% biochar decreased by 0.25-0.4 due to the loss of acidity in pyrolysis process. With respect to available P, 5% of the furfural addition increased available P content by 4-6 times in comparison to 2-5 times with biochar application. In reducing soil exchangeable sodium percentage (ESP), biochar is slightly superior to furfural because soil ESP reduced by 51% and 43% with 5% furfural and 5% biochar addition at the end of incubation. In addition, no significant differences were observed between furfural and biochar about their capacity to retain N, P in leaching solution and to increase CEC in soil. These facts may be caused by the relatively short incubation time. In general, furfural and biochar have different amendments depending on soil properties: furfural was more effectively to decrease pH and to increase available P, whereas biochar played a more important role in increasing SOC and reducing ESP of saline soil.

  3. Influence of frozen storage on herbicide degradation capacity in surface and subsurface sandy soils.

    PubMed

    Mortensen, Sarah K; Jacobsen, Carsten S

    2004-12-15

    The degradation of MCPA and metribuzin was investigated in laboratory batch experiments using fresh and frozen-stored soil samples from the unsaturated zone of a sandy soil. Mineralization potentials measured in fresh and frozen-stored soils were similar, and mineralization kinetics in surface and subsurface soils could be fitted using the same kinetic models. MCPA mineralization data from all three horizons were best described with the exponential growth form of the three-half-order model. During the mineralization of MCPA, growth in MCPA-degrading microbial populations was confirmed by increases in the abundance of tfdA genes following MCPA exposure. In contrast to MCPA, metribuzin mineralization followed zero-order kinetics, and very little metribuzin was mineralized (<1%) in all three of the investigated soil horizons. In addition, metribuzin dissipation and metabolite formation were also measured in surface and subsurface soils using LC-MS/MS. Differences in metribuzin dissipation were observed in the A-horizon at the beginning of the experiment and resulted in substantially different 50% disappearance time, DT50, values for frozen-stored (36 days) and fresh (<15 days) soil samples. However, the % of metribuzin remaining in fresh and frozen-stored surface soils was comparable from day 37 and thereafter. PMID:15669321

  4. Estimation of Nitrogen Pools in Irrigated Potato Production on Sandy Soil Using the Model SUBSTOR

    PubMed Central

    Prasad, Rishi; Hochmuth, George J.; Boote, Kenneth J.

    2015-01-01

    Recent increases in nitrate concentrations in the Suwannee River and associated springs in northern Florida have raised concerns over the contributions of non-point sources. The Middle Suwannee River Basin (MSRB) is of special concern because of prevalent karst topography, unconfined aquifers and sandy soils which increase vulnerability of the ground water contamination from agricultural operations- a billion dollar industry in this region. Potato (Solanum tuberosum L.) production poses a challenge in the area due to the shallow root system of potato plants, and low water and nutrient holding capacity of the sandy soils. A four-year monitoring study for potato production on sandy soil was conducted on a commercial farm located in the MSRB to identify major nitrogen (N) loss pathways and determine their contribution to the total environmental N load, using a partial N budget approach and the potato model SUBSTOR. Model simulated environmental N loading rates were found to lie within one standard deviation of the observed values and identified leaching loss of N as the major sink representing 25 to 38% (or 85 to 138 kg ha-1 N) of the total input N (310 to 349 kg ha-1 N). The crop residues left in the field after tuber harvest represented a significant amount of N (64 to 110 kg ha-1N) and posed potential for indirect leaching loss of N upon their mineralization and the absence of subsequent cover crops. Typically, two months of fallow period exits between harvest of tubers and planting of the fall row crop (silage corn). The fallow period is characterized by summer rains which pose a threat to N released from rapidly mineralizing potato vines. Strategies to reduce N loading into the groundwater from potato production must focus on development and adoption of best management practices aimed on reducing direct as well as indirect N leaching losses. PMID:25635904

  5. Estimation of nitrogen pools in irrigated potato production on sandy soil using the model SUBSTOR.

    PubMed

    Prasad, Rishi; Hochmuth, George J; Boote, Kenneth J

    2015-01-01

    Recent increases in nitrate concentrations in the Suwannee River and associated springs in northern Florida have raised concerns over the contributions of non-point sources. The Middle Suwannee River Basin (MSRB) is of special concern because of prevalent karst topography, unconfined aquifers and sandy soils which increase vulnerability of the ground water contamination from agricultural operations--a billion dollar industry in this region. Potato (Solanum tuberosum L.) production poses a challenge in the area due to the shallow root system of potato plants, and low water and nutrient holding capacity of the sandy soils. A four-year monitoring study for potato production on sandy soil was conducted on a commercial farm located in the MSRB to identify major nitrogen (N) loss pathways and determine their contribution to the total environmental N load, using a partial N budget approach and the potato model SUBSTOR. Model simulated environmental N loading rates were found to lie within one standard deviation of the observed values and identified leaching loss of N as the major sink representing 25 to 38% (or 85 to 138 kg ha(-1) N) of the total input N (310 to 349 kg ha(-1) N). The crop residues left in the field after tuber harvest represented a significant amount of N (64 to 110 kg ha(-1) N) and posed potential for indirect leaching loss of N upon their mineralization and the absence of subsequent cover crops. Typically, two months of fallow period exits between harvest of tubers and planting of the fall row crop (silage corn). The fallow period is characterized by summer rains which pose a threat to N released from rapidly mineralizing potato vines. Strategies to reduce N loading into the groundwater from potato production must focus on development and adoption of best management practices aimed on reducing direct as well as indirect N leaching losses. PMID:25635904

  6. Bromide transport in a sandy and a silty soil - a comparative lysimeter study

    NASA Astrophysics Data System (ADS)

    Schober, L.; Iden, S. C.; Durner, W.

    2009-04-01

    The aim of this study was a comparison of bromide leaching through a silty and a sandy soil and the characterization of systematic differences in solute transport in these undisturbed soils of differing texture. The amount of seepage water and bromide concentrations in the water were measured in 5 lysimeters for each soil type for a period of 460 days. Additionally, meteorological data were measured next to the lysimeter station for this period. The water transport regime of the lysimeters was simulated by means of a numerical solution of the Richards equation using the software package HYDRUS 1D. The observed bromide transport was simulated by steady-state approximation, applying the simulation tool CXTFIT, which is implemented in the software package STANMOD, version 2.0. Analysis of the measured data showed that a correct reproduction of the water balance was possible, but required the adaptation of soil-dependent crop coefficients for the potential transpiration of Phacelia and Winter Rape. The mean bromide transport through the sandy soil could be approximately reproduced assuming a bromide uptake by plants. Observed double peaks of some of the individual breakthrough curves, however, indicated that the actual transport regime in the lysimeters was subject to local heterogeneity which cannot be covered by the effective one-dimensional transport model. Bromide transport through the silty soil showed an unexplained mass deficit of nearly 90 % of the applied bromide and the detection of a mean distinct bromide peak in seepage water after percolation of only 0.5 pore volumes. It was not possible to simulate this behaviour with an effective 1D equilibrium or nonequilibrium convection-dispersion model.

  7. Tillage Effects on Bulk Density and Hydraulic Properties of a Sandy Loam Soil in the Mon-Dak Region, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effects of conventional (CT) and strip (ST) tillage practices on bulk density (BD), water content (MC), infiltration rate (Ir) and hydraulic conductivity (Ks) in a Lihen sandy loam soil. Soil cores were collected from each plot at 0 to 10 and 10 to 30 cm depths under each tillage pr...

  8. Bulk density, water content and hydraulic properties of a sandy loam soil following conventional or strip tillage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effects of conventional (CT) and strip (ST) tillage practices on bulk density ('b), water content ('w), infiltration rate (Ir) and hydraulic conductivity (Ks) of plots in a Lihen sandy loam soil during the 2007 and 2008 growing seasons. We measured 'b and 'w using soil cores collect...

  9. Estimating water retention curves for sandy soils at the Doñana National Park, SW Spain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The determination of soil water retention curves (SWRC) in the laboratory is a slow and tedious task, which is especially challenging for sandy soils due to their low water retention capacity and large water content changes for small pressure head differences. Due to spatial variability within larg...

  10. Use of Fly Ash as a Liming Material for Corn and Soybean Production on an Acidic Sandy Soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fly ash (FA) produced from subbituminous coal combustion can potentially serve as a lime material for crop production in acidic soils in areas. A five-year study was conducted to determine if FA can be used as a liming material in an acid sandy soil under corn and soybean grain production. Fly ash...

  11. Aggregate-associated carbon and nitrogen in reclaimed sandy loam soils

    SciTech Connect

    Wick, A.F.; Stahl, P.D.; Ingram, L.J.

    2009-11-15

    Minimal research has been conducted on aggregate, C, and N in coarse-textured soils used to reclaim surface coal mine lands. Furthermore, little is known about the contribution different plant communities make to the recovery of aggregation in these soils. Two chronosequences of semiarid reclaimed sites with sandy loam soils were sampled under shrub- and grass-dominated communities. Aggregation, aggregate fractions, and associated C and N were measured. No definitive trends of increasing macroaggregates between sites were observed undershrubs; however, macro- and microaggregation was greater in the 16-yr-old (0.20 and 0.23 kg aggregate kg{sup -1} soil, respectively) than in the 5-yr-old soils (0.02 and 0.08 kg aggregate kg{sup -1} soil, respectively) under grasses. Although C and N concentrations were drastically reduced (50-75%) with mining activity between the <1-yr-old and native soils, aggregate C and N concentrations tinder shrubs and grasses were similar to each other and to the native soils in the 5-yr-old site. Sods under grass in the 16-yr-old site had lower available and aggregate-occluded C and N concentrations than the 5-yr-old site, while C and N concentrations did not change between 5- and 16-yr-old soils under shrubs. Conversely, aggregate C and N pool sizes under shrubs and grasses both increased with site age to conditions similar to those observed in the native soil. Reclaimed shrub site soils had consistently higher C concentrations in the older reclaimed sites (10 and 16 yr old) than the soils under grasses, indicating greater accumulation and retention of C and N in organic material under shrub than grass communities in semiarid reclaimed sites.

  12. Modeling aeolian transport of soil-bound plutonium: considering infrequent but normal environmental disturbances is critical in estimating future dose.

    PubMed

    Michelotti, Erika A; Whicker, Jeffrey J; Eisele, William F; Breshears, David D; Kirchner, Thomas B

    2013-06-01

    Dose assessments typically consider environmental systems as static through time, but environmental disturbances such as drought and fire are normal, albeit infrequent, events that can impact dose-influential attributes of many environmental systems. These phenomena occur over time frames of decades or longer, and are likely to be exacerbated under projected warmer, drier climate. As with other types of dose assessment, the impacts of environmental disturbances are often overlooked when evaluating dose from aeolian transport of radionuclides and other contaminants. Especially lacking are predictions that account for potential changing vegetation cover effects on radionuclide transport over the long time frames required by regulations. A recently developed dynamic wind-transport model that included vegetation succession and environmental disturbance provides more realistic long-term predictability. This study utilized the model to estimate emission rates for aeolian transport, and compare atmospheric dispersion and deposition rates of airborne plutonium-contaminated soil into neighboring areas with and without environmental disturbances. Specifically, the objective of this study was to utilize the model results as input for a widely used dose assessment model (CAP-88). Our case study focused on low levels of residual plutonium found in soils from past operations at Los Alamos National Laboratory (LANL), in Los Alamos, NM, located in the semiarid southwestern USA. Calculations were conducted for different disturbance scenarios based on conditions associated with current climate, and a potential future drier and warmer climate. Known soil and sediment concentrations of plutonium were used to model dispersal and deposition of windblown residual plutonium, as a function of distance and direction. Environmental disturbances that affected vegetation cover included ground fire, crown fire, and drought, with reoccurrence rates for current climate based on site historical

  13. Dynamics of carbon pools in post-agrogenic sandy soils of southern taiga of Russia

    PubMed Central

    2010-01-01

    Background Until recently, a lot of arable lands were abandoned in many countries of the world and, especially, in Russia, where about half a million square kilometers of arable lands were abandoned in 1961-2007. The soils at these fallows undergo a process of natural restoration (or self-restoration) that changes the balance of soil organic matter (SOM) supply and mineralization. Results A soil chronosequence study, covering the ecosystems of 3, 20, 55, 100, and 170 years of self-restoration in southern taiga zone, shows that soil organic content of mineral horizons remains relatively stable during the self-restoration. This does not imply, however, that SOM pools remain steady. The C/N ratio of active SOM reached steady state after 55 years, and increased doubly (from 12.5 - 15.6 to 32.2-33.8). As to the C/N ratio of passive SOM, it has been continuously increasing (from 11.8-12.7 to 19.0-22.8) over the 170 years, and did not reach a steady condition. Conclusion The results of the study imply that soil recovery at the abandoned arable sandy lands of taiga is incredibly slow process. Not only soil morphological features of a former ploughing remained detectable but also the balance of soil organic matter input and mineralization remained unsteady after 170 years of self-restoration. PMID:20420668

  14. Phytotoxicity and uptake of nitroglycerin in a natural sandy loam soil.

    PubMed

    Rocheleau, Sylvie; Kuperman, Roman G; Dodard, Sabine G; Sarrazin, Manon; Savard, Kathleen; Paquet, Louise; Hawari, Jalal; Checkai, Ronald T; Thiboutot, Sonia; Ampleman, Guy; Sunahara, Geoffrey I

    2011-11-15

    Nitroglycerin (NG) is widely used for the production of explosives and solid propellants, and is a soil contaminant of concern at some military training ranges. NG phytotoxicity data reported in the literature cannot be applied directly to development of ecotoxicological benchmarks for plant exposures in soil because they were determined in studies using hydroponic media, cell cultures, and transgenic plants. Toxicities of NG in the present studies were evaluated for alfalfa (Medicago sativa), barnyard grass (Echinochloa crusgalli), and ryegrass (Lolium perenne) exposed to NG in Sassafras sandy loam soil. Uptake and degradation of NG were also evaluated in ryegrass. The median effective concentration values for shoot growth ranged from 40 to 231 mg kg(-1) in studies with NG freshly amended in soil, and from 23 to 185 mg kg(-1) in studies with NG weathered-and-aged in soil. Weathering-and-aging NG in soil did not significantly affect the toxicity based on 95% confidence intervals for either seedling emergence or plant growth endpoints. Uptake studies revealed that NG was not accumulated in ryegrass but was transformed into dinitroglycerin in the soil and roots, and was subsequently translocated into the ryegrass shoots. The highest bioconcentration factors for dinitroglycerin of 685 and 40 were determined for roots and shoots, respectively. Results of these studies will improve our understanding of toxicity and bioconcentration of NG in terrestrial plants and will contribute to ecological risk assessment of NG-contaminated sites. PMID:21975007

  15. Biochar application to sandy and loamy soils for agricultural nutrient management

    NASA Astrophysics Data System (ADS)

    Gronwald, Marco; Don, Axel; Tiemeyer, Baerbel; Helfrich, Mirjam

    2014-05-01

    Soil fertility of agricultural soils is challenged by nutrients losses and increasing soil acidification. Furthermore, leached nutrients negatively affect the quality of ground and surface water 1]. In addition to the possible soil carbon sequestration by applying biochars, many positive soil-improving properties are attributed to biochars. The application of biochars to agricultural - especially sandy - soils could reduce leaching of nutrients and may improve their availability 1,2]. Thus, biochar application to agricultural fields could be an ecologically and economically viable option to improve soils' fertility. However, biochar properties strongly depend on their feedstock and production process 3]. Various types of biochars (pyrolysis char, hydrochar (produced at 200 and 250° C); feedstocks: digestate, Miscanthus and wood chips) were used to determine sorption kinetics and sorption isotherms for the major nutrients Ca, Mg, K, NH4 and NO3 as a function of biochar types in different soil substrates (sand, loess). In addition, the biochars were washed to create free binding sites on the chars' surface that simulate aged char. We compared the simulated aged char with biochars that was aged in-situ at a field experiment for seven months. The first results showed that pyrochars have the largest retention potential for NO3 and hydrochars have retention potential for NH4. Washing of biochars turned them from a PO4 and NH4 source into an adsorber, especially for hydrochars. Highest leaching was observed for biochars from digestates likely due to the high nutrient content of digestates. But the different ions may lead to pH-dependent interactions between each other and the chars' surface that override the adsoption effects. In this context, cation-bridge and ligand bindings 4,5] need to be further investigated. Most of the fresh, unwashed biochars were a source of nutrients with hardly any detectable nutrient retention. Pyrochars showed the highest potential for anion

  16. Biochar increases plant available water in a sandy soil under an aerobic rice cropping system

    NASA Astrophysics Data System (ADS)

    de Melo Carvalho, M. T.; de Holanda Nunes Maia, A.; Madari, B. E.; Bastiaans, L.; van Oort, P. A. J.; Heinemann, A. B.; Soler da Silva, M. A.; Petter, F. A.; Meinke, H.

    2014-03-01

    The main objective of this study was to assess the impact of biochar rate (0, 8, 16 and 32 t ha-1) on the water retention capacity (WRC) of a sandy Dystric Plinthosol. The applied biochar was a by-product of slow pyrolysis (∼450 °C) of eucalyptus wood, milled to pass through a 2000 μm sieve that resulted in a material with an intrinsic porosity ≤10 μm and a specific surface area of ∼3.2 m2 g-1. The biochar was incorporated into the top 15 cm of the soil under an aerobic rice system. Our study focused on both the effects on WRC and rice yields at 2 and 3 years after application. Undisturbed soil samples were collected from 16 plots in two soil layers (5-10 and 15-20 cm). Soil water retention curves were modelled using a nonlinear mixed model which appropriately accounts for uncertainties inherent of spatial variability and repeated measurements taken within a specific soil sample. We found an increase in plant available water in the upper soil layer proportional to the rate of biochar, with about 0.8% for each t ha-1 of biochar amendment at 2 and 3 years after application. The impact of biochar on soil WRC was most likely related to an increase in overall porosity of the sandy soil, which was evident from an increase in saturated soil moisture and macro porosity with 0.5% and 1.6% for each t ha-1 of biochar applied, respectively. The increment in soil WRC did not translate into an increase in rice yield, essentially because in both seasons the amount of rainfall during critical period for rice production exceeded 650 mm. The use of biochar as a soil amendment can be a worthy strategy to guarantee yield stability under water limited conditions. Our findings raise the importance of assessing the feasibility of very high application rates of biochar and the inclusion of a detailed analysis of its physical and chemical properties as part of future investigations.

  17. Biochar reduces copper toxicity in Chenopodium quinoa Willd. In a sandy soil.

    PubMed

    Buss, Wolfram; Kammann, Claudia; Koyro, Hans-Werner

    2012-01-01

    Mining, smelting, land applications of sewage sludge, the use of fungicides containing copper (Cu), and other human activities have led to widespread soil enrichment and contamination with Cu and potentially toxic conditions. Biochar (BC) can adsorb several substances, ranging from herbicides to plant-inhibiting allelochemicals. However, the range of potential beneficial effects on early-stage plant growth with regard to heavy metal toxicity is largely unexplored. We investigated the ameliorating properties of a forestry-residue BC under Cu toxicity conditions on early plant growth. Young quinoa plants () were grown in the greenhouse in the presence of 0, 2, and 4% BC application (w/w) added to a sandy soil with 0, 50, or 200 μg g Cu supplied. The plants without BC showed severe stress symptoms and reduced growth shortly after Cu application of 50 μg g and died at 200 μg Cu g. Increasing BC concentrations in the growth medium significantly increased the plant performance without Cu toxicity or under Cu stress. At the 4% BC application rate, the plants with 200 μg g Cu almost reached the same biomass as in the control treatment. In the presence of BC, less Cu entered the plant tissues, which had reduced Cu concentrations in the order roots, shoots, leaves. The amelioration effect also was reflected in the plant-soil system CO gas exchange, which showed clear signs of improvement with BC presence. The most likely ameliorating mechanisms were adsorption of Cu to negatively charged BC surfaces and an improvement of the water supply. Overall, BC seems to be a beneficial amendment with the potential to ameliorate Cu toxicity in sandy soils. Further research with a broad spectrum of different soil types, BCs, and crop plants is required. PMID:22751058

  18. Degradation pathway and field-scale DT50 determination of Boscalid in a sandy Soil

    NASA Astrophysics Data System (ADS)

    Karlsson, Anneli S.; Weihermüller, Lutz; Tappe, Wolfgang; Mukherjee, Santanu; Spielvogel, Sandra

    2016-04-01

    The research on environmental fate of pesticides has received increasing attention within the last decades and the persistence of several compounds in soil matrices is well documented. However, the fate of the new fungicide Boscalid (introduced in 2003) is not yet completely investigated. The aim of this study was to analyze the environmental fate of Boscalid in a sandy soil. Three years after the second application on a cropland site in Kaldenkirchen, Germany, 65 undisturbed soil samples from the plough layer were derived. Boscalid residues were extracted using Accelerated Solvent Extraction (ASE) and measured with UPLC-MS/MS. The Boscalid residues ranged between 0.12 and 0.53 μg kg‑1with a field mean of 0.20 ± 0.09 μg kg‑1. These results differed considerably from the predicted field concentration of 16.89 μg kg‑1 (calculated from the application rate) and half-lives (DT50) of 104-182 days compared to 345 days reported in literature. Adjusting the extraction efficiency to 20% could not explain the large difference. Therefore, an incubation study with 14C-labeled Boscalid was conducted to measure the DT50 under controlled conditions. Here, the DT50 values were in the range of values stated in literature (297-337 days compared to 345 days) but still much larger than the DT50 based on the field-study values (104-182 days). Our results indicate that Boscalid dissipation under field conditions is much faster at agricultural sites with sandy soil type as expected from laboratory incubation experiments. Future experiments with Boscalid will be conducted in two different soils with different particle size. A laboratory experiment with uniformly 13C-labeled Boscalid will provide insight into the uptake and incorporation in microbial biomass.

  19. Reactive transport controls on sandy acid sulfate soils and impacts on shallow groundwater quality

    NASA Astrophysics Data System (ADS)

    Salmon, S. Ursula; Rate, Andrew W.; Rengel, Zed; Appleyard, Steven; Prommer, Henning; Hinz, Christoph

    2014-06-01

    Disturbance or drainage of potential acid sulfate soils (PASS) can result in the release of acidity and degradation of infrastructure, water resources, and the environment. Soil processes affecting shallow groundwater quality have been investigated using a numerical code that integrates (bio)geochemical processes with water, solute, and gas transport. The patterns of severe and persistent acidification (pH < 4) in the sandy, carbonate-depleted podzols of a coastal plain could be reproduced without calibration, based on oxidation of microcrystalline pyrite after groundwater level decrease and/or residual groundwater acidity, due to slow vertical solute transport rates. The rate of acidification was limited by gas phase diffusion of oxygen and hence was sensitive to soil water retention properties and in some cases also to oxygen consumption by organic matter mineralization. Despite diffusion limitation, the rate of oxidation in sandy soils was rapid once pyrite-bearing horizons were exposed, even to a depth of 7.5 m. Groundwater level movement was thus identified as an important control on acidification, as well as the initial pyrite content. Increase in the rate of Fe(II) oxidation lead to slightly lower pH and greater accumulation of Fe(III) phases, but had little effect on the overall amount of pyrite oxidized. Aluminosilicate (kaolinite) dissolution had a small pH-buffering effect but lead to the release of Al and associated acidity. Simulated dewatering scenarios highlighted the potential of the model for risk assessment of (bio)geochemical impacts on soil and groundwater over a range of temporal and spatial scales.

  20. Leaching losses of two nutrients and an herbicide from two sandy soils during transient drainage

    SciTech Connect

    Mansell, R.S.; Wheeler, W.B.; Calvert, D.W.

    1980-09-01

    Shallow-tilled (ST) and deep-tilled (DT) plots of an acid, sandy soil were used to measure changes in potassium, nitrogen nitrates, and Terbacil concentrations in subsurface drainage water from the plots. Fertilizer and Terbacil herbicide was applied to the soil. Transient water flow was applied to the plots for a 2-wk period after 7.6 cm of irrigation had been achieved. Drainage water contained higher concentrations of all solutes than did DT drainage water. In the DT soil, the discharges of potassium, nitrogen producing nitrates, and terbacil were only 29.6, 37.0, and 13.9% respectively as large as those in the ST soil. Total cumulative drainage from DT soil was only 51.1% that from ST soil. Thus, relatively small quantities of irrigation and rainfall produced relatively large nutrient discharges. As irrigation was begun soon after fertilizer application, the leaching loss of these solutes would be expected to be greater than if water application had occurred later. 13 references, 8 figures, 5 tables.

  1. Estimation of pollutant partition in sandy soils with different water contents.

    PubMed

    Albergaria, José Tomás; Alvim-Ferraz, Maria da Conceição M; Delerue-Matos, Maria Cristina F

    2010-12-01

    The objectives of this work were: (1) to identify an isotherm model to relate the contaminant contents in the gas phase with those in the solid and non-aqueous liquid phases; (2) to develop a methodology for the estimation of the contaminant distribution in the different phases of the soil; and (3) to evaluate the influence of soil water content on the contaminant distribution in soil. For sandy soils with negligible contents of clay and natural organic matter, contaminated with benzene, toluene, ethylbenzene, xylene, trichloroethylene (TCE), and perchloroethylene (PCE), it was concluded that: (1) Freundlich's model showed to be adequate to relate the contaminant contents in the gas phase with those in the solid and non-aqueous liquid phases; (2) the distribution of the contaminants in the different phases present in the soil could be estimated with differences lower than 10% for 83% of the cases; and (3) an increase of the soil water content led to a decrease of the amount of contaminant in the solid and non-aqueous liquid phases, increasing the amount in the other phases. PMID:20069453

  2. Depth distribution of preferential flow patterns in a sandy loam soil as affected by tillage

    NASA Astrophysics Data System (ADS)

    Petersen, C. T.; Hansen, S.; Jensen, H. E.

    Dye-tracer studies using the anionic dye Brilliant Blue FCF were conducted on a structured sandy loam soil (Typic Agrudalf). 25 mm of dye solution was applied to the surface of 11 1.6 x 1.6 m field plots, some of which had been subjected to conventional seed bed preparation (harrowing) while others had been rotovated to either 5 or 15 cm depth before sowing. The soil was excavated to about 160 cm depth one or two days after dye application. Flow patterns and structural features appearing on vertical or horizontal cross sections were examined and photographed. The flow patterns were digitized, and depth functions for the number of activated flow pathways and the degree of dye coverage were calculated. Dye was found below 100 cm depth on 26 out of 33 vertical cross sections made in conventionally tilled plots showing that preferential flow was a prevailing phenomenon. The depth-averaged number of stained flow pathways in the 25-100 cm layer was significantly smaller in a plot rotovated to 5 cm depth than in a conventionally tilled plot, both under relatively dry initial soil conditions and when the entire soil profiles were initially at field capacity. There were no examples of dye penetration below 25 cm depth one month after deep rotovation. Distinct horizontal structures in flow patterns appearing at 20-40 cm depth coupled with changes in flow domains indicated soil layering with abrupt changes in soil structure and hydraulic properties.

  3. Phytotoxicity of nitroaromatic energetic compounds freshly amended or weathered and aged in sandy loam soil.

    PubMed

    Rocheleau, Sylvie; Kuperman, Roman G; Martel, Majorie; Paquet, Louise; Bardai, Ghalib; Wong, Stephen; Sarrazin, Manon; Dodard, Sabine; Gong, Ping; Hawari, Jalal; Checkai, Ronald T; Sunahara, Geoffrey I

    2006-01-01

    The toxicities of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), 2,4-dinitrotoluene (2,4-DNT), and 2,6-dinitrotoluene (2,6-DNT) to terrestrial plants alfalfa (Medicago sativa L.), Japanese millet (Echinochloa crusgalli L.), and perennial ryegrass (Lolium perenne L.) were determined in Sassafras sandy loam soil using seedling emergence, fresh shoot, and dry mass measurement endpoints. A 13-week weathering and aging of energetic materials in soils, which included wetting and drying cycles, and exposure to sunlight of individual soil treatments, was incorporated into the study design to better reflect the soil exposure conditions in the field than toxicity determinations in freshly amended soils. Definitive toxicity tests showed that dinitrotoluenes were more phytotoxic for all plant species in freshly amended treatments based on EC20 values for dry shoot ranging from 3 to 24mgkg(-1) compared with values for TNB or TNT ranging from 43 to 62mgkg(-1). Weathering and aging of energetic materials (EMs) in soil significantly decreased the toxicity of TNT, TNB or 2,6-DNT to Japanese millet or ryegrass based on seedling emergence, but significantly increased the toxicity of all four EMs to all three plant species based on shoot growth. Exposure of the three plant species to relatively low concentrations of the four compounds initially stimulated plant growth before the onset of inhibition at greater concentrations (hormesis). PMID:16112172

  4. Improving irrigation efficiency of sandy soils by subsurface water retaining membranes

    NASA Astrophysics Data System (ADS)

    Guber, Andrey; Smucker, Alvin; Berhanu, Samrawi

    2014-05-01

    Sustainable crop production in sandy soils is challenging due to low soil water holding capacity and high water permeability. The subsurface water retention technology (SWRT) is a relatively new long-term approach that offers precision control of water and nutrients in the root zone. However, multiple design of SWRT membrane configurations and spatial distributions require more modeling for best application in arid regions with relevant irrigation methods. The objective of this study was to define optimal geometric parameters of the SWRT membranes and the most accurate irrigation rates for corn production in sandy soils. HYDRUS-2D model, that describes two-dimensional water flow in unsaturated soil, was calibrated and validated on data in a large sand-filled lysimeter with SWRT membranes installed at different depths with different aspect ratios. The model adequately reproduced soil water content dynamics measured at 12 locations inside the sand profile. Then HYDRUS-2D simulations were repeated with different SWRT installation depths and aspect ratios. The installation depths in these simulations were 20 cm, 40 cm, and 60 cm, while the aspect ratios were 2:1, 3:1, 5:1 and 10:1. The results of simulations confirmed water holding capacity of the soil can be differentially controlled by aspect ratios of SWRT membranes. SWRT membranes with an aspect ratio of 2:1 substantially increased soil water content at 20-cm soil layer above the membrane, and this effect diminished with increasing aspect ratio of the membrane. Installation depth within the soil profile had no significant effect on water loss. The HYDRUS-2D simulations were repeated with SWRT installed at depth of 20 cm for sprinkle, surface drip and subsurface drip irrigation. Corn irrigation was triggered at pressure head of -30cm at a depth of 15 cm for all irrigation techniques. Simulated water losses by deep infiltration in sands without SWRT membranes approached 60% with approximately 15% losses when SWRT

  5. Arbuscular mycorrhizal fungal community divergence within a common host plant in two different soils in a subarctic Aeolian sand area.

    PubMed

    Francini, Gaia; Männistö, Minna; Alaoja, Vilhelmiina; Kytöviita, Minna-Maarit

    2014-10-01

    There is rising awareness that different arbuscular mycorrhizal (AM) fungi have different autoecology and occupy different soil niches and that the benefits they provide to the host plant are dependent on plant-AM fungus combination. However, the role and community composition of AM fungi in succession are not well known and the northern latitudes remain poorly investigated ecosystems. We studied AM fungal communities in the roots of the grass Deschampsia flexuosa in two different, closely located, successional stages in a northern Aeolian sand area. The AM fungal taxa richness in planta was estimated by cloning and sequencing small subunit ribosomal RNA genes. AM colonization, shoot δ (13)C signature, and %N and %C were measured. Soil microbial community structure and AM fungal mycelium abundance were estimated using phospholipid (PLFA) and neutral lipid (NLFA) analyses. The two successional stages were characterized by distinct plant, microbial, and fungal communities. AM fungal species richness was very low in both the early and late successional stages. AM frequency in D. flexuosa roots was higher in the early successional stage than in the late one. The AM fungal taxa retrieved belonged to the genera generally adapted to Arctic or extreme environments. AM fungi seemed to be important in the early stage of the succession, suggesting that AM fungi may help plants to better cope with the harsh environmental conditions, especially in an early successional stage with more extreme environmental fluctuations. PMID:24687606

  6. Transport of simazine in unsaturated sandy soil and predictions of its leaching under hypothetical field conditions.

    PubMed

    Suárez, Francisco; Bachmann, Jaime; Muñoz, José F; Ortiz, Cristian; Tyler, Scott W; Alister, Claudio; Kogan, Marcelo

    2007-12-01

    The potential contamination of groundwater by herbicides is often controlled by processes in the vadose zone, through which herbicides travel before entering groundwater. In the vadose zone, both physical and chemical processes affect the fate and transport of herbicides, therefore it is important to represent these processes by mathematical models to predict contaminant movement. To simulate the movement of simazine, a herbicide commonly used in Chilean vineyards, batch and miscible displacement column experiments were performed on a disturbed sandy soil to quantify the primary parameters and processes of simazine transport. Chloride (Cl(-)) was used as a non-reactive tracer, and simazine as the reactive tracer. The Hydrus-1D model was used to estimate the parameters by inversion from the breakthrough curves of the columns and to evaluate the potential groundwater contamination in a sandy soil from the Casablanca Valley, Chile. The two-site, chemical non-equilibrium model was observed to best represent the experimental results of the miscible displacement experiments in laboratory soil columns. Predictions of transport under hypothetical field conditions using the same soil from the column experiments were made for 40 years by applying herbicide during the first 20 years, and then halting the application and considering different rates of groundwater recharge. For recharge rates smaller than 84 mm year(-1), the predicted concentration of simazine at a depth of 1 m is below the U.S. EPA's maximum contaminant levels (4 microg L(-1)). After eight years of application at a groundwater recharge rate of 180 mm year(-1) (approximately 50% of the annual rainfall), simazine was found to reach the groundwater (located at 1 m depth) at a higher concentration (more than 40 microg L(-1)) than the existing guidelines in the USA and Europe. PMID:17604874

  7. Nitrogen mineralization and nitrate leaching of a sandy soil amended with different organic wastes.

    PubMed

    Burgos, Pilar; Madejón, Engracia; Cabrera, Francisco

    2006-04-01

    Organic wastes can be recycled as a source of plant nutrients, enhancing crop production by improving soil quality. However, the study of the dynamic of soil nutrient, especially the N dynamic, after soil application of any organic material is vital for assessing a correct and effective use of the material, minimizing the losses of nitrate in leachates and avoiding the negative environmental effects that it may cause in groundwater. To estimate the effect of three organic materials, a municipal solid waste compost (MWC), a non-composted paper mill sludge (PS), and an agroforest compost (AC) on the N dynamic of a sandy soil two experiments were carried out: an incubation experiment and a column experiment. The incubation experiment was conducted to estimate the N mineralization rate of the different soil-amendment mixtures. The soil was mixed with the organic amendments at a rate equivalent to 50,000 kg ha(-1) and incubated during 40 weeks at constant moisture content (70% of its water-holding capacity) and temperature (28 degrees C) under aerobic conditions. Organic amendment-soil samples showed an immobilization of N during the first weeks, which was more noticeable and longer in the case of PS-treated soil compared to the other two amendments due to its high C/N ratio. After this immobilization stage, a positive mineralization was observed for all treatment, especially in MWC treated soil. Contemporaneously a 1-year column (19 cm diameter and 60 cm height) experiment was carried out to estimate the nitrate losses from the soil amended with the same organic materials. Amendments were mixed with the top soil (0-15 cm) at a rate equivalent to 50,000 kg ha(-1). The columns were periodically irrigated simulating rainfall in the area of study, receiving in total 415 mm of water, and the water draining was collected during the experimental period and analysed for NO3-N. At the end of the experimental period NO3-N content in soil columns at three depths (0-20, 20-35 and

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  9. Effect of the application of various wastewater sludges on the properties of sandy soil.

    PubMed

    Asik, Barış Bülent; Aydinalp, Cumhur; Katkat, Ali Vahap; Sagban, Fatma Olcay Topaç

    2015-02-01

    This research was conducted to determine the effect of various wastewater sludge (domestic type (B), mixture of industry and domestic type (L), aerobic food industry (P), anaerobic food industry (M)) levels on the properties of sandy soil, including pH, electrical conductivity (EC), and the levels of available N (NH4 and NO3) and P, diethylenetriamine pentaaceticacid (DTPA)-extractable microelements and heavy metals. An incubation experiment was performed in which sludges were applied at rates of 0, 40, 80, 120, and 160 tons ha(-1), and the effects on the soil properties were measured over a period of 150 days. Soil pH decreased and electrical conductivity increased with increasing levels of sludge application. The levels of NH4-N, NO3-N, available P, and DTPA-extractable heavy metals also increased with the application rate of the sludge. NO3-N content increased and NH4-N content decreased over time. The most unfavorable effects on soil properties were observed with the B sludge. Other soil characteristics changed according to the sludge properties. PMID:25632907

  10. Application of bimetallic iron (BioCAT slurry) for pentachlorophenol removal from sandy soil.

    PubMed

    Dien, Nguyen Thanh; De Windt, Wim; Buekens, Alfons; Chang, Moo Been

    2013-05-15

    Bimetallic iron nanoparticles have mostly been applied to the degradation of chlorinated compounds in the aqueous phase. In this study, the degradation of pentachlorophenol (PCP) spiked into sandy soil is considered as a first exploratory step for remediating PCP in real contaminated soil using a commercial preparation of bimetallic iron (Trade name BioCAT). After 21 days of treatment a PCP removal efficiency of 90% was achieved, along with 70% dechlorination efficiency, for a dosage of 600 mg BioCAT slurry/kg soil. Degradation of PCP by BioCAT follows first order kinetics in PCP. Stepwise dechlorination is the main pathway of PCP elimination from soil slurries contacted with BioCAT. Such dechlorination is confirmed by the appearance of intermediate products, as well as by release of chlorides. Additionally, the increasing pH value and the rapid decrease of the oxidation/reduction potential (ORP) also attest to the reductive dechlorination of PCP. The reaction products comprehend lower chlorinated phenols, including three TeCP isomers, four TrCP isomers, four DCP isomers, two MCP isomers and phenol. These findings indicate that BioCAT could be applied for field treatment of PCP-contaminated soil under ambient conditions. PMID:23500793

  11. Characterization of vegetation and soils of rehabilitated sandy wastelands at the Usinsk oilfields (the Komi Republic)

    NASA Astrophysics Data System (ADS)

    Likhanova, I. A.; Khabibullina, F. M.; Kurakov, A. V.

    2008-09-01

    The soils and phytocenoses developed over 13 years after four procedures of rehabilitation of sandy wastelands in the area of Usinsk oilfields (the northernmost taiga) are characterized. The planting of pine seedlings and especially the sowing of perennial grasses, along with the improvement of the substrate by application of peat and fertilizers, were the most efficient rehabilitation technologies as compared to the planting of only willow cuttings or 7-to 19-year-old pine wildings. On the plots where grasses were sown and pine seedlings were planted, the plant communities were at the preclimax succession stage (small-leaved tree species and shrubs) before the regeneration of the coniferous forest. The input of abundant plant residues have led to the formation of weakly developed soils with higher contents of organic carbon and hydrolyzable nitrogen as compared to their concentrations in the initial substrate. However, they were much lower as compared with the reference peaty-podzolic iron-illuvial soil. In the upper horizons of the weakly developed soils, the number of colony-forming units of bacteria and fungi and the mycobiota diversity were close to those in the reference soil, but the activity of the microbiological processes remained substantially lower in these horizons.

  12. Manure Refinement Affects Apple Rhizosphere Bacterial Community Structure: A Study in Sandy Soil

    PubMed Central

    Zhang, Qiang; Sun, Jian; Liu, Songzhong; Wei, Qinping

    2013-01-01

    We used DNA-based pyrosequencing to characterize the bacterial community structure of the sandy soil of an apple orchard with different manure ratios. Five manure percentages (5%, 10%, 15%, 20% and 25%) were examined. More than 10,000 valid reads were obtained for each replicate. The communities were composed of five dominant groups (Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteria and Bacteroidetes), of which Proteobacteria content gradually decreased from 41.38% to 37.29% as manure ratio increased from 0% to 25%, respectively. Redundancy analysis showed that 37 classes were highly correlated with manure ratio, 18 of which were positively correlated. Clustering revealed that the rhizosphere samples were grouped into three components: low manure (control, 5%) treatment, medium manure (10%, 15%) treatment and high manure (20%, 25%) treatment. Venn analysis of species types of these three groups revealed that the bacteria community difference was primarily reflected by quantity ratio rather than species variety. Although greater manure content led to higher soil organic matter content, the medium manure improved soil showed the highest urease activity and saccharase activity, while 5% to 20% manure ratio improvement also resulted in higher bacteria diversity than control and 25% manure ratio treatment. Our experimental results suggest that the use of a proper manure ratio results in significantly higher soil enzyme activity and different bacteria community patterns, whereas the use of excessive manure amounts has negative effect on soil quality. PMID:24155909

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

    PubMed

    Yang, Xin-guo; Song, Nai-ping

    2011-09-01

    By the methods of controlled and typical sampling, this paper analyzed the texture, salinization characteristics, cation exchange capacity (CEC), and their correlations in the 0-40 cm soil profiles of corn land, medlar land, and non-utilized land in Yanghuang irrigated area of Hongsipu, Northwest China. Under controlled sampling, the salt content in the soil profiles was 0.69-1.30 g x kg(-1) (except in non-utilized land where the 0-10 cm soil salt content was up to 1.74 g x kg(-1)), with no obvious salinization. The sodium adsorption ratio and exchangeable sodium percentage in the 20-40 cm soil layer of medlar land were 12.18 and 14.1%, respectively, and the total content of clay and silt in the 0-40 cm soil profile of medlar land was up to 37.3% whereas that in the 0-20 cm soil layer of corn land was only 13.5%. In the 20-40 cm soil layer of corn land, the indices of sandy desertification and salinization had significant correlations under controlled sampling but no correlations under typical sampling, while the CEC and the sandy desertification and salinization indices had significant correlations under typical sampling. In different land use types in the study area, soil sandy desertification and salinization had complicated interrelationships, and CEC could be used as the indicator for the changes in soil environmental quality. PMID:22126034

  14. Field scale boscalid residues and dissipation half-life estimation in a sandy soil.

    PubMed

    Karlsson, Anneli Sofia; Weihermüller, Lutz; Tappe, Wolfgang; Mukherjee, Santanu; Spielvogel, Sandra

    2016-02-01

    The aim of this study was to analyze the environmental fate of the fungicide boscalid in a sandy soil. Boscalid was applied in spring 2010/11 to a cropland site in western Germany. Three years after second application 65 undisturbed soil samples were taken. Boscalid was extracted using accelerated solvent extraction (ASE). Boscalid contents in the plough horizon ranged between 0.12 and 0.53 with a field mean of 0.20 ± 0.09 μg kg(-1). These contents were considerably lower compared to calculation using literature DT50 values, whereby a concentration of 16.89 μg kg(-1) was expected assuming a literature DT50 value of 345 days. Therefore, the measured field boscalid concentration only yields 1.2% of the expected value. To test whether the unknown extraction efficiency, losses from spray drift and interception can explain the mismatch between calculated and measured concentrations all these uncertainties were taken into account into calculations, but field concentrations and DT50 were still lower as expected. Leaching to deeper horizons was also studied but could not explain the discrepancy either. Moreover, a short-term incubation experiment using (14)C labelled boscalid revealed also shorter DT50 values of 297-337 compared to the 345 days taken from literature. However, this DT50 value is still considerably larger compared to the 104-224 days that were calculated based on the field experiment. Our results indicate that boscalid dissipation under field conditions is much faster at agricultural sites with sandy soil type as expected from laboratory incubation experiments. PMID:26688253

  15. Chemical contamination of soils in the New York City area following Hurricane Sandy.

    PubMed

    Mandigo, Amy C; DiScenza, Dana J; Keimowitz, Alison R; Fitzgerald, Neil

    2016-10-01

    This paper presents a unique data set of lead, arsenic, polychlorinated biphenyl (PCB), and polycyclic aromatic hydrocarbon (PAH) concentrations in soil samples collected from the metropolitan New York City area in the aftermath of Hurricane Sandy. Initial samples were collected by citizen scientists recruited via social media, a relatively unusual approach for a sample collection project. Participants in the affected areas collected 63 usable samples from basements, gardens, roads, and beaches. Results indicate high levels of arsenic, lead, PCBs, and PAHs in an area approximately 800 feet south of the United States Environmental Protection Agency (US EPA) Superfund site at Newtown Creek. A location adjacent to the Gowanus Canal, another Superfund site, was found to have high PCB concentrations. Areas of high PAH contamination tended to be near high traffic areas or next to sites of known contamination. While contamination as a direct result of Hurricane Sandy cannot be demonstrated conclusively, the presence of high levels of contamination close to known contamination sites, evidence for co-contamination, and decrease in number of samples containing measureable amounts of semi-volatile compounds from samples collected at similar locations 9 months after the storm suggest that contaminated particles may have migrated to residential areas as a result of flooding. PMID:26486130

  16. Effects of Maghnian bentonite on physical properties of sandy soils under semi-arid Mediterranean climate.

    PubMed

    Benkhelifa, M; Belkhodja, M; Daoud, Y; Tessier, D

    2008-01-01

    This research has for object to study the influence of clay addition, i.e., Maghnian bentonite, like deposit clay, in the physical properties of sandy materials from Mostaganem plateau (North-West Algeria) submitted to salinity and sodicity. The first result was to show that the clay content changes drastically the physical properties of clay-sand mixtures. Important differences were observed as a function of the sand particle size distribution. At given clay content, the saturated Hydraulic Conductivity (HCs) was lower when the sand size was small and spread. For the coarse sand the salinity was maintained, even for high clay contents, a significant hydraulic conductivity. One of the main characteristics of Maghnia clay is the presence of calcium carbonates in the natural material. In comparison to that of Mostaganem clay of other deposit, it appears less sensitive to sodicity. An important aspect is the initial state of the clay when used in addition to sands, i.e., disturbance, conditions of preparation of sand clay mixtures and presence of associated components such as carbonates. Maghnia clay appeared to be adapted to the improvement of sandy soils, not because its mineralogical characteristics, but for its natural cationic form and obviously the presence of calcite in it. PMID:18819588

  17. Combating wind erosion of sandy soils and crop damage in the coastal deserts: Wind tunnel experiments

    NASA Astrophysics Data System (ADS)

    Genis, Arthur; Vulfson, Leonid; Ben-Asher, Jiftah

    2013-06-01

    In the western Negev desert of Israel frequent sandstorms cause heavy damage to young lettuce, carrot, peanut and potato plants during the planting season. The damage of plants is based mainly on the mechanical impact of saltating sand particles, which causes irreversible injuries to the plant leaves. Current agro-technique measures taken to prevent wind damage to crop in Israel are based on high frequency irrigation. Although the high-frequency irrigation helps bind soil particles together by forming a soil crust, it is associated with the large waste of water, which is not practical under the arid conditions. Application of polyacrylamide (PAM) as a chemical stabilizer has proved to be effective for prevention of soil erosion, saving irrigation water and a stable growth of plants in the early stages. Although the technique of PAM application is not yet used commercially in Israel, the preliminary studies suggested that it might have the potential to reduce the damage to the plant leaves by sandstorms, providing both environmental and agricultural benefits. In this study the effectiveness of PAM for preventing sandstorms in the western Negev was also investigated. Optimal concentration and volume of PAM solution per hectare of bare sandy soil were determined. For this purpose a wind tunnel was used to determine wind velocities of the first and continuous detachment of particles. The ability of PAM application to minimize the damage of plants by sandstorms was experimentally verified using image analysis tools.

  18. Plant uptake and soil retention of phthalic acid applied to Norfolk sandy loam

    SciTech Connect

    Dorney, J.R.; Weber, J.B.; Overcash, M.R.; Strek, H.J.

    1985-01-01

    Plant uptake and soil retention of /sup 14/C carboxyl-labeled phthalic acid were studied at application rates of 0.6, 6.0, 60.0, and 600.0 ppm (soil dry weight) to Norfolk sandy loam (Typic Paleudult, fine loamy, kaolinitic, thermic). Height and dry weight of corn (Zea mays L. Pioneer 3368A) (21 day), tall fescue (Festuca arundinacea Schreb. Kentucky 31) (45 day) immature soybean (Glycine max (L.) Merr. Altoona) (21 day) plant, mature soybean plant, and mature wheat (Triticum aestivum L. Butte) straw were not affected by phthalic acid applied to soil. In addition, soybean seed and wheat seed dry weight were unaffected. Immature wheat (40 day) height decreased at the 600 ppm rate. Plant uptake of phthalic acid ranged from 0 to 23 ppm and was significantly above background for all plants and plant materials except soybean pods. Fescue and immature plants exhibited the highest concentration of phthalic acid while mature wheat plants and wheat seeds exhibited the least. Most of the phthalic acid volatilized or was decomposed from the soil by the end of the study; an average of only 5.7% of the originally applied chemical was recovered in both soil or plants. An average of 0.02% of the originally applied phthalic acid leached out of the treated zone. Considering the low toxicity of phthalic acid and its relatively rapid disappearance from soil, it is unlikely to become a health hazard from contaminated plants. However, plant uptake of other toxic organics could potentially become a hazard on soils treated with sludge containing significant quantities of these substances.

  19. Dryland cropping systems influence microbial biomass and enzyme activities in a sandy soil in a semiarid region

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In dryland ecosystems, crop establishment is not always guaranteed because precipitation may not be sufficient at planting. Sandy soils under dryland agriculture in the Texas High Plains region of USA have extremely low organic matter (OM) content (< 1%) and thus, hold low water and nutrients to su...

  20. Fate of thiodicarb and its metabolite methomyl in sandy loam soil under laboratory conditions.

    PubMed

    Bisht, Sushma; Chauhan, Reena; Kumari, Beena; Singh, Rajvir

    2015-07-01

    Fate of thiodicarb and its major metabolite in sandy loam soil were studied by applying thiodicarb (Larvin 75 WP) at 500 and 1000 g a. i. ha(-1) under laboratory conditions. Samples drawn periodically were analysed on GC-FTD equipped with capillary column. The average initial deposits of total thiodicarb (thiodicarb and methomyl) were 0.025 and 0.035 mg kg(-1) at single and double dosages, respectively. Residues of thiodicarb reached below the determination level (BDL) of 0.005 mg kg(-1) after 15 days. Half-life periods for total thiodicarb were calculated to be 5.90 and 8.29 days at two doses, respectively, following first-order kinetics. PMID:26070994

  1. Wastewater effects on montmorillonite suspensions and hydraulic properties of sandy soils

    SciTech Connect

    Tarchitzky, J.; Golobati, Y.; Keren, R.; Chen, Y.

    1999-06-01

    Recycled wastewater effluent is an important source of irrigation water in arid and semiarid regions. In these regions, however, irrigation water quality is one of the main factors limiting plant growth. Wastewater effluents generally contain high concentrations of suspended and dissolved solids, both organic and inorganic. Inorganic dissolved solids are only minimally removed from the effluent during conventional sewage treatment. As a result, most of the salts added during domestic and industrial usage remain in the irrigation water and may eventually reach the soil. A number of researchers have reported reduced hydraulic conductivity for soils to which treated wastewater has been applied. In this research, the influence of dissolved organic matter (DOM) contained in reclaimed wastewater effluents on the flocculation of montmorillonite and on the hydraulic properties of soils was studied. Flocculation values (FVs) for Na-montmorillonite increased with increasing concentrations of DOM at all pH levels analyzed. Maximum FV levels were exhibited for Na-montmorillonite at the highest DOM concentrations. The effect of DOM on FV can be explained by the mechanisms of edge-charge reversal and mutual flocculation. The hydraulic conductivity (HC) of a sandy soil was determined in the laboratory by leaching columns with an electrolyte solution chemically similar to that of the wastewater effluent (but without DOM). In columns treated with wastewater effluent, the HC exhibited a sharp decrease to only 20% of its initial value. The adverse effect of DOM on HC was evident for this soil despite a relatively low exchangeable sodium percentage (ESP). The reduction in HC is likely to be the result of decreases soil pore-size, which reflects two processes: (1) retention of part of the DOM during water percolation; and (2) a change in pore-size distribution due to swelling and dispersion of clay particles. The latter may result from a higher percentage of adsorbed sodium combined

  2. Copper Accumulation, Availability and Adsorption Capacity in Sandy Soils of Vineyards with Different Cultivation Duration

    NASA Astrophysics Data System (ADS)

    Mallmann, F. J. K.; Miotto, A.; Bender, M. A.; Gubiani, E.; Rheinheimer, D. D. S.; Kaminski, J.; Ceretta, C. A.; Šimůnek, J.

    2015-12-01

    Bordeaux mixture is a copper-based (Cu) fungicide and bactericide applied in vineyards to control plant diseases. Since it is applied several times per year, it accumulates in large quantities on plants and in soil. This study evaluates the Cu accumulation in, and desorption kinetics and adsorption capability of a sandy Ultisol in a natural field and in 3 vineyards for 5 (V1), 11 (V2), and 31 (V3) years in South of Brazil. Soil samples were collected in 8 depths (0-60 cm) of all four soil profiles, which all displayed similar soil properties. The following soil properties were measured: pH, organic matter (OM), soil bulk density, Cu total concentration, and Cu desorption and adsorption curves. A two first-order reactions model and the Langmuir isotherm were fitted to the desorption and adsorption curves, respectively. An increase in the total mass of Cu in the vineyards followed a linear regression curve, with an average annual increase of 7.15 kg ha-1. Cu accumulated down to a depth of 5, 20, and 30 cm in V1, V2 and V3, respectively, with the highest Cu content reaching 138.4 mg kg-1 in the 0-5 cm soil layer of V3. Cu desorption parameters showed a high correlation with its total concentration. Approximately 57 and 19% of total Cu were immediately and slowly available, respectively, indicating a high potential for plant absorption and/or downward movement. Cu concentrations extracted by EDTA from soil layers not affected by anthropogenic Cu inputs were very low. The maximum Cu adsorption capacity of the 0-5 and 5-10 cm soil layers increased with the vineyard age, reaching concentrations higher than 900 mg kg-1. This increase was highly related to OM and pH, which both increased with cultivation duration. Despite of low clay content of these soils, there is low risk of groundwater Cu contamination for actual conditions. However, high Cu concentrations in the surface layer of the long-term vineyards could cause toxicity problems for this and for companion crops.

  3. Dissolved Organic Carbon Dynamics Along Terrestrial-aquatic Flowpaths in a Catchment Dominated by Sandy Soils

    NASA Astrophysics Data System (ADS)

    Wickland, K.; Walker, J. F.; Hood, K.; Butler, K. D.

    2015-12-01

    Aquatic systems receive significant amounts of terrestrially-derived dissolved organic carbon (DOC) from their watersheds. The amount and nature received depends on terrestrial carbon source strength, processing and losses of carbon during transport, and hydrologic connectivity between terrestrial and aquatic systems. While much research has been done on terrestrial DOC dynamics along terrestrial-aquatic flowpaths, there is still considerable uncertainty in many areas including the importance of different carbon sources, microbial metabolism and sorption of DOC, and processing of carbon in groundwater. Here we investigate DOC dynamics in soils, groundwater, and stream waters at the USGS Water, Energy, and Biogeochemical (WEBB) Program research site in northern Wisconsin. This site is well-suited for studying DOC dynamics as soils are sandy and homogenous with small DOC sorption potential, and previous work has characterized the hydrology of the region in detail. We collected water samples over two years from soil pit lysimeters along a series of hillslope transects, from shallow and deep groundwater wells, and from a first-order stream receiving these waters. We measured DOC concentration, DOC optical properties, and biodegradability of DOC. Combined with historical DOC and companion water chemistry data we characterize DOC generation and loss along the following flowpaths: 1) infiltration through the unsaturated zone to the groundwater table, 2) shallow groundwater flow, and 3) long groundwater flowpaths of different origin (lake-derived vs. terrestrial-derived water).

  4. Percolation and transport in a sandy soil under a natural hydraulic gradient

    USGS Publications Warehouse

    Green, C.T.; Stonestrom, D.A.; Bekins, B.A.; Akstin, K.C.; Schulz, M.S.

    2005-01-01

    [1] Unsaturated flow and transport under a natural hydraulic gradient in a Mediterranean climate were investigated with a field tracer experiment combined with laboratory analyses and numerical modeling. Bromide was applied to the surface of a sandy soil during the dry season. During the subsequent rainy season, repeated sediment sampling tracked the movement of bromide through the profile. Analysis of data on moisture content, matric pressure, unsaturated hydraulic conductivity, bulk density, and soil texture and structure provides insights into parameterization and use of the advective-dispersive modeling approach. Capturing the gross features of tracer and moisture movement with model simulations required an order-of-magnitude increase in laboratory-measured hydraulic conductivity. Wetting curve characteristics better represented field results, calling into question the routine estimation of hydraulic characteristics based only on drying conditions. Measured increases in profile moisture exceeded cumulative precipitation in early winter, indicating that gains from dew drip can exceed losses from evapotranspiration during periods of heavy ("Tule") fog. A single-continuum advective-dispersive modeling approach could not reproduce a peak of bromide that was retained near the soil surface for over 3 years. Modeling of this feature required slow exchange of solute at a transfer rate of 0.5-1 ?? 10-4 d-1 with an immobile volume approaching the residual moisture content.

  5. Controlled release fertilizer increased phytoremediation of petroleum-contaminated sandy soil.

    PubMed

    Cartmill, Andrew D; Cartmill, Donita L; Alarcón, Alejandro

    2014-01-01

    A greenhouse experiment was conducted to determine the effect of the application of controlled release fertilizer [(CRF) 0, 4,6, or 8 kg m(-3)] on Lolium multiflorum Lam. survival and potential biodegradation of petroleum hydrocarbons (0, 3000, 6000, or 15000 mg kg(-1)) in sandy soil. Plant adaptation, growth, photosynthesis, total chlorophyll, and proline content as well as rhizosphere microbial population (culturable heterotrophic fungal and bacterial populations) and total petroleum hydrocarbon (TPH)-degradation were determined. Petroleum induced-toxicity resulted in reduced plant growth, photosynthesis, and nutrient status. Plant adaptation, growth, photosynthesis, and chlorophyll content were enhanced by the application of CRF in contaminated soil. Proline content showed limited use as a physiological indicator of petroleum induced-stress in plants. Bacterial and filamentous fungi populations were stimulated by the petroleum concentrations. Bacterial populations were stimulated by CRF application. At low petroleum contamination, CRF did not enhance TPH-degradation. However, petroleum degradation in the rhizosphere was enhanced by the application of medium rates of CRF, especially when plants were exposed to intermediate and high petroleum contamination. Application of CRF allowed plants to overcome the growth impairment induced by the presence of petroleum hydrocarbons in soils. PMID:24912225

  6. [Correlation Among Soil Organic Carbon, Soil Inorganic Carbon and the Environmental Factors in a Typical Oasis in the Southern Edge of the Tarim Basin].

    PubMed

    Gong, Lu; Zhu, Mei-ling; Liu, Zeng-yuan; Zhang, Xue-ni; Xie, Li-na

    2016-04-15

    We analyzed the differentiation among the environmental factors and soil organic/inorganic carbon contents of irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil by classical statistics methods, and studied the correlation between soil carbon contents and the environmental factor by redundancy analysis (RDA) in a typical oasis of Yutian in the southern edge of the Tarim Basin. The results showed that the average contents of soil organic carbon and soil inorganic carbon were 2.51 g · kg⁻¹ and 25.63 g · kg⁻¹ respectively. The soil organic carbon content of the irrigated desert soil was significantly higher than those of brown desert soil, saline soil and aeolian sandy soil, while the inorganic carbon content of aeolian sandy soil was significantly higher than those of other soil types. The soil moisture and nutrient content were the highest in the irrigated desert soil and the lowest in the aeolian sandy sail. All soil types had high degree of salinization except the irrigated desert soil. The RDA results showed that the impacts of environmental factors on soil carbon contents ranked in order of importance were total nitrogen > available phosphorus > soil moisture > ground water depth > available potassium > pH > total salt. The soil carbon contents correlated extremely significantly with total nitrogen, available phosphorus, soil moisture and ground water depth (P < 0.01), and it correlated significantly with available potassium and pH (P < 0.05). There was no significant correlation between soil carbon contents and other environmental factors (P > 0.05). PMID:27548977

  7. Patterns and possible mechanisms of soil CO2 uptake in sandy soil.

    PubMed

    Fa, Ke-Yu; Zhang, Yu-Qing; Wu, Bin; Qin, Shu-Gao; Liu, Zhen; She, Wei-Wei

    2016-02-15

    It has been reported that soils in drylands can absorb CO2, although the patterns and mechanisms of such a process remain under debate. To address this, we investigated the relationships between soil CO2 flux and meteorological factors and soil properties in Northwest China to reveal the reasons for "anomalous" soil CO2 flux in a desert ecosystem. Soil CO2 flux increased significantly and exponentially with surficial turbulence at the diel scale under dry conditions (P<0.05), whereas the relationship under wet conditions was insignificant. Furthermore, soil CO2 flux demonstrated remarkable negative correlation with soil air pressure (P<0.05) in both dry and wet conditions. Analysis considering Henry's Law indicated that soil water content was insufficient to dissolve the absorbed CO2 in dry conditions, but was sufficient in wet conditions. The concentration of soil HCO3(-) in the morning was higher than in the evening in dry conditions, but this pattern was reversed in wet conditions. These results imply that CO2 outgassing induced by turbulence, expansion of soil air, CO2 effusion from soil water, and carbonate precipitation during daytime can explain the abiotic diurnal CO2 release. Moreover, CO2 pumping from the atmosphere into the soil, caused mainly by carbonate dissolution, can account for nocturnal CO2 absorption in dry conditions. The abiotic soil CO2 flux pattern (CO2 absorption throughout the diel cycle) in wet conditions can be attributed to downward mass flow of soil CO2 and intensified soil air shrinkage, CO2 dissolving in soil water, and carbonate dissolution. These results provide a basis for determining the location of abiotic fixed carbon within soils in desert ecosystems. PMID:26674687

  8. Stability Behavior and Thermodynamic States of Iron and Manganese in Sandy Soil Aquifer, Manukan Island, Malaysia

    SciTech Connect

    Lin, Chin Yik; Abdullah, Mohd. Harun; Musta, Baba; Praveena, Sarva Mangala; Aris, Ahmad Zaharin

    2011-03-15

    A total of 20 soil samples were collected from 10 boreholes constructed in the low lying area, which included ancillary samples taken from the high elevation area. Redox processes were investigated in the soil as well as groundwater in the shallow groundwater aquifer of Manukan Island, Sabah, Malaysia. Groundwater samples (n = 10) from each boreholes were also collected in the low lying area to understand the concentrations and behaviors of Fe and Mn in the dissolved state. This study strives to obtain a general understanding of the stability behaviors on Fe and Mn at the upper unsaturated and the lower-saturated soil horizons in the low lying area of Manukan Island as these elements usually play a major role in the redox chemistry of the shallow groundwater. Thermodynamic calculations using PHREEQC showed that the groundwater samples in the study area are oversaturated with respect to goethite, hematite, Fe(OH){sub 3} and undersaturated with respect to manganite and pyrochroite. Low concentrations of Fe and Mn in the groundwater might be probably due to the lack of minerals of iron and manganese oxides, which exist in the sandy aquifer. In fact, high organic matters that present in the unsaturated horizon are believed to be responsible for the high Mn content in the soil. It was observed that the soil samples collected from high elevation area (BK) comprises considerable amount of Fe in both unsaturated (6675.87 mg/kg) and saturated horizons (31440.49 mg/kg) compared to the low Fe content in the low lying area. Based on the stability diagram, the groundwater composition lies within the stability field for Mn{sup 2+} and Fe{sup 2+} under suboxic condition and very close to the FeS/Fe{sup 2+} stability boundary. This study also shows that both pH and Eh values comprise a strong negative value thus suggesting that the redox potential is inversely dependent on the changes of pH.

  9. Phosphorus leaching in sandy outwash soils following potato-processing wastewater application.

    PubMed

    Zvomuya, Francis; Gupta, Satish C; Rosen, Carl J

    2005-01-01

    Land application of wastewater presents potential for ground water pollution if not properly managed. In situ breakthrough tests were conducted using potato (Solanum tuberosum L.)-processing wastewater and a Br tracer to characterize P leaching in seasonally frozen sandy outwash soils. In the first test, P and Br breakthrough were measured in a 7-m deep well following wastewater [2.94 mg L(-1) total P (TP); 280 mg L(-1) Br] application at the site that had 13.1 mg water-extractable P (WEP) kg(-1)and 94.4 mg Bray-1 P kg(-1). Bromide was detected in the well after approximately 0.4 pore volumes, but there was no P break-through after 7 pore volumes. In the second breakthrough test, wastewater containing 3.6 mg L(-1) TP and 259 mg L(-1) Br was applied on 1.5-m deep lysimeters at low (0.8 mg WEP kg(-1); 12.1 mg Bray-1 P kg(-1)) and high soil test P sites (104 mg WEP kg(-1); 585 mg Bray-1 P kg(-1)). Leachate TP concentration during the test remained constant (0.04 mg L(-1)) at the low P sites but increased from approximately 3.5 to 5.6 mg L(-1) at the high P sites. These results indicate no P leaching in low P soils, but leaching in high P soils, thus suggesting that most of the P leached at the high P sites was mainly due to desorption and dissolution of weakly adsorbed P from prior P applications. This was consistent with P transport simulations using the convective-dispersive equation. We conclude that P concentration in land-applied wastewater should be regulated based on soil test-P level plus wastewater P loading. PMID:15998849

  10. PCDD/PCDF behavior in low-temperature pyrolysis of PCP-contaminated sandy soil.

    PubMed

    Thuan, Ngo Thi; Dien, Nguyen Thanh; Chang, Moo Been

    2013-01-15

    This study investigates the behavior of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) formation, dechlorination and destruction in PCP-contaminated sandy soil by low-temperature thermal treatment. Experimental tests were carried out in a nitrogen atmosphere in the temperature range of 200-400 °C with a treatment time of 30 min. 70% of PCP removal from the soil was achieved, resulting in 1436±230 ng/kg, the highest PCDD/F formation at 250 °C; however, the highest toxic concentration was measured around 4.20±0.62 ng TEQ/kg at 300 °C with 80% PCP removal from the soil. Further analysis has revealed that OCDD is the most dominant congener that is supposed to be formed from the pyrolysis of PCP, while OCDF is the second prevailing congener, possibly due to pyrolysis of 2,3,4,5-TeCP being a main byproduct of PCP pyrolysis. Detection of less chlorinated dioxins and furans over 300 °C indicates the dechlorination of highly chlorinated dioxins and furans, especially octachlorinated dibenzo-p-dioxin (OCDD) at 350 °C and 400 °C. Desorption from soil was supposed as a main mechanism for the distribution of PCDD/Fs in the gaseous phase, and not much difference in dioxins and furan levels was observed at 350 °C and 400 °C in the gaseous phase. Therefore, 350 °C is the most appropriate temperature to remove most PCP and PCDD/Fs from soil, as well as to meet PCDD/F emission standards (0.1 ng I-TEQ/Nm(3)). PMID:23220751

  11. Characterization of biomass residues and their amendment effects on water sorption and nutrient leaching in sandy soil.

    PubMed

    Wang, Letian; Tong, Zhaohui; Liu, Guodong; Li, Yuncong

    2014-07-01

    In this study, we evaluated the efficiency of two types of biomass residues (fermentation residues from a bioethanol process, FB; brown mill residues from a papermaking process, BM) as amendments for a sandy soil. The characteristics of these residues including specific surface areas, morphologies and nutrient sorption capacity were measured. The effects of biorefinery residues on water and nutrient retention were investigated in terms of different particle sizes and loadings. The results indicated that bio-based wastes FB and BM were able to significantly improve water and nutrient retention of sandy soil. The residues with larger surface areas had better water and nutrient retention capability. Specifically, in the addition of 10% loading, FB and BM was able to improve water retention by approximately 150% and 300%, while reduce 99% of ammonium and phosphate concentration in the leachate compare to the soil control, respectively. PMID:24529394

  12. Quasi 3D modelling of water flow in the sandy soil

    NASA Astrophysics Data System (ADS)

    Rezaei, Meisam; Seuntjens, Piet; Joris, Ingeborg; Boënne, Wesley; De Pue, Jan; Cornelis, Wim

    2016-04-01

    Monitoring and modeling tools may improve irrigation strategies in precision agriculture. Spatial interpolation is required for analyzing the effects of soil hydraulic parameters, soil layer thickness and groundwater level on irrigation management using hydrological models at field scale. We used non-invasive soil sensor, a crop growth (LINGRA-N) and a soil hydrological model (Hydrus-1D) to predict soil-water content fluctuations and crop yield in a heterogeneous sandy grassland soil under supplementary irrigation. In the first step, the sensitivity of the soil hydrological model to hydraulic parameters, water stress, crop yield and lower boundary conditions was assessed after integrating models at one soil column. Free drainage and incremental constant head conditions were implemented in a lower boundary sensitivity analysis. In the second step, to predict Ks over the whole field, the spatial distributions of Ks and its relationship between co-located soil ECa measured by a DUALEM-21S sensor were investigated. Measured groundwater levels and soil layer thickness were interpolated using ordinary point kriging (OK) to a 0.5 by 0.5 m in aim of digital elevation maps. In the third step, a quasi 3D modelling approach was conducted using interpolated data as input hydraulic parameter, geometric information and boundary conditions in the integrated model. In addition, three different irrigation scenarios namely current, no irrigation and optimized irrigations were carried out to find out the most efficient irrigation regime. In this approach, detailed field scale maps of soil water stress, water storage and crop yield were produced at each specific time interval to evaluate the best and most efficient distribution of water using standard gun sprinkler irrigation. The results show that the effect of the position of the groundwater level was dominant in soil-water content prediction and associated water stress. A time-dependent sensitivity analysis of the hydraulic

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

    NASA Astrophysics Data System (ADS)

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

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

  14. Solute transport modeling under cultivated sandy soils and transient water regime.

    PubMed

    Gasser, M O; Caron, J; Laverdière, M R; Lagacé, R

    2002-01-01

    Drainable lysimeters offer the possibility to integrate heterogeneous solute leaching conditions caused by row crops and transient water regime, and to conveniently measure water and solute fluxes at the drainage outlet. To compare solute leaching behavior in and around drainable lysimeters operating under a transient water regime in potato (Solanum tuberosum L.) fields, parameters of the convective lognormal transfer (CLT) function model were fitted using bromide (Br-) flux concentrations (Cf) measured in lysimeters and from Br- resident concentrations (Cr) measured in adjacent soil cores. Expected mean values Ez(I) obtained from Cr and Cf CLT parameters were equivalent and well correlated (R2 = 0.78). However, estimated median values mu of the CLT function were smaller when derived from Cr (1.05 to 1.28) compared with Cf (1.23 to 2.14). Most mu values were also smaller than previously reported values for a 30-cm reference depth, indicating that 50% of solute mass would leach more readily in these coarse sandy soils. Higher variance and dispersion of Cr compared with those of Cf could be related to a smaller sampling support (sample size/sampling area) in the case of Cr measured by soil coring, or to disruption of solute transport mechanisms in the repacked lysimeter. Retained Br- in the top soil layer after 12 to 17 cm of cumulative drainage was indicated by measured Cr. Neither CLT function simulated well residual topsoil Cr values, indicating that Br- plant cycling or preferential flow probably interfered even though tuber Br- uptake was relatively small. PMID:12371192

  15. The nematicidal effect of some bacterial biofertilizers on Meloidogyne incognita in sandy soil

    PubMed Central

    El-Hadad, M.E.; Mustafa, M.I.; Selim, Sh.M.; El-Tayeb, T.S.; Mahgoob, A.E.A.; Abdel Aziz, Norhan H.

    2011-01-01

    In a greenhouse experiment, the nematicidal effect of some bacterial biofertilizers including the nitrogen fixing bacteria (NFB) Paenibacillus polymyxa (four strains), the phosphate solubilizing bacteria (PSB) Bacillus megaterium (three strains) and the potassium solubilizing bacteria (KSB) B. circulans (three strains) were evaluated individually on tomato plants infested with the root-knot nematode Meloidogyne incognita in potted sandy soil. Comparing with the uninoculated nematode-infested control, the inoculation with P. polymyxa NFB7, B. megaterium PSB2 and B. circulans KSB2, increased the counts of total bacteria and total bacterial spores in plants potted soil from 1.2 to 2.6 folds estimated 60 days post-inoculation. Consequently, the inoculation with P. polymyxa NFB7 increased significantly the shoot length (cm), number of leaves / plant, shoot dry weight (g) / plant and root dry weight (g) / plant by 32.6 %, 30.8 %, 70.3 % and 14.2 %, respectively. Generally, the majority treatments significantly reduced the nematode multiplication which was more obvious after 60 days of inoculation. Among the applied strains, P. polymyxa NFB7, B. megaterium PSB2 and B. circulans KSB2 inoculations resulted in the highest reduction in nematode population comparing with the uninoculated nematode-infested control. They recorded the highest reduction in numbers of hatched juveniles/root by 95.8 %, females/root by 63.75 % and juveniles/1kg soil by 57.8 %. These results indicated that these bacterial biofertilizers are promising double purpose microorganisms for mobilizing of soil nutrients (nitrogen, phosphate and potassium) and for the biological control of M. incognita. PMID:24031611

  16. Quantifying aeolian soil loss after forest conversion in the Chaco ecoregion

    NASA Astrophysics Data System (ADS)

    Sperl, Daniel; Veerle, Vanacker; Tibor, Dunai

    2016-04-01

    The Chaco ecoregion (NW Argentina) is characterized by the highest forest loss rates worldwide, as a result of agricultural expansion at agro-industrial scale. The conversion of dry forests to agricultural plots enhances the soil erosion vulnerability by exposure of bare soil after deforestation. The unconsolidated loess-type sediments are particularly susceptible to wind erosion during the prolonged dry season. In this study, the role of land use and management on soil erosion will be analysed. All investigated plots are characterized by flat topography. For this reason it is very likely that observed soil losses will be largely due to wind erosion, since such low gradients are not amenable to efficient water erosion. We hypothesise that changes in land use have a high impact on the mobilization of sediments in the Chaco ecoregion. We posit that a transformation from forest into crop/rangelands, will lead to enhanced mobilization of sediments by wind, whereas the establishment of no-tillage farming in this region might slow translocation rates down to near natural levels. Within this study we are using fallout radionuclides - a product of the atmospheric nuclear weapon testing era of the 1950s and 1960s - to investigate the impacts of wind erosion. This is possible since the used fallout radionuclides Plutonium (239+240Pu) and Caesium (137Cs) predominantly bind on small particle sizes, which can be transported by wind. Based on soil samples taken in three individual study regions, we examined the losses of fallout radionuclide inventories, from six agricultural plots per region, differing only in cultivation time (0-39 years). To gauge local fallout input, we further sampled two adjacent reference sites - so called stable surface - in each study region. For this study we measured the remaining activities of the radionuclide pair 239+240Pu via AMS and of 137Cs using a γ-spectrometer. The results for both radionuclides suggest that > 25 % of the initial inventory

  17. Exploring the potential of near-surface geophysical methods to delineate a shallow hardpan in a southeastern U.S. sandy coastal plain soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A hardpan, which is a dense soil layer near the ground surface, is an undesirable feature of many soils in the Southeast U.S., especially sandy Coastal Plain soils. Shallow hardpans restrict root growth and water penetration through the soil profile, in turn reducing the effective crop root zone and...

  18. Field Performance of Nine Soil Water Content Sensors on a Sandy Loam Soil in New Brunswick, Maritime Region, Canada

    PubMed Central

    Chow, Lien; Xing, Zisheng; Rees, Herb W.; Meng, Fanrui; Monteith, John; Stevens, Lionel

    2009-01-01

    An in situ field test on nine commonly-used soil water sensors was carried out in a sandy loam soil located in the Potato Research Center, Fredericton, NB (Canada) using the gravimetric method as a reference. The results showed that among the tested sensors, regardless of installation depths and soil water regimes, CS615, Trase, and Troxler performed the best with the factory calibrations, with a relative root mean square error (RRMSE) of 15.78, 16.93, and 17.65%, and a r2 of 0.75, 0.77, and 0.65, respectively. TRIME, Moisture Point (MP917), and Gopher performed slightly worse with the factory calibrations, with a RRMSE of 45.76, 26.57, and 20.41%, and a r2 of 0.65, 0.72, and 0.78, respectively, while the Gypsum, WaterMark, and Netafim showed a frequent need for calibration in the application in this region. PMID:22291570

  19. Field performance of nine soil water content sensors on a sandy loam soil in new brunswick, maritime region, Canada.

    PubMed

    Chow, Lien; Xing, Zisheng; Rees, Herb W; Meng, Fanrui; Monteith, John; Stevens, Lionel

    2009-01-01

    An in situ field test on nine commonly-used soil water sensors was carried out in a sandy loam soil located in the Potato Research Center, Fredericton, NB (Canada) using the gravimetric method as a reference. The results showed that among the tested sensors, regardless of installation depths and soil water regimes, CS615, Trase, and Troxler performed the best with the factory calibrations, with a relative root mean square error (RRMSE) of 15.78, 16.93, and 17.65%, and a r(2) of 0.75, 0.77, and 0.65, respectively. TRIME, Moisture Point (MP917), and Gopher performed slightly worse with the factory calibrations, with a RRMSE of 45.76, 26.57, and 20.41%, and a r(2) of 0.65, 0.72, and 0.78, respectively, while the Gypsum, WaterMark, and Netafim showed a frequent need for calibration in the application in this region. PMID:22291570

  20. Long-Term Observations of Dust Storms in Sandy Desert Environments

    NASA Astrophysics Data System (ADS)

    Yun, Hye-Won; Kim, Jung-Rack; Choi, Yun-Soo

    2015-04-01

    Mineral dust occupies the largest portion of atmospheric aerosol. Considering the numerous risks that dust poses for socioeconomic and anthropogenic activities, it is crucial to understand sandy desert environments, which frequently generate dust storms and act as a primary source of atmospheric aerosol. To identify mineral aerosol mechanisms, it is essential to monitor desert environmental factors involving dust storm generation in the long term. In this study, we focused on two major environmental factors: local surface roughness and soil moisture. Since installments of ground observation networks in sandy deserts are unfeasible, remote sensing techniques for mining desert environmental factors were employed. The test area was established within the Badain Jaran and Kubuqi Deserts in Inner Mongolia, China, where significant seasonal aeolian processes emit mineral dust that influences all of East Asia. To trace local surface roughness, we employed a multi-angle imaging spectroradiometer (MISR) image sequence to extract multi-angle viewing (MAV) topographic parameters such as normalized difference angular index, which represents characteristics of the target desert topography. The backscattering coefficient from various space-borne SAR and stereotopography were compared with MAV observations to determine calibrated local surface roughness. Soil moisture extraction techniques from InSAR-phase coherence stacks were developed and compiled with advanced scatterometer (ASCAT) soil moisture data. Combined with metrological information such as the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA interim, correlations between intensity of sand dune activity as a proxy of aeolian processes in desert environments, surface wind conditions, and surface soil moisture were traced. Overall, we have confirmed that tracking sandy desert aeolian environments for long-term observations is feasible with space-borne, multi-sensor observations when combined with

  1. Effect of biochar and compost application on quantity, quality and stability of organic carbon in sandy soil

    NASA Astrophysics Data System (ADS)

    Holes, Annamaria; Szegi, Tamas; Fuchs, Marta; Micheli, Erika; Aleksza, Laszlo

    2014-05-01

    Nowadays the amount of waste is increasing as a consequence of civilization development. Significant proportion of municipal waste is biodegradable. For the treatment of these wastes composting and pyrolysis can be one solution. Many studies were published on the effects of composts in soils, but on combined application of biochars and composts only a limited number of articles are available. Total carbon content, water soluble organic carbon content and organic matter quality have decisive role in the utilization of soils. In our study the effects of combined application of biochars and compost on organic carbon quality, quantity and stability were measured in sandy soil. The sandy soil was mixed with different proportions (1w/w%, 2,5w/w%, 5w/w%, 10w/w%) of biochars. Two types of biochars produced by pyrolization were used: plant origin biochar (POB) and animal origin biochar (AOB). 20w/w% urban green compost was mixed into each sample in addition to biochars. After the 30 days of wet incubation soil organic carbon (SOC) content was determined by Walkley-Black method, while for the SOC quality measurements E4/E6 method was used. The dissolved organic carbon (DOC) was extracted from the soil samples by cold water, and determined by titrimetric method. The future purpose of our study is to find the optimal compost-biochar treatment in order to improve soil fertility and maximize crop yield.

  2. Irrigation and fertigation scheduling under drip irrigation for maize crop in sandy soil

    NASA Astrophysics Data System (ADS)

    Ibrahim, Mahmoud M.; El-Baroudy, Ahmed A.; Taha, Ahmed M.

    2016-01-01

    Field experiments was conducted to determine the best irrigation scheduling and the proper period for injecting fertilizers through drip irrigation water in a sandy soil to optimize maize yield and water productivity. Four irrigation levels (0.6, 0.8, 1.0 and 1.2) of the crop evapotranspiration and two fertigation periods (applying the recommended fertilizer dose in 60 and 80% of the irrigation time) were applied in a split-plot design, in addition to a control treatment which represented conventional irrigation and fertilization of maize in the studied area. The results showed that increasing the irrigation water amount and the fertilizer application period increased vegetative growth and yield. The highest grain yield and the lowest one were obtained under the treatment at 1.2 and of 0.6 crop evapotranspiration, respectively. The treatment at 0.8 crop evapotranspiration with fertilizer application in 80% of the irrigation time gave the highest water productivity (1.631 kg m-3) and saved 27% of the irrigation water compared to the control treatment. Therefore, this treatment is recommended to irrigate maize crops because of the water scarcity conditions of the studied area.

  3. Soil water repellency patterns following long-term irrigation with waste water in a sandy calcareous soil, SE Spain

    NASA Astrophysics Data System (ADS)

    Mataix-Solera, J.; García-Irles, L.; Morugán, A.; Doerr, S. H.; García-Orenes, F.; Atanassova, I.; Navarro, M. A.; Ayguadé, H.

    2009-04-01

    One of the consequences of long-term irrigation with waste water can be the development of soil water repellency (WR). Its emergence can affect soil-water balance, irrigation efficiency and crop yield. Water repellency development has been suggested to be controlled by parameters such as organic matter quantity and type present in the waste water, soil properties (particularly the texture), and the overall time period of irrigation. Here we examine the effect of long-term (~20 years) irrigation with low quality waste-water on soil wettability under a Populus alba tree stand used as a "green filter". The plot exhibited considerable micro-topography (ridges and furrows) and consisted of sandy calcareous soil (Xerofluvent). Water repellency and organic carbon content (OC) were studied in 160 samples taken from the plot and from an adjacent area used as control (no irrigated). From the control area 40 samples were taken from the first 5 cm of mineral soil (C samples). From the irrigated plot a total of 120 samples were collected. To account for the micro-topography of the terrain, 40 samples each were taken from ridges (R samples; 0-5 cm depth), furrows (F samples; 0-5 cm depth), and from furrows at depth (FD samples, 5-10 cm depth). Soil WR was assessed in the laboratory for all air dry samples using the water drop penetration time test (WDPT Test). Samples with WDPT ? 5 seconds were classified as non-repellent. Organic carbon content (OC) was analyzed in all samples by potassium dichromate oxidation method. We also carried out a detailed chemical characterisation of the organic matter in two furrow samples that exhibited contrasting wettability, but no major difference in OC content (F10: WDPT 9960s, OC 6.7%; F31: WDPT 10s, OC 7.5%). Following accelerated solvent extraction with Dichloro-methane/MeOH (95:5), the extract was analysed by GC-MS. All samples from the control area (C) were wettable (mean WDPT=1s). In the irrigated plot, water repellency was present for 48

  4. Fundamental properties of soils for complex dynamic loadings: Dynamic constitutive modeling of sandy soils

    NASA Astrophysics Data System (ADS)

    Dass, W.; Merkle, D. H.; Bratton, J. L.

    1983-04-01

    Constitutive modeling of cohesionless soil for both standard static test conditions and insitu impulsive dynamic load conditions is discussed in this annual report. Predicted laboratory response for several different types of models is evaluated using data from a coordinated testing program. The modeling of insitu soil response to explosive events (CIST and DISC Test) is considered, and the laboratory-derived models are tested for their convenience and accuracy in predicting ground motions. Several important laboratory and insitu phenomena which were not reflected by the model exercises are discussed. Based on the conclusions from this study, testing and modeling requirements for dynamic loading situations are proposed.

  5. Effect of biochar amendment on sorption and leaching of nitrate, ammonium, and phosphate in a sandy soil.

    PubMed

    Yao, Ying; Gao, Bin; Zhang, Ming; Inyang, Mandu; Zimmerman, Andrew R

    2012-11-01

    When applied to soils, it is unclear whether and how biochar can affect soil nutrients. This has implications both to the availability of nutrients to plants or microbes, as well as to the question of whether biochar soil amendment may enhance or reduce the leaching of nutrients. In this work, a range of laboratory experiments were conducted to determine the effect of biochar amendment on sorption and leaching of nitrate, ammonium, and phosphate in a sandy soil. A total of thirteen biochars were tested in laboratory sorption experiments and most of them showed little/no ability to sorb nitrate or phosphate. However, nine biochars could remove ammonium from aqueous solution. Biochars made from Brazilian pepperwood and peanut hull at 600°C (PH600 and BP600, respectively) were used in a column leaching experiment to assess their ability to hold nutrients in a sandy soil. The BP600 biochar effectively reduced the total amount of nitrate, ammonium, and phosphate in the leachates by 34.0%, 34.7%, and 20.6%, respectively, relative to the soil alone. The PH600 biochar also reduced the leaching of nitrate and ammonium by 34% and 14%, respectively, but caused additional phosphate release from the soil columns. These results indicate that the effect of biochar on the leaching of agricultural nutrients in soils is not uniform and varies by biochar and nutrient type. Therefore, the nutrient sorption characteristics of a biochar should be studied prior to its use in a particular soil amendment project. PMID:22763330

  6. No-tillage lessens soil CO2 emissions the most under arid and sandy soil conditions: results from a meta-analysis

    NASA Astrophysics Data System (ADS)

    Abdalla, Khatab; Chivenge, Pauline; Ciais, Philippe; Chaplot, Vincent

    2016-06-01

    The management of agroecosystems plays a crucial role in the global carbon cycle with soil tillage leading to known organic carbon redistributions within soils and changes in soil CO2 emissions. Yet, discrepancies exist on the impact of tillage on soil CO2 emissions and on the main soil and environmental controls. A meta-analysis was conducted using 46 peer-reviewed publications totaling 174 paired observations comparing CO2 emissions over entire seasons or years from tilled and untilled soils across different climates, crop types and soil conditions with the objective of quantifying tillage impact on CO2 emissions and assessing the main controls. On average, tilled soils emitted 21 % more CO2 than untilled soils, which corresponded to a significant difference at P<0.05. The difference increased to 29 % in sandy soils from arid climates with low soil organic carbon content (SOCC < 1 %) and low soil moisture, but tillage had no impact on CO2 fluxes in clayey soils with high background SOCC (> 3 %). Finally, nitrogen fertilization and crop residue management had little effect on the CO2 responses of soils to no-tillage. These results suggest no-tillage is an effective mitigation measure of carbon dioxide losses from dry land soils. They emphasize the importance of including information on soil factors such as texture, aggregate stability and organic carbon content in global models of the carbon cycle.

  7. Degradation and sorption of metribuzin and primary metabolites in a sandy soil.

    PubMed

    Henriksen, Trine; Svensmark, Bo; Juhler, René K

    2004-01-01

    Leaching to the ground water of metabolites from the herbicide metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5-one] has been measured in a Danish field experiment in concentrations exceeding the European Union threshold limit for pesticides at 0.1 microg/L. In the present work, degradation and sorption of metribuzin and the metabolites desamino-metribuzin (DA), diketo-metribuzin (DK), and desamino-diketo-metribuzin (DADK) were studied in a Danish sandy loam topsoil and subsoil from the field in question, using accelerated solvent extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Fast dissipation of metribuzin and the metabolites was observed in the topsoil, with 50% disappearance within 30 to 40 d. A two-compartment model described degradation of metribuzin and DA, whereas that of DADK could be described using first-order kinetics. Part of the dissipation was probably due to incorporation into soil organic matter. Degradation in subsoil occurred very slowly, with extrapolated half-lives of more than one year. Sorption in the topsoil followed the order DA > metribuzin > DK > DADK. Subsoil sorption was considerably lower, and was hardly measurable for metribuzin and DK. Abiotic degradation was considerably higher in the topsoil than the subsoil, especially concerning the de-amination step, indicating that organic matter may be related to the degradation process. The present results confirm observations of metribuzin and transformation product leaching made in the field experiment and demonstrate the need for knowledge on primary metabolites when assessing the risk for pesticide leaching. PMID:15074814

  8. Using Biochar composts for improving sandy vineyard soils while reducing the risk of

    NASA Astrophysics Data System (ADS)

    Kammann, Claudia; Mengel, Jonathan; Mohr, Julia; Muskat, Stefan; Schmidt, Hans-Peter; Löhnertz, Otmar

    2016-04-01

    In recent years, biochar has increasingly been discussed as an option for sustainable environmentalmanagement, combining C sequestration with the aim of soil fertility improvement. Biochar has shownpositive effects in viticulture before (Genesio et al. 2015) which were largely attributed to improved water supply to the plants. However, in fertile temperate soils, the use of pure, untreated biochar does not guarantee economic benefits on the farm level (Ruysschaert et al., 2016). Hence, recent approaches started introducing biochar in management of nutrient-rich agricultural waste, e.g. in compost production (Kammann et al. 2015). Compost is frequently used in German vineyards for humus buildup and as a slow-release organic fertilizer. This, and increasingly mild, precipitation-rich winters, promoting mineralization, increase the risk of unwanted nitrate leaching losses into surface and ground waters during winter. To investigate if biochar pure, or biochar-compost mixtures and -products may have the potential to reduce nitrate leaching, we set up the following experiment: Either 30 or 60 t ha-1 of the following additives were mixed into the top 30 cm of sandy soil in large (120 L) containers, and planted with oneRiesling grapevine (Clone 198-30 GM) per container: Control (no addition), pure woody biochar, pure compost, biochar-compost (produced from the same organic feedstock than the compost, with 20 vol. - % of a woody biochar added), and pure compost plus pure biochar (same mixing ratio as in the former product). Once monthly, containers were exposed to simulated heavy rainfall that caused drainage. Leachates were collected from an outlet at the bottom of the containers, and analyzed for nutrients. The nutrient-rich additives containing compost all improved grape biomass and yield, most markedly pure compost and biochar-compost; same amendments were not significantly different. However,while the addition of the lower amount (30 t ha-1) of compost reduced nitrate

  9. Effects of fertilizer application to sweet corn (Zea mays.) grown on sandy soil.

    PubMed

    Orosz, Ferenc; Jakab, Samuel; Losak, Tomas; Slezak, Katalin

    2009-11-01

    In our experiment we tried to find out what kind of eventual changes in the environment and in plant chemical composition occurred in response to different fertilizer treatments applied to sweet corn (Zea mays convar. saccharata) grown on sandy soil with low humus content. The ploughed layer contained <1% CaCO3 and around 1% humus. The soil was very well supplied with P, well supplied with K, Mg, Mn and Cu, and weakly supplied with N and Ca. The treatments were planned in accordance with the recommendations, with a planned unhusked ear yield of 16 tons per hectare, of the new environmental friendly advisory system recently elaborated for field vegetable crops in Hungary. The treatments applied included: G1 (blank control)(N0P0K0), G2(N222.5P22.2K143), G3(N445 P22.5 K143), G4(N222.5 P22.5K143), G5(N222.5P22.5 K286), G6(N222.5 P22.5 K143) + Mg(1.52). According to our findings, of the composition parameters of the grains of the treatments with no fertilizer application, the invert and reducing sugar contents (4.42%, respectively 2.59% relative to fresh weight(-1)) in grains were the highest among the treatments. The same conclusion was drawn on the K 120.2, Mg 13.3, Fe 0.24, Cu 0.66 mg 100 g(-1) grain dry weight levels among minerals. In the case of the basic treatment (G2) recommended by the advisory system we obtained favourable results for the measured parameters, including yields. Invert and reducing sugar contents were (3.26% respectively 1.97% relative to fresh weight(-1)), and mineral contents K 101.9; Mg 11.8; Fe 0.21; Cu 0.56 mg 100 g(-1) dry weight. In the grains, no translocation of toxic elements was observed in response to the direct or indirect effect of the treatments. PMID:20329385

  10. Factors driving the carbon mineralization priming effect in a sandy loam soil amended with different types of biochar

    NASA Astrophysics Data System (ADS)

    Cely, P.; Tarquis, A. M.; Paz-Ferreiro, J.; Méndez, A.; Gascó, G.

    2014-06-01

    The effect of biochar on the soil carbon mineralization priming effect depends on the characteristics of the raw materials, production method and pyrolysis conditions. The goal of the present study is to evaluate the impact of three different types of biochar on physicochemical properties and CO2 emissions of a sandy loam soil. For this purpose, soil was amended with three different biochars (BI, BII and BIII) at a rate of 8 wt% and soil CO2 emissions were measured for 45 days. BI is produced from a mixed wood sieving from wood chip production, BII from a mixture of paper sludge and wheat husks and BIII from sewage sludge. Cumulative CO2 emissions of biochars, soil and amended soil were well fit to a simple first-order kinetic model with correlation coefficients (r2) greater than 0.97. Results show a negative priming effect in the soil after addition of BI and a positive priming effect in the case of soil amended with BII and BIII. These results can be related to different biochar properties such as carbon content, carbon aromaticity, volatile matter, fixed carbon, easily oxidized organic carbon or metal and phenolic substance content in addition to surface biochar properties. Three biochars increased the values of soil field capacity and wilting point, while effects over pH and cation exchange capacity were not observed.

  11. Hydrodynamic parameters of a sandy soil determined by ground-penetrating radar inside a single ring infiltrometer

    NASA Astrophysics Data System (ADS)

    Léger, Emmanuel; Saintenoy, Albane; Coquet, Yves

    2014-07-01

    This study shows how Mualem-van Genuchten (M-vG) parameters can be obtained from GPR data acquired during water infiltration from a single ring infiltrometer in the case of a sandy soil. Water content profiles were generated at various time steps using HYDRUS-1D, based on particular values of the M-vG parameters and were converted to dielectric permittivity profiles using the Complex Refractive Index Method. The GprMax suite of programs was used to generate radargrams and to follow the wetting front progression in depth using the arrival time of the electromagnetic waves recorded by a ground-penetrating radar (GPR). Theoretically, the 1-D time convolution between reflectivity and GPR signal at any infiltration time step is related to the peak of the reflected signal recorded in the corresponding trace in the radargram. We used this relationship to invert the M-vG parameters for constant and falling head infiltrations using the Shuffled Complex Evolution (SCE-UA) algorithm. The method is presented on synthetic examples and on experiments carried out for a sandy soil. The parameters inverted are compared with values obtained in laboratory on soil samples and with disk infiltrometer measurements.

  12. A SIMPLIFIED METHOD FOR EVALUATING THE LIQUEFACTION OF SANDY SOIL CONFINED BY A LATTICE-TYPE DEEP MIXING WALL

    NASA Astrophysics Data System (ADS)

    Ishikawa, Akira; Shamoto, Yasuhiro; Jang, Gjiho; Kimura, Takumi

    A simplified method for evaluating the liquefaction of sandy soil confined by a lattice-type deep mixing wall is proposed in this paper. The method calculates the accumulative excess pore water pressure from the initial shear strain using an equivalent shear-stiffness model by homogenization method. The method uses only parameters that are clear in their physical meaning, and can evaluate not only the effect of variations in the external forces, but also the physical properties of the ground. This paper first explains the proposed idea and then presents a specific calculation procedure using an actual site plan.

  13. Impact of Offshore Wind Energy Plants on the Soil Mechanical Behaviour of Sandy Seafloors

    NASA Astrophysics Data System (ADS)

    Stark, Nina; Lambers-Huesmann, Maria; Zeiler, Manfred; Zoellner, Christian; Kopf, Achim

    2010-05-01

    Over the last decade, wind energy has become an important renewable energy source. Especially, the installation of offshore windfarms offers additional space and higher average wind speeds than the well-established windfarms onshore. Certainly, the construction of offshore wind turbines has an impact on the environment. In the framework of the Research at Alpha VEntus (RAVE) project in the German offshore wind energy farm Alpha Ventus (north of the island Borkum in water depths of about 30 m) a research plan to investigate the environmental impact had been put into place. An ongoing study focuses on the changes in soil mechanics of the seafloor close to the foundations and the development of scour. Here, we present results of the first geotechnical investigations after construction of the plants (ca. 1 - 6 months) compared to geotechnical measurements prior to construction. To study the soil mechanical behaviour of the sand, sediment samples from about thirty different positions were measured in the laboratory to deliver, e.g., grain size (0.063 - 0.3 mm), friction angles (~ 32°), unit weight (~ 19.9 kN/m³) and void ratios (~ 0.81). For acoustic visualisation, side-scan-sonar (towed and stationary) and multibeam-echosounders (hull mounted) were used. Data show a flat, homogenous seafloor prior to windmill erection, and scouring effects at and in the vicinity of the foundations afterwards. Geotechnical in-situ measurements were carried out using a standard dynamic Cone Penetration Testing lance covering the whole windfarm area excluding areas in a radius < 50 m from the installed windmills (due the accessibility with the required research vessel). In addition, the small free-fall penetrometer Nimrod was deployed at the same spots, and furthermore, in the areas close to the tripod foundations (down to a distance of ~ 5 m from the central pile). Before construction, CPT as well as Nimrod deployments confirm a flat, homogenous sandy area with tip resistance values

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

    PubMed

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

    2010-11-01

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

  15. A New approach for evaluate a sandy soil infiltration to calculate the permeability

    NASA Astrophysics Data System (ADS)

    Mechergui, M. Mohamed; Latifa Dhaouadi, Ms

    2016-04-01

    10 sites were chosen in the four ha field of Research Regional Center of Oasis Agriculture in Deguache (Tozeur). The soil is homogeneous to the depth of 120 cm; with a sandy texture (60% big sand, 20% small sand 13% silt and 7% clay); with a mean bulk density equal to 1.43g/cm3 and with field capacity and welting point equal respectively to 11.9 and 6 %. The time duration for each infiltration essay lasted between 352 and 554 minutes. The number of observation points for each infiltration curve varies between 31 and 40. The shape of the infiltration curves observed in all sites is in part similar to what observed in literature (high increase with time of cumulative infiltration for a short time and then a linear increase of this parameter to a time varying between 122 to 197 minutes depending on the site) and then something special a slowdown in the cumulative infiltration to the end of the essay. The (F(t) / t 1/2 versus t 1/2) plotted curves showed two distinguished parts: A linear relation to the time varying between 122 and 197 minutes confirming the validity of Philips model and a second part showed a slowdown in the slope to a time varying between 231 and 347 minutes depending on the site and then drop down to the end of the essay. This is may be due to the rearrangement of particles after a long time of infiltration which led to a decrease in hydraulic conductivity. To improve the calculation of the saturated hydraulic conductivity, we choose only the part that is validated by Philips model, the linear part. The number of omitted points in the cumulative infiltration varies between 11 and 22 points. By this method, the saturated hydraulic conductivity varies between 1 and 3.72 m/day with a mean equal to 2.35. However the previous technique used gave a mean value equal to 2.07. The new method is accurate and gives better results of K and sorbtivity.

  16. Distribution And Efficacy Of Drip-Applied Metam-Sodium Against The Survival Of Rhizoctonia Solani And Yellow Nutsedge In Plastic-Mulched Sandy Soil Beds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of metam-sodium application rate on soil residence time, spatial and temporal distributions of methyl isothiocyanate and pest control efficacy were studied in a Georgia sandy soil. Metam-sodium 420 gL-1 SL was drip applied at rates of 147 and 295Lha-1 in plastic-mulched raised beds. Meth...

  17. Aeolian Sediments on the northeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Stauch, G.; Lehmkuhl, F.

    2013-12-01

    The timing and spatial distribution of aeolian sediments on the northeastern Tibetan Plateau have gained increasing interest during the last decades. The formation of the aeolian deposits is often related to cold and dry climate conditions. However, further important parameters are the local geomorphological setting and sediment availability in the source areas of the sediments. Aeolian sediments including loess, sandy loess and sands are widespread in the catchment of the Donggi Cona on the northeastern Tibetan Plateau at around 4000 m asl. Detailed geomorphological mapping of the deposits and geochemical analyses of the sediments revealed varying sources throughout the Holocene. The timing of the sediment deposition is based on 43 OSL (optical stimulated luminescence) ages. Several phases of enhanced aeolian deposition took place during the Holocene. The accumulation of aeolian sands lasted from 10.5 until 7 ka. The main source area of these sands was a large alluvial fan. Parallel to the formation of the dunes loess was deposited on the adjacent slopes from 10.5 until 7.5 ka. These sediments most probably originate in the nearby Qaidam Basin. In contrast to the general linkage of aeolian sediments to dryer climate conditions formation of these aeolian deposits is related to wetter conditions due to a strengthening of the Asian Summer Monsoons. The wetter climate enhanced the trapping and continuous fixation of the aeolian sediments by vegetation. With the further strengthening of the Monsoon fluvial processes eroded the aeolian deposits at least until 6 ka. From about 3 ka to the present a reactivation of aeolian sands and the formation of new dunes took place. This reactivation is related to drier conditions on the north-eastern Tibetan Plateau. Additionally, an increased human influence might have enhanced the aeolian activity. Similar phases of enhanced aeolian activity have been documented in more than 170 available OSL ages from loess and aeolian sands in

  18. Transport of fullerene nanoparticles (nC60) in saturated sand and sandy soil: controlling factors and modeling.

    PubMed

    Zhang, Lunliang; Hou, Lei; Wang, Lilin; Kan, Amy T; Chen, Wei; Tomson, Mason B

    2012-07-01

    Understanding subsurface transport of fullerene nanoparticles (nC(60)) is of critical importance for the benign use and risk management of C(60). We examined the effects of several important environmental factors on nC(60) transport in saturated porous media. Decreasing flow velocity from approximately 10 to 1 m/d had little effect on nC(60) transport in Ottawa sand (mainly pure quartz), but significantly inhibited the transport in Lula soil (a sandy, low-organic-matter soil). The difference was attributable to the smaller grain size, more irregular and rougher shape, and greater heterogeneity of Lula soil. Increasing ionic strength and switching background solution from NaCl to CaCl(2) enhanced the deposition of nC(60) in both sand and soil columns, but the effects were more significant for soil. This was likely because the clay minerals (and possibly soil organic matter) in soil responded to changes of ionic strength and species differently than quartz. Anions in the mobile phase had little effect on nC(60) transport, and fulvic acid in the mobile phase (5.0 mg/L) had a small effect in the presence of 0.5 mM Ca(2+). A two-site transport model that takes into account both the blocking-affected attachment process and straining effects can effectively model the breakthrough of nC(60). PMID:22681192

  19. Biochar increases plant-available water in a sandy loam soil under an aerobic rice crop system

    NASA Astrophysics Data System (ADS)

    de Melo Carvalho, M. T.; de Holanda Nunes Maia, A.; Madari, B. E.; Bastiaans, L.; van Oort, P. A. J.; Heinemann, A. B.; Soler da Silva, M. A.; Petter, F. A.; Marimon, B. H., Jr.; Meinke, H.

    2014-09-01

    The main objective of this study was to assess the impact of biochar rate (0, 8, 16 and 32 Mg ha-1) on the water retention capacity (WRC) of a sandy loam Dystric Plinthosol. The applied biochar was a by-product of slow pyrolysis (∼450 °C) of eucalyptus wood, milled to pass through a 2000 μm sieve that resulted in a material with an intrinsic porosity ≤10 μm and a specific surface area of ∼3.2 m2 g-1. The biochar was incorporated into the top 15 cm of the soil under an aerobic rice system. Our study focused on both the effects on WRC and rice yields 2 and 3 years after its application. Undisturbed soil samples were collected from 16 plots in two soil layers (5-10 and 15-20 cm). Soil water retention curves were modelled using a nonlinear mixed model which appropriately accounts for uncertainties inherent of spatial variability and repeated measurements taken within a specific soil sample. We found an increase in plant-available water in the upper soil layer proportional to the rate of biochar, with about 0.8% for each Mg ha-1 biochar amendment 2 and 3 years after its application. The impact of biochar on soil WRC was most likely related to an effect in overall porosity of the sandy loam soil, which was evident from an increase in saturated soil moisture and macro porosity with 0.5 and 1.6% for each Mg ha-1 of biochar applied, respectively. The increment in soil WRC did not translate into an increase in rice yield, essentially because in both seasons the amount of rainfall during the critical period for rice production exceeded 650 mm. The use of biochar as a soil amendment can be a worthy strategy to guarantee yield stability under short-term water-limited conditions. Our findings raise the importance of assessing the feasibility of very high application rates of biochar and the inclusion of a detailed analysis of its physical and chemical properties as part of future investigations.

  20. Toxicities of dinitrotoluenes and trinitrobenzene freshly amended or weathered and aged in a sandy loam soil to Enchytraeus crypticus.

    PubMed

    Kuperman, Roman G; Checkai, Ronald T; Simini, Michael; Phillips, Carlton T; Kolakowski, Jan E; Kurnas, Carl W

    2006-05-01

    Scientifically based ecological soil-screening levels are needed to identify concentrations of contaminant energetic materials (EMs) in soil that present an acceptable ecological risk at a wide range of military installations. Insufficient information regarding the toxicity of 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), and 1,3,5-trinitrobenzene (TNB) to soil invertebrates necessitated toxicity testing. We adapted the standardized Enchytraeid Reproduction Test (International Standardization Organization 16387:2003) and selected Enchytraeus crypticus for these studies. Tests were conducted in Sassafras sandy loam soil, which supports relatively high bioavailability of nitroaromatic EMs. Weathering and aging procedures for EMs amended to test soil were incorporated into the study design to produce toxicity data that better reflect the soil exposure conditions in the field compared with toxicity in freshly amended soils. This included exposing hydrated, EM-amended soils in open glass containers in the greenhouse to alternating wetting and drying cycles. Definitive tests established that the order of EM toxicity to E. crypticus based on the median effect concentration values for juvenile production in either freshly amended or weathered and aged treatments was (from the greatest to least toxicity) TNB > 2,4-DNT > 2,6-DNT. Toxicity to E. crypticus juvenile production was significantly increased in 2,6-DNT weathered and aged soil treatments compared with toxicity in freshly amended soil, based on 95% confidence intervals. This result shows that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information regarding ecotoxicological effects of energetic contaminants in soil. PMID:16704071

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

    NASA Astrophysics Data System (ADS)

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

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

  2. Vegetation pattern variation, soil degradation and their relationship along a grassland desertification gradient in Horqin Sandy Land, northern China

    NASA Astrophysics Data System (ADS)

    Zuo, Xiaoan; Zhao, Halin; Zhao, Xueyong; Guo, Yirui; Yun, Jianying; Wang, Shaokun; Miyasaka, Takafumi

    2009-09-01

    The Horqin Sandy Land is one of the most severely desertified regions in northern China. Plant communities and soil conditions at five stages of grassland desertification (potential, light, moderate, severe and very severe) were selected for the study of vegetation pattern variation relating to soil degradation. The results showed that vegetation cover, species richness and diversity, aboveground biomass (AGB), underground biomass, litter, soil organic carbon (C), total nitrogen (N), total phosphorus (P), electrical conductivity, very fine sand (0.1-0.05 mm) content and silt (0.05-0.002 mm) content decreased with the desertification development. Plant community succession presented that the palatable herbaceous plants gave place to the shrub species with asexual reproduction and sand pioneer plants. The decline of vegetation cover and AGB was positively related to the loss of soil organic C and total N with progressive desertification ( P < 0.01). The multivariate statistical analysis showed that plant community distribution, species diversity and ecological dominance had the close relationship with the gradient of soil nutrients in the processes of grassland desertification. These results suggest that grassland desertification results in the variation of vegetation pattern which presents the different composition and structure of plant community highly influenced by the soil properties.

  3. Estimating water retention curves for sandy soils at the Doñana National Park, SW Spain

    NASA Astrophysics Data System (ADS)

    Prados Garcia, M. Luisa; Vanderlinden, Karl; Guardiola-Albert, Carolina; Giraldez Cervera, Juan Vicente; Guber, Andrey K.; Pachepsky, Yakov A.

    2010-05-01

    The determination of soil water retention curves (SWRC) in the laboratory is a slow and tedious task, which is especially challenging for sandy soils due to their low water retention capacity and large water content changes for small pressure head differences. Due to spatial variability within larger areas and difficulties to obtain minimally disturbed soil samples, especially under dry conditions, laboratory measurements of the SWRCs are only suitable for guidance, as a consequence of their low representativity and accuracy. This work was developed within the framework of a research project on the ecohydrological behaviour of the soil-plant-atmosphere system within the Doñana National Park (SW Spain). In order to characterise the hydrological behaviour of the soils, a good estimation of water retention curves and hydraulic parameters is needed. Ten locations within the study area were equipped with soil moisture sensors (ECH2O-EC20, Decagon Devices Inc.) to monitor volumetric water content at different depths throughout the vadose zone. These data allow the estimation of water fluxes and recharge of the underlying aquifer, which plays a crucial role in the wetland system of the Park, declared by UNESCO as Biosphere Reserve. In this work three methods for estimating SWRCs were developed and compared. First, sand and kaolin suction tables were used to obtain SWRCs for both minimally disturbed and disturbed samples. Second, SWRC were estimated with HYDRUS-1D using the monitored volumetric soil water content data. Finally, SWRCs were estimated using the additivity hypothesis, based on the idea that SWRCs can be approximated by summing up SWRCs corresponding to different particle-size and pore-space classes of which the soil is composed. Particle-size distributions were determined in the laboratory while water retention data for the different particle-size classes were taken from literature. The comparison of these three methods allowed us to define their strengths

  4. Investigation of Interactive Effects on Water Flow and Solute Transport in Sandy Loam Soil Using Time Domain Reflectometry

    PubMed Central

    Merdun, Hasan

    2012-01-01

    Surface-applied chemicals move through the unsaturated zone with complex flow and transport processes due to soil heterogeneity and reach the saturated zone, resulting in groundwater contamination. Such complex processes need to be studied by advanced measurement and modeling techniques to protect soil and water resources from contamination. In this study, the interactive effects of factors like soil structure, initial soil water content (SWC), and application rate on preferential flow and transport were studied in a sandy loam field soil using measurement (by time domain reflectometry (TDR)) and modeling (by MACRO and VS2DTI) techniques. In addition, statistical analyses were performed to compare the means of the measured and modeled SWC and EC, and solute transport parameters (pore water velocity and dispersion coefficient) in 12 treatments. Research results showed that even though the effects of soil structural conditions on water and solute transport were not so clear, the applied solution moved lower depths in the profiles of wet versus dry initial SWC and high application rate versus low application rates. The effects of soil structure and initial SWC on water and solute movement could be differentiated under the interactive conditions, but the effects of the application rates were difficult to differentiate under different soil structural and initial SWC conditions. Modeling results showed that MACRO had somewhat better performance than VS2DTI in the estimation of SWC and EC with space and time, but overall both models had relatively low performances. The means of SWC, EC, and solute transport parameters of the 12 treatments were divided into some groups based on the statistical analyses, indicating different flow and transport characteristics or a certain degree nonuniform or preferential flow and transport in the soil. Conducting field experiments with more interactive factors and applying the models with different approaches may allow better understanding

  5. [Effects of Different Residue Part Inputs of Corn Straws on CO2 Efflux and Microbial Biomass in Clay Loam and Sandy Loam Black Soils].

    PubMed

    Liu, Si-yi; Liang, Ai-zhen; Yang, Xue-ming; Zhang, Xiao-ping; Jia, Shu-xia; Chen, Xue-wen; Zhang, Shi-xiu; Sun, Bing-jie; Chen, Sheng-long

    2015-07-01

    The decomposed rate of crop residues is a major determinant for carbon balance and nutrient cycling in agroecosystem. In this study, a constant temperature incubation study was conducted to evaluate CO2 emission and microbial biomass based on four different parts of corn straw (roots, lower stem, upper stem and leaves) and two soils with different textures (sandy loam and clay loam) from the black soil region. The relationships between soil CO2 emission, microbial biomass and the ratio of carbon (C) to nitrogen (N) and lignin of corn residues were analyzed by the linear regression. Results showed that the production of CO2 was increased with the addition of different parts of corn straw to soil, with the value of priming effect (PE) ranged from 215. 53 µmol . g-1 to 335. 17 µmol . g -1. Except for corn leaves, the cumulative CO2 production and PE of clay loam soil were significantly higher than those in sandy loam soil. The correlation of PE with lignin/N was obviously more significant than that with lignin concentration, nitrogen concentration and C/N of corn residue. The addition of corn straw to soil increased the contents of MBC and MBN and decreased MBC/MBN, which suggested that more nitrogen rather than carbon was conserved in microbial community. The augmenter of microbial biomass in sandy loam soil was greater than that in clay loam soil, but the total dissolved nitrogen was lower. Our results indicated that the differences in CO2 emission with the addition of residues to soils were primarily ascribe to the different lignin/N ratio in different corn parts; and the corn residues added into the sandy loam soil could enhance carbon sequestration, microbial biomass and nitrogen holding ability relative to clay loam soil. PMID:26489342

  6. Community-specific impacts of exotic earthworm invasions on soil carbon dynamics in a sandy temperate forest.

    PubMed

    Crumsey, Jasmine M; Le Moine, James M; Capowiez, Yvan; Goodsitt, Mitchell M; Larson, Sandra C; Kling, George W; Nadelhoffer, Knute J

    2013-12-01

    Exotic earthworm introductions can alter above- and belowground properties of temperate forests, but the net impacts on forest soil carbon (C) dynamics are poorly understood. We used a mesocosm experiment to examine the impacts of earthworm species belonging to three different ecological groups (Lumbricus terrestris [anecic], Aporrectodea trapezoides [endogeic], and Eisenia fetida [epigeic]) on C distributions and storage in reconstructed soil profiles from a sandy temperate forest soil by measuring CO2 and dissolved organic carbon (DOC) losses, litter C incorporation into soil, and soil C storage with monospecific and species combinations as treatments. Soil CO2 loss was 30% greater from the Endogeic x Epigeic treatment than from controls (no earthworms) over the first 45 days; CO2 losses from monospecific treatments did not differ from controls. DOC losses were three orders of magnitude lower than CO2 losses, and were similar across earthworm community treatments. Communities with the anecic species accelerated litter C mass loss by 31-39% with differential mass loss of litter types (Acer rubrum > Populus grandidentata > Fagus grandifolia > Quercus rubra > or = Pinus strobus) indicative of leaf litter preference. Burrow system volume, continuity, and size distribution differed across earthworm treatments but did not affect cumulative CO2 or DOC losses. However, burrow system structure controlled vertical C redistribution by mediating the contributions of leaf litter to A-horizon C and N pools, as indicated by strong correlations between (1) subsurface vertical burrows made by anecic species, and accelerated leaf litter mass losses (with the exception of P. strobus); and (2) dense burrow networks in the A-horizon and the C and N properties of these pools. Final soil C storage was slightly lower in earthworm treatments, indicating that increased leaf litter C inputs into soil were more than offset by losses as CO2 and DOC across earthworm community treatments. PMID

  7. Experimental studies on the physico-mechanical properties of jet-grout columns in sandy and silty soils

    NASA Astrophysics Data System (ADS)

    Akin, Muge K.

    2016-04-01

    The term of ground improvement states to the modification of the engineering properties of soils. Jet-grouting is one of the grouting methods among various ground improvement techniques. During jet-grouting, different textures of columns can be obtained depending on the characteristics of surrounding subsoil as well as the adopted jet-grouting system for each site is variable. In addition to textural properties, strength and index parameters of jet-grout columns are highly affected by the adjacent soil. In this study, the physical and mechanical properties of jet-grout columns constructed at two different sites in silty and sandy soil conditions were determined by laboratory tests. A number of statistical relationships between physical and mechanical properties of soilcrete were established in this study in order to investigate the dependency of numerous variables. The relationship between qu and γd is more reliable for sandy soilcrete than that of silty columns considering the determination coefficients. Positive linear relationships between Vp and γd with significantly high determination coefficients were obtained for the jet-grout columns in silt and sand. The regression analyses indicate that the P-wave velocity is a very dominant parameter for the estimation of physical and mechanical properties of jet-grout columns and should be involved during the quality control of soilcrete material despite the intensive use of uniaxial compressive strength test. Besides, it is concluded that the dry unit weight of jet-grout column is a good indicator of the efficiency of employed operational parameters during jet-grouting.

  8. Crop water use efficiency following biochar application on maize cropping systems on sandy soils of tropical semiarid eastern Indonesia

    NASA Astrophysics Data System (ADS)

    Sukartono, S.; Utomo, W.

    2012-04-01

    A field study was conducted to evaluate the effect of biochar on crop water use efficiency under three consecutive maize cropping system on sandy loam of Lombok, eastern Indonesia from December 2010 to October 2011.The treatments tested were: coconut shell- biochar (CSB), cattle dung-biochar (CDB), cattle manure applied at only early first crop (CM1) and cattle manure applied at every planting time (CM2) and no organic amendment as the control. Evaluation after the end of third maize, the application of organic amendments (biochar and cattle manure) slightly altered the pore size distribution resulting changes in water retention and the available water capacity. The available water capacity was relatively comparable between biochar treated soils (0.206 cm3 cm-3) and soil treated with cattle manure applied at every planting time (0.220 cm3 cm-3). Water use efficiency (WUE) of maize under biochars were 9.44 kg/mm (CSB) and 9.24 kg/mm (CDB) while WUE for CM1 and CM2 were 8.54 and 9.97 kg/mm respectively, and control was 8.08 kg/mm. Thus, biochars as well as cattle manure applied at every planting time improved water use efficiency by 16.83% and 23.39 respectively compared to control. Overall, this study confirms that biochar and cattle manure are both valuable amendments for improving water use efficiency and to sustain maize production in the sandy loam soils of semiarid North Lombok, eastern Indonesia. However, unlike bicohar, in order to maintain its posivtive effect, cattle manure should be applied at every planting time, and this make cattle manure application is more costly. Keywords: Biochar, organic management, catle manure, water retention, maize yield

  9. The origin and early genesis of clay bands in youthful sandy soils along lake Michigan, U.S.A.

    USGS Publications Warehouse

    Berg, R.C.

    1984-01-01

    A beach ridge and dune complex with good radiocarbon control sampling the last 3500 radiocarbon years B.P. provides new insights on the early genesis of clay bands in sandy soils. Soil profiles were sampled by age groups, described in the field, and then subjected to laboratory analyses for particle-size distribution, pH, organic carbon, carbonate minerals, and extractable iron and manganese. This study suggests that small increases in pH, brought about by small increases in carbonate content within the soil profile, are responsible for flocculating small amounts of illuviated clay. This process, along with a transition to a greater hydraulic conductivity with soil depth due to coarser textures in any given profile, partly explains the existence and possible reason for the initiation of illuvial zones and eventually for clay-band horizons. A pronounced increase in the thickness of incipient clay-band horizons in soils older than 2300 years appears due to finer textures in the parent materials than are present in younger soils. Because of slightly reduced porosity and lower permeability, carbonates and a high pH are retained in both illuvial and eluvial horizons of some of these older soils. In addition, only in those profiles older than 2300 years do clay and iron oxide concentrations coincide and is there some suggestion of greater amounts of extractable manganese in horizons of minimum iron and clay. A pronounced segregation of clay-iron bands is not apparent at the study area but should occur in future years as additional amounts of iron and clay are deposited. ?? 1984.

  10. Removal of Fast Flowing Nitrogen from Marshes Restored in Sandy Soils

    PubMed Central

    Sparks, Eric L.; Cebrian, Just; Smith, Sara M.

    2014-01-01

    Groundwater flow rates and nitrate removal capacity from an introduced solution were examined for five marsh restoration designs and unvegetated plots shortly after planting and 1 year post-planting. The restoration site was a sandy beach with a wave-dampening fence 10 m offshore. Simulated groundwater flow into the marsh was introduced at a rate to mimic intense rainfall events. Restoration designs varied in initial planting density and corresponded to 25%, 50%, 75% and 100% of the plot area planted. In general, groundwater flow was slower with increasing planting density and decreased from year 0 to year 1 across all treatments. Nevertheless, removal of nitrate from the introduced solution was similar and low for all restoration designs (3–7%) and similar to the unvegetated plots. We suggest that the low NO3− removal was due to sandy sediments allowing rapid flow of groundwater through the marsh rhizosphere, thereby decreasing the contact time of the NO3− with the marsh biota. Our findings demonstrate that knowledge of the groundwater flow regime for restoration projects is essential when nutrient filtration is a target goal of the project. PMID:25353607

  11. Introducing a New International Society of Aeolian Research

    NASA Astrophysics Data System (ADS)

    Zobeck, T. M.; Lee, J.; Lancaster, N.; Bullard, J. E.

    2008-12-01

    Aeolian research is a long-standing and rapidly growing area of geological study where scientists of many disciplines meet to investigate the effects of wind on the surface of the Earth and other planetary bodies such as Mars and Titan. Fields of study in aeolian research cover a broad spectrum ranging from developing a basic scientific understanding of the fundamental physical processes of grain motion to the effects of soil erosion on landscape health and environmental sustainability. Aeolian research also includes studies of the effects of aeolian particles on global climate, air quality, and human health, coastal sand transport processes, land degradation, dune migration, the formation of sand seas, and much more. A growing number of international conferences have been organized to focus specifically on aeolian phenomena and a vast number of scholarly publications have been produced to support the science. One popular bibliography includes over 30,000 citations and hundreds of peer-reviewed papers are published each year. Until very recently, no scientific society specifically dealing with aeolian research has been available. The new International Society of Aeolian Research (ISAR) that has been organized to bring together aeolian scientists from around the world. The new society was created to promote contacts among researchers in aeolian processes and related subjects for discussion and comparison of research, to initiate conferences (such as the International Conference on Aeolian Research), to organize excursions, and support the publication of a peer-reviewed scientific journal. The International Society of Aeolian Research sponsors the new Elsevier journal Aeolian Research in support of these activities. This paper will provide further details about the new society and the journal. Please see www.aeolianresearch.org for details.

  12. Water retention curves of loamy-sandy soils: Transient evaporation method versus steady-state tension and pressure techniques

    NASA Astrophysics Data System (ADS)

    Winkler, G.; Eberhard, E.; Fank, J.; Birk, S.

    2009-12-01

    Water retention curves of loamy-sandy soils at the agricultural test site Wagna (Austria) were measured using both the simplified evaporation method according to Schindler (Arch. Acker- u. Pflanzenbau u. Bodenkd. Berlin 24, 1-7, 1980) and steady-state tension and pressure techniques. The soil was sampled with 250-ccm and 100-ccm steel pipes for the evaporation method and the steady-state technique, respectively. In the transient evaporation method two tensiometers with a measurement range between 0 and 850 hPa are installed at a depth of 1.25 cm and 3.75 cm in a sample of 5 cm in height; the mean values of the two tensiometers and the water contents measured by weighing are used to obtain the water retention curve. The steady-state method employs a tension table (sand box) at tensions below 100 hPa and a pressure extractor at tensions between 300 hPa and 15,000 hPa; the water content is measured by weighing after the sample has equilibrated at the tension value set on the table or plate. First results of both methods suggest that the soil samples release water over the entire tension range measured. In particular, the release of water at very low tension values may suggest the presence of macropores. Despite the generally good agreement between the two methods, the values appear to deviate systematically close to saturation. This is potentially caused by the large relative error of the tension measurement close to saturation. Alternatively, the different size of the samples used for the evaporation experiment (250 ccm) and the steady-state method (100 ccm) might play a role. Because of the limited measurement range of the tensiometers used for the evaporation method, the measured curve must be extrapolated between 850 hPa and 15,000 hPa to allow comparison with the steady-state method. To this end, it was attempted to match the Brooks-Corey, the Van-Genuchten, and a bimodal Van-Genuchten retention function to the data from the evaporation experiments. This involves

  13. Mobilization and co-transport of pyrene in the presence of Pseudomonas aeruginosa UG2 biosurfactants in sandy soil columns

    SciTech Connect

    Lafrance, P.; Lapointe, M.

    1998-12-31

    Washing technologies are currently applied for the remediation of contaminated soils. The efficiency of biosurfactants produced by Pseudomonas aeruginosa strains to mobilize some hydrocarbons sorbed on soils has already been demonstrated. However, few studies have been made to define optimal procedures for the injection of these rhamnolipids in soil. This study examines (1) the efficiency of the biosurfactants produced by P. aeruginosa UG2 to mobilize pyrene from a contaminated sandy loam as compared to that of sodium dodecyl sulfate (SDS); (2) the injection procedures that might affect the efficiency of pyrene mobilization using UG2 biosurfactants; and (3) the co-transport of UG2 biosurfactants and pyrene. Based on the experimental results, it would be advantageous to use a high UG2 biosurfactant concentration, a high pore water velocity, and possibly a flow interruption of more than 15 h in order to reduce the injected volume and the duration of the treatment required. The 0.25% UG2 biosurfactant concentration greatly enhanced pyrene transport and could facilitate contaminant recovery.

  14. Features of abandoned cemetery soils on sandy substrates in Northern Poland

    NASA Astrophysics Data System (ADS)

    Majgier, L.; Rahmonov, O.; Bednarek, R.

    2014-06-01

    Morphological and chemical features of cemetery soils (Necrosols and undisturbed cemetery soils) have been studied with Northern Poland as an example. Special attention has been given to the contents of the total phosphorus (as an indicator of the anthropogenic impact); the organic carbon; the total nitrogen; the calcium carbonate; and the changes in the acidity and total Ca, Na, K, Al, Fe, Mg, Zn, Cd, and Pb. The soil profiles have been compared to the control soil (a Brunic Arenosol according to the WRB classification) occurring beyond the cemetery area. The changes in the studied burial soils are mainly manifested in their morphology: the disturbance of the primary genetic horizons and the presence of mixed soil horizons and artifacts (bones, coffin remains, limestone-concrete debris of the cemetery infrastructure). Such changes in the chemical properties as an increase in the contents of the organic carbon and total nitrogen and the soil reaction were observed. Our studies have shown that the highest Ptotal concentration is observed in the A horizons of the anthropogenic burial horizons and undisturbed cemetery soils. The content of phosphorus in the Necrosols is significantly higher than that in the control soil profile, as is observed for the Cgrb layers of burial Necrosols. The morphology and chemistry of the undisturbed cemetery soils are very similar to those of the control profile.

  15. Distributions of labeled nitrogen in the profile of a fertilized sandy soil

    SciTech Connect

    Mansell, R.S.; Fiskell, J.G.A.; Calvert, D.V.; Rogers, J.S.

    1986-02-01

    Isotopically labeled (/sup 15/N-depleted) ammonium sulfate (115 kg N ha/sup -1/) was applied to a Spodosol in a citrus grove, to determine the fate and subsequent distributions of NO/sub 3/-N and NH/sub 4/-N in the soil profile. The soil was tile-drained, and citrus trees were located on soil beds. The authors examined three soil management treatments: the original A1 horizon (ST): deep mixing of A1 and A2 horizons with the underlying Spodic horizon (DT); and incorporation of 56 Mg ha/sup -1/ of dolomitic limestone, along with deep mixing (DTL) of the profile. Soil samples were taken to the 70-cm depth in ST and to the 95-cm depth in DT and DTL soils and were extracted with 1 M KCl. Extracts were chemically analyzed for NH/sub 4/-N and NO/sub 3/-N concentrations and isotopic analysis was performed by mass spectroscopy. At 12 d after fertilization, both NH/sub 4/-N and NO/sub 3/-N values in the ST soil profile exceeded corresponding values for DT and DTL soils. This N was derived primarily from the fertilizer. With time, concentrations of both NH/sub 4/-N and NO/sub 3/-N decreased in profiles for all three soils; however, N concentrations in the ST soil consistently exceeded corresponding values for DT and DTL profiles.

  16. Roughness configuration matters for aeolian sediment flux

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The parameterisation of surface roughness effects on aeolian sediment transport is a key source of uncertainty in wind erosion models. Roughness effects are typically represented by bulk drag-partitioning schemes that scale the threshold friction velocity (u*t) for soil entrainment by the ratio of s...

  17. Anatomy and controlling factors of a Late Cretaceous Aeolian sand sheet: The Marília and the Adamantina formations, NW Bauru Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Basilici, Giorgio; Führ Dal'Bó, Patrick Francisco

    2010-04-01

    Few previous studies have given significant consideration to the palaeosols in aeolian sand sheet sedimentary successions and, mainly, to their palaeoenvironmental and stratigraphic meaning in interaction with the deposits. These themes are considered in this study that deals with the depositional architecture and the factors controlling the construction, accumulation and preservation of an ancient aeolian sand sheet, that forms part of the Adamantina and Marília formations, in the Bauru Basin (Late Cretaceous, Brazil). In the NW portion of the Bauru Basin, these two units, ca 220 m thick, consist of sandstone, and secondarily of sandy conglomerate and mudstone, and are characterised by vertically alternated palaeosols and deposits. Facies analyses of the deposits and macroscopic characterisation of the palaeosols in 45 outcrops were integrated with laboratory analyses that consisted in descriptions of slabs of rock samples, petrographic analyses, clay mineralogy determination, geochemical analyses of the major oxides, and micromorphological characterisation of the palaeosols. Three architectural elements were recognised: palaeosols, wind-ripple-dominated aeolian sand sheet deposits, and ephemeral river deposits. The palaeosols constitute 66% of the entire sedimentary succession, and consist principally of Aridisols and, subordinately, of Alfisols, Vertisols, and Entisols. The wind-ripple-dominated aeolian sand sheet deposits (25%) are composed of sandstone, organised in translatent climbing wind-ripple strata, and secondarily of sandstone and mudstone deposited by infrequent floods. The ephemeral river deposits (9%) consist of sandy conglomerates 4 m thick and ca 2 km wide. Wind-ripple-dominated aeolian sand sheet deposits formed during relatively dry climate period on an unstable topographic surface of an aeolian sand sheet, where aeolian deposition or erosion prevailed. Palaeosols and ephemeral river deposits formed in a more humid climate period on a stable

  18. Nitrogen Amendment Stimulated Decomposition of Maize Straw-Derived Biochar in a Sandy Loam Soil: A Short-Term Study

    PubMed Central

    Lu, Weiwei; Ding, Weixin; Zhang, Junhua; Zhang, Huanjun; Luo, Jiafa; Bolan, Nanthi

    2015-01-01

    This study examined the effect of nitrogen (N) on biochar stability in relation to soil microbial community as well as biochar labile components using δ13C stable isotope technology. A sandy loam soil under a long-term rotation of C3 crops was amended with biochar produced from maize (a C4 plant) straw in absence (BC0) and presence (BCN) of N and monitored for dynamics of carbon dioxide (CO2) flux, phospholipid fatty acids (PLFAs) profile and dissolved organic carbon (DOC) content. N amendment significantly increased the decomposition of biochar during the first 5 days of incubation (P < 0.05), and the proportions of decomposed biochar carbon (C) were 2.30% and 3.28% in BC0 and BCN treatments, respectively, during 30 days of incubation. The magnitude of decomposed biochar C was significantly (P < 0.05) higher than DOC in biochar (1.75%) and part of relatively recalcitrant biochar C was mineralized in both treatments. N amendment increased soil PLFAs concentration at the beginning of incubation, indicating that microorganisms were N-limited in test soil. Furthermore, N amendment significantly (P < 0.05) increased the proportion of gram-positive (G+) bacteria and decreased that of fungi, while no noticeable changes were observed for gram-negative (G−) bacteria and actinobacteria at the early stage of incubation. Our results indicated that N amendment promoted more efficiently the proliferation of G+ bacteria and accelerated the decomposition of relatively recalcitrant biochar C, which in turn reduced the stability of maize straw-derived biochar in test soil. PMID:26192282

  19. Nitrogen Amendment Stimulated Decomposition of Maize Straw-Derived Biochar in a Sandy Loam Soil: A Short-Term Study.

    PubMed

    Lu, Weiwei; Ding, Weixin; Zhang, Junhua; Zhang, Huanjun; Luo, Jiafa; Bolan, Nanthi

    2015-01-01

    This study examined the effect of nitrogen (N) on biochar stability in relation to soil microbial community as well as biochar labile components using δ13C stable isotope technology. A sandy loam soil under a long-term rotation of C3 crops was amended with biochar produced from maize (a C4 plant) straw in absence (BC0) and presence (BCN) of N and monitored for dynamics of carbon dioxide (CO2) flux, phospholipid fatty acids (PLFAs) profile and dissolved organic carbon (DOC) content. N amendment significantly increased the decomposition of biochar during the first 5 days of incubation (P < 0.05), and the proportions of decomposed biochar carbon (C) were 2.30% and 3.28% in BC0 and BCN treatments, respectively, during 30 days of incubation. The magnitude of decomposed biochar C was significantly (P < 0.05) higher than DOC in biochar (1.75%) and part of relatively recalcitrant biochar C was mineralized in both treatments. N amendment increased soil PLFAs concentration at the beginning of incubation, indicating that microorganisms were N-limited in test soil. Furthermore, N amendment significantly (P < 0.05) increased the proportion of gram-positive (G+) bacteria and decreased that of fungi, while no noticeable changes were observed for gram-negative (G-) bacteria and actinobacteria at the early stage of incubation. Our results indicated that N amendment promoted more efficiently the proliferation of G+ bacteria and accelerated the decomposition of relatively recalcitrant biochar C, which in turn reduced the stability of maize straw-derived biochar in test soil. PMID:26192282

  20. Sensitivity of water stress in a two-layered sandy grassland soil to variations in groundwater depth and soil hydraulic parameters

    NASA Astrophysics Data System (ADS)

    Rezaei, M.; Seuntjens, P.; Joris, I.; Boënne, W.; Van Hoey, S.; Campling, P.; Cornelis, W. M.

    2015-07-01

    Monitoring and modeling tools may improve irrigation strategies in precision agriculture. We used non-invasive soil moisture monitoring, a crop growth and a soil hydrological model to predict soil-water content fluctuations and crop yield in a heterogeneous sandy grassland soil under supplementary irrigation. The sensitivity of the model to hydraulic parameters, water stress, crop yield and lower boundary conditions was assessed. Free drainage and incremental constant head conditions was implemented in a lower boundary sensitivity analysis. A time-dependent sensitivity analysis showed that changes in soil water content are mainly affected by the soil saturated hydraulic conductivity Ks and the Mualem-van Genuchten retention curve shape parameters n and α. Results further showed that different parameter optimization strategies (two-, three-, four- or six-parameter optimizations) did not affect the calculated water stress and water content as significantly as does the bottom boundary. For this case, a two-parameter scenario, where Ks was optimized for each layer under the condition of a constant groundwater depth at 135-140 cm, performed best. A larger yield reduction, and a larger number and longer duration of stress conditions occurred in the free drainage condition as compared to constant boundary conditions. Numerical results showed that optimal irrigation scheduling using the aforementioned water stress calculations can save up to 12-22 % irrigation water as compared to the current irrigation regime. This resulted in a yield increase of 4.5-6.5 %, simulated by crop growth model.

  1. Studies in Aeolian geology

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1988-01-01

    The objective of the research was to assess the significance of aeolian (windblown) processes in the evolution of planetary surfaces. The approach was to use wind tunnel simulations, field studies of possible analogs, and analyses of spacecraft data.

  2. Olive mill wastewater stabilization in open-air ponds: impact on clay-sandy soil.

    PubMed

    Jarboui, Raja; Sellami, Fatma; Kharroubi, Adel; Gharsallah, Néji; Ammar, Emna

    2008-11-01

    The aim of this work was to study the natural biodegradation of the stored olive mill wastewater (OMW) in ponds and the infiltration as well as the impact on soil of the effluent in the evaporation pond used for the storage over the past eight years. For this, two approaches were considered. First, a laboratory-scale column was used for the infiltration of OMW through soil (clay and sand) to predict the effect of the clayey soil in reducing OMW pollution. Second, the ponds including the effluent annually stored and having this clayey structure were investigated. At the laboratory-scale, a modification of OMW contents was noticed, with the elimination of 95% of total suspended solids (TSS), 60% of chemical oxygen demand (COD), 40% of total organic carbon (TOC), 50% of total P, 50% of phenols and 40% of minerals (K+, Mg++ and Na+). The experimented soil was able to restrain the considerable effects of OMW pollution. In the ponds, the granulometric characteristics, the physico-chemical and the biological parameters of the soil profile from the contaminated pond were compared to those of a control soil, located near the contaminated pond. Property modifications of the contaminated soil were noted, especially pH, electrical conductivity, COD and microflora. These changes can be explained by the infiltration of OMW constituents, which were noticed in the soil layers, especially phenolic compounds that have a negative effect on the ground water. PMID:18337092

  3. Microbial community structure and functionality under peanut based cropping systems in a sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is little information on soil microbial and biochemical properties, important for nutrient cycling and organic matter dynamics, as affected by different peanut (Arachis hypogaea L.) cropping systems and how they relate to soil quality and functioning and system sustainability. We studied a sa...

  4. Persistence of bifenthrin in sandy loam soil as affected by microbial community.

    PubMed

    Sharma, Divya; Singh, Shashi Bala

    2012-06-01

    Soil was fortified with bifenthrin at the level of 10 μg g(-1) soil. Soil samples were drawn at regular intervals of 0, 10, 20, 30 and 40 days. For extraction of bifenthrin, soil was extracted with acetone. Clean up was done by liquid-liquid partitioning with dichloromethane after diluting with brine solution. Quantification of bifenthrin residues was done by GC using mega bore column and ECD detector. Recovery of bifenthrin in soil ranged between 92.6 % and 93.8 % at 0.5 and 1.0 μg g(-1). The instrumental limit of detection of bifenthrin was 0.005 μg mL(-1) and LOQ for soil by this method was found to be 0.05 μg g(-1). The calibration curve was found to be linear within range the range of 0.01 and 0.10 μg mL(-1) concentration. The DT(50) (disappearance time for 50 % loss) of bifenthrin at the level of 10 μg g(-1) in sterile and non sterile soil were found to be 330 and 147 days, respectively. A vast difference in the half life of sterile and non sterile soil indicated the presence of potential microbes for bifenthrin degradation. PMID:22476257

  5. Microbial community structure and functionality under peanut based cropping systems in a sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little information is available on soil microbial and biochemical properties, important for understanding nutrient cycling and organic matter (OM) dynamics, as affected by different peanut (Arachis hypogaea L.) cropping systems and how they relate to soil functioning. Peanut is typically produced i...

  6. Microbial community structure and functionality under peanut based cropping systems in a sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little information is available on soil microbial and biochemical properties, important for understanding nutrient cycling and organic matter (OM) dynamics, as affected by different peanut cropping systems and how they relate to soil functioning. Thus, we studied a Tifton loamy sand (fine-loamy, ka...

  7. A field wind tunnel study of fine dust emissions in sandy soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A portable field wind tunnel has been developed to allow measurements of dust emissions from soil surfaces to test the premise that dust concentration and properties are highly correlated with surface soil properties, as modified by crop management system. In this study, we report on the effect of ...

  8. Physical and hydraulic properties of a sandy loam soil under zero, shallow and deep tillage practices

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over the centuries, tillage has been an important agronomic practice that has been used to mechanically alter soil properties and enhance the soil ecosystem for growth of crops. A 4-yr study investigated the impact of no-tillage (NT), shallow tillage at a 10-cm depth (ST), and deep tillage at a 30-c...

  9. Quantifying the impact of preferential flow on solute transport to tile drains in a sandy field soil

    NASA Astrophysics Data System (ADS)

    Larsson, M. H.; Jarvis, N. J.; Torstensson, G.; Kasteel, R.

    1999-02-01

    The objective of this study was to quantify the impact of preferential finger flow on solute leaching to tile drains and shallow groundwater in a water repellent sandy soil. Measurements of site hydrology and bromide movement were made during a six-month period following application in autumn 1994 to a 900 m 2 plot. A dye tracing study was also conducted and this confirmed the presence of finger flow in the water repellent topsoil. Water flow and bromide transport was simulated using a mobile-immobile concept, in which a fraction of the soil volume is assumed not to participate in transport. With calibration of 'difficult' parameters (e.g. the fractional mobile volume), and accounting for significant water inflows to the plot from the surroundings, there was a good agreement between simulated and observed hydrology and solute transport patterns at the site. Mass balance calculations showed that ca. 46% of the bromide application was lost to the tile drains in the winter period following application, while 16% was lost in shallow lateral groundwater flow. Comparisons between one- and two-domain simulations showed that preferential flow reduced soil water contents and increased drainflow in the early autumn, leading to a more rapid bromide transport to depth. Nevertheless, the impact of preferential finger flow on leaching was minor for the non-reactive tracer bromide in this experiment, presumably because it was applied to relatively wet soil. However, scenario simulations for autumn application of a short half-life pesticide showed more significant effects, with leaching increased by ca. 80% because of preferential flow (from 1.2% to 2.2% of the applied amount).

  10. Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

    NASA Astrophysics Data System (ADS)

    Felderer, B.; Boldt-Burisch, K. M.; Schneider, B. U.; Hüttl, R. F. J.; Schulin, R.

    2012-07-01

    Large areas of land are restored with un-weathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were found to preferentially proliferate into nutrient-rich patches. Phosphorus (P) is of primary interest in this respect because its availability is often low in unweathered soils, limiting especially the growth of leguminous plants. However, leguminous plants occur frequently among the pioneer plant species on such soils as they only depend on atmospheric nitrogen (N) fixation as N source. In this study we investigated the relationship between root growth allocation of the legume Lotus corniculatus and soil P distribution on recently restored land. As test sites the experimental Chicken Creek Catchment (CCC) in eastern Germany and a nearby experimental site (ES) with the same soil substrate were used. We established two experiments with constructed heterogeneity, one in the field on the experimental site and the other in a climate chamber. In addition we conducted high-density samplings on undisturbed soil plots colonized by L. corniculatus on the ES and on the CCC. In the field experiment, we installed cylindrical ingrowth soil cores (4.5×10 cm) with and without P fertilization around single two-month-old L. corniculatus plants. Roots showed preferential growth into the P-fertilized ingrowth-cores. Preferential root allocation was also found in the climate chamber experiment, where single L. corniculatus plants were grown in containers filled with ES soil and where a lateral portion of the containers was additionally supplied with a range of different P concentrations. In the

  11. Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

    NASA Astrophysics Data System (ADS)

    Felderer, B.; Boldt-Burisch, K. M.; Schneider, B. U.; Hüttl, R. F. J.; Schulin, R.

    2013-03-01

    Large areas of land are restored with unweathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were found to preferentially proliferate into nutrient-rich patches. Phosphorus (P) is of primary interest in this respect because its availability is often low in unweathered soils, limiting especially the growth of leguminous plants. However, leguminous plants occur frequently among the pioneer plant species on such soils, as they only depend on atmospheric nitrogen (N) fixation as N source. In this study we investigated the relationship between root growth allocation of the legume Lotus corniculatus and soil P distribution on recently restored land. As test sites, the experimental Chicken Creek Catchment (CCC) in eastern Germany and a nearby experimental site (ES) with the same soil substrate were used. We established two experiments with constructed heterogeneity, one in the field on the experimental site and the other in a climate chamber. In addition, we conducted high-density samplings on undisturbed soil plots colonized by L. corniculatus on the ES and on the CCC. In the field experiment, we installed cylindrical ingrowth soil cores (4.5 × 10 cm) with and without P fertilization around single two-month-old L. corniculatus plants. Roots showed preferential growth into the P-fertilized ingrowth-cores. Preferential root allocation was also found in the climate chamber experiment, where single L. corniculatus plants were grown in containers filled with ES soil and where a lateral portion of the containers was additionally supplied with a range of different P concentrations. In

  12. Phosphate reactivity in long-term poultry litter-amended southern Delaware sandy soils

    USGS Publications Warehouse

    Arai, Y.; Livi, K.J.T.; Sparks, D.L.

    2005-01-01

    Eutrophication caused by dissolved P from poultry litter (PL)-amended agricultural soils has been a serious environmental concern in the Delaware-Maryland-Virginia Peninsula (Delmarva), USA. To evaluate state and federal nutrient management strategies for reducing the environmental impact of soluble P from long-term PL-amended Delaware (DE) soils, we investigated (i) inorganic P speciation; (ii) P adsorption capacity; and (iii) the extent of P desorption. Although the electron microprobe (EMP) analyses showed a strong correlation between P and Al/Fe, crystalline Al/Fe-P precipitates were not detected by x-ray diffraction (XRD). Instead, the inorganic P fractionation analyses showed high levels of oxalate extractable P, Al, and Fe fractions (615-858, 1215-1478, and 337-752 mg kg-1, respectively), which were susceptible to slow release during the long-term (30-d) P desorption experiments at a moderately acidic soil pHwater. The labile P in the short-term (24-h) desorption studies was significantly associated with oxalate and F extractable Fe and Al, respectively. This was evident in an 80% reduction maximum in total desorbable P from NH4 oxalate/F pretreated soils. In the adsorption experiments, P was strongly retained in soils at near targeted pH of lime (???6.0), but P adsorption gradually decreased with decreasing pH near the soil pHwater (???5.0). The overall findings suggest that P losses from the can be suppressed by an increase in the P retention capacity of soils via (i) an increase in the number of lime applications to maintain soil pHwater at near targeted pH values, and/or (ii) alum/iron sulfate amendments to provide additional Al- and Fe-based adsorbents. ?? Soil Science Society of America.

  13. Cumulative effects of sewage sludge and effluent mixture application on soil properties of a sandy soil under a mixture of star and kikuyu grasses in Zimbabwe

    NASA Astrophysics Data System (ADS)

    Madyiwa, S.; Chimbari, M.; Nyamangara, J.; Bangira, C.

    Although sewage effluent and sludge provides nutrients for plant growth, its continual use over extended periods can result in the accumulation of heavy metals in soils and in grass to levels that are detrimental to the food chain. This study was carried in 2001 out at Firle farm, owned by the Municipality of Harare, to assess heavy metal loading on a sandy soil and uptake of the metals by pasture grass consisting of a mixture of Cynodon nlemfuensis (star grass) and Pennisetum clandestinum Chiov (kikuyu grass) following sewage effluent and sludge application for 29 years. Firle Farm receives treated effluent and sludge emanating from domestic and industrial sources. Soil and grass samples were taken from the study area, consisting of 3 ha of non-irrigated area (control) and 1.3 ha of irrigated area. Both the soil and grass samples were tested for Cu, Zn, Ni and Pb using atomic absorption spectrophotometry. Sewage sludge addition resulted in high levels of soil pollution, especially in the 20 cm horizon, in the irrigated area when compared to the control. Grasses took up moderate levels of Cu and Zn, and limited levels of Pb. Nickel was not detectable in grasses despite high levels in the irrigated soil. Copper uptake was several times higher than the suggested potentially toxic level of 12 mg/kg [Soil Science Society of America, Micronutrients in agriculture, second ed., Wisconsin, USA, 1991]. Lead uptake averaged 1.0 mg/kg, which was below 10 mg/kg the suggested limit for agronomic crops [E.M. Seaker, Zinc, copper, cadmium and lead in minespoil, water and plants from reclaimed mine land amended with sewage sludge, 1991]. Cu and Zn showed relatively higher mobility down the soil profile than Ni and Pb. Even then, the concentrations in the lower soil layers were very small, suggesting that the metals were unlikely to contaminate groundwater. There was no direct correlation between metal levels in soils and grasses. It was postulated that it is the bio

  14. Efficacy of Biosolids in Assisted Phytostabilization of Metalliferous Acidic Sandy Soils with Five Grass Species

    PubMed Central

    Kacprzak, Malgorzata; Grobelak, Anna; Grosser, Anna; Prasad, M. N. V.

    2013-01-01

    The role of sewage sludge as an immobilising agent in the phytostabilization of metal-contaminated soil was evaluated using five grass species viz., Dactylis glomerata L., Festuca arundinacea Schreb., F. rubra L., Lolium perenne L., L. westerwoldicum L. The function of metal immobilization was investigated by monitoring pH, Eh and Cd, Pb, and Zn levels in column experiment over a period of 5-months. Grasses grown on sewage sludge-amendments produced high biomass in comparison to controls. A significant reduction in metal uptake by plants was also observed as a result of sewage sludge application, which was attributed to decreased bioavailability through soil stabilisation. We have observed that the sludge amendment decreased metal bioavailability and concentrations in soil at a depth of 25 cm, in contrast to untreated columns, where metal concentrations in the soil solution were very high. PMID:24912245

  15. Aeolian controls of soil geochemistry and weathering fluxes in high-elevation ecosystems of the Rocky Mountains, Colorado

    USGS Publications Warehouse

    Lawrence, Corey R.; Reynolds, Richard L.; Kettterer, Michael E.; Neff, Jason C.

    2013-01-01

    When dust inputs are large or have persisted for long periods of time, the signature of dust additions are often apparent in soils. The of dust will be greatest where the geochemical composition of dust is distinct from local sources of soil parent material. In this study the influence of dust accretion on soil geochemistry is quantified for two different soils from the San Juan Mountains of southwestern Colorado, USA. At both study sites, dust is enriched in several trace elements relative to local rock, especially Cd, Cu, Pb, and Zn. Mass-balance calculations that do not explicitly account for dust inputs indicate the accumulation of some elements in soil beyond what can be explained by weathering of local rock. Most observed elemental enrichments are explained by accounting for the long-term accretion of dust, based on modern isotopic and geochemical estimates. One notable exception is Pb, which based on mass-balance calculations and isotopic measurements may have an additional source at one of the study sites. These results suggest that dust is a major factor influencing the development of soil in these settings and is also an important control of soil weathering fluxes. After accounting for dust inputs in mass-balance calculations, Si weathering fluxes from San Juan Mountain soils are within the range observed for other temperate systems. Comparing dust inputs with mass-balanced based flux estimates suggests dust could account for as much as 50–80% of total long-term chemical weathering fluxes. These results support the notion that dust inputs may sustain chemical weathering fluxes even in relatively young continental settings. Given the widespread input of far-traveled dust, the weathering of dust is likely and important and underappreciated aspect of the global weathering engine.

  16. Orthophosphate Leaching in St. Augustinegrass and Zoysiagrass Grown in Sandy Soil under Field Conditions.

    PubMed

    Gonzalez, Ronald F; Sartain, Jerry B; Kruse, Jason K; Obreza, Thomas A; O'Connor, George A; Harris, Willie G

    2013-01-01

    Phosphorus (P) is required to maintain healthy, high-quality, warm-season turf. However, excessive P applications to soils with poor P retention capabilities may lead to leaching losses to groundwater. This field study was conducted to determine the maximum P fertilizer application rate to (Walt.) [Kuntze] 'Floratam' St. Augustinegrass (St. Augustinegrass) and 'Empire' zoysiagrass (zoysiagrass) below which P leaching is minimized. Five P levels ranging from 0 to 5.0 g P m yr were surface applied as triple superphosphate. Turf was established on an uncoated, low-P sand with negligible P retention capacity. Leaf and root growth, tissue P concentration, soil P concentration, soil P saturation, leachate volume, and orthophosphate (P) concentration in leachates were measured. Mehlich 1-extractable soil P (M1-P) and soil P saturation ratio (PSR) increased with time as the P rate increased. Lower M1-P and PSR values were measured with St. Augustinegrass, which absorbed more P than did zoysiagrass. The root system of St. Augustinegrass was larger and deeper compared with zoysiagrass, promoting greater P uptake and less P leaching. If tissue analysis indicates that P fertilization is required and the soil has the capacity to retain additional P, application of 0.8 g P m yr to zoysiagrass and 1.07 g P m yr to St. Augustinegrass is appropriate and does not result in increased P leaching. PMID:23673941

  17. Holocene aeolian activities in the southeastern Mu Us Desert, China

    NASA Astrophysics Data System (ADS)

    Jia, Feifei; Lu, Ruijie; Gao, Shangyu; Li, Jinfeng; Liu, Xiaokang

    2015-12-01

    Aeolian deposits from three sites in the Mu Us Desert were used to reconstruct the history of aeolian activities during the Holocene. The results of the lithologies, chronologies and proxy indicators showed that aeolian activities occurred at ∼9.96 cal ka BP, 7.9-6.9 ka BP, 6.4 ka BP and 3.8 cal ka BP∼. The cold event that occurred around 6.4 ka BP interrupted the Holocene Optimum period, which is largely consistent with the findings from sediments in adjacent regions and the monsoon areas of China. Combined with punished OSL and 14C ages of aeolian deposits samples in this region, the environmental changes in the Mu Us Desert were divided into four stages. Active sand dunes dominated before 11 ka BP. Aeolian activities occurred regionally from 11 to 8.5 ka BP and typical sandy paleosol widely developed with episodic aeolian activities between 8.5 and 4 ka BP. Dunes have reactivated and active sand dunes have gradually increased since 4 ka BP. Comparisons with the other paleoclimatic records indicated that the evolution of the Mu Us Desert was closely related to the East Asian monsoon. Paleosol development depended more on the precipitation brought by the East Asian summer monsoon (EASM). The stronger East Asian winter monsoon (EAMW) and higher isolation resulted in the aeolian activities in the early Holocene, while during the mid-Holocene the fluctuating EAWM played a more important role in inducing episodic aeolian activities. The environmental deterioration during the late Holocene can be related to weakened EASM or to increased anthropogenic influence.

  18. Persistence of fensulfothion in a sandy-loam soil and uptake by rutabagas, carrots and radishes using microplots

    SciTech Connect

    Greenhalgh, R.; Read, D.C.

    1981-01-01

    Field microplots were treated with 141 and 282 ppm fensulfothion and 37.1 and 74.2 ppm fensulfothion sulfone. These concentrations are equivalent to field treatment rates of 8.48 and 16.96 kg AI/ha, fensulfothion, and 2.23 and 4.47 kg AI/ha, fensulfothion sulfone, respectively, for banded application (10 cm wide, rows 80 cm apart). The half-lives in a sandy loam soil were 30-39 and 14-23 days, respectively. Fensulfothion sulfone and sulfide were the main derivatives found in fensulfothion treated soil. The maximum levels of these derivatives were 21.22 and 22.95 ppm, respectively for the 8.48 kg/ha treatment and 33.90 and 42.45 ppm, respectively, for the higher treatment, which occurred between 30-60 days. Carrots appeared to take up more fensulfothion from soil than rutabagas or radishes. The residue levels at harvest decreased in the order carrot peel greater than pulp greater than rutabagas root greater than peel greater than pulp. Residue levels of fensulfothion and sulfone in radishes were similar to those found in rutabagas. The ratio sulfoxide/sulfone in rutabagas ranged from 0.4-1.5 and in carrots from 1.7-7.6. This phenomenon is thought to be due to oxidative enzyme systems present in rutabagas. Dimethyl phosphorothioic acid, but not dimethyl phosphoric acid was detected (max. 1.33 ppm) in some rutabagas samples but not in carrots.

  19. Sensitivity of water stress in a two-layered sandy grassland soil to variations in groundwater depth and soil hydraulic parameters

    NASA Astrophysics Data System (ADS)

    Rezaei, M.; Seuntjens, P.; Joris, I.; Boënne, W.; Van Hoey, S.; Campling, P.; Cornelis, W. M.

    2016-01-01

    Monitoring and modelling tools may improve irrigation strategies in precision agriculture. We used non-invasive soil moisture monitoring, a crop growth and a soil hydrological model to predict soil water content fluctuations and crop yield in a heterogeneous sandy grassland soil under supplementary irrigation. The sensitivity of the soil hydrological model to hydraulic parameters, water stress, crop yield and lower boundary conditions was assessed after integrating models. Free drainage and incremental constant head conditions were implemented in a lower boundary sensitivity analysis. A time-dependent sensitivity analysis of the hydraulic parameters showed that changes in soil water content are mainly affected by the soil saturated hydraulic conductivity Ks and the Mualem-van Genuchten retention curve shape parameters n and α. Results further showed that different parameter optimization strategies (two-, three-, four- or six-parameter optimizations) did not affect the calculated water stress and water content as significantly as does the bottom boundary. In this case, a two-parameter scenario, where Ks was optimized for each layer under the condition of a constant groundwater depth at 135-140 cm, performed best. A larger yield reduction, and a larger number and longer duration of stress conditions occurred in the free drainage condition as compared to constant boundary conditions. Numerical results showed that optimal irrigation scheduling using the aforementioned water stress calculations can save up to 12-22 % irrigation water as compared to the current irrigation regime. This resulted in a yield increase of 4.5-6.5 %, simulated by the crop growth model.

  20. Remediation of oil-contaminated sandy soil in a slurry reactor

    SciTech Connect

    Puskas, K.; Al-Awadhi, N.; Abdullah, F.

    1995-09-01

    The soil slurry reactor was investigated as an alternative technology for removal of the oily material from the soil. The experiments revealed that significant reduction of the crude oil components can be achieved if favorable conditions, e.g., temperature, oxygen, and nutrients, are ensured for the degradation processes. The degradation of the oily material was followed by different analytical techniques. In addition to the analysis of the total extractable matter (TEM), chemical oxygen demand (COD), and nutrients, individual alkanes (including the isoprenoid alkanes, pristane and phytane) and polyaromatic hydrocarbons (PAHs) were determined to characterize the degradation process. It was concluded that the slurry reactor can be an effective technology to reduce the TEM in the soil. Aliphatic hydrocarbons biodegraded within 5 to 10d, whereas four-and more-ring PAHs were present in the slurry even after 40d. 17 refs., 6 figs., 3 tabs.

  1. The aeolian wind tunnel

    NASA Technical Reports Server (NTRS)

    Iversen, J. D.

    1991-01-01

    The aeolian wind tunnel is a special case of a larger subset of the wind tunnel family which is designed to simulate the atmospheric surface layer winds to small scale (a member of this larger subset is usually called an atmospheric boundary layer wind tunnel or environmental wind tunnel). The atmospheric boundary layer wind tunnel is designed to simulate, as closely as possible, the mean velocity and turbulence that occur naturally in the atmospheric boundary layer (defined as the lowest portion of the atmosphere, of the order of 500 m, in which the winds are most greatly affected by surface roughness and topography). The aeolian wind tunnel is used for two purposes: to simulate the physics of the saltation process and to model at small scale the erosional and depositional processes associated with topographic surface features. For purposes of studying aeolian effects on the surface of Mars and Venus as well as on Earth, the aeolian wind tunnel continues to prove to be a useful tool for estimating wind speeds necessary to move small particles on the three planets as well as to determine the effects of topography on the evolution of aeolian features such as wind streaks and dune patterns.

  2. Development of soil, land-use and management data bases for Aeolian research in eight western states, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erosion by wind is a severe problem that degrades air quality and visibility in the Pacific Northwest United States. Air quality is a regional concern that requires the use of an air quality model to simulate/forecast agricultural dust emissions, dispersion, and transport across a vast mosaic o...

  3. Monitoring of nitrate leaching in sandy soils: comparison of three methods.

    PubMed

    Zotarelli, Lincoln; Scholberg, Johannes M; Dukes, Michael D; Muñoz-Carpena, Rafael

    2007-01-01

    Proper N fertilizer and irrigation management can reduce nitrate leaching while maintaining crop yield, which is critical to enhance the sustainability of vegetable production on soils with poor water and nutrient-holding capacities. This study evaluated different methods to measure nitrate leaching in mulched drip-irrigated zucchini, pepper, and tomato production systems. Fertigation rates were 145 and 217 kg N ha(-1) for zucchini; 192 and 288 kg N ha(-1) for pepper; and 208 and 312 kg N ha(-1) for tomato. Irrigation was either applied at a fixed daily rate or based on threshold values of soil moisture sensors placed in production beds. Ceramic suction cup lysimeters, subsurface drainage lysimeters and soil cores were used to access the interactive effects of N rate and irrigation management on N leaching. Irrigation treatments and N rate interaction effects on N leaching were significant for all crops. Applying N rates in excess of standard recommendations increased N leaching by 64, 59, and 32%, respectively, for pepper, tomato, and zucchini crops. Independent of the irrigation treatment or nitrogen rate, N leaching values measured from the ceramic cup lysimeter-based N leaching values were lower than the values from the drainage lysimeter and soil coring methods. However, overall nitrate concentration patterns were similar for all methods when the nitrate concentration and leached volume were relatively low. PMID:17526874

  4. Water quality and surfactant effects on the water repellency of a sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Differences in irrigation water quality may affect the water repellency of soils treated or untreated with surfactants. Using simulated irrigations, we evaluated water quality and surfactant application rate effects upon the water repellency of a Quincy sand (Xeric Torripsamment). We used a split ...

  5. Evaluation of factors affecting nitrous oxide emission and N transformation in a sandy loam soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A better understanding of the complex factors affecting nitrous oxide (N2O) emission and potential mitigation practices will assist in developing strategies to improve the sustainability of agricultural production systems. Using surface soil collected from a pomegranate orchard, a series of laborato...

  6. Biochar pyrolyzed at two temperatures impacts E. coli transport through a sandy soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The incorporation of biochar – a charcoal-like material generated during the pyrolysis of biomass – into soils has been proposed as a means of sequestering carbon from the atmosphere and reducing greenhouse gas emissions. In addition, several studies have demonstrated environmental benefits to bioch...

  7. Soil C dynamics in a 26-year CRP chronosequence on an Amarillo fine sandy loam

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Conservation Reserve Program (CRP) sequesters more carbon (C) on private lands than any other federally administered program, but the rate and maximum amount of sequestered SOC is dependent on inherent soil properties (e.g. texture), local climate, and initial restoration efforts. We estimated t...

  8. Modelling Furrow Irrigation-Induced Erosion on a Sandy Loam Soil in Samaru, Northern Nigeria

    PubMed Central

    Dibal, Jibrin M.; Igbadun, H. E.; Ramalan, A. A.; Mudiare, O. J.

    2014-01-01

    Assessment of soil erosion and sediment yield in furrow irrigation is limited in Samaru-Zaria. Data was collected in 2009 and 2010 and was used to develop a dimensionless model for predicting furrow irrigation-induced erosion (FIIE) using the dimensional analyses approach considering stream size, furrow length, furrow width, soil infiltration rate, hydraulic shear stress, soil erodibility, and time flow of water in the furrows as the building components. One liter of water-sediment samples was collected from the furrows during irrigations from which sediment concentrations and soil erosion per furrow were calculated. Stream sizes Q (2.5, 1.5, and 0.5 l/s), furrow lengths X (90 and 45 m), and furrow widths W (0.75 and 0.9 m) constituted the experimental factors randomized in a split plot design with four replications. Water flow into and out of the furrows was measured using cutthroat flumes. The model produced reasonable predictions relative to field measurements with coefficient of determination R 2 in the neighborhood of 0.8, model prediction efficiency NSE (0.7000), high index of agreement (0.9408), and low coefficient of variability (0.4121). The model is most sensitive to water stream size. The variables in the model are easily measurable; this makes it better and easily adoptable.

  9. Clinoptilolite zeolite influence on inorganic nitrogen in silt loam and sandy agricultural soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Development of best management practices can help improve inorganic nitrogen (N) availability to plants and reduce nitrate-nitrogen (NO3-N) leaching in soils. This study was conducted to determine the influence of the zeolite mineral Clinoptilolite (CL) additions on NO3-N and ammonium-nitrogen (NH4...

  10. Clinoptilolite zeolite influence on nitrogen in a manure-amended sandy agricultural soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Development of best management practices can help improve inorganic nitrogen (N) availability to plants and reduce nitrate-nitrogen (NO3-N) leaching in soils. This study was conducted to determine the influence of the zeolite mineral clinoptilolite (CL) additions on NO3-N and ammonium-nitrogen (NH4-...

  11. Clinoptilolite Zeolite Influence on Inorganic Nitrogen in Silt Loam and Sandy Agricultural Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Development of best management practices can help improve inorganic nitrogen (N) availability to plants and reduce nitrate-nitrogen (NO3-N) leaching in soils. This study was conducted to determine the influence of the zeolite mineral Clinoptilolite (CL) additions on NO3-N and ammonium-nitrogen (NH4...

  12. Soil organic carbon and total nitrogen responses after 34 years of tillage of a sandy ultisol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conservation tillage and crop management strategies are available to increase soil organic carbon (SOC) and total nitrogen (TN) contents, but long-term (> 30 yrs) field results quantifying these increases are sparse. Our objectives were to quantity above ground biomass inputs and changes in vertica...

  13. Draft Genome Sequence of Jeotgalibacillus soli DSM 23228, a Bacterium Isolated from Alkaline Sandy Soil

    PubMed Central

    Chan, Kok-Gan; Yaakop, Amira Suriaty; Chan, Chia Sing; Ee, Robson; Tan, Wen-Si; Gan, Han Ming

    2015-01-01

    Jeotgalibacillus soli, a bacterium capable of degrading N-acyl homoserine lactone, was isolated from a soil sample in Portugal. J. soli constitutes the only Jeotgalibacillus species isolated from a non-marine source. Here, the draft genome, several interesting glycosyl hydrolases, and its putative N-acyl homoserine lactonases are presented. PMID:25999554

  14. Soil disturbance alters plant community composition and decreases mycorrhizal carbon allocation in a sandy grassland.

    PubMed

    Schnoor, Tim Krone; Mårtensson, Linda-Maria; Olsson, Pål Axel

    2011-11-01

    We have studied how disturbance by ploughing and rotavation affects the carbon (C) flow to arbuscular mycorrhizal (AM) fungi in a dry, semi-natural grassland. AM fungal biomass was estimated using the indicator neutral lipid fatty acid (NLFA) 16:1ω5, and saprotrophic fungal biomass using NLFA 18:2ω6,9. We labeled vegetation plots with (13)CO(2) and studied the C flow to the signature fatty acids as well as uptake and allocation in plants. We found that AM fungal biomass in roots and soil decreased with disturbance, while saprotrophic fungal biomass in soil was not influenced by disturbance. Rotavation decreased the (13)C enrichment in NLFA 16:1ω5 in soil, but (13)C enrichment in the AM fungal indicator NLFA 16:1ω5 in roots or soil was not influenced by any other disturbance. In roots, (13)C enrichment was consistently higher in NLFA 16:1ω5 than in crude root material. Grasses (mainly Festuca brevipila) decreased as a result of disturbance, while non-mycorrhizal annual forbs increased. This decreases the potential for mycorrhizal C sequestration and may have been the main reason for the reduced mycorrhizal C allocation found in disturbed plots. Disturbance decreased the soil ammonium content but did not change the pH, nitrate or phosphate availability. The overall effect of disturbance on C allocation was that more of the C in AM fungal mycelium was directed to the external phase. Furthermore, the functional identity of the plants seemed to play a minor role in the C cycle as no differences were seen between different groups, although annuals contained less AM fungi than the other groups. PMID:21614616

  15. Long-term reactivity of lung and mediastinal lymph nodes following intratracheal instillation of sandy loam soil or Mount St. Helens volcanic ash

    SciTech Connect

    Sanders, C.L.; Rhoads, K.; Mahaffey, J.A.

    1983-01-01

    The effects of Ritzville sandy loam soil and Mount St. Helens volcanic ash particles on the lung and mediastinal lymph nodes of Fischer rats were studied about 400 days after intratracheal instillation. A total of 22 or 77 mg of soil or ash was given in two or seven equally divided, consecutive, weekly intervals as a suspension in 0.5 ml saline. Significantly elevated levels of lipid-phosphorus and protein were found in lung lavages of rats given ash compared to those given soil. An enhanced histological degree of granulomatous reactivity, lipoproteinosis, fibrosis, and bronchiolar hyperplasia was seen in ash-exposed rats as compared to soil-exposed rats. Mediastinal lymph nodes of ash-exposed rats were 8-18 times larger than those of soil-exposed rats due to abundant cellular microgranuloma formation and early fibrosis. Mount St. Helens volcanic ash is apparently more biologically reactive than soil particles commonly found in eastern Washington.

  16. Long-term reactivity of lung and mediastinal lymph nodes following intratracheal instillation of sandy loam soil or Mount St. Helens volcanic ash.

    PubMed

    Sanders, C L; Rhoads, K; Mahaffey, J A

    1983-10-01

    The effects of Ritzville sandy loam soil and Mount St. Helens volcanic ash particles on the lung and mediastinal lymph nodes of Fischer rats were studied about 400 days after intratracheal instillation. A total of 22 or 77 mg of soil or ash was given in two or seven equally divided, consecutive, weekly intervals as a suspension in 0.5 ml saline. Significantly elevated levels of lipid-phosphorus and protein were found in lung lavages of rats given ash compared to those given soil. An enhanced histological degree of granulomatous reactivity, lipoproteinosis, fibrosis, and bronchiolar hyperplasia was seen in ash-exposed rats as compared to soil-exposed rats. Mediastinal lymph nodes of ash-exposed rats were 8-18 times larger than those of soil-exposed rats due to abundant cellular microgranuloma formation and early fibrosis. Mount St. Helens volcanic ash is apparently more biologically reactive than soil particles commonly found in eastern Washington. PMID:6617611

  17. Nitrogen mineralization and transformation from composts and biosolids during field incubation in a sandy soil

    SciTech Connect

    He, Z.L.; Alva, A.K.; Yan, P.; Li, Y.C.; Calvert, D.V.; Stoffella, P.J.; Banks, D.J.

    2000-02-01

    Field evaluation of nutrient release from composts is important to estimate nutrient contribution to crops, potential leaching of nutrients, and, ultimately, to determine optimum application rates, timing, and placement of composts. Field incubation and laboratory analyses were conducted to evaluate the mineralization rate and transformation of N in biosolids (BSD), yard waste (YW), and West Palm Beach co-compost (WPCC). Each of the composts or biosolids was packed into PVC columns and inserted vertically into the upper layer of an Oldsmar fine sand of raised citrus beds. The top end of the PVC column was capped to prevent excessive leaching of nutrients from the columns. The moisture equilibrium between the incubated sample and the soil in the field was attained through the bottom and four side holes of each column, which were separated from the contacting soil by 400-mesh nylon screen. A set of the incubated columns was removed at monthly intervals, and the soil underlying each column was sampled to analyze for KCl-extractable NH{sub 4}-N and NO{sub 3}-N. Total C and N of the incubated samples were determined at the end of the 1-year incubation.

  18. Imaging saline tracer infiltration into unsaturated sandy soil using full-waveform inversion of cross-borehole ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Looms, M. C.; Haarder, E. B.; Keskinen, J.; Nielsen, L.; Van Der Kruk, J.; Klotzsche, A.

    2015-12-01

    Cross-borehole ground penetrating radar (GPR) can provide high-resolution (tens of centimeter) information of the subsurface between boreholes located 5-10 m apart. The method is minimal invasive and therefore provides a unique opportunity to image subsurface variability not possible with standard point-scale equipment, such as TDR- and/or capacitance probes. Full-waveform inversion (FWI) of cross-borehole GPR uses the entire waveform of the transmitted electromagnetic signal. The recorded data contains information on the travel time of the pulse, as well as the attenuation, resulting in moisture content and electrical conductivity images of the subsurface using just one method. Few case studies of cross-borehole GPR FWI using real data have been published to date. The majority of these studies focus on estimating the variation in porosity in the saturated zone (e.g. in gravel aquifers, fractured metamorphic rock, and heterogeneous chalk sediments). In this study, we use cross-borehole GPR to monitor the infiltration of a saline tracer into an unsaturated sandy soil. In September 2011, saline water was added across a 142 m2 area at an agricultural field site in Denmark. A total of 3.3 mm saline water was applied mimicking a natural infiltration event. During the following year, the tracer infiltration into the subsurface was monitored using cross-borehole GPR at weekly to monthly intervals. Furthermore, five cores were extracted within the field site to obtain independent profiles of soil moisture and pore water conductivity for comparison. The cross-borehole GPR data were inverted using ray-based and FWI techniques. For the FWI an appropriate starting model and an effective wavelet must be estimated. Preliminary results indicate that the data modeled for the FWI results mimic better the measured data compared to the ray-based results. However, more research is needed to investigate the influence of the used starting model and the effective wavelet estimation.

  19. [Mechanisms of grass in slope erosion control in Loess sandy soil region of Northwest China].

    PubMed

    Zhao, Chun-Hong; Gao, Jian-En; Xu, Zhen

    2013-01-01

    By adopting the method of simulated precipitation and from the viewpoint of slope hydrodynamics, in combining with the analysis of soil resistance to erosion, a quantitative study was made on the mechanisms of grass in controlling the slope erosion in the cross area of wind-water erosion in Loess Plateau of Northwest China under different combinations of rainfall intensity and slope gradient, aimed to provide basis to reveal the mechanisms of vegetation in controlling soil erosion and to select appropriate vegetation for the soil and water conservation in Loess Plateau. The grass Astragalus adsurgens with the coverage about 40% could effectively control the slope erosion. This grass had an efficiency of more than 70% in reducing sediment, and the grass root had a greater effect than grass canopy. On bare slope and on the slopes with the grass plant or only the grass root playing effect, there existed a functional relation between the flow velocity on the slopes and the rainfall intensity and slope gradient (V = DJ(0.33 i 0.5), where V is flow velocity, D is the comprehensive coefficient which varies with different underlying surfaces, i is rainfall intensity, and J is slope gradient). Both the grass root and the grass canopy could markedly decrease the flow velocity on the slopes, and increase the slope resistance, but the effect of grass root in decreasing flow velocity was greater while the effect in increasing resistance was smaller than that of grass canopy. The effect of grass root in increasing slope resistance was mainly achieved by increasing the sediment grain resistance, while the effect of canopy was mainly achieved by increasing the slope form resistance and wave resistance. The evaluation of the soil resistance to erosion by using a conceptual model of sediment generation by overland flow indicated that the critical shear stress value of bare slope and of the slopes with the grass plant or only the grass root playing effect was 0.533, 1.672 and 0

  20. Distinct effects of moisture and air contents on acoustic properties of sandy soil.

    PubMed

    Oshima, Takuya; Hiraguri, Yasuhiro; Okuzono, Takeshi

    2015-09-01

    Knowledge of distinct effects of moisture content and air volume on acoustic properties of soil is sought to predict the influence of human activities such as cultivation on acoustic propagation outdoors. This work used an impedance tube with the two-thickness method to investigate such effects. For a constant moisture weight percentage, the magnitude of the characteristic impedance became smaller and the absorption coefficient became higher with increase of the air space ratio. For a constant air space ratio, the absorption coefficient became larger and the magnitude of the propagation constant became smaller with increasing moisture weight percentage. PMID:26428823

  1. Effect of rainfall and tillage direction on the evolution of surface crusts, soil hydraulic properties and runoff generation for a sandy loam soil

    NASA Astrophysics Data System (ADS)

    Ndiaye, Babacar; Esteves, Michel; Vandervaere, Jean-Pierre; Lapetite, Jean-Marc; Vauclin, Michel

    2005-06-01

    The study was aimed at evaluating the effect of rainfall and tillage-induced soil surface characteristics on infiltration and runoff on a 2.8 ha catchment located in the central region of Senegal. This was done by simulating 30 min rain storms applied at a constant rate of about 70 mm h -1, on 10 runoff micro-plots of 1 m 2, five being freshly harrowed perpendicularly to the slope and five along the slope (1%) of the catchment. Runoff was automatically recorded at the outlet of each plot. Hydraulic properties such as capillary sorptivity and hydraulic conductivity of the sandy loam soil close to saturation were determined by running 48 infiltration tests with a tension disc infiltrometer. That allowed the calculation of a mean characteristic pore size hydraulically active and a time to ponding. Superficial water storage capacity was estimated using data collected with an electronic relief meter. Because the soil was subject to surface crusting, crust-types as well as their spatial distribution within micro-plots and their evolution with time were identified and monitored by taking photographs at different times after tillage. The results showed that the surface crust-types as well as their tillage dependent dynamics greatly explain the decrease of hydraulic conductivity and sorptivity as the cumulative rainfall since tillage increases. The exponential decaying rates were found to be significantly greater for the soil harrowed along the slope (where the runoff crust-type covers more than 60% of the surface after 140 mm of rain) than across to the slope (where crusts are mainly of structural (60%) and erosion (40%) types). That makes ponding time smaller and runoff more important. Also it was shown that soil hydraulic properties after about 160 mm of rain were close to those of untilled plot not submitted to any rain. That indicates that the effects of tillage are short lived.

  2. 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.

  3. Biochar amendment affects leaching potential of copper and nutrient release behavior in contaminated sandy soils.

    PubMed

    Bakshi, Santanu; He, Zhenli L; Harris, Willie G

    2014-11-01

    Copper (Cu) contamination to soil and water is a worldwide concern. Biochar has been suggested to remediate degraded soils. In this study, column leaching and chemical characterization were conducted to assess effects of biochar amendment on Cu immobilization and subsequent nutrient release in Cu-contaminated Alfisol and Spodosol. The results indicate that biochar is effective in binding Cu (30 and 41%, respectively, for Alfisol with and without spiked Cu; 36 and 43% for Spodosol) and reducing Cu leaching loss (from ∼47 to 10% for the Cu-spiked Alfisol and from 48 to 9% for the Cu-spiked Spodosol). Copper was likely retained on biochar surfaces through complexation, as suggested by Fourier-transform infrared spectra. Biochar amendment converts a portion of Cu from available pool to more stable forms, thus resulting in decreased activities of free Cu and increased activity of organic Cu complexes in leachate. Reduction of >0.45-μm solids and nanoparticles concentrations in leachate was also observed. In addition, biochar application rate was correlated negatively with P, Ca, Mg, Zn, Mn, and NH-N concentration ( < 0.05) but positively with K and Na concentration ( < 0.05) in leachates. These results documented the potential of biochar as an effective amendment for Cu immobilization and mitigation of leaching risk for some nutrients. PMID:25602206

  4. Hydrodispersive characterization of a sandy porous medium by tracer tests carried out in laboratory on undisturbed soil samples

    NASA Astrophysics Data System (ADS)

    Ferrante, Aldo Pedro; Fallico, Carmine; Rios, Ana C.; Fernanda Rivera, Maria; Santillan, Patricio; Salazar, Mario

    2013-04-01

    The contamination of large areas and correspondent aquifers often imposes to implement some recovery operations which are generally complex and very expensive. Anyway, these interventions necessarily require the preventive characterization of the aquifers to be reclaimed and in particular the knowledge of the relevant hydrodispersive parameters. The determination of these parameters requires the implementation tracer tests for the specific site (Sauty JP, 1978). To reduce cost and time that such test requires tracer tests on undisturbed soil samples, representative of the whole aquifer, can be performed. These laboratory tests are much less expensive and require less time, but the results are certainly less reliable than those obtained by field tests for several reasons, including the particular scale of investigation. In any case the hydrodispersive parameters values, obtained by tests carried out in laboratory, can provide useful information on the considered aquifer, allowing to carry out initial verifications on the transmission and propagation of the pollutants in the aquifer considered. For this purpose, tracer tests with inlet of short time were carried out in the Soil Physics Laboratory of the Department of Soil Protection (University of Calabria), on a series of sandy soil samples with six different lengths, repeating each test with three different water flow velocities (5 m/d; 10 m/s and 15 m/d) (J. Feyen et al., 1998). The lengths of the samples taken into account are respectively 15 cm, 24 cm, 30 cm, 45 cm, 60 cm and 75 cm, while the solution used for each test was made of 100 ml of water and NaCl with a concentration of this substance corresponding to 10 g/L. For the porous medium taken into consideration a particle size analysis was carried out, resulting primarily made of sand, with total porosity equal to 0.33. Each soil sample was placed in a flow cell in which was inlet the tracer from the bottom upwards, measuring by a conductivimeter the

  5. Impact of slurry management strategies on potential leaching of nutrients and pathogens in a sandy soil amended with cattle slurry.

    PubMed

    Fangueiro, D; Surgy, S; Napier, V; Menaia, J; Vasconcelos, E; Coutinho, J

    2014-12-15

    For farmers, management of cattle slurry (CS) is now a priority, in order to improve the fertilizer value of the slurry and simultaneously minimize its environmental impact. Several slurry pre-treatments and soil application methods to minimize ammonia emissions are now available to farmers, but the impact of such management strategies on groundwater is still unclear. A laboratory experiment was performed over 24 days in controlled conditions, with undisturbed soil columns (sandy soil) in PVC pipes (30 cm high and 5.7 cm in diameter). The treatments considered (4 replicates) were: a control with no amendment (CTR), injection of whole CS (WSI), and surface application of: whole CS (WSS), acidified (pH 5.5) whole CS (AWSS), the liquid fraction obtained by centrifugation of CS (LFS), and acidified (pH 5.5) liquid fraction (ALFS). An amount of CS equivalent to 240 kg N ha(-1) was applied in all treatments. The first leaching event was performed 72 h after application of the treatments and then leaching events were performed weekly to give a total of four irrigation events (IEs). All the leachates obtained were analyzed for mineral and organic nitrogen, electrical conductivity (EC), pH, total carbon, and phosphorus. Total coliforms and Escherichia coli were also quantified in the leachates obtained in the first IE. The results show that both acidification and separation had significant effects on the composition of the leachates: higher NO3(-) concentrations were observed for the LFS and ALFS relative to all the other treatments, throughout the experiment, and lower NO3(-) concentrations were observed for acidified relative to non-acidified treatments at IE2. Acidification of both the LF and WS led to higher NH4(+) concentrations as well as an increase of EC for treatment ALFS relative to the control, in the first IE, and lower pH values in the AWSS. Furthermore, the E. coli and total coliform concentrations in AWSS, LFS, and ALFS were significantly higher than in

  6. Hurricane Sandy

    Atmospheric Science Data Center

    2015-03-05

    ... over Hurricane Sandy as the storm approached the U.S. east coast on October 28, 2012. The image at left covers an area 250 miles (400 ... are readily apparent in the low-level winds off the eastern coast of Florida, with speeds exceeding 45 mph (20 meters per second). The ...

  7. Influence of a Rhamnolipid Biosurfactant on the Transport of Bacteria through a Sandy Soil

    PubMed Central

    Bai, G.; Brusseau, M. L.; Miller, R. M.

    1997-01-01

    The objective of this study was to investigate the influence of an anionic rhamnolipid biosurfactant on the transport of bacterial cells through soil under saturated conditions. Three cell types with various hydrophobicities, i.e., Pseudomonas aeruginosa ATCC 9027, ATCC 27853, and ATCC 15442, were used in this study. In a series of experiments, columns packed with sterile sand were saturated with sterile artificial groundwater for 15 h, and then 3 pore volumes of (sup3)H-labeled bacterial suspensions with various rhamnolipid concentrations was pumped through the column. This was followed by 4 pore volumes of the rhamnolipid solution alone. The measured bacterial cell breakthrough curves were optimized by using an advection-dispersion transport model incorporating two-domain reversible sorption (instantaneous and rate limited) and with two first-order sink terms for irreversible adsorption. The influence of the rhamnolipid on the surface charge densities of the bacteria and the porous medium was also investigated. The results show that the rhamnolipid enhanced the transport of all cell types tested. For example, the rhamnolipid increased the recovery of the most hydrophilic strain, ATCC 9027, from 22.5 to 56.3%. Similarly, the recovery of ATCC 27853 increased from 36.8 to 49.4%, and the recovery of ATCC 15442, the most hydrophobic strain, increased from 17.7 to 40.5% in the presence of the rhamnolipid. The negative surface charge density of the porous medium was increased, while the surface charge density of the bacteria was not changed in the presence of the rhamnolipid. The model results suggest that the rhamnolipid predominantly affected irreversible adsorption of cells. PMID:16535601

  8. The relevance of in-situ and laboratory characterization of sandy soil hydraulic properties for soil water simulations

    NASA Astrophysics Data System (ADS)

    Rezaei, Meisam; Seuntjens, Piet; Shahidi, Reihaneh; Joris, Ingeborg; Boënne, Wesley; Al-Barri, Bashar; Cornelis, Wim

    2016-03-01

    Field water flow processes can be precisely delineated with proper sets of soil hydraulic properties derived from in situ and/or laboratory experiments. In this study we analyzed and compared soil hydraulic properties obtained by traditional laboratory experiments and inverse optimization tension infiltrometer data along the vertical direction within two typical Podzol profiles with sand texture in a potato field. The main goal was to identify proper sets of hydraulic parameters and to evaluate their relevance on hydrological model performance for irrigation management purposes. Tension disc infiltration experiments were carried out at four and five different depths for both profiles at consecutive negative pressure heads of 12, 6, 3 and 0.1 cm. At the same locations and depths undisturbed samples were taken to determine Mualem-van Genuchten (MVG) hydraulic parameters (θr, residual water content, θs, saturated water content, α and n, shape parameters and Kls, lab saturated hydraulic conductivity) in the laboratory. Results demonstrated horizontal differences and vertical variability of hydraulic properties. The tension disc infiltration data fitted well in inverse modeling using Hydrus 2D/3D in combination with final water content at the end of the experiment, θf. Four MVG parameters (θs, α, n and field saturated hydraulic conductivity Kfs) were estimated (θr set to zero), with estimated Kls and α values being relatively similar to values from Wooding's solution which used as initial value and estimated θs corresponded to (effective) field saturated water content, θf. The laboratory measurement of Kls yielded 2-30 times higher values than the field method Kfs from top to subsoil layers, while there was a significant correlation between both Ks values (r = 0.75). We found significant differences of MVG parameters θs, n and α values between laboratory and field measurements, but again a significant correlation was observed between laboratory and field MVG

  9. Microvirga makkahensis sp. nov., and Microvirga arabica sp. nov., isolated from sandy arid soil.

    PubMed

    Veyisoglu, Aysel; Tatar, Demet; Saygin, Hayrettin; Inan, Kadriye; Cetin, Demet; Guven, Kiymet; Tuncer, Munir; Sahin, Nevzat

    2016-02-01

    The taxonomic positions of two Gram-negative strains, SV1470(T) and SV2184P(T), isolated from arid soil samples, were determined using a polyphasic approach. Analysis of the 16S rRNA gene and the concatenated sequences of three housekeeping gene loci (dnaK, rpoB and gyrB) confirmed that the strains belong to the genus Microvirga. Strain SV1470(T) was found to be closely related to Microvirga vignae BR3299(T) (98.8 %), Microvirga flocculans TFB(T) (98.3 %) and Microvirga lupini Lut6(T) (98.2 %), whilst similarity to other type strains of the genus ranged from 97.8 to 96.3 %; strain SV2184P(T) was found to be closely related to Microvirga aerilata 5420S-16(T) (98.0 %), Microvirga zambiensis WSM3693(T) (97.8 %) and M. flocculans ATCC BAA-817(T) (97.4 %), whilst similarity to other type strains of the genus ranged from 97.2 to 95.9 %. The G + C content of the genomic DNA was determined to be 61.5 mol % for strain SV1470(T) and 62.1 mol % for strain SV2184P(T). Both strains were found to have the same quinone system, with Q-10 as the major ubiquinone. The polar lipid profile of strain SV1470(T) was found to consist of phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid and one unidentified aminolipid, while that of strain SV2184P(T) consisted of phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, one unidentified aminolipid, one unidentified aminophospholipid and two unidentified phospholipids. DNA-DNA relatedness studies showed that the two strains belong to different genomic species. The strains were also distinguished using a combination of phenotypic properties. Based on the genotypic and phenotypic data, the novel species Microvirga makkahensis sp. nov. (type strain SV1470(T) = DSM 25394(T) = KCTC 23863(T) = NRRL-B 24875(T)) and Microvirga arabica sp. nov. (type strain SV2184P(T) = DSM 25393(T) = KCTC 23864(T) = NRRL-B 24874(T)) are proposed. PMID:26671415

  10. Dolomite phosphate rock (DPR) application in acidic sandy soil in reducing leaching of phosphorus and heavy metals-a column leaching study.

    PubMed

    Yang, Yuangen; He, Zhenli; Yang, Xiaoe; Stoffella, Peter J

    2013-06-01

    A column leaching study was designed to investigate the leaching potential of phosphorus (P) and heavy metals from acidic sandy soils applied with dolomite phosphate rock (DPR) fertilizers containing varying amounts of DPR material and N-Viro soils. DPR fertilizers were made from DPR materials mixing with N-Viro soils at the ratios of 30, 40, 50, 60, and 70 %, and applied in acidic sandy soils at the level of 100 mg available P per kilogram soil. A control and a soluble P chemical fertilizer were also included. The amended soils were incubated at room temperature with 70 % field water holding capacity for 21 days before packed into a soil column and subjected to leaching. Seven leaching events were conducted at days 1, 3, 7, 14, 28, 56, and 70, respectively, and 258.9 mL of deionized water was applied at each leaching events. The leachate was collected for the analyses of pH, electrical conductivity (EC), dissolved organic carbon (DOC), major elements, and heavy metals. DPR fertilizer application resulted in elevations up to 1 unit in pH, 7-10 times in EC, and 20-40 times in K and Ca concentrations, but 3-10 times reduction in P concentration in the leachate as compared with the chemical fertilizer or the control. After seven leaching events, DPR fertilizers with adequate DPR materials significantly reduced cumulative leaching losses of Fe, P, Mn, Cu, and Zn by 20, 55, 3.7, 2.7, and 2.5 times than chemical fertilizer or control. Even though higher cumulative losses of Pb, Co, and Ni were observed after DPR fertilizer application, the loss of Pb, Co, and Ni in leachate was <0.10 mg (in total 1,812 mL leachate). Significant correlations of pH (negative) and DOC (positive) with Cu, Pb, and Zn (P<0.01) in leachate were observed. The results indicated that DPR fertilizers had a great advantage over the soluble chemical fertilizer in reducing P loss from the acidic sandy soil with minimal likelihood of heavy metal risk to the water environment. pH elevation and high

  11. Mitigation of Water Stress on Apple Trees under Rotational Irrigation Conditions by Increasing the Application Rate of Organic Fertilizers to Sandy Soils

    NASA Astrophysics Data System (ADS)

    Hamed, Lamy Mamdoh Mohamed; Ramadan Eid, Abdelraouf; Mohsmed Rabie Abdellatif Abdelaziz, Adel; Fathy Abdelsalam Essa, El-Sayed

    2016-04-01

    Egypt, as part of Mediterranean regions, is characterized by irregular and low rainfall amount which varies between (30-150 mm.year‑1), and characterized also by high temperature which increase the rate of evapotranspiration from the cultivated soil. On the other hand, New reclaimed soils are mostly occupies around 84 % of total area of Egypt, which is mainly sandy soils. These soils generally characterized by low water capacity holding, soil organic matter, and weak in nutrients retention. Under these conditions which have a great influence on crop production, there is a great needing to increase the crop water use efficiency and increasing of nutrient retention in sandy soils. In this context, two field experiments were carried out on sand soil located in north Cairo-Egypt at the experimental farm of National Research Center, El-NUBARIA, (latitude 30° 30' N, and longitude 30° 19' E). The effect of compost rates on soil hydraulic characteristics, fruit yields, quality traits, and water use efficiency and productivity of apple tree (Apple Anna Cultivar), was studied under deficit irrigation conditions. Four rates of compost [I1: control, I2: 12 ton.ha‑1., I3: 24 ton.ha‑1., I4: 36 ton.ha‑1. and I5:48 ton.ha‑1.] were applied under irrigation frequencies of (IF1 :once per week; IF2 :twice per week, IF3 :three times per week). The obtained results indicated that by increasing the application rate of compost, the available water capacity and saturated water content of sandy soil have been enhanced. In the same time, the fruit yield, quality traits and water productivity were increased by increasing the application rate of compost. It is worthy to mention that the I5IF3 treatment gave the highest values of fruit yield, quality traits and water productivity, whereas I1IF1 treatment gave the lowest values of all the above mentioned variables. As result, for apple cultivation in El-NUBARIA region, the recommended rate of compost is 48 ton.ha‑1 and irrigation

  12. [Effects of understory removal and nitrogen addition on the soil chemical and biological properties of Pinus sylvestris var. mongolica plantation in Keerqin Sandy Land].

    PubMed

    Lin, Gui-Gang; Zhao, Qiong; Zhao, Lei; Li, Hui-Chao; Zeng, De-Hui

    2012-05-01

    A full factorial experiment was conducted to study the effects of understory removal and nitrogen addition (8 g x m(-2)) on the soil NO(3-)-N and NH(4+)-N concentrations, potential net nitrogen mineralization rate (PNM) and nitrification rate (PNN), microbial biomass C (MBC) and N (MBN), MBC/MBN, urease and acid phosphomonoesterase activities, and Olsen-P concentration in a Pinus sylvestris var. mongolica plantation in Keerqin Sandy Land during a growth season. Understory removal decreased the soil NH(4+)-N concentration, PNM, MBC, and MBN/MBN significantly, increased the soil Olsen-P concentration, but had little effects on the soil NO(3-)-N concentration, PNN, and urease and acid phosphomonoesterase activities. Nitrogen addition increased the soil NO(3-)-N concentration, PNM and PNN significantly, but had little effects on the other test properties. The interaction between understory removal and nitrogen addition had significant effects on the soil NH(4+)-N concentration, but little effects on the soil NO(3-)-N concentration. However, the soil NO(3-)-N concentration in the plots of understory removal with nitrogen addition was increased by 27%, compared with the plots of nitrogen addition alone, which might lead to the leaching of NO3-. It was suggested that understory vegetation could play an important role in affecting the soil chemical and biological properties in Mongolian pine plantations, and hence, the importance of understory vegetation should not be neglected when the forest management and restoration were implemented. PMID:22919826

  13. Aeolian processes on Venus

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1989-01-01

    This review assesses the potential aeolian regime on Venus as derived from spacecraft observations, laboratory simulations, and theoretical considerations. The two requirements for aeolian processes (a supply of small, loose particles and winds of sufficient strength to move them) appear to be met on Venus. Venera 9, 10, 13, and 14 images show particles considered to be sand and silt size on the surface. In addition, dust spurts (grains 5 to 50 microns in diameter) observed via lander images and inferred from the Pioneer-Venus nephalometer experiments suggest that the particles are loose and subject to movement. Although data on near surface winds are limited, measurements of 0.3 to 1.2 m/sec from the Venera lander and Pioneer-Venus probes appear to be well within the range required for sand and dust entrainment. Aeolian activity involves the interaction of the atmosphere, lithosphere, and loose particles. Thus, there is the potential for various physical and chemical weathering processes that can effect not only rates of erosion, but changes in the composition of all three components. The Venus Simulator is an apparatus used to simulate weathering under venusian conditions at full pressure (to 112 bars) and temperature (to 800 K). In one series of tests, the physical modifications of windblown particles and rock targets were assessed and it was shown that particles become abraded even when moved by gentle winds. However, little abrasion occurs on the target faces. Thus, compositional signatures for target rocks may be more indicative of the windblown particles than of the bedrock. From these and other considerations, aeolian modifications of the venusian surface may be expected to occur as weathering, erosion, transportation, and deposition of surficial materials. Depending upon global and local wind regimes, there may be distinctive sources and sinks of windblown materials. Radar imaging, especially as potentially supplied via the Magellan mission, may enable the

  14. Aeolian Transport of Invertebrates

    NASA Astrophysics Data System (ADS)

    Gill, T. E.; Walsh, E. J.; Wallace, R. L.; Rojo, L.; Rivas, J. A.

    2012-12-01

    Playas and other ephemeral desert wetlands are preferential terrestrial landforms for dust emission. These sites also are habitat for a diverse assemblage of minute invertebrates. When wetlands desiccate, these invertebrates survive as resting stages (propagules). Thus, playas serve as isolated, ephemeral, biogeographical islands for aquatic invertebrates, but it is unclear how propagules disperse across distances as far as hundreds of kilometers to colonize hydrologically disconnected basins. Aeolian transport (anemochory) may provide the mechanism, especially since many invertebrate propagules are long-lived, aerodynamically shaped, possess low-density, and their size (30-600 μm) falls within the same texture as aeolian dust and sand grains. We are collecting and culturing wind-transported sediment to document its ability to serve in the dispersal of aridland invertebrate propagules. Deposited aeolian sediment was collected from marble-type traps placed on the roof of the Biological Sciences Building at the University of Texas, El Paso, during 19 individual regional-scale Chihuahuan Desert blowing dust/sand events between April 2010 and May 2012. Known source areas for these dust events include playas and ephemeral streams ~40- 150 km upwind. The mean dry grain size of the deposited sediment for each event ranged from 66 to 141 μm. Clean-water rinses of material from each event or standard rehydrations for culturing invertebrates were monitored microscopically for the appearance of organisms. Invertebrates hatched from the sediment of 13 events. Ciliates were detected in each of those samples: gastrotrichs appeared in three samples, nematodes and bdelloid rotifers in two samples, and clam shrimp in one. We have also rehydrated aeolian sediments, collected in standard dust traps, from many dust-emitting playas in Southwest North America and hatched viable organisms including all those previously mentioned as well as branchiopods, fairy shrimp, copepods

  15. Robotic Measurement of Aeolian Processes

    NASA Astrophysics Data System (ADS)

    Roberts, S.; Duperret, J. M.; Jerolmack, D. J.; Lancaster, N.; Nikolich, G.; Shipley, T. F.; Van Pelt, R. S.; Zobeck, T. M.; Koditschek, D. E.

    2015-12-01

    Local and regional measurements of sand transport and dust emission in complex natural settings presently lack spatiotemporal resolution adequate to inform models relevant for land management, climate policy, and the basic science of geomorphology. Deployments of wind, sand and dust sensors sophisticated enough to begin unpacking the complex relations among wind turbulence, surface roughness, sand flux and dust emission remain largely stationary. Aerial observations from satellites, planes and even UAVs help fill in, but none of these modalities offer the hope of "capturing the action" by being at the right place at the right time relative to the highly localized nature of sediment transport during wind storms. We have been developing a legged robot capable of rapidly traversing desert terrain, and are now adapting it to serve as a platform for scientific instrumentation. We aim to field a semi-autonomous, reactive mobile sensory package suited to the needs of aeolian science that can address the limitations of existing alternatives. This presentation reports on early trials in the Jornada LTER and White Sands National Monument aimed at gathering measurements of airflow and rates of sand transport on a dune face, assessing the role of roughness elements such as vegetation in modifying the wind shear stresses incident on the surface, and estimating erosion susceptibility in a natural arid soil. We will solicit ideas from the audience about other potentially interesting and viable measurement targets. Future close collaboration between aeolian, cognitive and robotics scientists such as we hope to promote through this presentation may yield machines with scientifically relevant sensory suites possessing sufficient autonomy to operate in-situ at the most intense episodes of wind and sediment movement under conditions far too uncomfortable and hazardous for human presence.

  16. Contemporary research in aeolian geomorphology

    NASA Astrophysics Data System (ADS)

    Bauer, B. O.

    2009-04-01

    The first International Conference on Aeolian Geomorphology (ICAR) was held in 1986, and every four years since then, aeolian geomorphologists from around the world have assembled to discuss their research and to showcase recent advancements in understanding and modeling of aeolian processes. A content analysis of the "Bibliography of Aeolian Research" [Stout, J.E., Warren, A., Gill, T.E., 2009. Publication trends in aeolian research: An analysis of the Bibliography of Aeolian Research. Geomorphology 105, 6-17 (this volume)] shows that the number of publications on aeolian topics has increased exponentially from the mid-20th Century with approximately 50 publications per year to about 500 publications per year when the first ICAR was held, to almost 1000 publications per year currently. Areas of focus have shifted historically from initial concerns with aeolian erosion and dust events as isolated phenomenon of localized curiosity or only regional importance, to comprehensive physically-based investigations and modeling of the mechanics of aeolian transport. Recently, more applied studies have been motivated by the recognition of the importance of aeolian processes to dust emissions into the atmosphere (with relevance for human health and for meteorological conditions and climate change) and within regional management contexts (especially on coasts where impending sea-level rise is of great concern and in arid and semi-arid environments given the dependence of sediment surface stability and remobilization on meteorological and ecological conditions). Aeolian geomorphology is a rapidly growing sub-discipline of Geomorphology that offers rich opportunities for interdisciplinary collaborations with colleagues from the Atmospheric Sciences, Climatology, Sedimentology, Quaternary Geology, Fluid Mechanics, Physics, Mathematics, Computer Science, Physical Geography, Ecology, and Agricultural Sciences, as well as our counterparts in fluvial, coastal, and arid

  17. Cadmium adsorption on plant- and manure-derived biochar and biochar-amended sandy soils: impact of bulk and surface properties.

    PubMed

    Xu, Dongyu; Zhao, Ye; Sun, Ke; Gao, Bo; Wang, Ziying; Jin, Jie; Zhang, Zheyun; Wang, Shuifeng; Yan, Yu; Liu, Xitao; Wu, Fengchang

    2014-09-01

    To investigate the role of the bulk and surface composition of both biochar and biochar-amended soils in the adsorption of Cd(2+), as well as the influence of different biochars added to the soils on Cd(2+) adsorption, swine-manure-derived biochars (BSs) and wheat-straw-derived biochars (BWs) were produced at 300, 450, and 600°C. These biochars were added to a sandy soil to investigate the effect of biochars on the adsorption of Cd(2+) by soil. The significantly higher surface C content of the amended soils compared to their bulk C content suggests that the minerals of the biochar-amended soils are most likely covered primarily by biochars. The maximum adsorption capacity (Qmax,total) of the BSs was 10-15 times higher than that of the BWs due to the high polarity and ash content of the BSs. The polarity ((N+O)/C) of the low-temperature biochars greatly affected their Cd(2+) adsorption. The Qmax,total of the BS-amended soils increased with increasing dose, whereas the Qmax,total of the BW-amended soils showed the opposite behavior, which was attributed to the different surface composition characteristics of the two types of soil. The BSs were more effective in immobilizing Cd(2+) upon application to the soil relative to the BWs. This study elucidates the spatial distribution of biochars in biochar-amended soils and highlights the importance of the surface composition of the investigated samples in Cd(2+) adsorption. PMID:24997935

  18. The Icelandic volcanic aeolian environment: Processes and impacts - A review

    NASA Astrophysics Data System (ADS)

    Arnalds, Olafur; Dagsson-Waldhauserova, Pavla; Olafsson, Haraldur

    2016-03-01

    Iceland has the largest area of volcaniclastic sandy desert on Earth or 22,000 km2. The sand has been mostly produced by glacio-fluvial processes, leaving behind fine-grained unstable sediments which are later re-distributed by repeated aeolian events. Volcanic eruptions add to this pool of unstable sediments, often from subglacial eruptions. Icelandic desert surfaces are divided into sand fields, sandy lavas and sandy lag gravel, each with separate aeolian surface characteristics such as threshold velocities. Storms are frequent due to Iceland's location on the North Atlantic Storm track. Dry winds occur on the leeward sides of mountains and glaciers, in spite of the high moisture content of the Atlantic cyclones. Surface winds often move hundreds to more than 1000 kg m-1 per annum, and more than 10,000 kg m-1 have been measured in a single storm. Desertification occurs when aeolian processes push sand fronts and have thus destroyed many previously fully vegetated ecosystems since the time of the settlement of Iceland in the late ninth century. There are about 135 dust events per annum, ranging from minor storms to >300,000 t of dust emitted in single storms. Dust production is on the order of 30-40 million tons annually, some traveling over 1000 km and deposited on land and sea. Dust deposited on deserts tends to be re-suspended during subsequent storms. High PM10 concentrations occur during major dust storms. They are more frequent in the wake of volcanic eruptions, such as after the Eyjafjallajökull 2010 eruption. Airborne dust affects human health, with negative effects enhanced by the tubular morphology of the grains, and the basaltic composition with its high metal content. Dust deposition on snow and glaciers intensifies melting. Moreover, the dust production probably also influences atmospheric conditions and parameters that affect climate change.

  19. Comparison of mill mud, soybean cropping system, and fertilizer nutrient sources for sugarcane on a sandy soil.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improving soil organic matter and soil fertility are important factors in the sustainability of sugarcane production. A 3-yr field trial was established in 2004 on a sand soil (greater than 90% sand) in Florida to compare the effect of organic and inorganic nutrient sources on soil fertility and su...

  20. Optical Properties of Aeolian Dusts Common to West Texas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Both recent models and historical events such as the Dust Bowl and volcanic eruptions have illustrated aerosols can play a significant role in climate change through direct and indirect optical effects. Soil dust aerosols generated by Aeolian processes represent a significant fraction of the total ...

  1. [Effects of different vegetation restoration patterns on the diversity of soil nitrogen-fixing microbes in Hulunbeier sandy land, Inner Mongolia of North China].

    PubMed

    Li, Gang; Wang, Li-Juan; Li, Yu-Jie; Qiao, Jiang; Zhang, Hai-Fang; Song, Xiao-Long; Yang, Dian-Lin

    2013-06-01

    By using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and sequence analysis, this paper studied the nifH gene diversity and community structure of soil nitrogen-fixing microbes in Hulunbeier sandy land of Inner Mongolia under four years management of five vegetation restoration modes, i. e., mixed-planting of Agropyron cristatum, Hedysarum fruticosum, Caragana korshinskii, and Elymus nutans (ACHE) and of Agropyron cristatum and Hedysarum fruticosum (AC), and mono-planting of Caragana korshinskii (UC), Agropyron cristatum (UA), and Hedysarum fruticosum (UH), taking the bare land as the control (CK). There existed significant differences in the community composition of nitrogen-fixing microbes among the five vegetation restoration patterns. The Shannon index of the nifH gene was the highest under ACHE, followed by under AC, UC, UA, and UH, and the lowest in CK. Except that UH and CK had less difference in the Shannon index, the other four vegetation restoration modes had a significantly higher Shannon index than CK (P < 0.05). The phylogenetic analysis showed that the soil nitrogen-fixing microbes under UA, UH, and UC were mainly of cyanobacteria, but the soil nitrogen-fixing microbes under AC and ACHE changed obviously, mainly of proteobacteria, and also of cyanobacteria. The canonical correlation analysis showed that the soil total phosphorus, available phosphorus, total nitrogen, and nitrate nitrogen contents under the five vegetation restoration modes had significant effects on the nitrogen-fixing microbial communities, and there existed significant correlations among the soil total phosphorus, available phosphorus, total nitrogen, and nitrate nitrogen. It was suggested that the variations of the community composition of soil nitrogen-fixing microbes under the five vegetation restoration modes were resulted from the interactive and combined effects of the soil physical and chemical factors. PMID:24066552

  2. Aeolian sand ripples around plants.

    PubMed

    Zhang, Qian-Hua; Miao, Tian-De

    2003-05-01

    Plants in the desert may locally change the aeolian process, and hence the pattern of sand ripples traveling nearby. The effect of plants on ripples is investigated using a coupled map lattice model with nonuniform coupling coefficients. PMID:12786143

  3. Gully annealing by aeolian sediment: field and remote-sensing investigation of aeolian-hillslope-fluvial interactions, Colorado River corridor, Arizona, USA

    NASA Astrophysics Data System (ADS)

    Sankey, Joel B.; Draut, Amy E.

    2014-09-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This study of gully annealing by aeolian sediment, spanning 95 km along the Colorado River corridor in Glen, Marble, and Grand Canyon, Arizona, USA, employed field and remote sensing observations, including digital topographic modelling. Results indicate that aeolian sediment activity can be locally effective at counteracting gully erosion. Gullies are less prevalent in areas where surficial sediment undergoes active aeolian transport, and have a greater tendency to terminate in active aeolian sand. Although not common, examples exist in the record of historical imagery of gullies that underwent infilling by aeolian sediment in past decades and evidently were effectively annealed. We thus provide new evidence for a potentially important interaction of aeolian-hillslope-fluvial processes, which could affect dryland regions substantially in ways not widely recognized. Moreover, because the biologic soil crust plays an important role in determining aeolian sand activity, and so in turn the extent of gully development, this study highlights a critical role of geomorphic-ecologic interactions in determining arid-landscape evolution.

  4. Radar-aeolian roughness project

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Dobrovolskis, A.; Gaddis, L.; Iversen, J. D.; Lancaster, N.; Leach, Rodman N.; Rasnussen, K.; Saunders, S.; Vanzyl, J.; Wall, S.

    1991-01-01

    The objective is to establish an empirical relationship between measurements of radar, aeolian, and surface roughness on a variety of natural surfaces and to understand the underlying physical causes. This relationship will form the basis for developing a predictive equation to derive aeolian roughness from radar backscatter. Results are given from investigations carried out in 1989 on the principal elements of the project, with separate sections on field studies, radar data analysis, laboratory simulations, and development of theory for planetary applications.

  5. Hydrogeology of Stromboli volcano, Aeolian Islands (Italy) from the interpretation of resistivity tomograms, self-potential, soil temperature and soil CO2 concentration measurements

    NASA Astrophysics Data System (ADS)

    Revil, A.; Finizola, A.; Ricci, T.; Delcher, E.; Peltier, A.; Barde-Cabusson, S.; Avard, G.; Bailly, T.; Bennati, L.; Byrdina, S.; Colonge, J.; di Gangi, F.; Douillet, G.; Lupi, M.; Letort, J.; Tsang Hin Sun, E.

    2011-09-01

    To gain a better insight of the hydrogeology and the location of the main tectonic faults of Stromboli volcano in Italy, we collected electrical resistivity measurements, soil CO2 concentrations, temperature and self-potential measurements along two profiles. These two profiles started at the village of Ginostra in the southwest part of the island. The first profile (4.8 km in length) ended up at the village of Scari in the north east part of the volcano and the second one (3.5 km in length) at Forgia Vecchia beach, in the eastern part of the island. These data were used to provide insights regarding the position of shallow aquifers and the extension of the hydrothermal system. This large-scale study is complemented by two high-resolution studies, one at the Pizzo area (near the active vents) and one at Rina Grande where flank collapse areas can be observed. The Pizzo corresponds to one of the main degassing structure of the hydrothermal system. The main degassing area is localized along a higher permeability area corresponding to the head of the gliding plane of the Rina Grande sector collapse. We found that the self-potential data reveal the position of an aquifer above the villages of Scari and San Vincenzo. We provide an estimate of the depth of this aquifer from these data. The lateral extension of the hydrothermal system (resistivity ˜15-60 ohm m) is broader than anticipated extending in the direction of the villages of Scari and San Vincenzo (in agreement with temperature data recorded in shallow wells). The lateral extension of the hydrothermal system reaches the lower third of the Rina Grande sector collapse area in the eastern part of the island. The hydrothermal body in this area is blocked by an old collapse boundary. This position of the hydrothermal body is consistent with low values of the magnetization (<2.5 A m-1) from previously published work. The presence of the hydrothermal body below Rina Grande raises questions about the mechanical stability

  6. High-quality draft genome sequence of Enterobacter sp. Bisph2, a glyphosate-degrading bacterium isolated from a sandy soil of Biskra, Algeria

    PubMed Central

    Benslama, Ouided; Boulahrouf, Abderrahmane

    2016-01-01

    Enterobacter sp. strain Bisph2 was isolated from a sandy soil from Biskra, Algeria and exhibits glyphosate-degrading activity. Multilocus sequence analysis of the 16S rRNA, rpoB, hsp60, gyrB and dnaJ genes demonstrated that Bisph2 might be a member of a new species of the genus Enterobacter. Genomic sequencing of Bisph2 was used to better clarify the relationships among Enterobacter species. Annotation and analysis of the genome sequence showed that the 5.535.656 bp genome of Enterobacter sp. Bisph2 consists in one chromosome and no detectable plasmid, has a 53.19% GC content and 78% of genes were assigned a putative function. The genome contains four prophages of which 3 regions are intact and no CRISPER was detected. The nucleotide sequence of this genome was deposited into DDBJ/EMBL/GenBank under the accession JXAF00000000. PMID:27222800

  7. High-quality draft genome sequence of Enterobacter sp. Bisph2, a glyphosate-degrading bacterium isolated from a sandy soil of Biskra, Algeria.

    PubMed

    Benslama, Ouided; Boulahrouf, Abderrahmane

    2016-06-01

    Enterobacter sp. strain Bisph2 was isolated from a sandy soil from Biskra, Algeria and exhibits glyphosate-degrading activity. Multilocus sequence analysis of the 16S rRNA, rpoB, hsp60, gyrB and dnaJ genes demonstrated that Bisph2 might be a member of a new species of the genus Enterobacter. Genomic sequencing of Bisph2 was used to better clarify the relationships among Enterobacter species. Annotation and analysis of the genome sequence showed that the 5.535.656 bp genome of Enterobacter sp. Bisph2 consists in one chromosome and no detectable plasmid, has a 53.19% GC content and 78% of genes were assigned a putative function. The genome contains four prophages of which 3 regions are intact and no CRISPER was detected. The nucleotide sequence of this genome was deposited into DDBJ/EMBL/GenBank under the accession JXAF00000000. PMID:27222800

  8. Effects of Monotypic and Binary Mixtures of Metal Oxide Nanoparticles on Microbial Growth in Sandy Soil Collected from Artificial Recharge Sites

    PubMed Central

    Ko, Kyung-Seok; Ha, Kyoochul; Kong, In Chul

    2015-01-01

    The potential effects of monotypic and binary metal oxide nanoparticles (NPs, ZnO, NiO, Co3O4 and TiO2) on microbial growth were evaluated in sandy soil collected from artificial recharge sites. Microbial growth was assessed based on adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), and viable cell counts (VCC). Microbial growth based on ATP content and VCC showed considerable differences depending on NP type and concentration, whereas DHA did not significantly change. In general, ZnO NPs showed the strongest effect on microbial growth in all measurements, showing an EC50 value of 10.9 mg/L for ATP content. The ranking (EC50) of NPs based on their effect on microbial growth assessed by ATP content and VCC was ZnO > Co3O4 > NiO > TiO2. Upon exposure to binary NP mixtures, synergistic and additive modes of action were observed for ATP content and VCC, respectively. The ranges of observed (P(O)) and expected (P(E)) activity were 83%–92% and 78%–82% of the control (p-value 0.0010) based on ATP content and 78%–95% and 72%–94% of the control (p-value 0.8813) based on VCC under the tested conditions, respectively. The results indicate that the effects of NP mixtures on microbial growth in the sandy soil matrix were as great, or greater, than those of single NPs. Therefore, understanding the effects of single NPs and NP mixtures is essential for proper ecological risk assessment. Additionally, these findings demonstrate that the evaluation of NP effects may be profoundly influenced by the method of microbial growth measurement. PMID:26610489

  9. Effects of Monotypic and Binary Mixtures of Metal Oxide Nanoparticles on Microbial Growth in Sandy Soil Collected from Artificial Recharge Sites.

    PubMed

    Ko, Kyung-Seok; Ha, Kyoochul; Kong, In Chul

    2015-01-01

    The potential effects of monotypic and binary metal oxide nanoparticles (NPs, ZnO, NiO, Co₃O₄ and TiO₂) on microbial growth were evaluated in sandy soil collected from artificial recharge sites. Microbial growth was assessed based on adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), and viable cell counts (VCC). Microbial growth based on ATP content and VCC showed considerable differences depending on NP type and concentration, whereas DHA did not significantly change. In general, ZnO NPs showed the strongest effect on microbial growth in all measurements, showing an EC50 value of 10.9 mg/L for ATP content. The ranking (EC50) of NPs based on their effect on microbial growth assessed by ATP content and VCC was ZnO > Co₃O₄ > NiO > TiO₂. Upon exposure to binary NP mixtures, synergistic and additive modes of action were observed for ATP content and VCC, respectively. The ranges of observed (P(O)) and expected (P(E)) activity were 83%-92% and 78%-82% of the control (p-value 0.0010) based on ATP content and 78%-95% and 72%-94% of the control (p-value 0.8813) based on VCC under the tested conditions, respectively. The results indicate that the effects of NP mixtures on microbial growth in the sandy soil matrix were as great, or greater, than those of single NPs. Therefore, understanding the effects of single NPs and NP mixtures is essential for proper ecological risk assessment. Additionally, these findings demonstrate that the evaluation of NP effects may be profoundly influenced by the method of microbial growth measurement. PMID:26610489

  10. Accumulation of hexahydro-1,3,5-trinitro-1,3,5-triazine by the earthworm Eisenia andrei in a sandy loam soil.

    PubMed

    Sarrazin, Manon; Dodard, Sabine G; Savard, Kathleen; Lachance, Bernard; Robidoux, Pierre Y; Kuperman, Roman G; Hawari, Jalal; Ampleman, Guy; Thiboutot, Sonia; Sunahara, Geoffrey I

    2009-10-01

    The heterocyclic polynitramine hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a highly energetic compound found as a soil contaminant at some defense installations. Although RDX is not lethal to soil invertebrates at concentrations up to 10,000 mg/kg, it decreases earthworm cocoon formation and juvenile production at environmentally relevant concentrations found at contaminated sites. Very little is known about the uptake of RDX in earthworms and the potential risks for food-chain transfer of RDX in the environment. Toxicokinetic studies were conducted to quantify the bioaccumulation factors (BAFs) using adult earthworms (Eisenia andrei) exposed for up to 14 d to sublethal concentrations of nonlabeled RDX or [14C]RDX in a Sassafras sandy loam soil. High-performance liquid chromatography of acetonitrile extracts of tissue and soil samples indicated that nonlabeled RDX can be accumulated by the earthworm in a concentration- and time-dependent manner. The BAF, expressed as the earthworm tissue to soil concentration ratio, decreased from 6.7 to 0.1 when the nominal soil RDX concentrations were increased from 1 to 10,000 mg/kg. Tissue concentrations were comparable in earthworms exposed to nonlabeled RDX or [14C]RDX. The RDX bioaccumulation also was estimated using the kinetically derived model (BAFK), based on the ratio of the uptake to elimination rate constants. The established BAFK of 3.6 for [14C]RDX uptake was consistent with the results for nonlabeled RDX. Radioactivity also was present in the tissue residues of [14C]RDX-exposed earthworms following acetonitrile extraction, suggesting the formation of nonextractable [14C]RDX metabolites associated with tissue macromolecules. These findings demonstrated a net accumulation of RDX in the earthworm and the potential for food-chain transfer of RDX to higher-trophic-level receptors. PMID:19432505

  11. Identification of a late Quaternary alluvial-aeolian sedimentary sequence in the Sichuan Basin, China

    NASA Astrophysics Data System (ADS)

    Feng, Jin-Liang; Ju, Jian-Ting; Chen, Feng; Hu, Zhao-Guo; Zhao, Xiang; Gao, Shao-Peng

    2016-03-01

    The late Quaternary sedimentary sequence in the northwestern part of the Sichuan Basin consists of five lithological units and with increasing depth include the: Chengdu Clay; Brown Clay; Red Clay; Sandy Silt; and basal Muddy Gravel. The genesis, provenance and age of the sediments, as well as the possible presence of hiatuses within this sequence are debated. Measurements of grain-size, magnetic susceptibility, quartz content, quartz δ18O values, element composition, and Sr-Nd isotopic concentrations of samples from a typical sedimentary sequence in the area provides new insights into the genesis and history of the sequence. The new data confirm that the sediments in study site are alluvial-aeolian in origin, with basal alluvial deposits overlain by aeolian deposits. Like the uppermost Chengdu Clay, the underlying Brown Clay and Red Clay are aeolian in origin. In contrast, the Silty Sand, like the basal Muddy Gravel, is an alluvial deposit and not an aeolian deposit as previously thought. Moreover, the succession of the aeolian deposits very likely contains two significant sedimentary hiatuses. Sedimentological analysis demonstrates that the source materials for the aeolian deposits in the northwestern part of the Sichuan Basin and those on the eastern Tibetan Plateau are different. Furthermore, the loess deposits on the eastern Tibetan Plateau are derived from heterogeneous local sources.

  12. [Horizontal transport of nitrate in main soil groups of Huang-Huai-Hai Plain].

    PubMed

    Chen, Xiaomin; Deng, Jiancai; Zhang, Jiabao; Zhu, Anning; Pan, Youyu

    2002-09-01

    The horizontal transport of nitrate in main soil groups (yellow fluvo-aquic soils and aeolian sandy soil) in Huang-Huai-Hai Plain was studied. The results were as follows: the horizontal transport velocity of nitrate decreased with the distance of the tracer source in power function. Due to different soil property in soil profile, the curves of horizontal transport of nitrate were difference. The horizontal transport velocity of nitrate was controlled by the concentration gradient and soil water potential gradient in 20 cm of horizontal soil column. It was stable after 20 cm, which was controlled by soil matric potential. The horizontal transport velocity of nitrate was in a sharp positive relation with the soil moisture content and changed with exponential function. The concentration of nitrate in horizontal transport decreased with the unsaturated soil water diffusivity increased and changed with logarithmic function. PMID:12533936

  13. Microbial response to salinity stress in a tropical sandy soil amended with native shrub residues or inorganic fertilizer.

    PubMed

    Sall, Saïdou Nourou; Ndour, Ndèye Yacine Badiane; Diédhiou-Sall, Siré; Dick, Richard; Chotte, Jean-Luc

    2015-09-15

    Soil degradation and salinization caused by inappropriate cultivation practices and high levels of saltwater intrusion are having an adverse effect on agriculture in Central Senegal. The residues of Piliostigma reticulatum, a local shrub that coexists with crops, were recently shown to increase particulate organic matter and improve soil quality and may be a promising means of alleviating the effects of salinization. This study compared the effects of inorganic fertilizer and P. reticulatum residues on microbial properties and the ability of soil to withstand salinity stress. We hypothesized that soils amended with P. reticulatum would be less affected by salinity stress than soils amended with inorganic fertilizer and control soil. Salinity stress was applied to soil from a field site that had been cultivated for 5 years under a millet/peanut crop rotation when microbial biomass, phospholipid fatty acid (PLFA) community profile, catabolic diversity, microbial activities were determined. Microbial biomass, nitrification potential and dehydrogenase activity were higher by 20%, 56% and 69% respectively in soil with the organic amendment. With salinity stress, the structure and activities of the microbial community were significantly affected. Although the biomass of actinobacteria community increased with salinity stress, there was a substantial reduction in microbial activity in all soils. The soil organically amended was, however, less affected by salinity stress than the control or inorganic fertilizer treatment. This suggests that amendment using P. reticulatum residues may improve the ability of soils to respond to saline conditions. PMID:26143083

  14. Non-Linear finite element analysis of cone penetration in layered sandy loam soil-considering precompression stress state

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Axisymmetric finite element (FE) method was developed using a commercial computer program to simulate cone penetration process in layered granular soil. Soil was considered as a non-linear elastic plastic material which was modeled using variable elastic parameters of Young’s Modulus and Poisson’s r...

  15. Quantity and nature of water-extractable organic matter from sandy loam soils with potato cropping managements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water-extractable organic matter (WEOM) is part of the soil labile organic matter components. In this work, we evaluated the level and nature of soil WEOM from a long-term (6-year) potato crop rotation field experiment. The contents of water-extractable organic C (WEOC) were higher in continuous pot...

  16. Biodiversity impact of the aeolian periglacial geomorphologic evolution of the Fontainebleau Massif (France)

    NASA Astrophysics Data System (ADS)

    Thiry, M.; Liron, M. N.

    2009-04-01

    imposing, with blocks piling up and rising well off the sandy slopes. The sandstone "platières" are mostly bare as say above. Downwind, in the eastern district, the landforms are more subdued. The deflation is less extensive, the sandstone scarps and chaos are partly sanded up, with drift sand amassing at the lee side of the scarps. The "platières" have a sand cover that favours often the development of a tree stratum composed almost entirely of pine and birch trees. Aeolian landforms and biodiversity Despite the Atlantic climate forest cover and the human interventions, the imprints of the aeolian features inherited from the Quaternary periglacial climates still mark deeply the Fontainebleau landscapes. The aeolian actions command partly the present-day relief and vegetation biodiversity: (1) Tall oak and beech groves on the plateaus and in the lowlands covered with fine calcareous sand dunes and loess on which develop brown soils (prevailing in the eastern district of the massif); (2) Birch, pine trees and herbaceous stratum on the dry and acidic podzols established on the quartzose Fontainebleau Sand forming the windup scraps, sandstone chaos and associated dunes (dominant in the western district); (3) And finally dry moors with calluna, heather and birch on the sandstone "platières" stripped off by the aeolian deflation together with wet and peaty moors with sphagnum and moor-grass in the blowout depressions. The opposition between the western and the eastern districts of the massif was even more pronounced a few centuries ago, before man intervened vigorously to wooden the western area with massive import of pine trees. This phytogeographical diversity of the landscape is directly inherited from the periglacial aeolian actions and contributes to the striking biodiversity of the Fontainebleau Massif. The biological richness of the Fontainebleau Massif has been noticed as soon as 1664 (Barillon d'Amoncourt, 1664) and today have been inventoried 6.000 vegetable

  17. Detecting Patterns of Aeolian Transport Direction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The magnitude and direction of aeolian transport are of direct interest to those engaged in the study of aeolian processes. Although the magnitude of sediment transport has been studied extensively, the study of aeolian transport direction has garnered less attention. This paper describes the deve...

  18. [Characteristics of N2, N2O, NO, CO2 and CH4 Emissions in Anaerobic Condition from Sandy Loam Paddy Soil].

    PubMed

    Cao, Na; Wang, Rui; Liao, Ting-ting; Chen, Nuo; Zheng, Xun-hua; Yao, Zhi-sheng; Zhang, Hai; Butterbach-Bahl, Klaus

    2015-09-01

    Understanding the characteristics of the production of nitrogen gases (N2, N2O and NO), CO2 and CH4 in anaerobic paddy soils is not only a prerequisite for an improved mechanistic understanding of key microbial processes involved in the production of atmospheric greenhouse gases (GHG), but might also provide the basis for designing greenhouse gas mitigation strategies. Moreover, quantifying the composition fractions of denitrification gaseous products is of key importance for improving parameterization schemes of microbial processes in process-oriented models which are increasingly used for assessing soil GHG emissions at site and national scales. In our experiments we investigated two sandy loam soils from two paddy fields. The initial concentrations of soil nitrate and dissolved organic carbon (DOC) were set at approximately 50 mg.kg-1 and mg.kg-1, respectively, by adding a mixture solution of KNO3 and glucose. The emissions of N2, N2O NO, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each soil sample were measured simultaneously, using a gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that the accumulative emissions of N2, N2O and NO of the two soil samples for the entire incubation period were 6 - 8, 20, and 15 - 18 mg.kg-1, respectively. By measuring the cumulative emissions of denitrification gases (N, = N2 + N2O + NO) we were able to explain 95% to 98% of observed changes in s1ifr nilrate concentrations. The mass fractions of N2, N2O and NO emissions to Nt were approximately 15% -19%, 47% -49%, and 34% -36%, respectively. Thus, in our experiments N2O and NO were the main products of denitrification for the entire incubation period. However, as the temporal courses of hourly or daily production of the denitrification gases showed, NO production dominated and peaked firstly, and then N2O, before finally N2 became the dominant product. Our results show the high temporal dynamic of

  19. Gully annealing by aeolian sediment: field and remote-sensing investigation of aeolian-hillslope-fluvial interactions, Colorado River corridor, Arizona, USA

    USGS Publications Warehouse

    Sankey, Joel B.; Draut, Amy E.

    2014-01-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This study of gully annealing by aeolian sediment, spanning 95 km along the Colorado River corridor in Glen, Marble, and Grand Canyon, Arizona, USA, employed field and remote sensing observations, including digital topographic modelling. Results indicate that aeolian sediment activity can be locally effective at counteracting gully erosion. Gullies are less prevalent in areas where surficial sediment undergoes active aeolian transport, and have a greater tendency to terminate in active aeolian sand. Although not common, examples exist in the record of historical imagery of gullies that underwent infilling by aeolian sediment in past decades and evidently were effectively annealed. We thus provide new evidence for a potentially important interaction of aeolian–hillslope–fluvial processes, which could affect dryland regions substantially in ways not widely recognized. Moreover, because the biologic soil crust plays an important role in determining aeolian sand activity, and so in turn the extent of gully development, this study highlights a critical role of geomorphic–ecologic interactions in determining arid-landscape evolution.

  20. Landscape and soil development in Lower Lusatia - results from archaeological and soil-geomorphological investigations on a small dune field nearby Jänschwalde (Brandenburg, Germany)

    NASA Astrophysics Data System (ADS)

    Nicolay, Alexander; Schulz, Deborah; Raab, Thomas; Raab, Alexandra

    2014-05-01

    Within the apron of the opencast mine Jänschwalde (SE Brandenburg, Germany) archaeological excavations on a multiple populated small dune were complemented with soil-geomorphological investigations in the vicinity. Archaeological findings in the dune stratigraphy (especially cremation graves) are intercalated within aeolian sediments and/or buried soils and thus give a record of the Late Quaternary geomorphodynamic and soil development. The archaeological results confirm the presence of Mesolithic and Neolithic populations at the study site. The Mesolithic to Neolithic factory sites are preferably located on slightly elevated places like the remnants of late glacial dunes. On these late glacial aeolian sediments subsequently a podzol formation took place, indicating stable environmental conditions. At the excavation site, this soil was buried by aeolian drift sands in which a cemetery was found. According to grave goods and grave type the excavated bi-ritual cemetery was created at the end of the 3rd and used until the early 5th century AD (Late Roman Iron Age to Migration Period). Within this period the aeolian activity, proven by about 1 m deep drift sands, increased and a small dune was formed wherein 4 inhumation and approx. 26 cremation graves (Schichtgräberfeld) were documented. The cremation graves were mainly recorded as small reddish/gray 5-20 cm thick sandy layers which were separated by the drift sand layers. Soil-geomorphological investigations, two kilometers north of the excavated cremation and settle-ment site corroborate the detected phases of morphological stability and aeolian activity in this time period. Our complementing investigations indicate that the Late Roman Iron Age to Migration Period population had affected the landscape due to deforestation and agricultural land use.

  1. Effects of Different Factors on Water Flow and Solute Transport Investigated by Time Domain Reflectometry in Sandy Clay Loam Field Soil.

    PubMed

    Merdun, Hasan

    2012-09-01

    Factors affecting preferential flow and transport in the vadose zone need to be investigated by experiments and simulations to protect groundwater against surface applied chemicals. The objectives of this study were to investigate the effects of several factors (soil structure, initial soil water content (SWC), and application rate) and their interactions on the extent of preferential flow and transport in a sandy clay loam field soil using the time domain reflectometry (TDR) for measuring SWC and electrical conductivity (EC) in 12 treatments, modeling (by HYDRUS-1D and VS2DTI) the measured SWC and EC, and conducting statistical tests for comparing the means of the measured and modeled SWC and EC and solute transport parameters (pore water velocity and dispersion coefficient) obtained by inversely fitting in the CXTFIT program. The study results showed that the applied solution moved faster in the undisturbed, wet initial SWC, and higher application rate experimental conditions than in the disturbed, dry initial SWC, and lower application rate, respectively, based on the analysis of the changes in TDR measured SWC and EC with depth at 1, 2, 5, and 15 h of the experiments. However, the effects of interactive factors or treatments on water flow and solute transport were not clear enough. The modeling results showed that HYDRUS-1D was better than VS2DTI in the estimation of EC and especially SWC, but overall the models had relatively low performances in the simulations. Statistical test results also showed that the treatments had different flow and transport characteristics because they were divided into different groups in terms of the means of SWC and EC and solute transport parameters. These results suggest that similar experiments with more distinct interactions and modeling studies with different approaches need to be considered for better understanding the complex flow and transport processes in the vadose zone. PMID:23002311

  2. Continuous in situ measurements of volcanic gases with a diode-laser-based spectrometer: CO2 and H2O concentration and soil degassing at Vulcano (Aeolian islands: Italy)

    PubMed Central

    De Rosa, Maurizio; Gagliardi, Gianluca; Rocco, Alessandra; Somma, Renato; De Natale, Paolo; De Natale, Giuseppe

    2007-01-01

    We report on a continuous-measurement campaign carried out in Vulcano (Aeolian islands, Sicily), devoted to the simultaneous monitoring of CO2 and H2O concentrations. The measurements were performed with an absorption spectrometer based on a semiconductor laser source emitting around a 2-μm wavelength. The emitted radiation was selectively absorbed by two molecular ro-vibrational transitions specific of the investigated species. Data for CO2 and H2O concentrations, and CO2 soil diffusive flux using an accumulation chamber configuration, were collected at several interesting sampling points on the island (Porto Levante beach- PLB, Fossa Grande Crater – FOG- and Valley of Palizzi, PAL). CO2/H2O values, measured on the ground, are very similar (around 0.019 (± 0.006)) and comparable to the previous discrete detected values of 0.213 (Fumarole F5-La Fossa crater rim) and 0.012 (Fumarole VFS – Baia Levante beach) obtaid during the 1977–1993 heating phase of the crater fumaroles. In this work much more homogeneous values are found in different points of the three sites investigated. The field work, although carried out in a limited time window (25th–28th August 2004), pointed out the new apparatus is suitable for continuous gas monitoring of the two species and their ratios, which are important geochemical indicators of volcanic activity, for which other reliable continuous monitoring systems are not yet available. PMID:17448243

  3. Speciation of organic matter in sandy soil size fractions as revealed by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiménez-Morillo, Nicasio T.; González-Vila, Francisco J.; Jordán, Antonio; Zavala, Lorena M.; de la Rosa, José M.; González-Pérez, José A.

    2015-04-01

    This research deals with the assessment of organic matter structural differences in soil physical fractions before and after lipid extractions. Soil samples were collected in sandy soils, Arenosols (WRB 2006) from the Doñana National Park (SW Spain) under different vegetation cover: cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Two size fractions; coarse (C: 1-2 mm) and fine (F: 0.05-0.25 mm) were studied from each soil. . In addition, the two fractions from each soil were exhaustively Soxhlet extracted with a Dichlorometane-Methanol (3:1) mixture to obtain the lipid-free fractions (LF) from each size fraction (LFC and LFF). The composition of the organic matter at a molecular level in the different soil fractions was approached by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy. These techniques are complementary and have been found suitable for the structural characterization of complex organic matrices (Moldoveanu, 1998; Piccolo and Stevenson, 1982); whereas Py-GC/MS provides detailed structural information of individual compounds present and a finger-printing of soil organic matter, FT-IR is informative about major functional groups present. The advantages of these techniques are well known: no need for pretreatment are fast to perform, highly reproducible and only small amount of samples are needed. Soil size fractions show contrasting differences in organic matter content (C 4-7 % and F > 40 %) and conspicuous differences were found in the pyrolysis products released by the fractions studied. The main families of pyrolysis compounds have well defined macromolecular precursors, such as lignin, polypeptides, polysaccharides and lipids (González-Vila et al., 2001). The C fractions yield higher relative abundance of lignin and polysaccharide derived pyrolysis compounds. Regarding the differences in the soil organic matter as affected by the different vegetation covers

  4. Fate of Tetrabromobisphenol A (TBBPA) and Formation of Ester- and Ether-Linked Bound Residues in an Oxic Sandy Soil.

    PubMed

    Li, Fangjie; Wang, Jiajia; Jiang, Bingqi; Yang, Xue; Nastold, Peter; Kolvenbach, Boris; Wang, Lianhong; Ma, Yini; Corvini, Philippe François-Xavier; Ji, Rong

    2015-11-01

    Bound-residue formation is a major dissipation process of most organic xenobiotics in soil. However, both the formation and nature of bound residues of tetrabromobisphenol A (TBBPA) in soil are unclear. Using a 14C-tracer, we studied the fate of TBBPA in an oxic soil during 143 days of incubation. TBBPA dissipated with a half-life of 14.7 days; at the end of incubation, 19.6% mineralized and 66.5% formed bound residues. Eight extractable metabolites were detected, including TBBPA methyl ethers, single-ring bromophenols, and their methyl ethers. Bound residues (mostly bound to humin) rapidly formed during the first 35 days. The amount of those humin-bound residues then quickly decreased, whereas total bound residues decreased slowly. By contrast, residues bound to humic acids and fulvic acids increased continuously until a plateau was reached. Ester- and ether-linked residues accounted for 9.6-27.0% of total bound residues during the incubation, with ester linkages being predominant. Residues bound via ester linkages consisted of TBBPA, TBBPA monomethyl ether, and an unknown polar compound. Our results indicated that bound-residue formation is the major pathway of TBBPA dissipation in oxic soil and provide first insights into the chemical structure of the reversibly ester-linked bound residues of TBBPA and its metabolites. PMID:26444952

  5. INDICATORS OF NITRATE LEACHING LOSS UNDER DIFFERENT LAND USE OF CLAYEY AND SANDY SOILS IN SOUTHEASTERN OKLAHOMA

    EPA Science Inventory

    Evidence of increasing nitrate (NO3-) leaching losses from soils under various land use systems has elevated the interest and need to find better land management practices. An essential step in developing new management practices is understanding of the com...

  6. Dynamic sorption of ammonium by sandy soil in fixed bed columns: Evaluation of equilibrium and non-equilibrium transport processes.

    PubMed

    Jellali, S; Diamantopoulos, E; Kallali, H; Bennaceur, S; Anane, M; Jedidi, N

    2010-01-01

    The release of excess nitrogen-containing compounds into groundwater is a major concern in aquifer recharge by the Soil Aquifer Treatment (SAT) process. Ammonium (NH(4)(+)) is one of the most nocive and common nitrogen compounds in wastewaters. In order to assess the risk of wastewater use for aquifer recharge, NH(4)(+)adsorption onto Souhil wadi soil sampled from the SAT pilot plant (Nabeul, Tunisia) was studied using laboratory columns experiments. Several experiments were conducted using aqueous synthetic solutions under different aqueous ammonium concentrations and flow rates. Furthermore, a real wastewater solution was used to test the effect of competitive cations contents on NH(4)(+) adsorption. Afterwards, the Hydrus-1D model was used in inverse mode to simulate the ammonium transport through the Souhil wadi soil. For the synthetic solutions, the adsorbed ammonium amount varied from 1 to 30.7 mg kg(-1) for aqueous ammonium concentrations between 4.9 and 36.4 mg L(-1). The linear isotherm model was found to be the most suitable for describing this adsorption. The flow rate decrease from 45 to 15 mL min(-1) induced an increase in the ammonium adsorption capacity by 49%. Indeed, the lesser the flow rate is, the longer the residence time and the higher the exchange between the aqueous solution and soil matrix. The use of wastewater instead of aqueous synthetic solution decreased about 7 times the Souhil wadi adsorption capacity of ammonium because of its relatively high concentrations of competitive ions such as calcium and magnesium. The use of the Hydrus-1D model showed that the chemical non-equilibrium model was the best to simulate the ammonium transport through the laboratory soil columns. PMID:20034727

  7. DIFFUSION AND EMISSIONS OF 1,3-DICHLOROPROPENE IN FLORIDA SANDY SOIL IN MICROPLOTS AFFECTED BY SOIL MOISTURE, ORGANIC MATTER, AND PLASTIC FILM.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fumigant 1,3-dichloropropene (1,3-D) is a methyl bromide alternative for preplant soil treatment. The objective was to determine effects of soil water and plastic cover on dispersion and emissions of 1,3-D in a Florida soil (Arredondo fine sand). Liquid 1,3-D was injected at 30-cm depths at 8 po...

  8. Effects of variations in hydrogeological parameters on water-table mounding in sandy loam and loamy sand soils beneath stormwater infiltration basins

    NASA Astrophysics Data System (ADS)

    Thompson, Anita; Nimmer, Mike; Misra, Debasmita

    2010-03-01

    The two-dimensional variably-saturated numerical model HYDRUS-2D, previously calibrated to recharge events from an infiltration basin, was used to predict water-table mounding under hypothetical basin design scenarios, and the primary factors that affect water-table mounding were evaluated. Infiltration basins are often utilized in urban environments to recharge stormwater to the aquifer. As a result of localized recharge beneath these basins, mound formation may reduce the thickness of the unsaturated zone available to filter pollutants and may reduce the infiltration rate of the basin. Understanding the effects of various physical factors on water-table mound formation is important for infiltration basin siting. For sandy loam and loamy sand subsurface materials, mound heights increased as the thickness of both the unsaturated and saturated zones decreased. Mound heights increased as the initial soil moisture, basin size and ponding depth increased. A thin sedimentation layer on the basin floor delayed mound formation, but only slightly decreased the maximum mound height. This analysis could be used in future selection of infiltration basin locations; however, the analysis is limited to conditions that represent only a select range of basin design conditions and parameters typical of a glacial till environment in Wisconsin, USA.

  9. Speciation of organic matter in sandy soil size fractions as revealed by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiménez-Morillo, Nicasio T.; González-Vila, Francisco J.; Jordán, Antonio; Zavala, Lorena M.; de la Rosa, José M.; González-Pérez, José A.

    2015-04-01

    This research deals with the assessment of organic matter structural differences in soil physical fractions before and after lipid extractions. Soil samples were collected in sandy soils, Arenosols (WRB 2006) from the Doñana National Park (SW Spain) under different vegetation cover: cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Two size fractions; coarse (C: 1-2 mm) and fine (F: 0.05-0.25 mm) were studied from each soil. . In addition, the two fractions from each soil were exhaustively Soxhlet extracted with a Dichlorometane-Methanol (3:1) mixture to obtain the lipid-free fractions (LF) from each size fraction (LFC and LFF). The composition of the organic matter at a molecular level in the different soil fractions was approached by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy. These techniques are complementary and have been found suitable for the structural characterization of complex organic matrices (Moldoveanu, 1998; Piccolo and Stevenson, 1982); whereas Py-GC/MS provides detailed structural information of individual compounds present and a finger-printing of soil organic matter, FT-IR is informative about major functional groups present. The advantages of these techniques are well known: no need for pretreatment are fast to perform, highly reproducible and only small amount of samples are needed. Soil size fractions show contrasting differences in organic matter content (C 4-7 % and F > 40 %) and conspicuous differences were found in the pyrolysis products released by the fractions studied. The main families of pyrolysis compounds have well defined macromolecular precursors, such as lignin, polypeptides, polysaccharides and lipids (González-Vila et al., 2001). The C fractions yield higher relative abundance of lignin and polysaccharide derived pyrolysis compounds. Regarding the differences in the soil organic matter as affected by the different vegetation covers

  10. Studies in Martian Aeolian Geology

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    2001-01-01

    This report gives the results from the investigation through March 15, 1999 for the first two years of the three year investigation (year 3 runs from March 1, 1999 to February 27, 2000). The investigation included three tasks, all involving windblown dust (particles a few micrometers in diameter) to simulate the aeolian regime on Mars. Experiments were conducted primarily in the Mars Surface Wind Tunnel (MARSWIT) at NASA-Ames Research Center.

  11. Optical properties of Aeolian dusts common to West Texas

    NASA Astrophysics Data System (ADS)

    Ma, Lulu; Zobeck, Ted M.; Hsieh, Daniel H.; Holder, Dean; Morgan, Cristine L. S.; Thompson, Jonathan E.

    2011-11-01

    Both recent models and historical events such as the Dust Bowl and volcanic eruptions have illustrated aerosols can play a significant role in climate change through direct and indirect optical effects. Soil dust aerosols generated by Aeolian processes represent a significant fraction of the total mass burden of atmospheric particles. Central to a better understanding of the climate effects of dust aerosols is knowledge of their optical properties. This research study utilized a dust generator and several instruments to determine certain optical properties of Aeolian dust mimics created by the Amarillo and Pullman soil types native to the panhandle of Texas, USA. Values for the mass-extinction coefficient ranged between 1.74 and 2.97 m 2 g -1 at 522 nm depending on how mass concentration was determined. Single-scatter albedo (SSA) for both soil types ranged from 0.947 to 0.980 at visible wavelengths with SSA increasing at longer wavelengths. Angstrom absorption exponents were measured as 1.73 for Pullman and 2.17 for Amarillo soil. Observed Angstrom extinction exponents were 0.110 and 0.168 for the Pullman and Amarillo soil types. The optical properties reported may be of use for optical based estimates of soil erosion and aid in understanding how regional soil dusts may alter radiative transport presently and during historical events such as the Dust Bowl era.

  12. [Dynamics of heavy metals in the holocene aeolian loess-soil profile in the upper-reaches of the Huaihe River].

    PubMed

    He, Zhong; Huang, Chun-chang; Pang, Jiang-li; Wang, Li-jun; Li, Xin-yan

    2006-07-01

    Upon the exploration and research in the field, we determined the content of Pb, Zn, Cu, Mn, Cr, Co, Ni, Ti, V, Nb at YPC loess-soil site on the X-ray Fluorescence. In the stage of loess accumulation, the content of these heavy metals are very low and the variances are very little, which can be served as the background value of paleosol formation. In the stage of Holocene Megathermal, the content of these heavy metals are increased greatly, because the eluviations and transmigrations of freely soluble elements under warm and humidity environment. In the stage of modern soil( MS), the content of Pb are increased gradually, and there are abruptly increase in the depth of 8cm below the ground, which are the records of sedimentation and accumulation of atmospheric pollutant. PMID:16881302

  13. Leaching behaviour of pendimethalin causes toxicity towards different cultivars of Brassica juncea and Brassica campestris in sandy loam soil

    PubMed Central

    Bandyopadhyay, Subhendu; Choudhury, Partha P.

    2009-01-01

    An experiment was conducted at the farm of Zonal Adaptive Research Station, Uttar Banga Krishi Viswavidhyalaya, Pundibari, Cooch Behar, West Bengal to evaluate the effect of pendimethalin on the yield, weed density and phytotoxicity in different varieties of rai (Brassica juncea) and yellow sarson (B. campestris var. yellow sarson) under higher soil moisture regime in Terai region of West Bengal. Pre-emergence application of pendimethalin at higher dose i.e. 1.0 kg/ha recorded higher plant mortality (30.92%) due to the presence of higher concentration of pendimethalin residue (0.292 µg/g) till the tenth day of crop age and consequently had the reduced yield (12.59 q/ha) than the dose of 0.7 kg/ha (13.33 q/ha) where plant mortality was only 12.62% due to comparatively lower level of pendimethalin residue (0.192 µg/g). Although the application of pendimethalin at the rate of 1.0 kg/ha was able to control weed more efficiently (18.96/m2) than the dose of 0.7 kg/ha (30.41/m2) and subsequent lower doses. The herbicide leached down to the root zone resulting in phytotoxicity towards crop. Yellow sarson group (Brassica campestris) showed more susceptibility than rai (Brassica juncea) group against pendimethalin application at higher doses. PMID:21217862

  14. Leaching behaviour of pendimethalin causes toxicity towards different cultivars of Brassica juncea and Brassica campestris in sandy loam soil.

    PubMed

    Bandyopadhyay, Subhendu; Choudhury, Partha P

    2009-12-01

    An experiment was conducted at the farm of Zonal Adaptive Research Station, Uttar Banga Krishi Viswavidhyalaya, Pundibari, Cooch Behar, West Bengal to evaluate the effect of pendimethalin on the yield, weed density and phytotoxicity in different varieties of rai (Brassica juncea) and yellow sarson (B. campestris var. yellow sarson) under higher soil moisture regime in Terai region of West Bengal. Pre-emergence application of pendimethalin at higher dose i.e. 1.0 kg/ha recorded higher plant mortality (30.92%) due to the presence of higher concentration of pendimethalin residue (0.292 µg/g) till the tenth day of crop age and consequently had the reduced yield (12.59 q/ha) than the dose of 0.7 kg/ha (13.33 q/ha) where plant mortality was only 12.62% due to comparatively lower level of pendimethalin residue (0.192 µg/g). Although the application of pendimethalin at the rate of 1.0 kg/ha was able to control weed more efficiently (18.96/m(2)) than the dose of 0.7 kg/ha (30.41/m(2)) and subsequent lower doses. The herbicide leached down to the root zone resulting in phytotoxicity towards crop. Yellow sarson group (Brassica campestris) showed more susceptibility than rai (Brassica juncea) group against pendimethalin application at higher doses. PMID:21217862

  15. Contribution of nitrous oxide and methan to the overall climate impact of maize on well-drained sandy soils of north-east Germany

    NASA Astrophysics Data System (ADS)

    Andres, M.; Hagemann, U.; Pohl, M.; Sommer, M.; Augustin, J.

    2012-04-01

    Erosion effects and the influence of organic fertiliser (fermentation residues, FR) on the climate impact and greenhouse gas (GHG) emissions of N2O, CH4 and CO2 were investigated at an experimental field side in the lowlands of north-east Germany during the years 2010 and 2011. This intensively used agricultural landscape is glacially shaped and characterized by well-drained sandy and loamy soils. Erosion effects on GHG exchange were investigated for energy maize at the CarboZALF-D project site near Dedelow, Uckermark. In addition to a non-eroded haplic luvisol (reference), emissions were measured for three eroded soil types: a) eroded haplic luvisol, b) haplic regosol (calcaric) and c) endogleyic colluvic regosol (deposition side). In a second field trial, the impact of organic fertilization on GHG emissions was assessed for a range of FR fertilization (0-200% N) and compared to a non-fertilized and a minerally fertilized control. Only 70% of the N content of the FR was assumed to be available for plants. Discontinuous measurements of N2O and CH4 were carried out bi-weekly using the closed-chamber method and 20-minute interval sampling. Gas samples were analysed using a gas chromatograph. Gas fluxes were calculated using linear regression, interpolated and finally cumulated. CO2 flux measurements of ecosystem respiration (Reco) and net ecosystem exchange (NEE) were conducted every four weeks by using a non-flow-through non-steady-state closed chamber system (Livingston and Hutchinson 1995) based on Drösler (2005). Measurement gaps of NEE were filled by modeling the Reco fluxes using the Lloyd-Taylor (Lloyd and Taylor 1994) method and the gross primary production (GPP) fluxes using Michaelis-Menten (Michaelis and Menten 1913) modeling approach. Annual NEE balances were then calculated based on the modeled Reco and GPP fluxes. All investigated soil types were C sinks, storing up to 9,6 t CO2eq ha-1 yr-1. As expected for this well-drained soils, the climate impact

  16. Publication trends in Aeolian research: An analysis of the biblography of Aeolian research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An analysis of the Bibliography of Aeolian Research has provided information regarding publication trends in aeolian research. Overall, results suggest that there has been a significant increase in the number of publications per year since the first aeolian-research publication appeared in 1646. P...

  17. Martian aeolian processes, sediments, and features

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Lancaster, Nicholas; Lee, Steven; Thomas, Peter

    1992-01-01

    In this review of the aeolian regime on Mars, consideration is given to the sources and characteristics of the particles that are involved in aeolian processes and the winds that are required to set grains into motion. Dust storms are reviewed and previous observations and the mechanisms of dust-storm generation are assessed. Various aeolian features, including dunes and albedo features, as well as windblown mantle deposits are discussed. In planning for future missions to Mars, aeolian processes must be taken into account. Surface modifications by the wind and windblown deposits can influence remote-sensing observations, affect sampling strategies, and have detrimental effects on manned and unmanned spacecraft on the surface.

  18. Diffuse CO 2 soil degassing and CO 2 and H 2S concentrations in air and related hazards at Vulcano Island (Aeolian arc, Italy)

    NASA Astrophysics Data System (ADS)

    Carapezza, M. L.; Barberi, F.; Ranaldi, M.; Ricci, T.; Tarchini, L.; Barrancos, J.; Fischer, C.; Perez, N.; Weber, K.; Di Piazza, A.; Gattuso, A.

    2011-10-01

    La Fossa crater on Vulcano Island is quiescent since 1890. Periodically it undergoes "crises" characterized by marked increase of temperature (T), gas output and concentration of magmatic components in the crater fumaroles (T may exceed 600 °C). During these crises, which so far did not lead to any eruptive reactivation, the diffuse CO 2 soil degassing also increases and in December 2005 an anomalous CO 2 flux of 1350 tons/day was estimated by 1588 measurements over a surface of 1.66 km 2 extending from La Fossa crater to the inhabited zone of Vulcano Porto. The crater area and two other anomalously degassing sites (Levante Beach and Palizzi) have been periodically investigated from December 2004 to August 2010 for diffuse CO 2 soil flux. They show a marked variation with time of the degassing rate, with synchronous maxima in December 2005. Carbon dioxide soil flux and environmental parameters have been also continuously monitored for over one year by an automatic station at Vulcano Porto. In order to assess the hazard of the endogenous gas emissions, CO 2 and H 2S air concentrations have been measured by Tunable Diode Laser profiles near the fumaroles of the crater rim and of the Levante Beach area, where also the viscous gas flux has been estimated. In addition, CO 2 air concentration has been measured both indoor and outdoor in an inhabited sector of Vulcano Porto. Results show that in some sites usually frequented by tourists there is a dangerous H 2S air concentration and CO 2 exceeds the hazardous thresholds in some Vulcano houses. These zones should be immediately monitored for gas hazard should a new crisis arise.

  19. Altitudinal Contrasts in Drought-Driven Aeolian Microbial Inputs to Montane Soil Ecology: Impacts of a 500-Year Drought in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Aronson, E. L.; Carey, C.; Riebe, C. S.; Aciego, S.; Hart, S. C.

    2014-12-01

    Mounting evidence shows that California is currently experiencing the most severe drought since 1580, and it is likely that extreme droughts will become more common as the climate changes. Any drought - particularly one of this magnitude - can elevate dust transport, from fallow croplands and bare natural ecosystems, to sometimes distant locations. The transported dust may bring nutrients and microorganisms, with unknown, but potentially transformational, impacts on the ecosystems where dust is deposited. In this project, we are measuring the mass, provenance (using isotopic chemistry), chemical makeup, and microbial composition of dust transported to the Sierra Nevada mountain range. Dust is being collected at three sites along an elevational gradient in the Southern Sierra Critical Zone Observatory (SSCZO), ranging from 400 m to 2000 m elevation. At each site, dust has been collected monthly in Summer 2014 from passive dust collectors and from filters (1 um pore size) on the eddy covariance tower active CO2 samplers. To complement dust collection, soil samples (10 cm depth) have been collected within the footprint of the towers. Dust fluxes were found to be highest at the 2000 meter-high site, with a maximum of 231 mg dust collected in July 2014. The lowest dust fluxes were found at the medium elevation site, at 1100 m, with 21 mg dust in July. The provenance of dust samples will be determined using radiogenic strontium (Sr) and neodymium (Nd) isotopic tracers. Nutrients and microbial composition of dust and soil samples will also be analyzed. This approach will allow us to identify the effects of mega-droughts on i) dust-related contributions to the geobiology and biogeochemistry of soils and ecosystems, ii) the role of local versus distant dust sources of microorganisms, including bacteria, archaea and fungi, and of nutrients to the Sierra Nevada, and iii) the role of elevation in determining the ecological effects of mega-drought-induced dust transport. In the

  20. Aeolian Morphodynamics of Loess Landscapes

    NASA Astrophysics Data System (ADS)

    Mason, J. A.; Hanson, P. R.; Sweeney, M.; Loope, H. M.; Miao, X.; Lu, H.

    2012-12-01

    Striking aeolian landforms characterize loess landscapes of the Great Plains and Upper Mississippi Valley, USA, shaped in Late Pleistocene environments with many characteristics of modern deserts including large active dunefields. Similar aeolian morphodynamics are evident in northern China and the Columbia Basin, USA, and are clearly important for interpreting the paleoenvironmental record of loess. Four zones spanning the upwind margin of thick loess can be defined from landforms and surficial deposits. From upwind to downwind, they are: A) A largely loess-free landscape, with patchy to continuous aeolian sand mantling bedrock. B) Patchy loess deposits, often streamlined and potentially wind-aligned, intermingled with dunes and sand sheets; interbedding of loess and sand may be common. C) Thick, coarse loess with an abrupt upwind edge, with troughs, yardang-like ridges, and/or wind-aligned scarps recording large-scale wind erosion. D) Thinner, finer loess with little evidence of post-depositional wind erosion. The degree of development and spatial scale of these zones varies among the loess regions we studied. To explain this zonation we emphasize controls on re-entrainment of loess by the wind after initial deposition, across gradients of climate and vegetation. The role of saltating sand in dust entrainment through abrasion of fine materials is well known. Using the Portable In situ Wind Erosion Laboratory (PI-SWERL), we recently demonstrated that unvegetated Great Plains loess can also be directly entrained under wind conditions common in the region today (Sweeney et al., 2011, GSA Abstracts with Programs, Vol. 43, No. 5, p. 251). Rainfall-induced crusts largely prevent direct entrainment in fine loess, but appear less effective in coarse loess. We propose that in zone A, any loess deposited was both abraded by saltating sand and directly re-entrained, so none accumulated. Sparse vegetation in this zone was primarily an effect of climate, but the resulting

  1. COMPARISON OF GEOPROBE PRT AND AMS GVP SOIL-GAS SAMPLING SYSTEMS WITH DEDICATED VAPOR PROBES IN SANDY SOILS AT THE RAYMARK SUPERFUND SITE

    EPA Science Inventory

    A study was conducted near the Raymark Superfund Site in Stratford, Connecticut to compare results of soil-gas sampling using dedicated vapor probes, a truck-mounted direct-push technique - the Geoprobe Post-Run-Tubing (PRT) system, and a hand-held rotary hammer technique - the A...

  2. Atmospheric stability and diurnal patterns of aeolian saltation on the Llano Estacado

    NASA Astrophysics Data System (ADS)

    Lanigan, David; Stout, John; Anderson, William

    2016-06-01

    Aeolian transport is driven by aerodynamic surface stress imposed by turbulent winds in the Earth's atmospheric boundary layer (ABL). ABL regime is influenced by stratification, which can either enhance or suppress production of turbulence by shear associated with the vertical gradient of streamwise velocity. During the day and night, surface heat fluxes induce a negative (unstable) and positive (stable) vertical gradient of potential temperature, respectively, which modifies the role of buoyancy in turbulence production. During the brief morning and evening transition periods, the vertical gradient of potential temperature vanishes (neutral stratification). The Monin-Obukhov similarity theory describes how the vertical gradient of streamwise velocity varies with stratification. Simultaneous field measurement of wind speed and aeolian activity were obtained over a 218-day period on a bare, sandy surface on the high plains of the Llano Estacado region of west Texas. Wind speed was measured at a height of 2 m with a propeller-type anemometer and aeolian activity was measured at the surface with a piezoelectric saltation sensor. We have used the wind speed measurements within the framework of the Monin-Obukhov similarity theory to estimate "typical" shear velocity, u∗ , of the ABL as stratification is varied (characterized with the stability parameter). This approach results in a color flood contour of u∗ against time of day and stability parameter: the procedure demonstrates that aeolian activity is most likely to occur during the day, when buoyancy acts in conjunction with mechanical shear to increase u∗ .

  3. Modeling aeolian erosion in presence of vegetation

    NASA Astrophysics Data System (ADS)

    Dupont, S.; Bergametti, G.; Simoëns, S.

    2014-02-01

    Semiarid landscapes are characterized by vegetated surfaces. Understanding the impact of vegetation on aeolian soil erosion is important for reducing soil erosion or limiting crop damage through abrasion or burial. In the present study, a saltation model fully coupled with a large-eddy simulation airflow model is extended to vegetated landscapes. From this model, the sensitivity of sand erosion to different arrangements and type of plants (shrub versus tree) representative of semiarid landscapes is investigated and the wind erosion reduction induced by plants is quantified. We show that saltation processes over vegetated surfaces have a limited impact on the mean wind statistics, the momentum extracted from the flow by saltating particles being negligible compared to that extracted by plants. Simulated sand erosion patterns resulting from plant distribution, i.e., accumulation and erosion areas, appear qualitatively consistent with previous observations. It is shown that sand erosion reduction depends not only on vegetation cover but also on plant morphology and plant distribution relative to the mean wind direction. A simple shear stress partitioning approach applied in shrub cases gives similar trends of sand erosion reduction as the present model following wind direction and vegetation cover. However, the magnitude of the reduction appears significantly different from one approach to another. Although shrubs trap saltating particles, trees appear more efficient than shrubs to reduce sand erosion. This is explained by the large-scale sheltering effect of trees compared to the local shrub one.

  4. Holocene aeolian sediments on the NE Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Stauch, G.; Lehmkuhl, F.; Hilgers, A.; Zhao, H.

    2012-04-01

    The semiarid climate of the northeastern Tibetan Plateau supports the formation of different types of aeolian sediments and landforms during the Holocene. Aeolians silts and sands in the catchment of the Donggi Cona in an elevation above 4000m to 4800 m asl reflect variable climate conditions during that time as well as different sediment sources. Based on 51 OSL datings and catchment wide geomorphological mapping a complex pattern of long and short distance sediment transport has been reconstructed. Only few aeolian archives are preserved from the late Pleistocene in this mountain environment indicating cold and dry climate conditions which prevented a continuous accumulation. During the early Holocene a phase of increased aeolian sedimentation of sand at the slopes of the mountains has been reconstructed. The sand originated from a large alluvial fan which was highly active during the Pleistocene. In addition, a thin loess cover is preserved at a few sites in the neighboring mountains ranges. The sedimentation of the loess started around 2000 years later than the sedimentation of the sand at the foot slope. Both archives are related to an increase in precipitation at the northern margin of the Tibetan Plateau which was related to a strengthening of the Asian Monsoon during that time. The wetter climate conditions favored the development of a vegetation cover which leads to the trapping and fixation of the aeolian sediments. However, with a further strengthening of the Monsoon systems these archives subsequently eroded due to higher run off and accumulated as colluvial and fluvial deposits in the basins. These phase lasted until 6 ka. A second aeolian period started at around 3 ka with the formation new dunes in the basins. This period can be associated with dry and cold climate of the late Holocene supporting the reactivation of the sand in the area. This might be further enhanced by an increased human impact by grazing during the late Holocene and resulting

  5. Braidplain, floodplain and playa lake, alluvial-fan, aeolian and palaeosol facies composing a diversified lithogenetical sequence in the permian and triassic of South Devon (England)

    NASA Astrophysics Data System (ADS)

    Mader, Detlef

    provenance is highlighted by downcutting of steep scour holes and kolk pots with overhanging, undercut walls and by reworking of large blocks of sand which are mainly released gravitationally by collapse of undermined channel banks, with considerable stabilization of the aeolian sand by humidhesion permitting the formation of bizarre erosional morphologies and the reworking as clasts (apart from dispersing loose aeolian sand within the fluvial bed-load which is also of particular significance). Inundations from surrounding alluvial fans and adjoining fluvial channels results also in spreading out of aquatic bed-load veneers across the interdune flats which bury the aeolian dunes and wind ripple trains and thus interrupt deflation and wind-borne accumulation. Ventifact gravel testifies to grinding of facets by sand-blasting activity of strong winds and degradation of pebbly fluvial sediments by winnowing of the sandy matrix. Ventifacts which are concentrated as residual gravel lag veneers at the floor of the serir erg are of considerable importance in testifying to limited aeolian influence on fluvial deposition when reworked and dispersed within alluvial rudites. Calcrete palaeosol features comprise autochthonous carbonate precipitations and violet colour streaks as well as allochthonous Bröckelbank carbonate breccias. In situ carbonate precipitations from by crystallization of carbonate minerals in the soil as isometrical nodules, flat discs and vertical tubes. Progressive maturing gives rise to coalescence of isolated nodules to aggregates and amalgamation to dense crusts. In terms of time and space of origin of carbonate concretions, distinction has to be made between early formation during subaerial exposure and early to late subaqueous growth under a cover of water or precipitation within the ground after burial by younger sediments. The development of calcrete palaeosols is often limited to the origin of nodules and tubes within the sandy substrates, with infiltration

  6. Analyzing Hurricane Sandy

    NASA Astrophysics Data System (ADS)

    Convertino, Angelyn; Meyer, Stephan; Edwards, Becca

    2015-03-01

    Post-tropical Storm Sandy underwent extratropical transition shortly before making landfall in southern New Jersey October 29 2012. Data from this system was compared with data from Hurricane Ike (2008) which represents a classic hurricane with a clear eye wall and symmetry after landfall. Storm Sandy collided with a low pressure system coming in from the north as the hurricane made landfall on the US East coast. This contributed to Storm Sandy acting as a non-typical hurricane when it made landfall. Time histories of wind speed and wind direction were generated from data provided by Texas Tech's StickNet probes for both storms. The NOAA Weather and Climate program were used to generate radar loops of reflectivity during the landfall for both storms; these loops were compared with time histories for both Ike and Sandy to identify a relationship between time series data and storm-scale features identified on radar.

  7. Aeolian transport pathways along the transition from Tibetan highlands towards northwestern Chinese deserts

    NASA Astrophysics Data System (ADS)

    Nottebaum, Veit; Lehmkuhl, Frank; Stauch, Georg

    2014-05-01

    The identification and semi-quantification of aeolian transport pathways enhances the understanding of aeolian sediment archive formation and thus supports reliability and explanatory power concerning palaeoenvironmental reconstructions. Grain size analysis of 279 surface sediment samples from the transition of Tibetan highlands (Qilian Shan) towards northwestern Chinese deserts allows the differentiation of contributing pathways among three types of aeolian sediments: silty loess, sandy loess, and aeolian sands. The study area exhibits a high diversity of geomorphological surfaces due to varieties in relief, elevation and climatic conditions. Therefore, it provides the opportunity to investigate the characteristics of sediments in different geomorphological settings. Using the peaks of grain size frequency's standard deviation of primary loess allows identification of the most sensitive fractions to varying accumulation conditions. mU/fS-ratio (7 - 13 μm / 58 - 84 μm) of primary silty loess relates the far-travelled dust proportion to the locally transported fine sand component. In vicinity to fluvial channels in the foreland mU/fS-values are significantly decreased, whereas mU/fS-values increase with altitude (r2 = 0.74). This indicates higher contribution of long distance transport compared to lower regions. A prominent increase of mU/fS-values above 3000 m asl likely indicates an increasing contribution of fine and medium silt particles transported by Westerlies in higher altitudes. In contrast, lower areas seem to be more strongly influenced by low altitude monsoon currents (NW-Winter- / SE-summer monsoon). The difference in grain size properties is additionally enhanced by the contrasting geomorphologic settings along the mountain declivity: Plain foreland alluvial fans support fine sand supply and availability whereas steep high mountain topography provides only limited potential for fine sand deflation. Similarly, the relatively low relief in intramontane

  8. Effects of River Regulation on Aeolian Landscapes, Grand Canyon National Park, USA

    NASA Astrophysics Data System (ADS)

    Draut, A. E.

    2010-12-01

    Sediment deposits in the Colorado River corridor include fluvial sandbars and aeolian dune fields, and the fluvial deposits are the primary sediment source for sand in the aeolian dunes. This 7-year study examined the effects of river regulation at Glen Canyon Dam (alteration of flow regime, sediment-supply reduction, and consequent loss of fluvial sandbars) on aeolian landscapes downstream in Grand Canyon National Park. A comparative study was developed between aeolian landscapes in Grand Canyon, Arizona, and Cataract Canyon, Utah, upstream of Glen Canyon Dam and its reservoir (Lake Powell), where hydrology and sediment supply of the Colorado River are affected substantially less by artificial river regulation than occurs in Grand Canyon. Before closure of Glen Canyon Dam in 1963, sediment-rich floods (mean annual peak 2400 m3/s) formed sandbars from which wind moved sand inland to form aeolian dunes. After dam operations reduced the amplitude and frequency of high flows, and eliminated the mainstream fluvial sediment supply, Grand Canyon’s fluvial sandbars lost open sand area owing to erosion by river flows and the spread of riparian vegetation. Two types of aeolian landscapes now occur in Grand Canyon: (1) modern fluvial sourced, those downwind of post-dam sandbars; and (2) relict fluvial sourced, whose primary sediment source was deposits from pre-dam floods that were larger than any post-dam flows have been. Sediment supply has been reduced to type (1) dune fields because post-dam sandbars are smaller than in the pre-dam era; new sediment supply to type (2) dune fields essentially has been eliminated. Type 1 aeolian landscapes can receive new windblown sand from sandbars formed by controlled floods (1160 m3/s), which occurred in 1996, 2004, and 2008. Type 1 dune fields, being downwind and within 100 m of controlled-flood sandbars, have significantly higher aeolian sand-transport rates, more open sand, and less biologic soil crust than relict type 2 dune

  9. Aeolian and fluvial processes in dryland regions: the need for integrated studies

    USGS Publications Warehouse

    Belnap, Jayne; Munson, Seth M.; Field, Jason P.

    2011-01-01

    Aeolian and fluvial processes play a fundamental role in dryland regions of the world and have important environmental and ecological consequences from local to global scales. Although both processes operate over similar spatial and temporal scales and are likely strongly coupled in many dryland systems, aeolian and fluvial processes have traditionally been studied separately, making it difficult to assess their relative importance in drylands, as well as their potential for synergistic interaction. Land degradation by accelerated wind and water erosion is a major problem throughout the world's drylands, and although recent studies suggest that these processes likely interact across broad spatial and temporal scales to amplify the transport of soil resources from and within drylands, many researchers and land managers continue to view them as separate and unrelated processes. Here, we illustrate how aeolian and fluvial sediment transport is coupled at multiple spatial and temporal scales and highlight the need for these interrelated processes to be studied from a more integrated perspective that crosses traditional disciplinary boundaries. Special attention is given to how the growing threat of climate change and land-use disturbance will influence linkages between aeolian and fluvial processes in the future. We also present emerging directions for interdisciplinary needs within the aeolian and fluvial research communities that call for better integration across a broad range of traditional disciplines such as ecology, biogeochemistry, agronomy, and soil conservation.

  10. OSL versus 14C dating of sandy pedosediments as paleo-ecological archives in cultural landscapes

    NASA Astrophysics Data System (ADS)

    van Mourik, J. M.

    2009-04-01

    sections, the soil matrix of humic horizons of buried podzols seems to be undisturbed. But the results of pyrolysis / mass spectrometry point to change in chemical composition of SOM after burying, resulting in ‘rejuvenation'. Also another question, related to polycyclic driftsand deposits cannot be answered. Every cycle reflects a period of landscape instability (deposition) and landscape stability (soil development) but based on a 14C chronological framework it is impossible to separate time for active deposition and for soil formation. Recently, the technique of OSL dating was introduced in geoscience. OSL dating is excellent for aeolian sandy deposits with a high percentage of quartz grains. OSL age is defined as the time after the last bleaching by solar radiation of mineral grains. Or in other words, the start of a stable period without sand drifting. The results of OSL dating, applied on quartz grains, extracted from fimic horizons, show a time lag between the 14C dates of SOM and the OSL age of mineral grains. The paleoecological information (pollen grains are part of SOM) is not consequently correlated with the age of the mineral skeleton of the fimic horizon. An older soil organic matrix seems to be suspended in the voids of a younger mineral soil skeleton. OSL dating, applied on quartz grains, extracted from drift sand deposits, provide a chronological correct framework to separate periods with active sand drifting and periods with soil development. The introduction of an OSL based chronological framework improves knowledge of the development of soils and landforms in cultural landscapes. Paleoecological information, derived from element as fimic covers and polycyclic driftsand sequences, can be correlated.

  11. The Significant Roles of Landscape Pattern and Spatial Scale in Assessing Aeolian Desertification

    NASA Astrophysics Data System (ADS)

    Kang, W.; Kang, S.

    2015-12-01

    One of research focus in combating desertification is monitoring and assessing aeolian desertification by temporal satellite remote sensing imageries. Landscape heterogeneity hampers robust interpretation from the satellite imagery on the status and process of aoelian desertification in arid regions, for which scale effect on satellite-imagery interpretation must be investigated. In this study, area and degree of aeolian desertification were assessed at different spatial scales from 30m to 1km by using TM and Landsat8 imageries, respectively. Then, landscape pattern index was utilized to explain effect of spatial resolution on the satellite-based assessment of aeolian desertification in the middle of Mu Us and the west of Otindag Sandy Lands in Inner Mongolia of China. Our results indicate: (1) The middle of Mu Us was rehabilitated from 2000 to 2014 by reduction of desertified area from 12,861 km2 to 11,700 km2. Whereas, the desertified area of the west of Otindag fluctuated but rebounded during the last five years; (2) scale effects on the area and degree of desertified land were not significant, along the spatial resolution, the desertified area fluctuated from12,962km2 to 12,861km2 for Mu Us hinterland and from 7,752km2to 7,700km2 for Otindag west, which corresponds 0.78% and 0.67 % of relative variations, respectively. The aeolian desertification degree index(ADI) fluctuated from 0.36 to 0.35 for Mu Us hinterland and from 0.17 to 0.16 for Otindag west, which corresponds 2.78% and 5.88 % of relative variations, respectively. (3) scale effects on landscape pattern indices were significant, particular in landscape fragment; the correlation of spatial resolution and landscape fragment are positive(RMu Us2=0.76-0.77, ROtindag2=0.73-0.78). It was found substantial uncertainty in satellite-based assessment on aeolian desertification in Mu Us and Otindag Sandy Lands and the relevance of the uncertainty with the landscape pattern indices. Our study proposes more

  12. Bursts in discontinuous Aeolian saltation.

    PubMed

    Carneiro, M V; Rasmussen, K R; Herrmann, H J

    2015-01-01

    Close to the onset of Aeolian particle transport through saltation we find in wind tunnel experiments a regime of discontinuous flux characterized by bursts of activity. Scaling laws are observed in the time delay between each burst and in the measurements of the wind fluctuations at the fluid threshold Shields number θc. The time delay between each burst decreases on average with the increase of the Shields number until sand flux becomes continuous. A numerical model for saltation including the wind-entrainment from the turbulent fluctuations can reproduce these observations and gives insight about their origin. We present here also for the first time measurements showing that with feeding it becomes possible to sustain discontinuous flux even below the fluid threshold. PMID:26073305

  13. Bursts in discontinuous Aeolian saltation

    PubMed Central

    Carneiro, M. V.; Rasmussen, K. R.; Herrmann, H. J.

    2015-01-01

    Close to the onset of Aeolian particle transport through saltation we find in wind tunnel experiments a regime of discontinuous flux characterized by bursts of activity. Scaling laws are observed in the time delay between each burst and in the measurements of the wind fluctuations at the fluid threshold Shields number θc. The time delay between each burst decreases on average with the increase of the Shields number until sand flux becomes continuous. A numerical model for saltation including the wind-entrainment from the turbulent fluctuations can reproduce these observations and gives insight about their origin. We present here also for the first time measurements showing that with feeding it becomes possible to sustain discontinuous flux even below the fluid threshold. PMID:26073305

  14. Aeolian geomorphology from the global perspective

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1985-01-01

    Any planet or satellite having a dynamic atmosphere and a solid surface has the potential for experiencing aeolian (wind) processes. A survey of the Solar System shows at least four planetary objects which potentially meet these criteria: Earth, Mars, Venus, and possibly Titan, the largest satellite of Saturn. While the basic process is the same among these four objects, the movement of particles by the atmosphere, the aeolian environment is drastically different. It ranges from the hot (730 K), dense atmosphere of Venus to the extremely cold desert (218 K) environment of Mars where the atmospheric surface pressure is only approximately 7.5 mb. In considering aeolian processes in the planetary perspective, all three terrestrial planets share some common areas of attention for research, especially in regard to wind erosion and dust storms. Relevant properties of planetary objects potentially subject to aeolian processes are given in tabular form.

  15. Semiarid landscapes response to Aeolian processes during Holocene in Baikal Region

    NASA Astrophysics Data System (ADS)

    Dan'ko, Lidia; Opekunova, Marina

    2010-05-01

    Arid and semiarid landscapes play a significant role in global climate, biogeochemical, and hydrological processes. Regional analysis of the past aeolian processes is essential for improve our understanding of how various landscape and ecosystems responded to climate change in the past. Our investigation presents details on sand dunes and on loess-like sediments. The study areas are situated in the northern part of Baikal Region (Eastern Siberia). In its depressions, the so-called Barguzinskaya and Tunkinskaya Valley surrounded mountain ranges local dunefieds and loess-like sediments have developed. Present climate in the study areas is continental, characterized by low precipitation(mean annual 250-450 mm) and wide annual range of temperature. Field investigations indicate that the Holocene deposits of the Barguzinskaya and Tunkinskaya Valley are sealed the pedo-sedimentary interface. The analytical results suggest that one's represents a changeover from intensified soil formation to accelerated aeolian dust accumulation. The original content of calcium carbonate and gypsum at the base of some sections of loess-like sediments indicates the aeolian origin of these sediments. In whole, the soil horizons are a proof for humid phases. The change was forced by climatic aridity. Absolute dating of the organogenic components of soils (14C) indicate the age positions of the arid and humid climate phases. Our results indicate not only 1-4 long-time episodes of aeolian dust accumulation during the Holocene, but shot-time aeolian accumulation episodes, that were specific for Late Holocene. For example, in the Tunkinskaya Valley the Late Holocene soil formation replaced by aeolian deposit at 1700 - 1900, 800 and 200-250 years ago, in the Barguzinskaya Valley - about 3100 - 2900, 2300 and 600 years ago. It can be concluded that a periodical formation of the aeolian deposits in the semiarid landscapes during Holocene can be postulated. Aeolian and loess-like sediments of the

  16. Vegetation and substrate properties of aeolian dune fields in the Colorado River corridor, Grand Canyon, Arizona

    USGS Publications Warehouse

    Draut, Amy E.

    2011-01-01

    This report summarizes vegetation and substrate properties of aeolian landscapes in the Colorado River corridor through Grand Canyon, Arizona, in Grand Canyon National Park. Characterizing these parameters provides a basis from which to assess future changes in this ecosystem, including the spread of nonnative plant species. Differences are apparent between aeolian dune fields that are downwind of where modern controlled flooding deposits new sandbars (modern-fluvial-sourced dune fields) and those that have received little or no new windblown sand since river regulation began in the 1960s (relict-fluvial-sourced dune fields). The most substantial difference between modern- and relict-fluvial-sourced aeolian dune fields is the greater abundance of biologic soil crust in relict dune fields. These findings can be used with similar investigations in other geomorphic settings in Grand Canyon and elsewhere in the Colorado River corridor to evaluate the health of the Colorado River ecosystem over time.

  17. Coastal chevron deposits - sedimentology, methods and aeolian versus tsunamigenic origin

    NASA Astrophysics Data System (ADS)

    Spiske, Michaela; Garcia Garcia, Anna-Marietta; Tsukamoto, Sumiko; Schmidt, Volkmar

    2013-04-01

    The origin of v-shaped sediment bodies, so-called "chevrons", is currently controversially discussed. The term "chevron" is presently only defined in terms of the morphology of the sediment body, but not in terms of its genesis. Both an aeolian and an impact-tsunami origin are discussed. In this study, the sedimentology and origin of chevrons is investigated, examining deposits from the US west coast and the coast of Western Australia. We use internal structures obtained in trenches or by ground penetrating radar surveys, trenches, ages gained by radiocarbon and optically stimulated luminescence dating, grain size analysis and the general sediment composition. If the chevrons were deposited by a tsunami, all chevrons along one coastline should possess the same depositional ages, the grain-size distribution should be polymodal indicating various sediment sources and internal structures should be restricted mainly to normal grading. In case of an aeolian origin, the ages of the individual chevrons may vary and internal ages will reflect the migration of the sediment body. Furthermore, cross bedding should be present throughout the sediment body and soil horizons may represent inactive phases. Preliminary results indicate the presence of internal cross bedding and an unimodal grain-size distribution of the surveyed chevrons. Ages decrease in landward transport direction and to the top within vertical successions. At some locations soil layers intercalate between well sorted sands. The mean grain size of the chevron sands is 0.11-0.25 mm. A comparison of the chevron components with the mineral content of possible sediment sources (e.g., rivers, beaches, cliffs) shows that the chevrons are composed of the fine grain size fraction of the respective sources. Sediments of this grain size can easily be transported by aeolian forces under the local prevailing wind conditions. Terrestrial gastropods found within the chevrons give evidence of a long term development of these

  18. Spatial Heterogeneity of Soil Nutrients after the Establishment of Caragana intermedia Plantation on Sand Dunes in Alpine Sandy Land of the Tibet Plateau

    PubMed Central

    Li, Qingxue; Jia, Zhiqing; Zhu, Yajuan; Wang, Yongsheng; Li, Hong; Yang, Defu; Zhao, Xuebin

    2015-01-01

    The Gonghe Basin region of the Tibet Plateau is severely affected by desertification. Compared with other desertified land, the main features of this region is windy, cold and short growing season, resulting in relatively difficult for vegetation restoration. In this harsh environment, identification the spatial distribution of soil nutrients and analysis its impact factors after vegetation establishment will be helpful for understanding the ecological relationship between soil and environment. Therefore, in this study, the 12-year-old C. intermedia plantation on sand dunes was selected as the experimental site. Soil samples were collected under and between shrubs on the windward slopes, dune tops and leeward slopes with different soil depth. Then analyzed soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP) and available potassium (AK). The results showed that the spatial heterogeneity of soil nutrients was existed in C. intermedia plantation on sand dunes. (1) Depth was the most important impact factor, soil nutrients were decreased with greater soil depth. One of the possible reasons is that windblown fine materials and litters were accumulated on surface soil, when they were decomposed, more nutrients were aggregated on surface soil. (2) Topography also affected the distribution of soil nutrients, more soil nutrients distributed on windward slopes. The herbaceous coverage were higher and C. intermedia ground diameter were larger on windward slopes, both of them probably related to the high soil nutrients level for windward slopes. (3) Soil “fertile islands” were formed, and the “fertile islands” were more marked on lower soil nutrients level topography positions, while it decreased towards higher soil nutrients level topography positions. The enrichment ratio (E) for TN and AN were higher than other nutrients, most likely because C. intermedia is a leguminous

  19. Spatial Heterogeneity of Soil Nutrients after the Establishment of Caragana intermedia Plantation on Sand Dunes in Alpine Sandy Land of the Tibet Plateau.

    PubMed

    Li, Qingxue; Jia, Zhiqing; Zhu, Yajuan; Wang, Yongsheng; Li, Hong; Yang, Defu; Zhao, Xuebin

    2015-01-01

    The Gonghe Basin region of the Tibet Plateau is severely affected by desertification. Compared with other desertified land, the main features of this region is windy, cold and short growing season, resulting in relatively difficult for vegetation restoration. In this harsh environment, identification the spatial distribution of soil nutrients and analysis its impact factors after vegetation establishment will be helpful for understanding the ecological relationship between soil and environment. Therefore, in this study, the 12-year-old C. intermedia plantation on sand dunes was selected as the experimental site. Soil samples were collected under and between shrubs on the windward slopes, dune tops and leeward slopes with different soil depth. Then analyzed soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP) and available potassium (AK). The results showed that the spatial heterogeneity of soil nutrients was existed in C. intermedia plantation on sand dunes. (1) Depth was the most important impact factor, soil nutrients were decreased with greater soil depth. One of the possible reasons is that windblown fine materials and litters were accumulated on surface soil, when they were decomposed, more nutrients were aggregated on surface soil. (2) Topography also affected the distribution of soil nutrients, more soil nutrients distributed on windward slopes. The herbaceous coverage were higher and C. intermedia ground diameter were larger on windward slopes, both of them probably related to the high soil nutrients level for windward slopes. (3) Soil "fertile islands" were formed, and the "fertile islands" were more marked on lower soil nutrients level topography positions, while it decreased towards higher soil nutrients level topography positions. The enrichment ratio (E) for TN and AN were higher than other nutrients, most likely because C. intermedia is a leguminous shrub. PMID

  20. The contribution of micrometeorites to the iron stocks of buried podzols, developed in Late-glacial aeolian sand deposits (Brabant, The Netherlands)

    NASA Astrophysics Data System (ADS)

    van Mourik, Jan; de Vet, Sebastiaan

    2015-04-01

    (Mormoder). The exogenic origin of the micrometeorites could be confirmed by SEM-EDX analysis. Micrometeorites could accumulate on the surface level of the Initial Podzols during one century (between 1900 AD till the moment of sampling in 2013), on the surface level of the buried Podzols during eight millennia (between the moment of stabilization in the Preboreal and the moment of burying around 1200 AD). The soil conditions of the ectorganic horizons of (initial) Podzols are moist and acidic, promoting quick release of iron from micrometeorites. An additional source of Iron that could be added to the amount, released from the parent material. The extraction and identification of micrometeorites from ectorganic horizons of Initial Podzols helped illustrate that atmospheric deposition in the form of aerosol and aeolian (e.g. Saharan) dust, micrometeorites and other hydrolysable particles, contributes to soil development. The requisite active iron for podzolation can therefore be derived from chemical weathering of atmospheric iron sources in the acidic soil environment. Reference: 1. Van Mourik, J.M., Seijmonsbergen, A.C., Slotboom, R.T. and Wallinga, J., 2012. The impact of human land use on soils and landforms in cultural landscapes on aeolian sandy substrates (Maashorst, SE Netherlands). Quaternary International 265, 74-89. 2. Van Mourik, J.M. and de Vet, S.B. (2015). Iron stocks of buried Podzols: endogenic iron deficits and potential exogenic enrichment in the Maashorst region, SE Netherlands. Catena, accepted.

  1. Comparison of the stable-isotopic composition of soil water collected from suction lysimeters, wick samplers, and cores in a sandy unsaturated zone

    USGS Publications Warehouse

    Landon, M.K.; Delin, G.N.; Komor, S.C.; Regan, C.P.

    1999-01-01

    Soil water collected from suction lysimeters and wick samplers buried in the unsaturated zone of a sand and gravel aquifer and extracted from soil cores were analyzed for stable oxygen and hydrogen isotope values. Soil water isotopic values differed among the three sampling methods in most cases. However, because each sampling method collected different fractions of the total soil-water reservoir, the isotopic differences indicated that the soil water at a given depth and time was isotopically heterogeneous. This heterogeneity reflects the presence of relatively more and less mobile components of soil water. Isotopic results from three field tests indicated that 95–100% of the water collected from wick samplers was mobile soil water while samples from suction lysimeters and cores were mixtures of more and less mobile soil water. Suction lysimeter samples contained a higher proportion of more mobile water (15–95%) than samples from cores (5–80%) at the same depth. The results of this study indicate that, during infiltration events, soil water collected with wick samplers is more representative of the mobile soil water that is likely to recharge ground water during or soon after the event than soil water from suction lysimeters or cores.

  2. Evaluation of a new model of aeolian transport in the presence of vegetation

    USGS Publications Warehouse

    Li, Junran; Okin, Gregory S.; Herrick, Jeffrey E.; Belnap, Jayne; Miller, Mark E.; Vest, Kimberly; Draut, Amy E.

    2013-01-01

    Aeolian transport is an important characteristic of many arid and semiarid regions worldwide that affects dust emission and ecosystem processes. The purpose of this paper is to evaluate a recent model of aeolian transport in the presence of vegetation. This approach differs from previous models by accounting for how vegetation affects the distribution of shear velocity on the surface rather than merely calculating the average effect of vegetation on surface shear velocity or simply using empirical relationships. Vegetation, soil, and meteorological data at 65 field sites with measurements of horizontal aeolian flux were collected from the Western United States. Measured fluxes were tested against modeled values to evaluate model performance, to obtain a set of optimum model parameters, and to estimate the uncertainty in these parameters. The same field data were used to model horizontal aeolian flux using three other schemes. Our results show that the model can predict horizontal aeolian flux with an approximate relative error of 2.1 and that further empirical corrections can reduce the approximate relative error to 1.0. The level of error is within what would be expected given uncertainties in threshold shear velocity and wind speed at our sites. The model outperforms the alternative schemes both in terms of approximate relative error and the number of sites at which threshold shear velocity was exceeded. These results lend support to an understanding of the physics of aeolian transport in which (1) vegetation's impact on transport is dependent upon the distribution of vegetation rather than merely its average lateral cover and (2) vegetation impacts surface shear stress locally by depressing it in the immediate lee of plants rather than by changing the bulk surface's threshold shear velocity. Our results also suggest that threshold shear velocity is exceeded more than might be estimated by single measurements of threshold shear stress and roughness length

  3. Evaluation of a new model of aeolian transport in the presence of vegetation

    NASA Astrophysics Data System (ADS)

    Li, Junran; Okin, Gregory S.; Herrick, Jeffrey E.; Belnap, Jayne; Miller, Mark E.; Vest, Kimberly; Draut, Amy E.

    2013-03-01

    Aeolian transport is an important characteristic of many arid and semiarid regions worldwide that affects dust emission and ecosystem processes. The purpose of this paper is to evaluate a recent model of aeolian transport in the presence of vegetation. This approach differs from previous models by accounting for how vegetation affects the distribution of shear velocity on the surface rather than merely calculating the average effect of vegetation on surface shear velocity or simply using empirical relationships. Vegetation, soil, and meteorological data at 65 field sites with measurements of horizontal aeolian flux were collected from the Western United States. Measured fluxes were tested against modeled values to evaluate model performance, to obtain a set of optimum model parameters, and to estimate the uncertainty in these parameters. The same field data were used to model horizontal aeolian flux using three other schemes. Our results show that the model can predict horizontal aeolian flux with an approximate relative error of 2.1 and that further empirical corrections can reduce the approximate relative error to 1.0. The level of error is within what would be expected given uncertainties in threshold shear velocity and wind speed at our sites. The model outperforms the alternative schemes both in terms of approximate relative error and the number of sites at which threshold shear velocity was exceeded. These results lend support to an understanding of the physics of aeolian transport in which (1) vegetation's impact on transport is dependent upon the distribution of vegetation rather than merely its average lateral cover and (2) vegetation impacts surface shear stress locally by depressing it in the immediate lee of plants rather than by changing the bulk surface's threshold shear velocity. Our results also suggest that threshold shear velocity is exceeded more than might be estimated by single measurements of threshold shear stress and roughness length

  4. Sorting during Migration of Aeolian Megaripples

    NASA Astrophysics Data System (ADS)

    Sullivan, R. J., Jr.; Zimbelman, J. R.

    2014-12-01

    Aeolian sediments commonly are well sorted. However, aeolian megaripples (aka coarse-grained ripples or granule ripples) have bimodal grain size-frequencies. Distinguishing aeolian megaripple deposits from mixed grain size fluvial deposits is important, particularly for martian sedimentary rocks where implications for flowing water in the martian past (if revealed by legitimate fluvial deposits) are important mission drivers for rovers and landers. Aeolian megaripples are relatively minor components of terrestrial aeolian settings (e.g., as interdune features), but on Mars, megaripples have been encountered in many locations by landers and rovers, are durable due to indurated, armoring surface layers of very coarse sand, and therefore are likely candidates for preservation in the martian sedimentary rock record. Unfortunately, megaripple deposits preserved in martian sedimentary rocks must be recognized with much less data or context than obtained typically during terrestrial fieldwork. We have undertaken wind tunnel experiments and fieldwork to assist interpretations distinguishing aeolian megaripple deposits from mixed grain fluvial materials. Lags of coarse or very coarse sand from ancient aeolian environments within the White Rim Sandstone, Canyonlands NP, UT, and at some localities along the J2 Unconformity at Buckhorn Wash, UT, are well sorted, with a sharply defined maximum grain size in each case. We conducted wind tunnel experiments to explore whether the well-sorted, sharp cutoff in maximum grain size of the coarse fraction in these deposits could be diagnostic of aeolian megaripple formation and migration. Wind tunnel experiments involved 250 μm sand saltating against 600-2800 μm grains. For a given wind tunnel speed, only a narrow grain size range appeared on megaripple surfaces as these bedforms developed spontaneously from the bed; somewhat finer grains migrated rapidly downwind, while slightly coarser grains remained immobile. The physics of

  5. Changes in soil organic carbon and nitrogen capacities of Salix cheilophila Schneid along a revegetation chronosequence in semi-arid degraded sandy land of the Gonghe Basin, Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Jia, Z. Q.

    2014-11-01

    The Gonghe Basin is a sandified and desertified region of China, but the distribution of soil organic carbon (SOC) and total nitrogen (TN) along the cultivation chronosequence across this ecologically fragile region is not well understood. This study was carried out to understand the effects of restoration with Salix cheilophila for different periods of time (6, 11, 16, 21 years) to test whether it enhanced C and N storage. Soil samples, in four replications from seven depth increments (0-10, 10-20, 20-30, 30-50, 50-100, 100-150 and 150-200 cm), were collected in each stand. Soil bulk density, SOC, TN, aboveground biomass and root biomass were measured. Results indicated that changes occurred in both the upper and deeper soil layers with an increase in revegetation time. The 0-200 cm soil showed that the 6-year stand gained 3.89 Mg C ha-1 and 1.00 Mg N ha-1, which accounted for 40.82% of the original SOC and 11.06% of the TN of the 0-year stand. The 11-year stand gained 7.82 Mg C ha-1 and 1.98 Mg N ha-1 in the 0-200 cm soil layers, accounting for 58.06% of the SOC and 19.80% of the TN of the 0-year stand. The 16-year stand gained 11.32 Mg C ha-1 and 3.30 Mg N ha-1 in the 0-200 cm soil layers, accounting for 66.71% of the SOC and 21.98% of the TN of the 0-year stand. The 21-year stand gained 13.05 Mg C ha-1 and 5.45 Mg N ha-1 from the same soil depth, accounting for 69.79% of the SOC and 40.47% of the TN compared with the 0-year stand. The extent of these changes depended on soil depth and plantation age. The results demonstrated that, as stand age increased, the storage of SOC and TN increased. These results further indicated that restoration with S. cheilophila has positive impacts on the Gonghe Basin and has increased the capacity of SOC sequestration and N storage. The shrub's role as carbon sink is compatible with system management and persistence. The findings are significant for assessing C and N sequestration accurately in semi-arid degraded high, cold sandy

  6. Abstracts for the Planetary Geology Field Conference on Aeolian Processes

    NASA Technical Reports Server (NTRS)

    Greeley, R. (Editor); Black, D. (Editor)

    1978-01-01

    The Planetary Geology Field Conference on Aeolian Processes was organized at the request of the Planetary Geology Program office of the National Aeronautics and Space Administration to bring together geologists working on aeolian problems on earth and planetologists concerned with similar problems on the planets. Abstracts of papers presented at the conference are arranged herein by alphabetical order of the senior author. Papers fall into three broad categories: (1) Viking Orbiter and Viking Lander results on aeolian processes and/or landforms on Mars, (2) laboratory results on studies of aeolian processes, and (3) photogeology and field studies of aeolian processes on Earth.

  7. Biodiversity impact of the aeolian periglacial geomorphologic evolution of the Fontainebleau Massif (France)

    NASA Astrophysics Data System (ADS)

    Thiry, M.; Liron, M. N.

    2009-04-01

    Landscape features The geomorphology of the Fontainebleau Massif is noteworthy for its spectacular narrow ridges, up to 10 km long and 0.5 km wide, armored by tightly cemented sandstone lenses and which overhang sandy depressions of about 50m. Denudation of the sandstone pans lead to a highly contrasted landscape, with sandstone ridges ("platières") towering sandy depressions ("vallées") and limestone plateaus ("monts"). This forms the geological frame of the spectacular sceneries of the Fontainebleau Massif (Thiry & Liron, 2007). Nevertheless, there is little know about the erosive processes that have built-up these landscapes. Periglacial processes, and among them aeolian ones, appear significant in the development of the Fontainebleau Massif physiography. The periglacial aeolian geomorphology Dunes and dune fields are known since long and cover about 15% to 25% of the Fontainebleau Massif. The aeolian dunes developed as well on the higher parts of the landscape, as well as in the lower parts of the landscape. The dunes are especially well developed in the whole eastern part of the massif, whereas the western part of the massif is almost devoid of dunes. Nevertheless, detailed mapping shows that dunes can locally be found in the western district, they are of limited extension, restricted to the east facing backslope of outliers. Loamy-sand covers the limestone plateaus of the "monts". The loam cover is of variable thickness: schematically thicker in the central part of the plateaus, where it my reach 3 m; elsewhere it may thin down to 0,20-0,30 m, especially at the plateau edges. Blowout hollows are "negative" morphologies from where the sand has been withdrawed. Often these blowouts are decametric sized and well-delimited structures. Others, more complex structures, are made up of several elongated hectometric hollows relaying each other from and which outline deflation corridor more than 1 km long. A characteristic feature of these blowout hollows is the

  8. Postdam evolution of aeolian landscapes in the Colorado River corridor through Grand Canyon National Park, Arizona, USA

    NASA Astrophysics Data System (ADS)

    Draut, A. E.; Collins, B. D.; Fairley, H. C.; Rubin, D. M.

    2009-12-01

    Sediment deposits within the Colorado River corridor in Grand Canyon, USA, include fluvial sandbars and aeolian dune fields; fluvial deposits are the primary sediment source for the dune fields. We present a conceptual model describing evolution of aeolian landscapes in Grand Canyon, based upon field measurements of wind and sand transport and on surveys of vegetation and substrate properties. The data indicate that Glen Canyon Dam operations can affect geomorphic evolution above the elevation reached by river flows because of the link between fluvial deposition and aeolian transport of sediment. Evolution of aeolian landscapes, in turn, can affect the stability and preservation of archaeological material that occurs in numerous dune fields. Before closure of Glen Canyon Dam on the Colorado River in 1963, sediment-rich floods (mean annual flood 2400 m3/s) formed sandbars from which wind moved sand inland to form aeolian dunes. After dam operations reduced the amplitude and frequency of high flows, and eliminated the mainstream fluvial sediment supply, fluvial sandbars lost open sand area owing to erosion by river flows and the spread of riparian vegetation. Two types of aeolian landscapes now occur: (1) modern fluvial sourced, those downwind of postdam sandbars; and (2) relict fluvial sourced, which are not downwind of postdam sandbars and whose primary sediment source was deposits from predam floods that were larger than any postdam flows have been. Sediment supply has been reduced to type (1) dune fields because postdam sandbars are smaller than in the predam era; new sediment supply to type (2) dune fields has been essentially eliminated. Decreased aeolian sediment supply leads to increased vegetation and biologic soil crust in dune fields, and can result in greater susceptibility to gully formation during rainfall due to lack of infilling aeolian sand. Modern-fluvial-sourced dunes can receive new windblown sand from sandbars formed by controlled

  9. Engineered biochar from microwave-assisted catalytic pyrolysis of switchgrass for increasing water-holding capacity and fertility of sandy soil.

    PubMed

    Mohamed, Badr A; Ellis, Naoko; Kim, Chang Soo; Bi, Xiaotao; Emam, Ahmed El-Raie

    2016-10-01

    Engineered biochars produced from microwave-assisted catalytic pyrolysis of switchgrass have been evaluated in terms of their ability on improving water holding capacity (WHC), cation exchange capacity (CEC) and fertility of loamy sand soil. The addition of K3PO4, clinoptilolite and/or bentonite as catalysts during the pyrolysis process increased biochar surface area and plant nutrient contents. Adding biochar produced with 10wt.% K3PO4+10 wt.% clinoptilolite as catalysts to the soil at 2wt% load increased soil WHC by 98% and 57% compared to the treatments without biochar (control) and with 10wt.% clinoptilolite, respectively. Synergistic effects on increased soil WHC were manifested for biochars produced from combinations of two additives compared to single additive, which may be the result of increased biochar microporosity due to increased microwave heating rate. Biochar produced from microwave catalytic pyrolysis was more efficient in increasing the soil WHC due to its high porosity in comparison with the biochar produced from conventional pyrolysis at the same conditions. The increases in soil CEC varied widely compared to the control soil, ranging from 17 to 220% for the treatments with biochars produced with 10wt% clinoptilolite at 400°C, and 30wt% K3PO4 at 300°C, respectively. Strong positive correlations also exist among soil WHC with CEC and biochar micropore area. Biochar from microwave-assisted catalytic pyrolysis appears to be a novel approach for producing biochar with high sorption affinity and high CEC. These catalysts remaining in the biochar product would provide essential nutrients for the growth of bioenergy and food crops. PMID:27232966

  10. Evidence of global-scale aeolian dispersal and endemism in isolated geothermal microbial communities of Antarctica.

    PubMed

    Herbold, Craig W; Lee, Charles K; McDonald, Ian R; Cary, S Craig

    2014-01-01

    New evidence in aerobiology challenges the assumption that geographical isolation is an effective barrier to microbial transport. However, given the uncertainty with which aerobiological organisms are recruited into existing communities, the ultimate impact of microbial dispersal is difficult to assess. Here we use molecular genetic approaches to examine microbial communities inhabiting fumarolic soils on Mount Erebus, the southernmost geothermal site on Earth, to evaluate the ecological significance of global-scale microbial dispersal. There, hot, fumarolic soils provide an effective environmental filter to test the viability of organisms that have been distributed via aeolian transport over geological time. We find that cosmopolitan thermophiles dominate the surface, whereas endemic Archaea and members of poorly understood Bacterial candidate divisions dominate the immediate subsurface. These results imply that aeolian processes readily disperse viable organisms globally, where they are incorporated into pre-existing complex communities of endemic and cosmopolitan taxa. PMID:24846491

  11. Reconciling historical and contemporary evidence of aeolian-based, gully annealing processes in Glen, Marble, and Grand Canyon, USA

    NASA Astrophysics Data System (ADS)

    Sankey, J. B.; Draut, A. E.

    2013-12-01

    historical annealing using aerial photos from select reaches of the river from the 1930s to present. We examine contemporary evidence of annealing potential through analysis of the connectivity of active aeolian sediment sources with existing gullies. This includes remote sensing analyses of active aeolian sediment based on a multispectral biological soil crust index as a proxy for erodibility, vegetation cover and spacing derived from image classification, gully feature extraction from digital surface (elevation) models, and physically-based investigation of connectivity between these important landscape components. Results highlight the importance of interactions between aeolian and hillslope processes for counteracting contemporary gully erosion of concern for cultural and natural resource management.

  12. Paleosols can promote root growth of the recent vegetation - a case study from the sandy soil-sediment sequence Rakt, the Netherlands

    NASA Astrophysics Data System (ADS)

    Gocke, M. I.; Kessler, F.; van Mourik, J. M.; Jansen, B.; Wiesenberg, G. L. B.

    2015-12-01

    Soil studies commonly comprise the uppermost meter for tracing e.g. soil development. However, the maximum rooting depth of various plants significantly exceeds this depth. We hypothesized that deeper parts of the soil, soil parent material and especially paleosols provide beneficial conditions in terms of e.g. nutrient contents, thus supporting their utilization and exploitation by deep roots. We aimed to decipher the different phases of soil formation in Dutch drift- and coversands. The study site is located at Bedafse Bergen (SE Netherlands) in a 200 year old oak stand. A recent Podzol developed on driftsand covering a Plaggic Anthrosol that established in a relict Podzol on Late Glacial eolian coversand. Root-free soil and sediment samples, collected in 10-15 cm depth increments, were subjected to a multi-proxy physical and geochemical approach. The Plaggic Anthrosol revealed low bulk density and high phosphorous and organic carbon contents, whereas the relict Podzol was characterized by high iron and aluminum contents. Frequencies of fine (≤ 2 mm) and medium roots (2-5 mm) were determined on horizontal levels and the profile wall for a detailed pseudo-three-dimensional insight. On horizontal levels, living roots maximized in the uppermost part of the relict Podzol with ca. 4450 and 220 m-2, significantly exceeding topsoil root abundances. Roots of oak trees thus benefited from the favorable growth conditions in the nutrient-rich Plaggic Anthrosol, whereas increased compactness and high aluminum contents of the relict Podzol caused a strong decrease of roots. The approach demonstrated the benefit of comprehensive root investigation to support and explain pedogenic investigations of soil profiles, as fine roots can be significantly underestimated when quantified at the profile wall. The possible rooting of soil parent material and paleosols long after their burial confirmed recent studies on the potential influence of rooting to overprint sediment-(paleo)soil

  13. Effects of water treatment residuals and coal combustion byproduct amendments on properties of a sandy soil and impact on crop production – A pot experiment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Byproducts of coal combustion (such as fly ash: FA), livestock industry (such as chicken manure: CM, or animal manure, etc), or water treatment residuals (such as sewage sludge: SS, or incinerated sewage sludge: ISS) can be used as amendments to agricultural soils, provided that these byproducts (ap...

  14. Pedological constraints controlling the occurrence of mire plant bioindicators from north Atlantic formerly frozen soils to present-day Mediterranean sandy wet habitats

    NASA Astrophysics Data System (ADS)

    Geraldes, Miguel; da Conceição Freitas, Maria; Cruces, Anabela; Andrade, César; Oliva, Marc; Neto, Carlos; do Rosário Carvalho, Maria

    2013-04-01

    Unlocking the palaeoenvironmental context, in which present peaty sols in former cold regions of Western Europe, may contribute to the understanding of the actual distribution of three acid-soil vascular plants. Likewise can the role played by similar soil and water conditions (due to other context) be the key to explain their expansion further South. The present work aims to compare the origins and traits of such similar ecotons and to verify how these vascular plants can be use as bioindicators for the presence of peaty soils, picking the proper variables and their geographical variation fits in the Ecological amplitude of the species. The soil and the water are the two compartmeents in which some of the variables might control the present-day distributions of the three taxa. The reactions of a certain number of soil samples carefully taken at shallow depths in the profiles of peaty soils of mires or peat-reach habitats, which cover more than fifty tiny to moderate sampled areas of western Europe (Atlantic Façade and the Iberian Península) and Northwestern Morocco, are being determined in the laboratory of the Geology Department of the University of Lisbon, where some characteristic mire-akin plant taxa have their southernmost range, somewhat in disharmony with meso-to thermomediterranean climates (Rivas Martínez, Global Bioclimatics). Two samples (A and B) were collected per site, the A corresponding to the presence of one of the three bioindicators, the B dug where the species ceases to be present. The present soil processes in the northern part of this sampling is in many cases related to a cold region, glaciated or under periglacial conditions during LGM, but the sedimentary and hydrologic analogies further south might help to explain how euro-siberian species can migrate that long and withstand present-day warmer and drier climates. The pH values of samples were plotted against the depth, and curves, correlations and other possible relationships will be

  15. Measuring aeolian sand transport using acoustic sensors

    NASA Astrophysics Data System (ADS)

    Poortinga, Ate; van Rheenen, Hans; Ellis, Jean T.; Sherman, Douglas J.

    2015-03-01

    Acoustic sensors are frequently used to measure aeolian saltation. Different approaches are used to process the signals from these instruments. The goal of this paper is to describe and discuss a method to measure aeolian saltation with acoustic sensors. In a laboratory experiment, we measured the output from an advanced signal processing scheme on the circuit board of the saltiphone. We use a software implementation of this processing scheme to re-analyse data from four miniphones obtained during a field experiment. It is shown that a set of filters remove background noise outside the frequency spectrum of aeolian saltation (at 8 kHz), whereas signals within this frequency spectrum are amplified. The resulting analogue signal is a proxy of the energy. Using an AC pulse convertor, this signal can be converted into a digital and analogue count signal or an analogue energy signal, using a rectifier and integrator. Spatio-temporal correlation between field deployed miniphones increases by using longer integration times for signal processing. To quantify aeolian grain impact, it is suggested to use the analogue energy output, as this mode is able to detect changes in frequency and amplitude. The analogue and digital count signals are able to detect an increase in frequency, but are not able to detect an increase in signal amplitude. We propose a two-stage calibration scheme consisting of (1) a factory calibration, to set the frequency spectrum of the sensor and (2) a standardized drop-test conducted before and after the experiment to evaluate the response of the sensor.

  16. Formation of aeolian ripples and sand sorting.

    PubMed

    Manukyan, Edgar; Prigozhin, Leonid

    2009-03-01

    We present a continuous model capable of demonstrating some salient features of aeolian sand ripples: the realistic asymmetric ripple shape, coarsening of the ripple field at the nonlinear stage of ripple growth, saturation of ripple growth for homogeneous sand, typical size segregation of sand, and formation of armoring layers of coarse particles on ripple crests and windward slopes if the sand is inhomogeneous. PMID:19391931

  17. Aeolian particle flux profiles and transport unsteadiness

    NASA Astrophysics Data System (ADS)

    Bauer, Bernard O.; Davidson-Arnott, Robin G. D.

    2014-07-01

    Vertical profiles of aeolian sediment flux are commonly modeled as an exponential decay of particle (mass) transport with height above the surface. Data from field and wind-tunnel studies provide empirical support for this parameterization, although a large degree of variation in the precise shape of the vertical flux profile has been reported. This paper explores the potential influence of wind unsteadiness and time-varying intensity of transport on the geometry (slope, curvature) of aeolian particle flux profiles. Field evidence from a complex foredune environment demonstrates that (i) the time series of wind and sediment particle flux are often extremely variable with periods of intense transport (referred to herein as sediment "flurries") separated by periods of weak or no transport; (ii) sediment flurries contribute the majority of transport in a minority of the time; (iii) the structure of a flurry includes a "ramp-up" phase lasting a few seconds, a "core" phase lasting a few seconds to many tens of seconds, and a "ramp-down" phase lasting a few seconds during which the system relaxes to a background, low-intensity transport state; and (iv) conditional averaging of flux profiles for flurry and nonflurry periods reveals differences between the geometry of the mean profiles and hence the transport states that produce them. These results caution against the indiscriminate reliance on regression statistics derived from time-averaged sediment flux profiles, especially those with significant flurry and nonflurry periods, when calibrating or assessing the validity of steady state models of aeolian saltation.

  18. Influence of 20–Year Organic and Inorganic Fertilization on Organic Carbon Accumulation and Microbial Community Structure of Aggregates in an Intensively Cultivated Sandy Loam Soil

    PubMed Central

    Zhang, Huanjun; Ding, Weixin; He, Xinhua; Yu, Hongyan; Fan, Jianling; Liu, Deyan

    2014-01-01

    To evaluate the long–term effect of compost (CM) and inorganic fertilizer (NPK) application on microbial community structure and organic carbon (OC) accumulation at aggregate scale, soils from plots amended with CM, NPK and no fertilizer (control) for 20 years (1989–2009) were collected. Soil was separated into large macroaggregate (>2,000 μm), small macroaggregate (250–2,000 μm), microaggregate (53–250 μm), silt (2–53 μm) and clay fraction (<2 μm) by wet-sieving, and their OC concentration and phospholipid fatty acids (PLFA) were measured. The 20-year application of compost significantly (P<0.05) increased OC by 123–134% and accelerated the formation of macroaggregates, but decreased soil oxygen diffusion coefficient. NPK mainly increased OC in macroaggregates and displayed weaker influence on aggregation. Bacteria distributed in all aggregates, while fungi and actinobacteria were mainly in macroaggregates and microaggregates. The ratio of monounsaturated to branched (M/B) PLFAs, as an indicator for the ratio of aerobic to anaerobic microorganisms, increased inversely with aggregate size. Both NPK and especially CM significantly (P<0.05) decreased M/B ratios in all aggregates except the silt fraction compared with the control. The increased organic C in aggregates significantly (P<0.05) negatively correlated with M/B ratios under CM and NPK. Our study suggested that more efficient OC accumulations in aggregates under CM–treated than under NPK–treated soil was not only due to a more effective decrease of actinobacteria, but also a decrease of monounsaturated PLFAs and an increase of branched PLFAs. Aggregations under CM appear to alter micro-habitats to those more suitable for anaerobes, which in turn boosts OC accumulation. PMID:24667543

  19. Gully annealing by fluvially-sourced Aeolian sand: remote sensing investigations of connectivity along the Fluvial-Aeolian-hillslope continuum on the Colorado River

    USGS Publications Warehouse

    Sankey, Joel B.; East, Amy E.; Collins, Brian D.; Caster, Joshua

    2015-01-01

    Processes contributing to development of ephemeral gully channels are of great importance to landscapes worldwide, and particularly in dryland regions where soil loss and land degradation from gully erosion pose long-term, land-management problems. Whereas gully formation has been relatively well studied, much less is known of the processes that anneal gullies and impede their growth. This work investigates gully annealing by aeolian sediment, along the Colorado River downstream of Glen Canyon Dam in Glen, Marble, and Grand Canyons, Arizona, USA (Figure 1). In this segment of the Colorado River, gully erosion potentially affects the stability and preservation of archaeological sites that are located within valley margins. Gully erosion occurs as a function of ephemeral, rainfall-induced overland flow associated with intense episodes of seasonal precipitation. Measurements of sediment transport and topographic change have demonstrated that fluvial sand in some locations is transported inland and upslope by aeolian processes to areas affected by gully erosion, and aeolian sediment activity can be locally effective at counteracting gully erosion (Draut, 2012; Collins and others, 2009, 2012; Sankey and Draut, 2014). The degree to which specific locations are affected by upslope wind redistribution of sand from active channel sandbars to higher elevation valley margins is termed “connectivity”. Connectivity is controlled spatially throughout the river by (1) the presence of upwind sources of fluvial sand within the contemporary active river channel (e.g., sandbars), and (2) bio-physical barriers that include vegetation and topography that might impede aeolian sediment transport. The primary hypothesis of this work is that high degrees of connectivity lead to less gullying potential.

  20. Discrete Element Method simulations of the saturation of aeolian sand transport

    NASA Astrophysics Data System (ADS)

    Pähtz, Thomas; Omeradžić, Amir; Carneiro, Marcus V.; Araújo, Nuno A. M.; Herrmann, Hans J.

    2015-03-01

    The saturation length of aeolian sand transport (Ls), characterizing the distance needed by wind-blown sand to adapt to changes in the wind shear, is essential for accurate modeling of the morphodynamics of Earth's sandy landscapes and for explaining the formation and shape of sand dunes. In the last decade, it has become a widely accepted hypothesis that Ls is proportional to the characteristic distance needed by transported particles to reach the wind speed (the "drag length"). Here we challenge this hypothesis. From extensive numerical Discrete Element Method simulations, we find that, for medium and strong winds, Ls∝Vs2/g, where Vs is the saturated value of the average speed of sand particles traveling above the surface and g is the gravitational constant. We show that this proportionality is consistent with a recent analytical model, in which the drag length is just one of four similarly important length scales relevant for sand transport saturation.

  1. Publication trends in aeolian research: An analysis of the Bibliography of Aeolian Research

    NASA Astrophysics Data System (ADS)

    Stout, John E.; Warren, Andrew; Gill, Thomas E.

    2009-04-01

    An analysis of the Bibliography of Aeolian Research has provided information regarding publication trends in aeolian research. Results suggest that there has been a significant increase in the number of publications per year since the first aeolian-research publication appeared in 1646. Rates of publication have increased from only three publications in the 17th Century to nearly three publications per day in the 21st Century. The temporal distribution of publications follows a complex pattern that is influenced by many factors. In the 17th and 18th Centuries, publications appear as isolated clusters indicating limited interest in aeolian research and limited opportunities for individuals to contribute to scientific literature. With time, many new scientific societies are formed and many new scientific journals are established, opening new opportunities for scientists to contribute to scientific discourse. Landmark publications open up new research areas and define new directions for aeolian research. General advances in science and technology provide new techniques for sampling blowing sand and dust. In addition, clear signs exist that publication rates respond to major environmental and climatic events, especially large-scale disasters that focus attention on wind erosion and blowing dust. The Sirocco dust events of 1901-1903, the North American Dust Bowl of the1930s, and the recent sand and dust storm problems in China have all led to significant increases in the number of publications in aeolian research. Rates of publication are negatively influenced by major political and social upheavals, especially global conflicts such as World Wars I and II. Sudden shifts in government structure and support can also influence publication rates. A good example is the increased publication rates in China following the end of the Cultural Revolution, a trend that continues today.

  2. Estimating Sample Size and Persistence of Entomogenous Nematodes in Sandy Soils and Their Efficacy Against the Larvae of Diaprepes abbreviatus in Florida

    PubMed Central

    Duncan, L. W.; McCoy, C. W.; Terranova, A. C.

    1996-01-01

    In two studies to estimate sampling requirements for entomogenous nematodes in the field, highest persistence of Heterorhabditis bacteriophora after application occurred beneath the canopies of mature citrus trees. Nematode persistence declined with distance from the center-line of the tree row toward the row-middles. Immediately after nematode application to soil, 32 samples (15 cm deep, 2.5-cm diameter) beneath a single tree were required to derive 95% confidence intervals that were within 40% of mean nematode population density. The estimated probability of measuring the mean density within 40%, using 32 samples, declined to 88% at 2 days post-application and to 76% at 7 days. The persistence in soil of Steinernema carpocapsae, S. riobravis, and two formulations containing H. bacteriophora and their efficacy against the larvae of Diaprepes abbreviatus were compared in a grove of 4-year-old citrus trees. Within 6 days, the recovered population densities of all nematodes declined to <5% of levels on day 0. The recovery of H. bacteriophora during the first 2 weeks was lower than that of the other two species. Steinemema riobravis and both formulations of H. bacteriophora reduced recovery of D. abbreviatus by more than 90% and 50%, respectively. Steinernema carpocapsae did not affect population levels of the insect. PMID:19277346

  3. The nature and formation of aeolian mineral dust material

    NASA Astrophysics Data System (ADS)

    Smalley, Ian; O'hara-Dhand, Ken; McLaren, Sue

    2013-04-01

    Aeolian dust affects climate and records past climates. It has become a much studied material but there has been a certain lack of emphasis on the actual nature of the dust, and an even greater neglect of actual production mechanisms for dust particles. Huge amounts of dust may be raised from the Bodele depression and other parts of North Africa, and much of it may be carried across the North Atlantic to aid in soil formation in Brazil. But what does it consist of? We know that much of the Bodele dust is diatoms from old Lake Chad, but what of the lithological inorganic mineral content? A very crude division of aeolian dust into large dust(say around 20-50um) and small dust (2-5um)has been proposed. Much of the study of loess has been confused by the failure to make this distinction, and similar problems may arise in the study of the finer fractions of aeolian dust. Much aeolian material is clay-mineral based- formed from clay mineral aggregates(CMA), from lake bottom sediments. This can form large dust particles, as in parna in Australia, but also contributes largely to small long travel aerosolic dust. Another major contributor is the quartz fragment. The large dust for classic loess deposits is mostly quartz silt- and there is considerable discussion about the controls that affect quartz silt. There are some interesting modalities in the world of quartz particle sedimentology which need to be examined. Quartz sand (say 200-500um) is the key initiating material and the formation processes for quartz sand have a down-the-line effect on the formation of smaller particles. The central observation is the action of two processes- a eutectic-like reaction in the proto-rock granite which defines the essential nature of sand particles, and the high-low displacive crystallographic transformation which introduces tensile stresses into the quartz particle systems. The limited range of eutectic particle size means a limited range of tensile stresses. A neat combination of

  4. Feedbacks between aeolian processes and ecosystem change in a degraded desert grassland in the southwestern US

    NASA Astrophysics Data System (ADS)

    Li, Junran

    2015-04-01

    The desert grassland in the southwestern US has undergone dramatic vegetation changes with many areas of grassland becoming shrublands in the last 150 years. A principle manifestation of such a land degradation is the wide distribution of fertile islands in once-homogenous landscapes, which changed soil resource redistributions through the movement of resources from plant interspaces to the area beneath plant canopies. A great deal of work has examined the role of water in nutrient reduction and enforcement of islands of fertility in the semiarid landscapes. However, little is known on the role of wind in the removal or redistribution of soil resources, and further the feedbacks between wind and ecosystem change in this area. In spring 2004, a vegetation removal experiment was established in the northern Chihuahuan Desert, southern New Mexico, where vegetation cover on the experimental plots were manually reduced to various levels to study the entire suite of aeolian processes, including erosion, transport, and deposition in creating and enforcing patchy distribution of vegetation. This experiment has been continually maintained for more than ten years, with the sampling and observation of vegetation cover, soil nutrients, sediment flux, topography, and plant physiology. The experimental results highlighted that the aeolian processes in the Chihuahuan Desert are able to change soil properties and community composition in as short as 3 three years. Further, the removal of grasses by 75% may trigger a very substantial increase of wind erosion and the removal of grass by 50% could cause significant amount of C and N loss due to wind erosion. Last but not least, the change of the spatial distribution of soil C and the micro-topography both point to the fact that aeolian processes contribute substantially to the dynamics of fertile islands in this desert grassland.

  5. Aeolian Processes and Features on Venus

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Bender, Kelly C.; Saunders, Stephen; Schubert, Gerald; Weitz, Catherine M.

    1997-01-01

    Aeolian features on Venus include dune fields, eroded hills (yardangs), wind streaks, (miniature dunes of 10 to 30 cm wavelength). Although and possibly microdunes (in repetitive imaging by Magellan did show changes in the appearance of the surface, these changes are attributed to radar artifacts as a consequence of look direction rather than to physical changes of the surface. Nonetheless, measurements of wind speeds near the surface of Venus and wind tunnel simulations suggest that aeolian processes could be currently active on Venus. Study of radar images of terrestrial analogs shows that radar wavelength, polarization, and viewing geometry, including look direction and incidence angle, all influence the detection of dunes, yardangs, and wind streaks. For best detection, dune crests and yardangs should be oriented perpendicular to look direction. Longer wavelength systems can penetrate sand sheets a meter or more thick, rendering them invisible, especially in arid regions. For wind streaks to be visible, there must be a contrast in surface properties between the streak and the background on which it occurs. Nonetheless, more than 6000 aeolian features have been found on Magellan images of Venus, the most common of which are various wind streaks. Mapping wind streak orientations enables near-surface wind patterns to be inferred for the time of their formation. Type P streaks are associated with parabolic ejecta crater deposits and are considered to have formed in association with the impact event. Most Type P streaks are oriented westward, indicative of the upper altitude superrotation winds of Venus. Non Type P streaks have occurrences and orientations consistent with Hadley circulation. Some streaks in the southern hemisphere are oriented to the northeast, suggesting a Coriolis effect.

  6. Aeolian processes and the bioshpere: Interactions and feedback loops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aeolian processes affect landform evolution, biogeochemical cycles, regional climate, human health, and desertification. The entrainment, transport and deposition of aeolian sediments are recognized as major drivers in the dynamics of the earth system and there is a growing interest in the scientif...

  7. Introducing a New International Society of Aeolian Research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aeolian research is long-standing and rapidly growing area of study where scientists of many disciplines meet to investigate the effects of wind on the surface of the Earth and other planetary bodies, such as Mars and Titan. Fields of study in aeolian research cover a broad spectrum ranging from dev...

  8. Recent Aeolian Dune Change on Mars

    NASA Technical Reports Server (NTRS)

    Bourke, M. C.; Edgett, K. S.; Cantor, B. A.

    2007-01-01

    Previous comparisons of Martian aeolian dunes in satellite images have not detected any change in dune form or position. Here, we show dome dunes in the north polar region that shrank and then disappeared over a period of 3.04 Mars years (5.7 Earth years), while larger, neighboring dunes showed no erosion or movement. The removal of sand from these dunes indicates that not only is the threshold wind speed for saltation exceeded under present conditions on Mars, but that any sand that is available for transport is likely to be moved. Dunes that show no evidence of change could be crusted, indurated. or subject to infrequent episodes of movement.

  9. Building of tropical beach ridges, northeastern Queensland, Australia: Cyclone inundation and aeolian decoration

    NASA Astrophysics Data System (ADS)

    Tamura, Toru; Nicholas, William; Brooke, Brendan; Oliver, Thomas

    2016-04-01

    Processes associated with tropical cyclones are thought responsible for building coarse sand beach ridges along the northeastern Queensland coast, Australia. While these ridges are expected to be geological records of the past cyclone, they question the general consensus of the aeolian genesis of sandy beach ridges. To explore the ridge-forming process, we carried out the GPR survey, auger drilling, pit excavation, grain-size analysis, and OSL dating for coarse sand beach ridges at the Cowley Beach, northeastern Queensland. The Cowley Beach is a mesotidal beach characterized by a low-tide terrace and steep beach face. Ten beach ridges are recognized along the survey transect that extends 700 m inland from the shore. 37 OSL ages are younger seawards, indicating the seaward accretion of the ridge sequence over the last 2700 years. The highest ridge is +5.1 m high above AHD (Australian Height Datum). Two GPR units are bounded by a groundwater surface at c. +1.5 m AHD. The upper unit is characterized by horizontal to hummocky reflectors punctuated by seaward dipping truncation surfaces. These reflectors in places form dome-like structure that appears to be the nucleus of a beach ridge. The shape and level (+2.5 m AHD) of the dome are similar to those of the present swash berm. The lower unit shows a sequence of reflectors that dip at an angle of present beach face. The sequence is dissected by truncation surfaces, some of which are continuous to those in the upper unit. Coarse sand mainly forms beach ridge deposits below +4.0 m AHD, while a few higher ridges have an upward fining layer composed of medium sand above +4.0 m, which is finer than aeolian ripples found on the backshore during the survey. In addition, pumice gravel horizons underlie the examined ridge crests. The sequence of seaward dipping reflectors indicates that the Cowley Beach, like other many sandy beaches, has prograded during onshore sand accretion by fairweather waves and has been eroded by storms

  10. Optimization of water and nitrogen application to menthol mint (Mentha arvensis L.) through sugarcane trash mulch in a sandy loam soil of semi-arid subtropical climate.

    PubMed

    Ram, Dasha; Ram, Muni; Singh, Ranjeet

    2006-05-01

    Studies were carried out to optimize the use of water and nutrients by the crop with three moisture regimes [0.9, 1.2 and 1.5 irrigation water:cumulative pan evaporation (IW:CPE) ratios], two variables of organic mulch (control and sugarcane trash at 7 t/ha) and three levels of nitrogen (0, 100 and 200 kg/ha). Soil moisture regimes maintained at 1.2 IW:CPE ratio significantly increased the crop growth and herb and essential oil yields as compared with that of 0.9 IW:CPE ratio. The increase in herb yield due to 1.5 and 1.2 IW:CPE ratios was recorded to be 28.5% and 19%, respectively, over the irrigation given at 0.9 IW:CPE ratio, with the corresponding increase in essential oil yield to the extent of 23.5% and 15.5%. Interaction effect of moisture regimes and nitrogen rates indicated that increasing levels of irrigation at the highest level of N (200 kg/ha) improved essential oil yield of the crop. Application of N at 200 kg/ha in the mulched plots significantly enhanced the N uptake by the crop and essential oil yield over the control and 100 kg N/ha applied in the mulched/or unmulched plots and 200 kg N/ha applied in the unmulched plots. Application of organic mulch and nitrogen at 200 kg/ha improved the water use efficiency (WUE) in menthol mint crop. Higher moisture regimes maintained up to 1.2 IW:CPE ratio increased the WUE. The quality of essential oil in terms of its major constituent, menthol, improved slightly with 1.2 IW:CPE ratio as compared to 0.9 and 1.5 IW:CPE ratios at first and second harvests of the crop. It is recommended that menthol mint crop could be grown profitably by providing 16 irrigations, that is 80 cm water (based on 1.2 IW:CPE ratio) and nitrogen at 200 kg/ha in the sugarcane trash mulched plots, which could give a highest benefit:cost ratio from menthol mint cropping. PMID:16005209

  11. Compositional trends in aeolian dust along a transect across the southwestern United States

    USGS Publications Warehouse

    Goldstein, H.L.; Reynolds, R.L.; Reheis, M.C.; Yount, J.C.; Neff, J.C.

    2008-01-01

    Aeolian dust strongly influences ecology and landscape geochemistry over large areas that span several desert ecosystems of the southwestern United States. This study evaluates spatial and temporal variations and trends of the physical and chemical properties of dust in the southwestern United States by examining dust deposited in natural depressions on high isolated surfaces along a transect from the Mojave Desert to the central Colorado Plateau. Aeolian dust is recognized in these depressions on the basis of textural, chemical, isotopic, and mineralogical characteristics and comparisons of those characteristics to the underlying bedrock units. Spatial and temporal trends suggest that although local dust sources are important to the accumulated material in these depressions, Mojave Desert dust sources may also contribute. Depth trends in the depressions suggest that Mojave sources may have contributed more dust to the Colorado Plateau recently than in the past. These interpretations point to the important roles of far-traveled aeolian dust for landscape geochemistry and imply future changes to soil geochemistry under changing conditions in far-distant dust source areas. Copyright 2008 by the American Geophysical Union.

  12. Mars sampling strategy and aeolian processes

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1988-01-01

    It is critical that the geological context of planetary samples (both in situ analyses and return samples) be well known and documented. Apollo experience showed that this goal is often difficult to achieve even for a planet on which surficial processes are relatively restricted. On Mars, the variety of present and past surface processes is much greater than on the Moon and establishing the geological context of samples will be much more difficult. In addition to impact hardening, Mars has been modified by running water, periglacial activity, wind, and other processes, all of which have the potential for profoundly affecting the geological integrity of potential samples. Aeolian, or wind, processes are ubiquitous on Mars. In the absence of liquid water on the surface, aeolian activity dominates the present surface as documented by frequent dust storms (both local and global), landforms such as dunes, and variable features, i.e., albedo patterns which change their size, shape, and position with time in response to the wind.

  13. Use of radar to assess aeolian processes

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Lancaster, N.; Gaddis, L.; Blumberg, D.; Debrovolskis, A.; Saunders, R. S.; Wall, S.; Iversen, J. D.; White, B.; Rasmussen, K. R.

    1991-01-01

    The interaction between wind and desert surfaces has important implications for sediment transport on Earth, Mars, and Venus, and for understanding the relationship between radar backscatter and aerodynamic roughness. Here, researchers report results from measurements of atmospheric boundary layer profiles, assessment of radar backscatter at P, L, and C wavelengths, and surface roughness in Death Valley, the Mojave Desert, and Lunar Lake, NV, and discuss the implications for aeolian process. The sites include playas, gravel and sand regs, alluvial fans, and lava flows. Boundary layer wind profiles were measured using anemometers at heights of 0.75, 1.25, 2.07, 3.44, 5.72, and 9.5 m; temperature sensors at heights of 1.3 and 9.6 m; and wind vanes at 9.7 and 1.5 m. Microtopographic measurements were made using a template and a laser-photo device to obtain RMS height. This study demonstrates that radar backscatter coefficients obtained from airborne and perhaps orbiting instruments could permit the derivation of aerodynamic roughness values for large areas. Such values, when combined with wind frequency data, could enable assessment of aeolian processes on a regional scale.

  14. Aeolian dust deposition rates in Northern French forests and inputs to their biogeochemical cycles

    NASA Astrophysics Data System (ADS)

    Lequy, Émeline; Legout, Arnaud; Conil, Sébastien; Turpault, Marie-Pierre

    2013-12-01

    This study describes the Aeolian dust deposition (ADD) in 4 sites of Northern France. Between December 2009 and March 2012, we sampled (i) Aeolian dust every four weeks, and (ii) 6 episodes of forecasted high atmospheric dust load mainly from the Saharan desert, the largest source of Aeolian dust in the world. These samples were treated with oxygen peroxide to remove organic matter so as to only compare the mineral fraction of the samples in the 4 sampling sites and to analyze their mineralogy. The solid samples contained the hardly soluble part of Aeolian dust (H-ADD). Its deposition was of 1.9 ± 0.3 g m-2 year-1 with a seasonal pattern of high deposition from spring to early autumn and a low deposition in winter. H-ADD deposition during the forecasted episodes of high atmospheric load did not systematically exceed the deposition rate during the rest of the sampling period. This indicates that such episodes little contributed to the annual H-ADD rate. The mineralogy revealed a heterogeneous set of minerals dominated by silicates with a common basis of major types (quartz, feldspars, mica, chlorite, kaolinite and interlayered clay minerals in every sample) with randomly trace minerals (Fe-oxides, sulfates, amphibole, talc, gibbsite and carbonates). The chemistry of H-ADD led to a dominant input of Si (up to 4.4 kg ha-1 year-1), while the nutrients inputs of Ca, K, Mg and P from ADD and the atmospheric organics (APD) in openfield were together of 1.5 ± 0.5 kg ha-1 year-1 with a high contribution of soluble minerals and organic matter of ca. 40% for Mg and K, and of ca. 80% for Ca and P. Nutrient inputs from APD are especially an interesting source of P for forests developed on acidic soils.

  15. Clear cutting (10-13th century) and deep stable economy (18-19th century) as responsible interventions for sand drifting and plaggic deposition in cultural landscapes on aeolian sands (SE-Netherlands).

    NASA Astrophysics Data System (ADS)

    van Mourik, Jan; Vera, Hein; Wallinga, Jakob

    2013-04-01

    The landscape in extensive areas in SE-Netherlands is underlain by coversand, deposited during the Late Glacial of the Weichselian. In the Preboreal, aeolian processes reduced soil formation. From the Preboreal to the Atlantic a deciduous climax forest developed. The geomorphology was a coversand landscape, composed of ridges (umbric podzols), coversand plains (gleyic podzols), coversand depressions (histic podzols) and small valleys (gleysols). The area was used by hunting people during the Late Paleolithic and Mesolithic. During the Bronze and Iron Ages the area was populated by people, living from forest grazing, shifting cultivation and trade. The natural deciduous forest gradually degraded into Calluna heath. The deforestation accelerated the soil acidification and affected the hydrology, which is reflected in drying out of ridges and wetting of depressions, promoting the development of histic podzols and even histosols. Aeolian erosion was during this period restricted to local, small scale sand drifting, related to natural hazards as forest fires and hurricanes and shifting cultivation. Sustainable crop productivity on chemically poor sandy substrates required application of organic fertilizers, composed of a mixture of organic litter and animal manure with a very low mineral compound, produced in shallow stables. At least since 1000 AD, heath management was regulated by a series of rules that aimed to protect the valuable heat lands against degradation. During the 11th, 12th and 13th centuries there was an increasing demand for wood and clear cutting transformed the majority of the forests in driftsand landscapes. The most important market was formed by the very wealthy Flemish cities. The exposed soil surface was subjected to wind erosion and sand drifting which endangered the Calluna heath, arable land and even farmhouses. As a consequence, umbric podzols, the natural climax soil under deciduous forests on coversand, degraded into larger scale driftsand

  16. Aeolian Sand Transport with Collisional Suspension

    NASA Technical Reports Server (NTRS)

    Jenkins, James T.; Pasini, Jose Miguel; Valance, Alexandre

    2004-01-01

    Aeolian transport is an important mechanism for the transport of sand on Earth and on Mars. Dust and sand storms are common occurrences on Mars and windblown sand is responsible for many of the observed surface features, such as dune fields. A better understanding of Aeolian transport could also lead to improvements in pneumatic conveying of materials to be mined for life support on the surface of the Moon and Mars. The usual view of aeolian sand transport is that for mild winds, saltation is the dominant mechanism, with particles in the bed being dislodged by the impact of other saltating particles, but without in-flight collisions. As the wind becomes stronger, turbulent suspension keeps the particles in the air, allowing much longer trajectories, with the corresponding increase in transport rate. We show here that an important regime exists between these two extremes: for strong winds, but before turbulent suspension becomes dominant, there is a regime in which in-flight collisions dominate over turbulence as a suspension mechanism, yielding transport rates much higher than those for saltation. The theory presented is based on granular kinetic theory, and includes both turbulent suspension and particle-particle collisions. The wind strengths for which the calculated transport rates are relevant are beyond the published strengths of current wind tunnel experiments, so these theoretical results are an invitation to do experiments in the strong-wind regime. In order to make a connection between the regime of saltation and the regime of collisional suspension, it is necessary to better understand the interaction between the bed and the particles that collide with it. This interaction depends on the agitation of the particles of the bed. In mild winds, collisions with the bed are relatively infrequent and the local disturbance associated with a collision can relax before the next nearby collision. However, as the wind speed increases, collision become more frequent

  17. Earth and planetary aeolian streaks: A review

    NASA Astrophysics Data System (ADS)

    Cohen-Zada, Aviv Lee; Blumberg, Dan Gabriel; Maman, Shimrit

    2016-03-01

    Wind streaks are abundant aeolian features that have been observed on planetary surfaces by remote sensing means. They have been widely studied, particularly on Mars and Venus and to a much lesser extent on Earth. In imagery, these streaks appear as elongated features that are easily distinguishable from their surroundings. Geomorphologically, these streaks have, thus far, been interpreted as the presence or absence of small loose particles on the surface, deposited or eroded, respectively, by wind. However, the use of different (optical and radar) remote-sensing tools to study wind streaks has led to uncertain interpretations of these features and has hindered their geomorphological definition. Since wind streaks indicate the prevailing wind direction at the time of their formation, they may be used to map near-surface winds and to estimate atmospheric circulation patterns. The aim of this article is to review the main studies focusing on wind streaks and to present the most up-to-date knowledge on this topic. Moreover, a new perspective for wind streak research is suggested: As 'wind streak' is a collective term for a variety of aeolian features that when viewed from above appear as distinctive albedo surface patterns, we suggest that the term should not be used to refer to a geomorphological feature. Since the definition of wind streaks is constrained to remote sensing rather than to geomorphology and is affected by the inherent biases of remote sensing methods, we suggest that 'wind streaks' should be used as a collective term for aeolian surfaces that are discernable from above as bright and dark patterns due to alterations in the characteristics of the surface or to the presence of bedforms. To better understand the mechanisms, time-frames, climate compatibility of wind streaks and the influences of remote sensing on their appearance, we have compiled a new database containing more than 2,900 Earth wind streaks. A comprehensive study of these Earth wind

  18. Hurricane Sandy -- Pass 1, Oct. 29, 2012

    NASA Video Gallery

    Hurricane Sandy was viewed Monday morning from the International Space Station as it orbited 260 miles above the Atlantic Ocean. Sandy had sustained winds of 90 miles an hour as the station passed ...

  19. Hurricane Sandy Prowls the Eastern Seaboard

    NASA Video Gallery

    An animation of satellite observations from Oct. 26-29, 2012, shows Hurricane Sandy move along the U.S. East coast and into the Mid-Atlantic and northeastern U.S. Sandy had still not made landfall ...

  20. Aeolian Removal of Dust Types from Photovoltaic Surfaces on Mars

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Perez-Davis, Marla E.

    1990-01-01

    Dust elevated in local or global dust storms on the Martian surface could settle on photovoltaic (PV) surfaces and seriously hamper their performance. Using a recently developed technique to apply a uniform dust layer, PV surface materials were subjected to simulated Martian winds in an attempt to determine whether natural aeolian processes on Mars would sweep off the settled dust. Three different types of dust were used. The effects of wind velocity, angle of attack, height above the Martian surface, and surface coating material were investigated. It was found that arrays mounted on an angle of attack approaching 45 deg show the most efficient clearing. Although the angular dependence is not sharp, horizontally mounted arrays required much higher wind velocities to clear off the dust. From this test it appears that the arrays may be erected quite near the ground, but previous studies have suggested that saltation effects can be expected to cause such arrays to be covered by soil if they are set up less than about a meter from the ground. Particle size effect appear to dominate over surface chemistry in these experiments, but additional tests are required to confirm this.

  1. Seismic tracking of Hurricane Sandy

    NASA Astrophysics Data System (ADS)

    Chen, X.; Wen, L.

    2013-12-01

    Very weak, narrow band seismic signals excited by Hurricane Sandy are detected in cross-correlations of continuous waveforms recorded by stations in eastern United States, at the end of October 2012. We analyze propagational properties of the signal and track the source locations using travel-time difference residual projection, from 26 October to 1 November 2012. We find that (1) the seismic signals driven by Hurricane Sandy are azimuthal dependent. Signals are correlated only within close azimuths from the source, (2) seismic signals propagate as Rayleigh surface wave with an average velocity of about 3.3 km/s, and (3) the inferred seismic source locations follow the path of Sandy before UTC 2012.10.30 12:00:00(about half a day after its landfall in New Jersey), but then deviate from the hurricane center and stay in the coastal area near New England for another 12 hours after the hurricane dissipated. Our research discovers the properties of seismic source excited by Hurricane Sandy and demonstrates the capability of using seismic data to real-time track a hurricane and estimate its direct impacts and the subsequent disasters after it dissipates.

  2. On Sandy Shores. Teacher's Guide.

    ERIC Educational Resources Information Center

    Strang, Craig; And Others

    The activities in this guide (for grades 2-4) transport students to the sandy shore, one of the most fascinating ecosystems on the planet. At this ecological juncture a multiplicity of life forms find ways to survive, thrive, and interact with each other. Using a wide variety of learning formats, students explore and deepen their understanding of…

  3. Persistent Aeolian Activity at Endeavour Crater, Mars

    NASA Astrophysics Data System (ADS)

    Chojnacki, M.; Michaels, T. I.; Fenton, L. K.

    2013-12-01

    Long-term monitoring of sites that are known to have active dunes and ripples is generally limited to 3 Mars-Years (MY). Here, we discuss new results of dune activity and albedo change in Endeavour crater (EC), Meridiani Planum (MP) that record eight MY of aeolian activity. MP dune fields often show large yearly variations in albedo; EC darkened by ~12% in TES albedo between MY 24 and 26 (from 0.14 to 0.12). THEMIS VIS albedo of dunes did not change significantly from MY 26 to 29, but did decrease notably (~15 %) in MY 30. These darkening events are most likely related to aeolian-driven dust cleaning (e.g., removal by saltating sand, dust devils). For example, the Opportunity rover (poised on the western rim of EC) observed evidence for a MY 31 dune field dust-clearing event. HiRISE monitoring of MP has shown it be one of the most active regions outside of north polar latitudes. Paired images of western EC taken 3 MY apart show clear evidence for dune modification that include: ripple migration, change in dune perimeters, exposure of previously buried light-toned rock, and/or burial of rock by sand (Fig. 1a-1b). Dune slip face movement is evident for most dunes, where crests and aprons advanced (2-7 m) in the downwind direction (to the SSE) at rates of 0.7-2.3 m per MY. Small dome dunes in the eastern EC were found to have a large degree of aeolian activity (e.g., deflation and/or translation) by an earlier study that used MGS-MRO images (MY 24-30). New MY 31 images validate earlier observations, showing clear evidence for bedform deflation where dunes often occupy less area (~50%) than in earlier MY 29 images (Fig. 1c-1d). Areal removal rates are on par with earlier estimates. Bedform modification and sand streamer orientation appear to be caused by a NNW wind regime, consistent with earlier observations, mesoscale modeling, and the transport direction of barchans to the west. Dunes in EC are now known to be periodically (consistently?) active from over a decade

  4. Abrasion by aeolian particles: Earth and Mars

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Marshall, J. R.; White, B. R.; Pollack, J. B.; Marshall, J.; Krinsley, D.

    1984-01-01

    Estimation of the rate of aeolian abrasion of rocks on Mars requires knowledge of: (1) particle flux, (2) susceptibilities to abrasion of various rocks, and (3) wind frequencies on Mars. Fluxes and susceptibilities for a wide range of conditions were obtained in the laboratory and combined with wind data from the Viking meteorology experiment. Assuming an abundant supply of sand-sized particles, estimated rates range up to 2.1 x 10 to the minus 2 power cm of abrasion per year in the vicinity of Viking Lander 1. This rate is orders of magnitude too great to be in agreement with the inferred age of the surface based on models of impact crater flux. The discrepancy in the estimated rate of abrasion and the presumed old age of the surface cannot be explained easily by changes in climate or exhumation of ancient surfaces. The primary reason is thought to be related to the agents of abrasion. At least some sand-sized (approx. 100 micrometers) grains appear to be present, as inferred from both lander and orbiter observations. High rates of abrasion occur for all experimental cases involving sands of quartz, basalt, or ash. However, previous studies have shown that sand is quickly comminuted to silt- and clay-sized grains in the martian aeolian regime. Experiments also show that these fine grains are electrostatically charged and bond together as sand-sized aggregates. Laboratory simulations of wind abrasion involving aggregates show that at impact velocities capable of destroying sand, aggregates from a protective veneer on the target surface and can give rise to extremely low abrasion rates.

  5. A Threshold Continuum for Aeolian Sand Transport

    NASA Astrophysics Data System (ADS)

    Swann, C.; Ewing, R. C.; Sherman, D. J.

    2015-12-01

    The threshold of motion for aeolian sand transport marks the initial entrainment of sand particles by the force of the wind. This is typically defined and modeled as a singular wind speed for a given grain size and is based on field and laboratory experimental data. However, the definition of threshold varies significantly between these empirical models, largely because the definition is based on visual-observations of initial grain movement. For example, in his seminal experiments, Bagnold defined threshold of motion when he observed that 100% of the bed was in motion. Others have used 50% and lesser values. Differences in threshold models, in turn, result is large errors in predicting the fluxes associated with sand and dust transport. Here we use a wind tunnel and novel sediment trap to capture the fractions of sand in creep, reptation and saltation at Earth and Mars pressures and show that the threshold of motion for aeolian sand transport is best defined as a continuum in which grains progress through stages defined by the proportion of grains in creep and saltation. We propose the use of scale dependent thresholds modeled by distinct probability distribution functions that differentiate the threshold based on micro to macro scale applications. For example, a geologic timescale application corresponds to a threshold when 100% of the bed in motion whereas a sub-second application corresponds to a threshold when a single particle is set in motion. We provide quantitative measurements (number and mode of particle movement) corresponding to visual observations, percent of bed in motion and degrees of transport intermittency for Earth and Mars. Understanding transport as a continuum provides a basis for revaluating sand transport thresholds on Earth, Mars and Titan.

  6. Aeolian transport of biota with dust: A wind tunnel experiment

    NASA Astrophysics Data System (ADS)

    Rivas, J. A., Jr.; Gill, T. E.; Van Pelt, R. S.; Walsh, E.

    2015-12-01

    Ephemeral wetlands are ideal sources for dust emission, as well as repositories for dormant stages of aquatic invertebrates. An important component of invertebrate dispersal and colonization to new areas is the ability to be entrained into the atmosphere. Aquatic invertebrate eggs fall within the size of dust and sand grains (30-600μm), are less dense and aerodynamically shaped. We have shown previously that aquatic invertebrates can be dispersed long distances in dust storms but the extent of transport of taxa based on diapausing egg size/morphology has not been investigated. Here, we control the wind erosion process in a wind tunnel to test entrainment of diapausing stages of brine shrimp, clam shrimp, tadpole shrimp, fairy shrimp, Daphnia, and the rotifers Brachionus plicatilis and B. calyciflorus into the air by saltation. Diapausing eggs were mixed with sterilized wind-erodible soil. The soil/egg mixture was moistened with distilled water and air dried to form a crust. Dust was generated in a wind tunnel by releasing sand grains that act as saltator material similar to wind-entrained natural sands. Maximum wind velocity was 10m/s and entrained particles were sampled through an isokinetic horizontal intake opening. Aeolian sediment was collected from three points in the system; transfer section for coarse sediment, the pan subtending a settling chamber for finer saltation-sized sediment, and two paper filters for suspension-sized sediment. Samples were then passed through 250 and 350 μm sieves to remove abrader sand and rehydrated with various sterile media depending on the type of organism. We retrieved viable brine, fairy, and tadpole shrimp, ostracods, Daphnia, and diapausing eggs of the rotifers after hydration. This experiment demonstrates that resting stages of many invertebrates can be wind-eroded due to size and egg morphology and remain viable under controlled conditions mimicking dust emission.

  7. Geologic Setting and Soil Physical Properties of the Mars Phoenix Landing Site

    NASA Astrophysics Data System (ADS)

    Arvidson, R. E.; Mellon, M. T.

    2008-12-01

    The Phoenix Lander touched down ~30 km to the southwest (68.22 N, 234.25 E) of the Amazonian aged, 10 km wide, bowl-shaped Heimdall impact crater. The lander is sitting on ejecta deposits from the Heimdall event that were emplaced as a ground hugging, volatile rich flow, interpreted to be a consequence of impact into icy soil and bedrock. The ejecta deposits have been differentially eroded by aeolian activity and reworked by permafrost-related processes into polygonal ground. Rock abundances are low relative to most of Mars and rocks are concentrated in troughs in between polygons and tend to be evenly spaced, implying an on-going process of polygon formation. Rocks range from tabular to rounded in shape and massive to vesicular in texture. Very few aeolian features (e.g., ripples or ventifacted rock surfaces) are evident, in contrast to the other Mars landing sites. Based on analyses of Mars Reconnaissance Orbiter CRISM hyperspectral data (~0.4 to 4 micrometers) and Phoenix observations, the surface cover is dominated by basaltic soils (sandy silts) and ferric-rich dust, with only contribution from minerals formed under aqueous conditions. The soil is cloddy and adheres to spacecraft surfaces, probably because of electrostatic charging. Densely-cemented icy soil is found within a few centimeters of the surface and once exposed and allowed to warm in the sunlight the ice eventually sublimates into the atmosphere, leaving behind soil lag deposits. The Phoenix landing site is unique relative to the other five sites (two Viking Landers, Pathfinder, Spirit and Opportunity rovers) because of the high latitude, location on relatively young ejecta emplaced as a volatile-rich flow, and because the ice table depth is predicted to have varied from centimeters to as much as a meter beneath the surface during orbital shifts associated with Martian Milankovitch cycles and consequent insolation over the northern latitudes.

  8. Science and Sandy: Lessons Learned

    NASA Astrophysics Data System (ADS)

    Werner, K.

    2013-12-01

    Following Hurricane Sandy's impact on the mid-Atlantic region, President Obama established a Task Force to '...ensure that the Federal Government continues to provide appropriate resources to support affected State, local, and tribal communities to improve the region's resilience, health, and prosperity by building for the future.' The author was detailed from NOAA to the Task Force between January and June 2013. As the Task Force and others began to take stock of the region's needs and develop plans to address them, many diverse approaches emerged from different areas of expertise including: infrastructure, management and construction, housing, public health, and others. Decision making in this environment was complex with many interests and variables to consider and balance. Although often relevant, science and technical expertise was not always at the forefront of this process. This talk describes the author's experience with the Sandy Task Force focusing on organizing scientific expertise to support the work of the Task Force. This includes a description of federal activity supporting Sandy recovery efforts, the role of the Task Force, and lessons learned from developing a science support function within the Task Force.

  9. Geographical Detector-Based Identification of the Impact of Major Determinants on Aeolian Desertification Risk.

    PubMed

    Du, Ziqiang; Xu, Xiaoming; Zhang, Hong; Wu, Zhitao; Liu, Yong

    2016-01-01

    Arid and semi-arid areas in North China are facing the challenge of a rising aeolian desertification risk (ADR) due to the intertwined effects of complex natural processes and intensified anthropogenic activities. An accurate quantitative assessment of the relationship between ADR and its determinants is beneficial for understanding the driving mechanisms of aeolian desertification and for controlling future desertification. Previous studies have failed to quantify the relative role of determinants driving ADR and have been limited in assessing their interactive impacts. In this study, a spatial variance analysis-based geographical detector methodology is used to quantify the effects of geological, physical, and human factors on the occurrence of ADR in an area characterized by mountains and hills in northern China. It is found that soil type, precipitation, and wind velocity are the major determinants of ADR, which implies that geological and physical elements (e.g., soil attribute) and climatic factors (e.g., precipitation and wind velocity) rather than human activities have played a greater role in the incidence of ADR. Particularly, the results show that the interaction of various determinants causes significant non-linearly enhanced impacts on the ADR. The findings of our study will assist local inhabitants and policy makers in developing measures for wind prevention and sand control to mitigate the effects of desertification in the region. PMID:26987114

  10. Geographical Detector-Based Identification of the Impact of Major Determinants on Aeolian Desertification Risk

    PubMed Central

    Du, Ziqiang; Xu, Xiaoming; Zhang, Hong; Wu, Zhitao; Liu, Yong

    2016-01-01

    Arid and semi-arid areas in North China are facing the challenge of a rising aeolian desertification risk (ADR) due to the intertwined effects of complex natural processes and intensified anthropogenic activities. An accurate quantitative assessment of the relationship between ADR and its determinants is beneficial for understanding the driving mechanisms of aeolian desertification and for controlling future desertification. Previous studies have failed to quantify the relative role of determinants driving ADR and have been limited in assessing their interactive impacts. In this study, a spatial variance analysis-based geographical detector methodology is used to quantify the effects of geological, physical, and human factors on the occurrence of ADR in an area characterized by mountains and hills in northern China. It is found that soil type, precipitation, and wind velocity are the major determinants of ADR, which implies that geological and physical elements (e.g., soil attribute) and climatic factors (e.g., precipitation and wind velocity) rather than human activities have played a greater role in the incidence of ADR. Particularly, the results show that the interaction of various determinants causes significant non-linearly enhanced impacts on the ADR. The findings of our study will assist local inhabitants and policy makers in developing measures for wind prevention and sand control to mitigate the effects of desertification in the region. PMID:26987114

  11. Aeolian beach ridges and their significance for climate and sea level: Concept and insight from the Levant coast (East Mediterranean)

    NASA Astrophysics Data System (ADS)

    Mauz, B.; Hijma, M. P.; Amorosi, A.; Porat, N.; Galili, E.; Bloemendal, J.

    2013-06-01

    Relict beach ridges of aeolian origin and associated soils are often used for inferring relative sea level and climate with contrasting results. Most studies link the aeolian coastal deposits to regressive phases, some to high sea-level stands, and a few to intermediate relative sea-level positions. We interpret the apparent contradictions as indicating the lack of an over-arching concept and the inconsistent usage of sea level-related terms. In this paper we present an integrated morpho-sedimentological concept for a microtidal, mid-latitudinal coast and review existing data from the Levant (East Mediterranean) coast to evaluate the concept and to eliminate nomenclatural confusion. A coastal depositional environment in a semi-arid environment consists of shallow-marine, aeolian and alluvial facies which together form an aeolian beach-ridge complex as a package of strata which respond simultaneously to sea-level change. A transgressive complex forms through reworking or overstepping of the coastal foredune and a regressive complex forms by downstepping. Under transgression the aeolian beach ridge represents the highstand deposit and its adjacent shallow marine sediment is the transgressive deposit. Under regression the complex represents the falling stage and the associated downdip surface marks the lowstand. On the Levant coast we find chronologically well-constrained, offlapping aeolian beach ridges as parts of six downstepping beach ridge complexes formed between ~ 200 ka and 10 ka. The complexes represent the falling stage systems tract (FSST) of a short-lived (5th-order) depositional sequence when the shoreline shifted from a position close to the modern coastline to the shelf or below the shelf edge. Three of these FSSTs and their up dip and down dip super bounding surface together form the 4th order (~ 100 ka) sequence of the last interglacial/glacial cycle. The absence of transgressive, highstand and lowstand systems tract is explained by the poor

  12. Direct numerical simulations of aeolian sand ripples

    PubMed Central

    Durán, Orencio; Claudin, Philippe; Andreotti, Bruno

    2014-01-01

    Aeolian sand beds exhibit regular patterns of ripples resulting from the interaction between topography and sediment transport. Their characteristics have been so far related to reptation transport caused by the impacts on the ground of grains entrained by the wind into saltation. By means of direct numerical simulations of grains interacting with a wind flow, we show that the instability turns out to be driven by resonant grain trajectories, whose length is close to a ripple wavelength and whose splash leads to a mass displacement toward the ripple crests. The pattern selection results from a compromise between this destabilizing mechanism and a diffusive downslope transport which stabilizes small wavelengths. The initial wavelength is set by the ratio of the sediment flux and the erosion/deposition rate, a ratio which increases linearly with the wind velocity. We show that this scaling law, in agreement with experiments, originates from an interfacial layer separating the saltation zone from the static sand bed, where momentum transfers are dominated by midair collisions. Finally, we provide quantitative support for the use of the propagation of these ripples as a proxy for remote measurements of sediment transport. PMID:25331873

  13. Direct numerical simulations of aeolian sand ripples.

    PubMed

    Durán, Orencio; Claudin, Philippe; Andreotti, Bruno

    2014-11-01

    Aeolian sand beds exhibit regular patterns of ripples resulting from the interaction between topography and sediment transport. Their characteristics have been so far related to reptation transport caused by the impacts on the ground of grains entrained by the wind into saltation. By means of direct numerical simulations of grains interacting with a wind flow, we show that the instability turns out to be driven by resonant grain trajectories, whose length is close to a ripple wavelength and whose splash leads to a mass displacement toward the ripple crests. The pattern selection results from a compromise between this destabilizing mechanism and a diffusive downslope transport which stabilizes small wavelengths. The initial wavelength is set by the ratio of the sediment flux and the erosion/deposition rate, a ratio which increases linearly with the wind velocity. We show that this scaling law, in agreement with experiments, originates from an interfacial layer separating the saltation zone from the static sand bed, where momentum transfers are dominated by midair collisions. Finally, we provide quantitative support for the use of the propagation of these ripples as a proxy for remote measurements of sediment transport. PMID:25331873

  14. Avalanche grainflow on a simulated aeolian dune

    NASA Astrophysics Data System (ADS)

    Sutton, S. L. F.; McKenna Neuman, C.; Nickling, W.

    2013-09-01

    Avalanches maintain the slipface of aeolian dunes, which alters their airflow characteristics and sediment dynamics, and results in the development of grainflow cross-bedding. We report on a series of experiments in which avalanches were observed on a 1:1 replica of a small (1.2 m brink height) transverse dune in the Dune Simulation Wind Tunnel under wind velocities of 8-11 m s-1. Changes in slipface topography were observed photographically and measured utilizing a 3-D laser scanner with 1 mm2 spatial resolution. Avalanches in noncohesive sands were observed to progress through scarp recession from the point of initiation and continue until the slope angle is reduced. Changes in local slope confirm that the steep, pre-avalanche mean slope relaxes to a uniform value equal to the angle of repose of the test sand (32°) over all involved portions of the slipface. Avalanche volumes are measured, and demonstrate that avalanche magnitude is independent of wind speed over the range of velocities observed. This independence provides the potential to significantly simplify the modeling of grainflow as a function of only the total cross brink sediment transport.

  15. Sedimentology of coastal chevron deposits - tsunamigenic versus aeolian origin

    NASA Astrophysics Data System (ADS)

    Garcia Garcia, A.; Spiske, M.; Tsukamoto, S.; Schmidt, V.

    2012-12-01

    The genesis of v-shaped coastal chevrons is currently controversially discussed. So far, chevrons are only described regarding their morphology, but not in terms of their origin. Two possible origins of chevrons are proposed: both aeolian transport and tsunami inundation are discussed as depositing processes. We present initial results of a detailed sedimentological survey of Holocene coastal chevrons from the American and Australian west coasts. The chevrons were measured and levelled using a differential GPS system. Large scale internal structures were recorded by ground penetrating radar imaging. Trenches were dug for sampling and analyzing small scale internal structures. The sediment samples were used for the analysis of grain-size distributions, mineral composition and content of marine microorganisms. Additional samples were taken for optically stimulated luminescence (OSL) and radiocarbon dating. Furthermore, we took reference samples from beaches, cliffs and rivers, which could act as potential sediment sources for the surveyed chevrons. Tsunami deposits are commonly polymodal, exhibit a grain-size decrease and tend to show better sorting in landward direction. Such trends are not present in the surveyed chevrons. Most samples are well to moderately well sorted and unimodal. The OSL ages decrease in transport direction and indicate a long term generation process, such as dune migration, rather than a short term event like a tsunami. This fact is additionally underlined by land snails found in different stratigraphic levels within the Australian chevrons. Furthermore, the occurrence of intercalated soil horizons implies a change of stable and active migration phases. The initial results of this study point out to an aoelian origin of coastal chevrons and do not support the previously supposed thesis of a tsunamigenic origin.

  16. Aeolian Removal of Dust Types from Photovoltaic Surfaces on Mars

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Perez-Davis, Marla E.; Marabito, Mark

    1990-01-01

    Dust elevated in local or global dust storms on the Martian surface could settle on photovoltaic (PV) surfaces and seriously hamper their performance. Using a recently developed technique to apply a uniform dust layer, PV surface materials were subjected to simulated Martian winds in an attempt to determine whether natural Aeolian processes on Mars would sweep off the settled dust. Three different types of dust were used; an optical polishing powder, basaltic "trap rock", and iron (III) oxide crystals. The effects of wind velocity, angle of attack, height above the Martian surface, and surface coating material were investigated. It was found that arrays mounted with an angle of attack approaching 45 degrees show the most efficient clearing. Although the angular dependence is not sharp, horizontally mounted arrays required significantly higher wind velocities to clear off the dust. From this test it appears that the arrays may be erected quite near the ground, but previous studies have suggested that saltation effects can be expected to cause such arrays to be covered by soil if they are set up less than about a meter from the ground. Particle size effects appear to dominate over surface chemistry in these experiments, but additional tests are required to confirm this. Providing that the surface chemistry of Martian dusts is not drastically different from simulated dust and that gravity differences have only minor effects, the materials used for protective coatings for photovoltaic arrays may be optimized for other considerations such as transparency, and chemical or abrasion resistance. The static threshold velocity is low enough that there are regions on Mars which experience winds strong enough to clear off a photovoltaic array if it is properly oriented. Turbulence fences proved to be an ineffective strategy to keep dust cleared from the photovoltaic surfaces.

  17. A discussion of the development of sandy land from the viewpoint of ecology

    SciTech Connect

    Hou Xueyu

    1983-01-01

    This article discusses the proper use of sandy land in China from the viewpoint of ecology. The many low-yield fields in every locality across China include sandy land that is unsuited to the cultivation of grains such as paddy rice, corn and wheat. Separate investigations of the northern plain and the southern coast between 1980 and 1982 demonstrated that sandy land in a warm climatic zone (e.g. Huang He) is suited to peanuts, soybeans and other oil-bearing crops; that forestation can be carried out on sandy land in Inner Mongolia and Xinjiang; and that coastal sandy land has much salinity and is best suited to growing horsetail beefwood. Moreover, the creation of windbreaks along the coasts of southern China has lessened the threat of wind-blown sand which had made rice not worth cultivating on sandy land. It is concluded that different crops can be grown on the sandy soil of China's temperate, warm, semitropical and tropical zones.

  18. Dust on Mars: An Aeolian Threat to Human Exploration?

    NASA Technical Reports Server (NTRS)

    Marshall, J.

    1999-01-01

    The NASA HEDS Program is duly concerned for human explorers regarding the potential hazard posed by the ubiquitous dust mantle on Mars. To evaluate properties of dust that could be hazardous to humans, the NMS 2001 Lander payload will include the Mars Environmental Compatibility Assessment (MECA) experiment. This includes optical and atomic-force microscopy to evaluate soil grains for shape and size, wet chemistry to evaluate toxic substances, electrometry to evaluate triboelectric charging, and test-material palets to evaluate electrostatic and magnetic adhesion, and the hardness/abrasiveness of soil grains; these experimental subcomponents are delivered samples by the camera-equipped robotic arm of the lander which will acquire material from depths of 0.5 to 1.0 m in the soil. Data returned by MECA will be of value to both the hEDS and planetary/astrobiology communities. Dust poses a threat to human exploration because the martian system does not hydrologically or chemically remove fine particles that are being continuously generated by thermal, aeolian, and colluvial weathering, and by volcanism and impact over billions of years. The dust is extremely fine-grained, in copious quantities, ubiquitous in distribution, continually mobile, and a source of poorly-grounded static charges -- a suite of characteristics posing a particulate and electrical threat to explorers and their equipment. Dust is mobilized on global and regional scales, but probably also unpredictably and violently at local scales by dust devils. The latter might be expected in great abundance owing to near surface atmospheric instability (dust devils were detected by Pathfinder during its brief lifetime). Preliminary laboratory experiments suggest that space-suit materials subjected to windblown dust may acquire a uniform, highly adhesive dust layer that is also highly cohesive laterally owing to electrostatic forces. This layer will obscure visibility through the helmet visor, penetrate joints

  19. Dust on Mars: An Aeolian Threat to Human Exploration?

    NASA Technical Reports Server (NTRS)

    Marshall, J.

    1999-01-01

    The NASA HEDS Program is duly concerned for human explorers regarding the potential hazard posed by the ubiquitous dust mantle on Mars. To evaluate properties of dust that could be hazardous to humans, the MPS 2001 Lander payload will include the Mars Environmental Compatibility Assessment (MECA) experiment. This includes optical and atomic-force microscopy to evaluate soil grains for shape and size, wet chemistry to evaluate toxic substances, electrometry to evaluate triboelectric charging, and test-material palets to evaluate electrostatic and magnetic adhesion, and the hardness/abrasiveness of soil grains; these experimental subcomponents are delivered samples by the camera-equipped robotic arm of the lander which will acquire material from depths of 0.5 to 1.0 m in the soil. Data returned by MECA will be of value to both the BEDS and planetary/astrobiology communities. Dust poses a threat to human exploration because the martian system does not hydrologically or chemically remove fine particles that are being continuously generated by thermal, aeolian, and colluvial weathering, and by volcanism and impact over billions of years. The dust is extremely fine-grained, in copious quantities, ubiquitous in distribution, continually mobile, and a source of poorly-grounded static charges -- a suite of characteristics posing a particulate and electrical threat to explorers and their equipment. Dust is mobilized on global and regional scales, but probably also unpredictably and violently at local scales by dust devils. The latter might be expected in great abundance owing to near surface atmospheric instability (dust devils were detected by Pathfinder during its brief lifetime). Preliminary laboratory experiments suggest that space-suit materials subjected to windblown dust may acquire a uniform, highly adhesive dust layer that is also highly cohesive laterally owing to electrostatic forces. This layer will obscure visibility through the helmet visor, penetrate joints

  20. Aeolian Slipface Processes on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Cornwall, Carin; Jackson, Derek; Bourke, Mary; Cooper, Andrew

    2016-04-01

    The surface of Mars is dominated by aeolian features and many locations show ripple and dune migration over the past decade with some sediment fluxes comparable to terrestrial dunes. One of the leading goals in investigating aeolian processes on Mars is to explore the boundary conditions of sediment transport, accumulation, and dune mor-phology in relation to wind regime as well as to quantify migration rates and sediment flux. We combine terrestrial field observations, 3D computational fluid dynamics (CFD) modeling and remote sensing data to investigate com-plex, small scale wind patterns and grainflow processes on terrestrial and martian dunes. We aim to constrain grain flow magnitudes and frequencies that occur on slipface slopes of dunes in order to improve estimates of martian dune field migration and sediment flux related to wind velocity and flow patterns. A series of ground-based, high resolution laser scans have been collected in the Maspalomas dune field in Gran Canaria, Spain to investigate grainflow frequency, morphology and slipface advancement. Analysis of these laser scans and simultaneous video recordings have revealed a variety of slipface activity. We identify 6 different grain-flow morphologies including, hourglass shape (classic alcove formation with deposit fan below), superficial flow (thin lenses), narrow trough (vertical lines cm in width), sheet, column (vertical alcove walls), and complex (combi-nation of morphologies triggered simultaneously in the same location). Hourglass grainflow morphologies were the most common and occurred regularly. The superficial and narrow trough morphologies were the second most com-mon and frequently occurred in between large grain flows. Sheet grainflows were rare and unpredictable. These flows involved large portions of the slipface (metres across) and mobilized a substantial amount of sediment in one event. We have compared these grainflow morphologies from Maspalomas to those in martian dune fields and

  1. Mass-height profile and total mass transport of wind eroded aeolian sediments from rangelands of the Indian Thar Desert

    NASA Astrophysics Data System (ADS)

    Mertia, R. S.; Santra, Priyabrata; Kandpal, B. K.; Prasad, R.

    2010-11-01

    Wind erosion is an active land degradation process in the Indian Thar Desert and severe dust storm events during hot summer months in the region are very common. Assessment of soil loss due to dust storm events from major land use systems of the Indian Thar Desert is highly essential for proper environmental planning. Characterization of the mass-height profile of wind eroded aeolian sediment is an important step to compute soil loss/mass transport but was not previously studied in the region. In the present study, aeolian mass fluxes (kg m -2) at different heights from soil surface were measured at two major rangelands in the Indian Thar Desert: Overgrazing rangeland at Jaisalmer (26°55'N and 70°57'E), and controlled grazing rangeland at Chandan (27°01'N and 71°01'E). Evaluation of several mass-height profile models revealed that a power decay function [ q( z) = az-b, where q( z) is the measured mass flux at an height of z (m) from soil surface; a and b are parameters of the equation] was best to characterize the mass-height relationship of aeolian sediments from the Indian Thar Desert. The average mass transport rate (kg m -1 day -1) or the total soil loss during hot summer months was significantly higher at the overgrazed rangeland site than at the controlled grazing rangeland site. Therefore, protection of existing rangelands, which comprise about 80% geographical area of the Indian Thar Desert may check the land degradation process due to wind erosion.

  2. Aeolian dust as a transport hazard

    NASA Astrophysics Data System (ADS)

    Baddock, M. C.; Strong, C. L.; Murray, P. S.; McTainsh, G. H.

    2013-06-01

    The effects of blowing dust on transport operations are often mentioned as one of the significant impacts of aeolian processes on human welfare. However, few studies have been presented to demonstrate this impact. This research examined official air traffic incident reports in Australia for inclusively 1969-2010 to characterise the hazard of blowing dust to aviation in the country, the first such study of its kind. For the 42 year record, 61 incidents were identified (mean 1.4 per annum), with the large majority occurring in the first half of the 1970s. Only 20% of incidents occurred from 1984 onwards. Australian dust activity has not decreased over time, and the reduction in incidents is partly explained by improvements in aviation technology. The centralisation of Air Traffic Control operations to major coastal cities may however have reduced pilot reporting of dust-induced aviation incidents. By type of dust activity, dust storms were associated with nearly half of the reported incidents and dust hazes produced around a quarter. Only 5% of incidents resulted in any physical damage to aircraft and only one case involving personal injury was reported. The majority of the adverse effects on aviation due to dust (nearly 60% of reported incidents) were related to difficulties for navigation and completion of scheduled journey. Since aircraft damage and bodily harm were rare, the impact of dust in Australia is mostly that of inconvenience and associated raised economic costs. From 1990, the temporal pattern of incidents does not show any significant increase despite several intensely dusty years associated with recent droughts. This suggests that Australian aviation safety may be relatively resistant to the adverse effects of atmospheric dust as a hazard.

  3. First X-Ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest Aeolian Bedform at Gale Crater

    NASA Technical Reports Server (NTRS)

    Bish, D. L.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Sarrazin, P.; Morris, R. V.; Ming, D. W.; Treiman, A. H.; Downs, R. T.; Morrison, S. M.; Yen, A. S.; Achilles, C. N.; Morookian, J. M.; Farmer, J. D.; Crisp, J. A.; Rampe, E. B.; Stolper, E. M.; DesMarais, D. J.; Spanovich, N.; Anderson, R. C.

    2013-01-01

    Numerous orbital and landed observations of the martian surface suggest a reasonably uniform martian soil composition, likely as a result of global aeolian mixing [1, 2]. Chemical data for martian soils are abundant [e.g., 2, 3], and phase information has been provided by lander thermal emission and Moessbauer spectroscopic measurements [3, 4, 5, 6]. However, until now no X-ray diffraction (XRD) data were available for martian soil nor has XRD ever been used on another body apart from Earth. XRD is generally considered the most definitive method for determining the crystalline phases in solid samples, and it is the method of choice for determining mineralogy. CheMin s first XRD analysis on Mars coincided with the 100th anniversary of the discovery of X-ray diffraction by von Laue. Curiosity delivered scooped samples of loose, unconsolidated material ("soil") acquired from an aeolian bedform at the Rocknest locality to instruments in the body of the rover (the laboratory). Imaging shows that the soil has a range of particle sizes, of 1-2 mm and smaller, presumably representing contributions from global, regional, and local sources.

  4. Laboratory Simulations of Martian and Venusian Aeolian Processes

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1999-01-01

    With the flyby of the Neptune system by Voyager, the preliminary exploration of the Solar System was accomplished. Data have been returned for all major planets and satellites except the Pluto system. Results show that the surfaces of terrestrial planets and satellites have been subjected to a wide variety of geological processes. On solid- surface planetary objects having an atmosphere, aeolian processes are important in modifying their surfaces through the redistribution of fine-grained material by the wind. Bedrock may be eroded to produce particles and the particles transported by wind for deposition in other areas. This process operates on Earth today and is evident throughout the geological record. Aeolian processes also occur on Mars, Venus, and possibly Titan and Triton, both of which are outer planet satellites that have atmospheres. Mariner 9 and Viking results show abundant wind-related landforms on Mars, including dune fields and yardangs (wind-eroded hills). On Venus, measurements made by the Soviet Venera and Vega spacecraft and extrapolations from the Pioneer Venus atmospheric probes show that surface winds are capable of transporting particulate materials and suggest that aeolian processes may operate on that planet as well. Magellan radar images of Venus show abundant wind streaks in some areas, as well as dune fields and a zone of possible yardangs. The study of planetary aeolian processes must take into account diverse environments, from the cold, low-density atmosphere of Mars to the extremely hot, high- density Venusian atmosphere. Factors such as threshold wind speeds (minimum wind velocity needed to move particles), rates of erosion and deposition, trajectories of windblown particles, and aeolian flow fields over various landforms are all important aspects of the problem. In addition, study of aeolian terrains on Earth using data analogous to planetary data-collection systems is critical to the interpretation of spacecraft information and

  5. Environmental history recorded in aeolian deposits under stone pavements, Mojave Desert, USA

    NASA Astrophysics Data System (ADS)

    Dietze, Michael; Dietze, Elisabeth; Lomax, Johanna; Fuchs, Markus; Kleber, Arno; Wells, Stephen G.

    2016-01-01

    Reconstructing the evolution of arid landscapes is challenged by limited availability of appropriate environmental archives. A widespread surface feature - stone pavement - traps aeolian fines and forms a special accretionary archive. Seven stone pavement-covered sections on basalt flows in the eastern Mojave Desert are condensed into a composite section, comprising five sedimentological units supported by an OSL-based chronology. Three of the units are of accretionary nature and each is covered by a stone pavement. They were deposited > 50.9-36.6 ka, < 36.6-14.2 ka and < 14.2 ka, and they are intimately coupled with the history of nearby Lake Mojave, which advances the current understanding of regional aeolian activity. End-member modeling analysis of grain-size distributions yielded seven sediment transport regimes. The accretionary system operates in two modes: A) episodic formation of a stone pavement by lateral processes once a vesicular horizon has formed on a barren surface; and B) accretion of dust and eventual burial of the clast layer. These findings improve current concepts about stone pavement evolution and their environmental proxy function in arid landscapes. Stone pavement-covered accretionary deposits are a new key archive that allows quantifying the relative importance of dust accretion, slope processes, soil formation and vegetation cover.

  6. 6. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION, LOOKING 306 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION, LOOKING 306 DEGREES NORTHWEST. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  7. 3. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 184 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 184 DEGREES SOUTH. SAME PHOTO AS OR-36-2. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  8. 7. SANDY RIVER BRIDGE AT TROUTDALE, PERSPECTIVE LOOKING EAST. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. SANDY RIVER BRIDGE AT TROUTDALE, PERSPECTIVE LOOKING EAST. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  9. 1. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 18 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 18 DEGREES NORTH. SAME PHOTO AS OR-36-1. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  10. 2. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 20 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. SANDY RIVER BRIDGE AT TROUTDALE, SOUTH END, LOOKING 20 DEGREES NORTH. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  11. 5. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION DETAIL, LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. SANDY RIVER BRIDGE AT TROUTDALE, EAST ELEVATION DETAIL, LOOKING 6 DEGREES NORTH. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  12. 4. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 224 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. SANDY RIVER BRIDGE AT TROUTDALE, NORTH END, LOOKING 224 DEGREES SOUTHWEST. - Historic Columbia River Highway, Sandy River Bridge at Troutdale, Historic Columbia River Highway spanning Sandy River, Troutdale, Multnomah County, OR

  13. Aeolian Sediment Transport Pathways and Aerodynamics at Troughs on Mars

    NASA Technical Reports Server (NTRS)

    Bourke, Mary C.; Bullard, Joanna E.; Barnouin-Jha, Olivier S.

    2004-01-01

    Interaction between wind regimes and topography can give rise to complex suites of aeolian landforms. This paper considers aeolian sediment associated wit11 troughs on Mars and identifies a wider range of deposit types than has previously been documented. These include wind streaks, falling dunes, "lateral" dunes, barchan dunes, linear dunes, transverse ridges, sand ramps, climbing dunes, sand streamers, and sand patches. The sediment incorporated into these deposits is supplied by wind streaks and ambient Planitia sources as well as originating within the trough itself, notably from the trough walls and floor. There is also transmission of sediment between dneTsh. e flow dynamics which account for the distribution of aeolian sediment have been modeled using two-dimensional computational fluid dynamics. The model predicts flow separation on the upwind side of the trough followed by reattachment and acceleration at the downwind margin. The inferred patterns of sediment transport compare well with the distribution of aeolian forms. Model data indicate an increase of wind velocity by approx. 30 % at the downwind trough margin. This suggests that the threshold wind speed necessary for sand mobilization on Mars will be more freqentmlye t in these inclined locations.

  14. Agriculture as a source of Aeolian sediment affecting air quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aeolian processes on agricultural lands have been examined for the past several decades on nearly every continent and has led to a better understanding of detachment, entrainment, transport, and deposition. Relatively little is known concerning the effect of these processes on air quality. In fact, ...

  15. Laboratory Simulations of Martian and Venusian Aeolian Processes

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1999-01-01

    The objective of this work was to conduct research in the Planetary Aeolian Facility (PAF) at NASA-Ames Research Center as a laboratory for the planetary science community and to carry-out experiments on the physics and geology of particles moved by winds, and for the development of instruments and spacecraft components for planetary missions.

  16. Treatment of contaminated groundwater in sandy layer under river bank by electrokinetic and ultrasonic technology.

    PubMed

    Chung, Ha I

    2007-01-01

    A series of laboratory experiments involving simple, ultrasonic, electrokinetic, electrokinetic/ ultrasonic flushing test were carried out for treatment and removal of heavy metal and hydrocarbon from contaminated groundwater in sandy layers under a river bank. The test results show that the electrokinetic/ultrasonic flushing technique is most effective for the removal of heavy metal and hydrocarbon from contaminated sandy layers by the coupling action of their own phenomena. It is shown that the electrokinetic technique is most effective to enhance the removal efficiency of heavy metal contaminants such as cadmium from contaminated sandy soil under the river bank; on the other hand the ultrasonic technique is most effective to enhance the removal efficiency of hydrocarbon contaminant, such as diesel fuel from contaminated soil. PMID:17305157

  17. Threshold wind velocity dynamics as a driver of aeolian sediment mass flux

    NASA Astrophysics Data System (ADS)

    Webb, Nicholas P.; Galloza, Magda S.; Zobeck, Ted M.; Herrick, Jeffrey E.

    2016-03-01

    Horizontal (saltation) mass flux is a key driver of aeolian dust emission. Estimates of the horizontal mass flux underpin assessments of the global dust budget and influence our understanding of the dust cycle and its interactions. Current equations for predicting horizontal mass flux are based on limited field data and are constrained to representing transport-limited equilibrium saltation, driven by the wind momentum flux in excess of an entrainment threshold. This can result in large overestimation of the sediment mass flux. Here we compare measurements of the soil entrainment threshold, horizontal mass flux, and their temporal variability for five undisturbed dryland soils to explore the role of threshold in controlling the magnitude of mass flux. Average and median entrainment threshold showed relatively small variability among sites and relatively small variability between seasons, despite significant differences in soil surface conditions. Physical and biological soil crusts had little effect on the threshold value, and threshold appeared to play a minor role in determining the magnitude of sediment transport. Our results suggest that horizontal mass flux was controlled more by the supply limitation and abrasion efficiency of saltators present as loose erodible material or originating from neighboring soil sources. The omission of sediment supply and explicit representation of saltation bombardment from horizontal flux equations is inconsistent with the process representation in dust emission schemes and contributes to uncertainty in model predictions. This uncertainty can be reduced by developing greater process fidelity in models to predict horizontal mass flux under both supply- and transport-limited conditions.

  18. Dynamics and composition of particles from an aeolian input event to the Sargasso Sea

    NASA Technical Reports Server (NTRS)

    Carder, K. L.; Steward, R. G.; Betzer, P. R.; Johnson, D. L.; Prospero, J. M.

    1986-01-01

    The present paper is concerned with studies related to the capture of aeolian mineral particles in the Sargasso Sea region in late June 1980. Attention is given to measurement techniques, aerosol sampling, particle trap sampling, investigations utilizing scanning electron microscopy, and the obtained results. Conceivable sources for nonbiogenic particles measured in the water column are related to fallout from the Mount St. Helens eruption and soil materials transported by winds from the North American or African continents. It is found that present aerosol transport models are not adequaely addressing the transport of giant particles from the Sahara to the Sargasso Sea. Data regarding the variation of Sargasso Sea aerosol mass concentrations with time are presented in a table.

  19. Towards a phoenix phase in aeolian research: shifting geophysical perspectives from fluvial dominance

    SciTech Connect

    Whicker, Jeffrey J; Field, Jason P; Breshears, David D

    2008-01-01

    Aeolian processes are a fundamental driver of earth surface dynamics, yet the importance of aeolian processes in a broader geosciences context may be overshadowed by an unbalanced emphasis on fluvial processes. Here we wish to highlight that aeolian and fluvial processes need to be considered in concert relative to total erosion and to potential interactions, that relative dominance and sensitivity to disturbance vary with mean annual precipitation, and that there are important scale-dependencies associated with aeolian-fluvial interactions. We build on previous literature to present relevant conceptual syntheses highlighting these issues. We then highlight the relative investments that have been made in aeolian research on dust emission and management relative to that in fluvial research on sediment production. Literature searches highlight that aeolian processes are greatly understudied relative to fluvial processes when considering total erosion in different environmental settings. Notably, within the USA, aeolian research was triggered by the Dust Bowl catastrophe of the 1930s, but the resultant research agencies have shifted to almost completely focusing on fluvial processes, based on number of remaining research stations and on monetary investments in control measures. However, numerous research issues associated with intensification of land use and climate change impacts require a rapid ramping up in aeolian research that improves information about aeolian processes relative to fluvial processes, which could herald a post-Dust Bowl Phoenix phase in which aeolian processes are recognized as broadly critical to geo- and environmental sciences.

  20. Hurricane Sandy From the International Space Station

    NASA Video Gallery

    The International Space Station flew high above Hurricane Sandy just before 12 p.m. CDT Thursday. The storm was located about 85 miles south-southeast of Great Exuma Island. The storm’s maximum s...

  1. Effects of aeolian erosion on microbial release from solids.

    NASA Technical Reports Server (NTRS)

    Gustan, E. A.; Olson, R. L.; Taylor, D. M.; Green, R. H.

    1972-01-01

    This study was initiated to determine the percentage of spores that would be expected to be released from the interior of solid materials by aeolian erosion on a planetary surface. Methyl methacrylate and Eccobond disks were fabricated so that each disk contained approximately 40,000 Bacillus subtilis var. niger spores. The disks were placed in a specially designed sandblasting device and eroded. Exposure periods of 0.5, 2 and 24 hours were investigated using filtered air to accelerate the sand. A series of tests was also conducted for a 0.5 hour period using carbon dioxide. Examination of the erosion products showed that less than 1% of the spores originally contained in the solids was released by aeolian erosion.

  2. The potential scale of aeolian structures on Venus

    NASA Technical Reports Server (NTRS)

    Marshall, J. R.; Greeley, Ronald

    1991-01-01

    Simulations of the Venusian aeolian environment with the Venus Wind Tunnel have shown that microdunes are formed during the entrainment of sand-sized material. These structures are several tens of centimeters long (2-3 cm high) and combine the morphological and behavioral characteristics of both full-scale terrestrial dunes and current ripples formed in subaqueous environments. Their similarity to both reflects the fact that the Venusian atmosphere has a density intermediate between air and water. Although the development of microdunes in the wind tunnel experiments was limited by tunnel dimensions, it is possible to make some predictions about their potential size on Venus, and the potential size of related aeolian structures. Microdunes are fluid-filled structures (as are dunes and current ripples) and as such have no theoretical upper limit to their size from a fluid dynamics viewpoint. Limitations to size observed in subaqueous structures are set by, for example, water depth; limitations to the size of dunes are set by, for example, sand supply. It is therefore reasonable to suppose that the microdunes on Venus could evolve into much larger features than those observed in experiments. In addition, the researchers note that current ripples (which are closely related to microdunes) are often found in association with giant ripples that have dimensions similar to aeolian dunes. Thus, it may be reasonable to assume that analogous large scale structures occur on Venus. Both (terrestrial) aeolian and subaqueous environments generate structures in excess of one hundred meters in wavelength. Such dimensions may therefore be applicable to Venusian bedforms. Analysis of Magellan data may resolve the issue.

  3. Niveo-aeolian and Denivation Deposits on Mars

    NASA Astrophysics Data System (ADS)

    Bourke, M. C.

    2004-12-01

    Hydrogen abundance data from the Gamma Ray Spectrometer on board the Mars Odyssey platform indicate that large areas of the North Polar Sand Sea have high concentrations (40-60% weight) of hydrogen molecules in the surface deposits. On Earth, cold region sand dunes often contain inter-bedded sand, snow and ice. These niveo-aeolian deposits have unique morphologies and sedimentary structures that are generally not found in warm desert dunes. An atlas of dune niveo-aeolian and denivation features was compiled from published studies of polar deserts on Earth. Features occur at a range of scales and signatures are both morphologic and stratigraphic. The atlas is used to identify similar features on Mars. Examination of high resolution Mars Orbiter Camera images of the North Polar Sand Sea and Southern Crater dune fields have identified several potential signatures of niveo-aeolian and denivation processes on Mars. These include: over steepened lee slopes, cornices, rounded slipface and/or crest, protruding ice cemented beds, alluvial meltwater channels and fans and sublimation avalanches. Other smaller-scale forms probably occur but are not detectable with current resolution data. While these findings have implications for our understanding of martian dune geomorphology, mobility and the geological evolution of the sand seas, they also highlight the potential for a significant volatile reservoir and biological habitat in sand dunes on Mars.

  4. Quantifying the provenance of aeolian sediments using multiple composite fingerprints

    NASA Astrophysics Data System (ADS)

    Liu, Benli; Niu, Qinghe; Qu, Jianjun; Zu, Ruiping

    2016-09-01

    We introduce a new fingerprinting method that uses multiple composite fingerprints for studies of aeolian sediment provenance. We used this method to quantify the provenance of sediments on both sides of the Qinghai-Tibetan Railway (QTR) in the Cuona Lake section of the Tibetan Plateau (TP), in an environment characterized by aeolian and fluvial interactions. The method involves repeatedly solving a linear mixing model based on mass conservation; the model is not limited to spatial scale or transport types and uses all the tracer groups that passed the range check, Kruskal-Wallis H-test, and a strict analytical solution screening. The proportional estimates that result from using different composite fingerprints are highly variable; however, the average of these fingerprints has a greater accuracy and certainty than any single fingerprint. The results show that sand from the lake beach, hilly surface, and gullies contribute, respectively, 48%, 31% and 21% to the western railway sediments and 43%, 33% and 24% to the eastern railway sediments. The difference between contributions from various sources on either side of the railway, which may increase in the future, was clearly related to variations in local transport characteristics, a conclusion that is supported by grain size analysis. The construction of the QTR changed the local cycling of materials, and the difference in provenance between the sediments that are separated by the railway reflects the changed sedimentary conditions on either side of the railway. The effectiveness of this method suggests that it will be useful in other studies of aeolian sediments.

  5. Characterizing the instability of aeolian environments using analytical reasoning

    NASA Astrophysics Data System (ADS)

    Houser, C.; Bishop, M. P.; Dobreva, I. D.; Barrineau, C. P.; Weymer, B. A.

    2013-12-01

    Characterization of aeolian systems is complicated by rapidly changing surface-process regimes, spatio-temporal scale dependencies, and subjective interpretation of imagery and spatial data. Stability and instability of the South Texas sand sheet is addressed using an artificial intelligence approach that integrates spatial information and analytical reasoning. Specifically, the purpose of this study is to determine if landscape evolutionary sequences could be mapped and characterized based on simple conceptual relationships amongst biophysical variables including topography, vegetation, surface moisture, wind speed, and surface erosion and deposition. A digital elevation model was derived from airborne LiDAR data and combined with moisture and vegetation indices computed using Spectral feature extraction from Landsat Thematic Mapper data. Our analysis reveals unique scale dependent spatial patterns and the use of fuzzy cognitive maps provides an analytical reasoning approach to address the complexity of aeolian environments in response to changes in climate forcing. The application to other Holocene aeolian deposits and the potential for this approach to model landscape evolution are also discussed.

  6. [Effect of grazing on sandy grassland ecosystem in Inner Mongolia].

    PubMed

    Zhao, Halin; Zhang, Tonghui; Zhao, Xueyong; Zhou, Ruilian

    2004-03-01

    This experiment was carried out for 5 years in Horqin sandy land, lnner Mongolia, which had 4 treatments: Non-grazing (NG), light grazing (LG), moderate grazing (MG) and over grazing (OG). The results showed that different grazing intensities resulted in different development trend of the pasture ecosystem, of which, the injury of OG on pasture ecosystem was very great. The plant diversity, vegetation coverage, plant height and primary productivity under continuous overgrazing for 5 year were 87.9%, 82.1%, 94.0% and 57.0%, respectively, lower than those in NG. The biomass on the OG pasture was only 2.1% of NG, and the contents of soil clay, C and N as well as the quantities of soil microbes and small animals in OG were respectively 6.0%, 31.9%, 25.0%, 95.0% and 75.9% lower than those in NG, but the soil hardness was raised by 274.0%. Especially, the secondary productivity of the pasture became negative from the third year, and the productive foundation of the pasture ecosystem was completely destroyed. Non-grazing was beneficial to pasture, and enclosure caused an increase in vegetation coverage, plant height and primary productivity. The vegetation coverage, plant height and soil status in LG and MG were not as good as those in NG, but were stable and didn't show worsening trend. Based on the above results, it's considered that on the sandy pasture in the semi-arid area of Inner Mongolia, the rational grass utilization ratio is 45%-50%, and the suitable loading capacity is 3-4 sheep unit.hm-2. PMID:15227991

  7. A Japan-Sino joint project, ADEC - Aeolian Dust Experiment on Climate Impact

    NASA Astrophysics Data System (ADS)

    Mikami, M.

    2004-05-01

    In recent years, aeolian dust has been thought to be an important factor of the climate system on the earth by the radiative forcing effect in the atmosphere and by the influence on the carbon dioxide cycle because deposited dust supplies nutrient salts for the phytoplankton on the ocean surface. Among them, radiative forcing direct and/or indirect effects are important factors of the global warming. Nevertheless, the reliability of the evaluation regarding the radiative forcing impact of aeolian dust is very low. [IPCC, 2001]. This is because the understanding and the model representations of dust entrainment, spatial and temporal distribution of dust, and optical properties of dust particles are not so accurate. Based on this background, Aeolian Dust Experiment on Climate Impact (ADEC) was started in April 2000 as a Japan-Sino Joint Project. The goal of this project is to evaluate the global dust supply to the atmosphere and its radiative forcing direct effect. For this purpose, we have made: 1) in situ observations at desert areas in China for wind erosion processes, 2) network observations from China to Japan, ranging from 80 to 140 East, for understanding spatial-size distribution, chemical, and optical properties of dust particles, and 3) numerical simulation by GCM dust model for evaluation of dust impact on the global climate over the past 50 years. This was planned as a five-year project and two intensive observations, IOP-1, April 12-25 2002, and IOP-2, March 15-26 2003, were put into practice. Intensive observations were made at 6 sites in China (Qira, Aksu, Dunhuang, Shapotou, Beijing, and Qingdao) and 4 sites in Japan (Naha, Fukuoka, Nagoya, and Tsukuba). Preliminary results show that 1) saltation flux at a gobi desert monitored by a newly developed sand particle counter was around 10 times larger than that of a sand dune, which will be caused by the difference of the parent soil size distribution of each ground condition, 2) the background of KOSA

  8. Seasonal Dynamics of Water Use Strategy of Two Salix Shrubs in Alpine Sandy Land, Tibetan Plateau

    PubMed Central

    Zhu, Yajuan; Wang, Guojie; Li, Renqiang

    2016-01-01

    Water is a limiting factor for plant growth and vegetation dynamics in alpine sandy land of the Tibetan Plateau, especially with the increasing frequency of extreme precipitation events and drought caused by climate change. Therefore, a relatively stable water source from either deeper soil profiles or ground water is necessary for plant growth. Understanding the water use strategy of dominant species in the alpine sandy land ecosystem is important for vegetative rehabilitation and ecological restoration. The stable isotope methodology of δD, δ18O, and δ13C was used to determine main water source and long-term water use efficiency of Salix psammophila and S. cheilophila, two dominant shrubs on interdune of alpine sandy land in northeastern Tibetan Plateau. The root systems of two Salix shrubs were investigated to determine their distribution pattern. The results showed that S. psammophila and S. cheilophila absorbed soil water at different soil depths or ground water in different seasons, depending on water availability and water use strategy. Salix psammophila used ground water during the growing season and relied on shallow soil water recharged by rain in summer. Salix cheilophila used ground water in spring and summer, but relied on shallow soil water recharged by rain in spring and deep soil water recharged by ground water in fall. The two shrubs had dimorphic root systems, which is coincident with their water use strategy. Higher biomass of fine roots in S. psammophila and longer fine roots in S. cheilophila facilitated to absorb water in deeper soil layers. The long-term water use efficiency of two Salix shrubs increased during the dry season in spring. The long-term water use efficiency was higher in S. psammophila than in S. cheilophila, as the former species is better adapted to semiarid climate of alpine sandy land. PMID:27243772

  9. Seasonal Dynamics of Water Use Strategy of Two Salix Shrubs in Alpine Sandy Land, Tibetan Plateau.

    PubMed

    Zhu, Yajuan; Wang, Guojie; Li, Renqiang

    2016-01-01

    Water is a limiting factor for plant growth and vegetation dynamics in alpine sandy land of the Tibetan Plateau, especially with the increasing frequency of extreme precipitation events and drought caused by climate change. Therefore, a relatively stable water source from either deeper soil profiles or ground water is necessary for plant growth. Understanding the water use strategy of dominant species in the alpine sandy land ecosystem is important for vegetative rehabilitation and ecological restoration. The stable isotope methodology of δD, δ18O, and δ13C was used to determine main water source and long-term water use efficiency of Salix psammophila and S. cheilophila, two dominant shrubs on interdune of alpine sandy land in northeastern Tibetan Plateau. The root systems of two Salix shrubs were investigated to determine their distribution pattern. The results showed that S. psammophila and S. cheilophila absorbed soil water at different soil depths or ground water in different seasons, depending on water availability and water use strategy. Salix psammophila used ground water during the growing season and relied on shallow soil water recharged by rain in summer. Salix cheilophila used ground water in spring and summer, but relied on shallow soil water recharged by rain in spring and deep soil water recharged by ground water in fall. The two shrubs had dimorphic root systems, which is coincident with their water use strategy. Higher biomass of fine roots in S. psammophila and longer fine roots in S. cheilophila facilitated to absorb water in deeper soil layers. The long-term water use efficiency of two Salix shrubs increased during the dry season in spring. The long-term water use efficiency was higher in S. psammophila than in S. cheilophila, as the former species is better adapted to semiarid climate of alpine sandy land. PMID:27243772

  10. The Topic Is Sandy Hook: A Program for Gifted and Talented Students at Sandy Hook.

    ERIC Educational Resources Information Center

    Grant, David

    "The Topic Is Sandy Hook" is an experiential 10-week program designed to provide special opportunities and educational experiences for 6th to 10th grade gifted and talented students. Sandy Hook, a natural resource in Monmouth County, New Jersey, is unique in its physical and historical features and provides an exceptionally rich environment in…

  11. Effects of river regulation on aeolian landscapes, Colorado River, southwestern USA

    USGS Publications Warehouse

    Draut, Amy E.

    2012-01-01

    Connectivity between fluvial and aeolian sedimentary systems plays an important role in the physical and biological environment of dryland regions. This study examines the coupling between fluvial sand deposits and aeolian dune fields in bedrock canyons of the arid to semiarid Colorado River corridor, southwestern USA. By quantifying significant differences between aeolian landscapes with and without modern fluvial sediment sources, this work demonstrates for the first time that the flow- and sediment-limiting effects of dam operations affect sedimentary processes and ecosystems in aeolian landscapes above the fluvial high water line. Dune fields decoupled from fluvial sand supply have more ground cover (biologic crust and vegetation) and less aeolian sand transport than do dune fields that remain coupled to modern fluvial sand supply. The proportion of active aeolian sand area also is substantially lower in a heavily regulated river reach (Marble–Grand Canyon, Arizona) than in a much less regulated reach with otherwise similar environmental conditions (Cataract Canyon, Utah). The interconnections shown here among river flow and sediment, aeolian sand transport, and biologic communities in aeolian dunes demonstrate a newly recognized means by which anthropogenic influence alters dryland environments. Because fluvial–aeolian coupling is common globally, it is likely that similar sediment-transport connectivity and interaction with upland ecosystems are important in other dryland regions to a greater degree than has been recognized previously.

  12. Mega-ripples in Iran: A new analog for transverse aeolian ridges on Mars

    NASA Astrophysics Data System (ADS)

    Foroutan, M.; Zimbelman, J. R.

    2016-08-01

    A new terrestrial analog site for transverse aeolian ridges (TARs) is described in this study. The Lut desert of Iran hosts large ripple-like aeolian bedforms, with the same horizontal length scales and patterns of TARs on Mars. Different classes of TARs and different types of other aeolian features such as sand dunes, zibars, dust devil tracks and yardangs can be found in this area, which signify an active aeolian region. This area represents a unique site to study the formation and evolution of these enigmatic features, with potential relevance toward a better understanding of TARs on Mars.

  13. Effects of river regulation on aeolian landscapes, Colorado River, southwestern USA

    NASA Astrophysics Data System (ADS)

    Draut, Amy E.

    2012-06-01

    Connectivity between fluvial and aeolian sedimentary systems plays an important role in the physical and biological environment of dryland regions. This study examines the coupling between fluvial sand deposits and aeolian dune fields in bedrock canyons of the arid to semiarid Colorado River corridor, southwestern USA. By quantifying significant differences between aeolian landscapes with and without modern fluvial sediment sources, this work demonstrates for the first time that the flow- and sediment-limiting effects of dam operations affect sedimentary processes and ecosystems in aeolian landscapes above the fluvial high water line. Dune fields decoupled from fluvial sand supply have more ground cover (biologic crust and vegetation) and less aeolian sand transport than do dune fields that remain coupled to modern fluvial sand supply. The proportion of active aeolian sand area also is substantially lower in a heavily regulated river reach (Marble-Grand Canyon, Arizona) than in a much less regulated reach with otherwise similar environmental conditions (Cataract Canyon, Utah). The interconnections shown here among river flow and sediment, aeolian sand transport, and biologic communities in aeolian dunes demonstrate a newly recognized means by which anthropogenic influence alters dryland environments. Because fluvial-aeolian coupling is common globally, it is likely that similar sediment-transport connectivity and interaction with upland ecosystems are important in other dryland regions to a greater degree than has been recognized previously.

  14. Geochronology of initial soils in Late-Holocene polycyclic drift-sand deposits (Weerterbergen, S.E. Netherlands)

    NASA Astrophysics Data System (ADS)

    van mourik, J. M.; Wallinga, J.

    2012-04-01

    extracted SOM are indeed not reliable. OSL dating works excellent for aeolian sandy deposits with a high percentage of quartz grains. The OSL age is defined as the time after the last bleaching by solar radiation of mineral grains. In contrast to 14C dating, application of OSL dating provides accurate information over the age of top and bottom of deposited sand beds and consequently over the time, available for soil development. Based on OSL dates, the micropodzols developed between 1700 and 1950 AD and reflect relatively stable periods (soil formation) in the landscape development after the introduction of the deep stable management.

  15. Transverse Aeolian Ridges on Mars: Sediment sources, volumes, and ages.

    NASA Astrophysics Data System (ADS)

    Berman, D. C.; Balme, M. R.

    2014-12-01

    Transverse Aeolian Ridges (TARs) are aeolian bedforms that are morphologically and dimensionally distinct from Large Dark Dune (LDD) fields, being generally brighter than, or of similar albedo to, the surrounding terrain. These features are significantly smaller than the LDDs, appear to form normal to local winds, and tend to have simple, transverse, ripple-like morphologies. Whether these small martian bedforms represent large granule ripples, small transverse dunes, or something else entirely is currently under debate. The spatial distribution of TARs provides important information about where on Mars aeolian sediments are concentrated, and determining their volume can help us constrain the sediment transport regime on Mars. Also, if we can determine if TARs were active only in the past, or whether TARs are mobile under today's wind conditions, then we can begin to assess when and where TARs are/were active over Mars' recent geological history. Thus TARs have the potential for being indicators/records of climate change on Mars. In this work we build on previous work [1,2] and focus on the local/regional scale. We have identified six regional study areas, each 5° by 5°, to investigate the behavior of TARs in detail; one in the northern hemisphere, three in the equatorial band, and two in the southern hemisphere. We have systematically mapped TAR and LDD deposits in each study area to constrain sediment transport pathways and identify sediment sources. In general, TAR sediments appear to be tied to local sources such as LDDs or layered terrains. HiRISE DTMs were utilized to measure TAR heights, widths, wavelengths, and lengths to calculate sediment volumes and estimate volumes over entire study areas based on mapping. Crater count analyses on contiguous TAR fields in the equatorial regions, where the bedforms appear more lithified, reveal ages of several million years. Mid-latitude TAR fields do not show any superposed craters, suggesting much younger deposits

  16. Aeolian sediment transport over gobi: Field studies atop the Mogao Grottoes, China

    NASA Astrophysics Data System (ADS)

    Tan, Lihai; Zhang, Weimin; Qu, Jianjun; Wang, Junzhan; An, Zhishan; Li, Fang

    2016-06-01

    This paper reports on field studies of aeolian sediment transport over a rough surface-gobi atop the Mogao Grottoes, China, in relation to sediment entrainment, saltation mass flux and transport rate prediction. Wind speeds were measured with five cup anemometers at different heights and sediment entrainment and transport measured with horizontal and vertical sediment traps coupled to weighing sensors, where sediment entrainment and transport were measured synchronously with wind speeds. Four sediment transport events, with a measurement duration ranging between 2.5 and 11 h, were studied. The entrainment threshold determined by the horizontal sediment trap varied between 0.28 and 0.33 m s-1, and the effect of non-erodible roughness elements-gravels increased the entrainment threshold approximately by 1.8 times compared to a uniform sand surface. Unlike the non-monotone curve shape of sediment flux density profile over gobi measured in wind tunnels, the flux density profile measured in the field showed an exponential form. Aeolian sediment transport over gobi could be predicted by an Owen-type saltation model: q = Aρ /gu∗ (u∗2 - u∗t2) , where q is sediment transport rate, A is a soil-related dimensionless factor, u∗ is the friction velocity, u∗t is the threshold friction velocity, g is the gravitational acceleration, ρ is the air density. This study indicates that the sediment flux sampling using horizontal and vertical sediment traps coupled to weighing sensors provides a practical method to determine values for A in this model that can provide good estimates of sediment transport rates in gobi areas.

  17. Effect of Holocene sea level change on aeolian activity in the coastal plain of Ras El Hekma area, NW coast of Egypt

    NASA Astrophysics Data System (ADS)

    Farghaly, Enas; Torab, Magdy

    2015-04-01

    Ras El Hekma area located in north western coast of Egypt, west of Alexandria city for about 220 km, in this area, environmental changes during the Holocene can be interpreted based on morphological and sedimentological similarities between Holocene geomorphic features such as cemented beaches and fossilized dunes with recent coastal features. Sand dunes and nebkhas are the most common aeolian landforms and they occur in semi-arid climatic conditions. The active separated coastal dunes and nebkhas dunes of Ras El-Hekma area are located between the swash zone and the coastal limestone ridges as well as in the coastal sabkhas. The effect of waves during storms reaches far beyond the actual beach and can cause great changes to sandy beaches at an exceptional speed. Sand accumulated by swash drifts with the wind on open beaches and bays. The aeolian sand, which originates from fluvial-marine sediments washed by sea waves. the available sediment depends on fluvial transport to the littoral zone and on biological activity in the carbonate environments as well as on longshore and cross-shore currents. This paper treats the coastal dunes in Ras El Hekma area in their entirety and defines the effects of sea level change on coastal sand dunes and sabkhas dunes, it depends upon field geomorphic surveying, sampling and mapping as well as satellite image interpretation using ENVI software and GIS techniques.

  18. Dynamic changes of sandy land in northwest of Beijing, China.

    PubMed

    Wang, Jing; He, Ting; Guo, Xudong; Liu, Aixia; Zhou, Qing

    2006-10-01

    The area northwest of Beijing is one of the most important regions where many organizations invest and pay most attention. The environmental problems in this region affect not only Beijing but also the surrounding area. Based on observation of the characteristics of the change in sandy land, this study classified four types of dynamic change of sandy land, including extended sandy land, the reversely changed sandy land, the potential sandy land and no change in sandy land. Then the process and the trend of changes in sandy land and their environmental impact on the area northwest of Beijing were analyzed. The results show that the area of sandy land has increased in this region in the period of 1991 to 2002. Change between sandy land and grassland was the dominant change. It is found that the monitoring zones of Hunshandake sandy land and north of Yin Shan are regions with high ratio of extended sandy land, and are connected with widespread potential change of sandy land. This implies that these two regions have a high probability of increase in sandy land in the future. On the other hand, in the monitoring zone of Horqin sandy land and Ba Shang Plateau and its surrounding area, desertification had been controlled and the area of sandy land is expected to decrease. This indicates that the direction of the sandstorm to Beijing is expected to gradually move to the northwest. Furthermore, the decreases in sandy land and the reversing change from arable land to grassland and forests in the study region will affect the land quality and atmosphere. And the logistic multiple regression (LMR) model was employed to better understand the complexity and processes of increases in sandy land. This model predicts that there is a high probability of increases in sandy land in north of Siziwang Banner, Zhengxiangbai Banner and Zhenglan Banner. Finally, suggestions to the ecological construction of the study area have been proposed. PMID:16758285

  19. Satellite Observations Monitor Outages From Superstorm Sandy

    NASA Astrophysics Data System (ADS)

    Molthan, Andrew; Jedlovec, Gary

    2013-01-01

    In late October 2012, Hurricane Sandy traveled across Jamaica, Cuba, and the Bahamas, then progressed northward along the eastern seaboard of the United States, resulting in numerous tropical storm warnings along the coasts of Florida and North Carolina. As the storm approached the Mid-Atlantic region, interaction with an upper-level low drew the cyclone inland, with the center passing just north of Atlantic City, N. J. In what media reports dubbed a "superstorm," Sandy produced hurricane-force winds, significant coastal storm surge, torrential rain, inland flooding, and extensive damage over a vast area. Further west of the cyclone center, strong winds increased wave activity throughout the Great Lakes, and heavy snowfall occurred across portions of Tennessee, Kentucky, and West Virginia. As of early November, more than 100 fatalities had been attributed to Sandy in the northeastern United States, with total economic losses of up to $50 billion [New York Times, 2012, and Walsh and Schwartz, 2012].

  20. An integrated coastal model for aeolian and hydrodynamic sediment transport

    NASA Astrophysics Data System (ADS)

    Baart, F.; den Bieman, J.; van Koningsveld, M.; Luijendijk, A. P.; Parteli, E. J. R.; Plant, N. G.; Roelvink, J. A.; Storms, J. E. A.; de Vries, S.; van Thiel de Vries, J. S. M.; Ye, Q.

    2012-04-01

    Dunes are formed by aeolian and hydrodynamic processes. Over the last decades numerical models were developed that capture our knowledge of the hydrodynamic transport of sediment near the coast. At the same time others have worked on creating numerical models for aeolian-based transport. Here we show a coastal model that integrates three existing numerical models into one online-coupled system. The XBeach model simulates storm-induced erosion (Roelvink et al., 2009). The Delft3D model (Lesser et al., 2004) is used for long term morphology and the Dune model (Durán et al., 2010) is used to simulate the aeolian transport. These three models were adapted to be able to exchange bed updates in real time. The updated models were integrated using the ESMF framework (Hill et al., 2004), a system for composing coupled modeling systems. The goal of this integrated model is to capture the relevant coastal processes at different time and spatial scales. Aeolian transport can be relevant during storms when the strong winds are generating new dunes, but also under relative mild conditions when the dunes are strengthened by transporting sand from the intertidal area to the dunes. Hydrodynamic transport is also relevant during storms, when high water in combination with waves can cause dunes to avalanche and erode. While under normal conditions the hydrodynamic transport can result in an onshore transport of sediment up to the intertidal area. The exchange of sediment in the intertidal area is a dynamic interaction between the hydrodynamic transport and the aeolian transport. This dynamic interaction is particularly important for simulating dune evolution at timescales longer than individual storm events. The main contribution of the integrated model is that it simulates the dynamic exchange of sediment between aeolian and hydrodynamic models in the intertidal area. By integrating the numerical models, we hope to develop a model that has a broader scope and applicability than

  1. Biochar effect on maize yield and soil characteristics in five conservation farming sites in Zambia

    USGS Publications Warehouse

    Cornelissen, Gerard; Martinsen, Vegard; Shitumbanuma, Victor; Alling, Vanja; Breedveld, Gijs D.; Rutherford, David W.; Sparrevik, Magnus; Hale, Sarah E.; Obia, Alfred; Mulder, Jan

    2013-01-01

    Biochar addition to agricultural soils can improve soil fertility, with the added bonus of climate change mitigation through carbon sequestration. Conservation farming (CF) is precision farming, often combining minimum tillage, crop rotation and residue retention. In the present farmer-led field trials carried out in Zambia, the use of a low dosage biochar combined with CF minimum tillage was tested as a way to increase crop yields. Using CF minimum tillage allows the biochar to be applied to the area where most of the plant roots are present and mirrors the fertilizer application in CF practices. The CF practice used comprised manually hoe-dug planting 10-L sized basins, where 10%–12% of the land was tilled. Pilot trials were performed with maize cob biochar and wood biochar on five soils with variable physical/chemical characteristics. At a dosage as low as 4 tons/ha, both biochars had a strong positive effect on maize yields in the coarse white aeolian sand of Kaoma, West-Zambia, with yields of 444% ± 114% (p = 0.06) and 352% ± 139% (p = 0.1) of the fertilized reference plots for maize and wood biochar, respectively. Thus for sandy acidic soils, CF and biochar amendment can be a promising combination for increasing harvest yield. Moderate but non-significant effects on yields were observed for maize and wood biochar in a red sandy clay loam ultisol east of Lusaka, central Zambia (University of Zambia, UNZA, site) with growth of 142% ± 42% (p > 0.2) and 131% ± 62% (p > 0.2) of fertilized reference plots, respectively. For three other soils (acidic and neutral clay loams and silty clay with variable cation exchange capacity, CEC), no significant effects on maize yields were observed (p > 0.2). In laboratory trials, 5% of the two biochars were added to the soil samples in order to study the effect of the biochar on physical and chemical soil characteristics. The large increase in crop yield in Kaoma soil was tentatively explained by a combination of an

  2. Flood Induced Increases in Aeolian Transport Along the Missouri River

    NASA Astrophysics Data System (ADS)

    Benthem, A. J.; Strong, L.; Schenk, E.; Skalak, K.; Hupp, C. R.; Galloway, J.

    2014-12-01

    In 2011, heavy winter snow melt combined with extensive spring rains caused the Missouri River to experience the most extensive flooding since the river was dammed in the 1950s. Large sections of the river banks, islands, and floodplains experienced weeks of prolonged inundation, resulting in extensive sand deposition as up to1 km inland from the established channel. Though locally variable, deposits of up to 3m of loose sand were deposited on the floodplain and extensive areas of shrub, grasslands, and agricultural fields were completely buried or had vegetation washed away in the inundation zone. The flooding also created a number of new unvegetated islands which provide important habitat for endangered species including the Piping Plover (Charadrius melodus). These newly created sand surfaces are unconsolidated and have very little vegetation to prevent aeolian transport. Strong sustained regional winds of up to 20m/s (45mph) cause substantial sediment fluxes which modify landscape topography, shift river morphology, and increase regional dust levels. Our study monitors and quantifies the increase in aeolian transport that occurred following flooding along the Garrison Reach, a 110 km section of free flowing Missouri River in North Dakota. In 2012 and 2013 we measured sand transport and accumulation rates using Leatherman style sand traps and erosion pins to at 9 sites of varying vegetation densities. We apply these flux rates to a high resolution remote sensing vegetation map to estimate the total flux of sand for this segment of the river. We also quantify total available new sand for transport using repeat Light Detection and Ranging (LiDAR) coverage from before and after the flood and examine the relationship between sand deposition and the rate of reestablishment of vegetation. All of these results are used to estimate the scale of flood induced aeolian processes and predict where they may continue to influence the landscape.

  3. Evaluation of a new model of aeolian transport in the presence of vegetation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aeolian transport is an important characteristic of many arid and semiarid regions worldwide that affects dust emission and ecosystem processes. The purpose of this paper is to evaluate a recent model of aeolian transport in the presence of vegetation [Okin, 2008]. This approach differs from previou...

  4. Aeolian sand ripples: experimental study of fully developed states.

    PubMed

    Andreotti, Bruno; Claudin, Philippe; Pouliquen, Olivier

    2006-01-20

    We report an experimental investigation of aeolian sand ripples, performed both in a wind tunnel and on stoss slopes of dunes. Starting from a flat bed, we can identify three regimes: appearance of an initial wavelength, coarsening of the pattern, and finally saturation of the ripples. We show that both initial and final wavelengths, as well as the propagative speed of the ripples, are linear functions of the wind velocity. Investigating the evolution of an initially corrugated bed, we exhibit nonlinear stable solutions for a finite range of wavelengths, which demonstrates the existence of a saturation in amplitude. These results contradict most of the models. PMID:16486644

  5. 3. SANDY RIVER (STARK ST.) BRIDGE, SOUTH END, LOOKING 295 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SANDY RIVER (STARK ST.) BRIDGE, SOUTH END, LOOKING 295 DEGREES WEST-SOUTHWEST. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  6. 1. SANDY RIVER (STARK ST.) BRIDGE, NORTH END, LOOKING 135 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. SANDY RIVER (STARK ST.) BRIDGE, NORTH END, LOOKING 135 DEGREES SOUTHEAST. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  7. 5. SANDY RIVER (STARK ST.) BRIDGE, EAST ELEVATION, LOOKING 194 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. SANDY RIVER (STARK ST.) BRIDGE, EAST ELEVATION, LOOKING 194 DEGREES SOUTH. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  8. 4. SANDY RIVER (STARK ST.) BRIDGE, WEST ELEVATION, LOOKING 118 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. SANDY RIVER (STARK ST.) BRIDGE, WEST ELEVATION, LOOKING 118 DEGREES EAST-SOUTHEAST. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  9. 2. SANDY RIVER (STARK ST.) BRIDGE, NORTH END, LOOKING 163 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. SANDY RIVER (STARK ST.) BRIDGE, NORTH END, LOOKING 163 DEGREES SOUTH. - Historic Columbia River Highway, Stark Street Bridge, Spanning Sandy River on Stark Street at Historic Columbia River Highway, Troutdale, Multnomah County, OR

  10. Responses of aeolian desertification to a range of climate scenarios in China

    NASA Astrophysics Data System (ADS)

    Wang, Xunming; Hua, Ting; Ma, Wenyong

    2016-06-01

    Aeolian desertification plays an important role in earth-system processes and ecosystems, and has the potential to greatly impact global food production. The occurrence of aeolian desertification has traditionally been attributed to increases in wind speed and temperature and decreases in rainfall. In this study, by integrating the aeolian desertification monitoring data and climate and vegetation indices, we found that although aeolian desertification is influenced by complex climate patterns and human activities, increases in rainfall and temperature and decreases in wind speed may not be the key factors of aeolian desertification controls in some regions of China. Our results show that, even when modern technical approaches are used, different approaches to desertification need to be applied to account for regional differences. These results have important implications for future policy decisions on how best to combat desertification.

  11. A Study of Sandy Beach Zonation.

    ERIC Educational Resources Information Center

    Alexander, Steve K.

    1991-01-01

    Describes the study of sandy beach zonations as a seashore activity for either high school or lower-level college courses in biology, ecology, or marine biology. Students first draw a profile of a beach scene and then collect specimens from the zones of the shore. In a laboratory, students identify their specimens and relate them to the beach…

  12. Post-Sandy, Schools Claw Back

    ERIC Educational Resources Information Center

    Maxwell, Lesli A.

    2012-01-01

    David Weiss, the superintendent in Long Beach, N.Y., wrestled with a slew of considerations last week as he weighed when to restart school, nine days after Hurricane Sandy wrecked his community. Just one of seven buildings had most of the essentials: electricity, heat, working fire alarms, sewage, and food. And, with many students and staff…

  13. Operational Group Sandy technical progress report

    USGS Publications Warehouse

    Department of the Interior Strategic Science Group

    2013-01-01

    This report documents results from the March 2013 deployment of the OGS. It includes background information on Hurricane Sandy and the federal response; the OGS methodology; scenarios for Hurricane Sandy’s impact on coastal communities and urban ecosystems; potential interventions to improve regional resilience to future major storms; a discussion of scenario results; and lessons learned about the OGS process.

  14. Particle-size fractionation of aeolian sand along a climatic and geomorphic gradient of the Sinai-Negev erg

    NASA Astrophysics Data System (ADS)

    Roskin, Joel; Katra, Itzhak; Blumberg, Dan G.

    2015-04-01

    This study examines changes in the aeolian sand fractions along the west-east aeolian transport path of the northern Sinai Peninsula - northwestern (NW) Negev erg of Egypt and Israel. This erg originates from the Nile Delta and is composed of currently active linear (seif) dunes in northern Sinai (its western part), and currently stabilized vegetated linear dunes (VLDs) in the NW Negev dunefield (its eastern part). Sand samples from the Nile Delta, northern Sinai and NW Negev were analyzed for particle-size distribution and sand grain morphology in accordance to their Eastern Mediterranean INQUA Dunes Atlas luminescence and radiocarbon chronologies. Linear seif dunes differ from VLDs in their vegetation cover, linearity, and dynamics. Although both are continuous landforms with similar orientations and sand-grain roundness values, the linear dunes of Sinai are coarser-grained than the Negev VLDs. The VLDs have a significantly higher proportion of very fine sand (125-50 μm) content and a varying but lower sand fining ratio defined as the ratio of fine sand percentage to very fine sand percentage. Very fine sands are suggested to have been winnowed by saltation and low suspension from source deposits and sand sheets. Detailed semi-quantitative examinations of sand grains by a SEM of a Negev VLD shows that most grains do not exhibit features that can be attributed to aeolian abrasion by sand grain-grain collisions. From these observations we infer that fractionation of sand was a major process leading to downwind fining along the studied aeolian transport path. We suggest that the very fine sand fraction of Nile Delta and Sinai sands has been transported downwind since the late middle Pleistocene. In the late Pleistocene, sand reached the NW Negev in the form of VLDs due to last-glacial period windiness of intensities unprecedented today and probably larger sediment supply. Generally current and inferred past decreasing wind velocities and increasing precipitation

  15. Synthesis on Quaternary aeolian research in the unglaciated eastern United States

    NASA Astrophysics Data System (ADS)

    Markewich, Helaine W.; Litwin, Ronald J.; Wysocki, Douglas A.; Pavich, Milan J.

    2015-06-01

    Late-middle and late Pleistocene, and Holocene, inland aeolian sand and loess blanket >90,000 km2 of the unglaciated eastern United States of America (USA). Deposits are most extensive in the Lower Mississippi Valley (LMV) and Atlantic Coastal Plain (ACP), areas presently lacking significant aeolian activity. They provide evidence of paleoclimate intervals when wind erosion and deposition were dominant land-altering processes. This study synthesizes available data for aeolian sand deposits in the LMV, the Eastern Gulf Coastal Plain (EGCP) and the ACP, and loess deposits in the Middle Atlantic Coastal Plain (MACP). Data indicate: (a) the most recent major aeolian activity occurred in response to and coincident with growth and decay of the Laurentide Ice Sheet (LIS); (b) by ∼40 ka, aeolian processes greatly influenced landscape evolution in all three regions; (c) aeolian activity peaked in OIS2; (d) OIS3 and OIS2 aeolian records are in regional agreement with paleoecological records; and (e) limited aeolian activity occurred in the Holocene (EGCP and ACP). Paleoclimate and atmospheric-circulation models (PCMs/ACMs) for the last glacial maximum (LGM) show westerly winter winds for the unglaciated eastern USA, but do not resolve documented W and SW winds in the SEACP and WNW and N winds in the MACP. The minimum areal extent of aeolian deposits in the EGCP and ACP is ∼10,000 km2. For the LMV, it is >80,000 km2. Based on these estimates, published PCMs/ACMs likely underrepresent the areal extent of LGM aeolian activity, as well as the extent and complexity of climatic changes during this interval.

  16. Spatial Patterns and Natural Recruitment of Native Shrubs in a Semi-arid Sandy Land

    PubMed Central

    Wu, Bo; Yang, Hongxiao

    2013-01-01

    Passive restoration depending on native shrubs is an attractive approach for restoring desertified landscapes in semi-arid sandy regions. We sought to understand the relationships between spatial patterns of native shrubs and their survival ability in sandy environments. Furthermore, we applied our results to better understand whether passive restoration is feasible for desertified landscapes in semi-arid sandy regions. The study was conducted in the semi-arid Mu Us sandy land of northern China with the native shrub Artemisia ordosica. We analyzed population structures and patterns of A. ordosica at the edges and centers of land patches where sand was stabilized by A. ordosica-dominated vegetation. Saplings were more aggregated than adults, and both were more aggregated at the patch edges than at the patch centers. At the patch edges, spatial association of the saplings with the adults was mostly positive at distances 0.3–6.6 m, and turned from positive to neutral, and even negative, at other distances. At the patch centers, the saplings were spaced almost randomly around the adults, and their distances from the adults did not seem to affect their locations. A greater number of A. ordosica individuals emerged at the patch edges than at the patch centers. Such patterns may have resulted from their integrative adjustment to specific conditions of soil water supply and sand drift intensity. These findings suggest that in semi-arid sandy regions, native shrubs that are well-adapted to local environments may serve as low-cost and competent ecological engineers that can promote the passive restoration of surrounding patches of mobile sandy land. PMID:23505489

  17. Rapid molecular assessment of the bioturbation extent in sandy soil horizons under pine using ester-bound lipids by on-line thermally assisted hydrolysis and methylation-gas chromatography/mass spectrometry.

    PubMed

    Nierop, Klaas G J; Verstraten, Jacobus M

    2004-01-01

    Each plant species has a unique chemical composition, and also within a given plant the various tissues differ from one another in their chemistry. These different compositions can be traced back after decay of the plant parts when they are transformed into soil organic matter (SOM). As a result, the composition of SOM reflects not only the plant origin, but also the various tissues, and the composition consequently provides an estimate of the contribution of above-ground vs. below-ground litter. From the latter distribution the extent of bioturbation (mixing of above-ground litter with the mineral soil) can be assessed. Application of thermally assisted hydrolysis and methylation (THM) using tetramethylammonium hydroxide (TMAH) and subsequent analysis by gas chromatography/mass spectrometry (GC/MS) releases all typical cutin- and suberin-derived aliphatic monomers (mono-, di- and trihydroxyalkanoic acids, alpha,omega-alkanedioic acids) as their methyl esters and/or ethers in a rapid manner. Using the distribution of omega-hydroxyalkanoic acids that are present in pine needle cutin (C(12) and C(14)) and not in root suberin, and those that are present in roots but not in needles (C(20) and C(22)), the extent of bioturbation (mixing of above-ground plant litter with the mineral soil) can be assessed. Similarly, the (9,16-dihydroxyhexadecanoic acid+9,10,18-trihydroxyoctadecanoic acid)/(C(20) + C(22) alpha,omega-alkanedioic acids) ratio reflects the degree of bioturbation. Three mineral soil profiles under Corsican pine with an A horizon that exhibited extensive bioturbation phenomena, and underlying C horizons with hardly any or no bioturbation, were investigated in order to examine the applicability of such an approach. It appeared that the A horizons contained all four mentioned omega-hydroxyalkanoic acids, while the C horizons contained virtually only the C(20) and C(22) members. The results not only suggest that bioturbation occurs in the A horizons, but also that

  18. Abundances and implications of volatile-bearing species from evolved gas analysis of the Rocknest aeolian deposit, Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Archer, Paul Douglas; Franz, Heather B.; Sutter, Brad; Arevalo, Ricardo D.; Coll, Patrice; Eigenbrode, Jennifer L.; Glavin, Daniel P.; Jones, John J.; Leshin, Laurie A.; Mahaffy, Paul R.; McAdam, Amy C.; McKay, Christopher P.; Ming, Douglas W.; Morris, Richard V.; Navarro-González, Rafael; Niles, Paul B.; Pavlov, Alex; Squyres, Steven W.; Stern, Jennifer C.; Steele, Andrew; Wray, James J.

    2014-01-01

    The Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory (MSL) rover Curiosity detected evolved gases during thermal analysis of soil samples from the Rocknest aeolian deposit in Gale Crater. Major species detected (in order of decreasing molar abundance) were H2O, SO2, CO2, and O2, all at the µmol level, with HCl, H2S, NH3, NO, and HCN present at the tens to hundreds of nmol level. We compute weight % numbers for the major gases evolved by assuming a likely source and calculate abundances between 0.5 and 3 wt.%. The evolution of these gases implies the presence of both oxidized (perchlorates) and reduced (sulfides or H-bearing) species as well as minerals formed under alkaline (carbonates) and possibly acidic (sulfates) conditions. Possible source phases in the Rocknest material are hydrated amorphous material, minor clay minerals, and hydrated perchlorate salts (all potential H2O sources), carbonates (CO2), perchlorates (O2 and HCl), and potential N-bearing materials (e.g., Martian nitrates, terrestrial or Martian nitrogenated organics, ammonium salts) that evolve NH3, NO, and/or HCN. We conclude that Rocknest materials are a physical mixture in chemical disequilibrium, consistent with aeolian mixing, and that although weathering is not extensive, it may be ongoing even under current Martian surface conditions.

  19. The diversity of permafrost-affected soils in the Lena River Delta and its hinterland

    NASA Astrophysics Data System (ADS)

    Zubrzycki, Sebastian; Kutzbach, Lars; Yakshina, Irina; Pfeiffer, Eva-Maria

    2013-04-01

    , the Holocene river terrace of the delta is in its main extent covered by a soil complex of Glacic Aquiturbels and Typic Historthels. The active floodplain levels are dominated by sandy or gleyic subgroups of the Orthel suborder as e.g. Psammentic Aquorthels or Typic Psammorthels. The surfaces of the Arga-Muora-Sise Island are frequently reshaped by aeolian sedimentation and erosion. The soils on these scarcely vegetated landscapes are dominated by cryoturbated and sand-rich soil subgroups with high moisture contents, e.g., various Psammoturbels and Aquiturbels. The modern soils covering the older Pleistocene ice-complex plains are influenced by wide ice-wedge net structures and consist of a soil complex of Glacic Aquiturbels and Ruptic Historthels. The widespread thermokarst depressions within the ice-complex are covered by Ruptic Histoturbels and Ruptic Historthels, whereas the slopes are dominated by various Aquiturbels and Fluvaquentic Historthels. For the largely unexplored Lena River Delta's hinterland it can be assumed that the active genesis of the soils lasts longer than in the active delta regions due to a much lower sedimentation and more stable surface conditions. In these regions widespread cryoturbated and peat-rich soil groups like Histoturbels and Historthels as well as Fibristels are found. An increased understanding of spatial variability and genesis of permafrost-affected soils is essential for meaningful predictions of climate change consequences in Arctic permafrost regions.

  20. Reduction in soil aggregation in response to dust emission processes

    NASA Astrophysics Data System (ADS)

    Swet, Nitzan; Katra, Itzhak

    2016-09-01

    Dust emission by aeolian (wind) soil erosion depends on the topsoil properties of the source area, especially on the nature of the aggregates where most dust particles are held. Although the key role of soil aggregates in dust emission, the response of soil aggregation to aeolian processes and its implications for dust emission remain unknown. This study focuses on aggregate size distribution (ASD) analyses before and after in-situ aeolian experiments in semiarid loess soils that are associated with dust emission. Wind tunnel simulations show that particulate matter (PM) emission and saltation rates depend on the initial ASD and shear velocity. Under all initial ASD conditions, the content of saltator-sized aggregates (63-250 μm) increased by 10-34% due to erosion of macro-aggregates (> 500 μm), resulting in a higher size ratio (SR) between the saltators and macro-aggregates following the aeolian erosion. The results revealed that the saltator production increases significantly for soils that are subjected to short-term (anthropogenic) disturbance of the topsoil. The findings highlight a decrease in soil aggregation for all initial ASD's in response to aeolian erosion, and consequently its influence on the dust emission potential. Changes in ASD should be considered as a key parameter in dust emission models of complex surfaces.

  1. The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management

    NASA Astrophysics Data System (ADS)

    Webb, Nicholas P.; Herrick, Jeffrey E.; Van Zee, Justin W.; Courtright, Ericha M.; Hugenholtz, Christopher H.; Zobeck, Ted M.; Okin, Gregory S.; Barchyn, Thomas E.; Billings, Benjamin J.; Boyd, Robert; Clingan, Scott D.; Cooper, Brad F.; Duniway, Michael C.; Derner, Justin D.; Fox, Fred A.; Havstad, Kris M.; Heilman, Philip; LaPlante, Valerie; Ludwig, Noel A.; Metz, Loretta J.; Nearing, Mark A.; Norfleet, M. Lee; Pierson, Frederick B.; Sanderson, Matt A.; Sharratt, Brenton S.; Steiner, Jean L.; Tatarko, John; Tedela, Negussie H.; Toledo, David; Unnasch, Robert S.; Van Pelt, R. Scott; Wagner, Larry

    2016-09-01

    The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the United States Department of Agriculture's Agricultural Research Service and Natural Resources Conservation Service, and the United States Department of the Interior's Bureau of Land Management, to address the need for a long-term research program to meet critical challenges in wind erosion research and management in the United States. The Network has three aims: (1) provide data to support understanding of basic aeolian processes across land use types, land cover types, and management practices, (2) support development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and (3) encourage collaboration among the aeolian research community and resource managers for the transfer of wind erosion technologies. The Network currently consists of thirteen intensively instrumented sites providing measurements of aeolian sediment transport rates, meteorological conditions, and soil and vegetation properties that influence wind erosion. Network sites are located across rangelands, croplands, and deserts of the western US.

  2. Assessing lithologic discontinuities and parent material uniformity within the Texas sandy mantle and implications for archaeological burial and preservation potential in upland settings

    NASA Astrophysics Data System (ADS)

    Ahr, Steven W.; Nordt, Lee C.; Driese, Steven G.

    2012-07-01

    Alfisols within the Texas Gulf Coast Plain commonly exhibit textural contrasts between sandy, artifact-bearing A-E horizons (i.e., sandy mantle), and artifact-sterile clay-rich Bt (argillic) horizons. This has invoked debate about parent material uniformity and pedogenic versus geomorphic sandy mantle origins, which has implications for the scientific value of buried archaeological sites. To improve our understanding of archaeological burial in upland settings, we evaluated parent material uniformity within five pedons to distinguish pedogenically derived textural changes from geomorphologically created lithologic discontinuities. Depth trends in clay-free particle size classes and stable/immobile Ti and Zr constituents failed to reveal lithologic discontinuities between the sandy mantle and Bt horizons, and the observed textural differences are interpreted to have resulted from pedogenic processes. This interpretation is supported by clay skins, fine clay increases in Bt horizons, and micromorphological observations. Consequently, artifacts buried in upland summits have likely moved down the soil profile due to biomantle processes. Deep sandy mantle sites, non-parallel contacts between the sandy mantle and Bt horizons, and paleogullies incised into Eocene bedrock are better explained by colluvial/soil creep processes adjacent to summits, where archaeological materials may exhibit preservation potential. No single explanation can account for sandy mantle origins, and we advocate a case-by-case approach.

  3. Threshold velocities for input of soil particles into the air by desert soils

    SciTech Connect

    Gillette, D.A.; Adams, J.; Endo, A.; Smith, D.; Kihl, R.

    1980-10-20

    Desert soils mostly from the Mojave Desert were tested for threshold friction velocity (the friction velocity above which soil erosion takes place) with an open-bottomed portable wind tunnel. Several geomorphological settings were chosen to be representative of much of the surface of the Mojave Desert, for example, playas, alluvial fans, and aeolian features. Variables which increase threshold velocity are decreasing proportion of sand, increasing size of dry aggregates of the soil, and increasing fraction of the soil mass larger than 1 mm. Threshold velocity increases with different types of soil surfaces in the following order: disturbed soils (except disturbed heavy clay soils), sand dunes, alluvial and aeolian sand deposits, disturbed playa soils, skirts of playas, playa centers, and desert pavement (alluvial deposits). 21 references, 5 figures, 6 tables.

  4. Ecological restoration and recovery in the wind-blown sand hazard areas of northern China: relationship between soil water and carrying capacity for vegetation in the Tengger Desert.

    PubMed

    Li, XingRong; Zhang, ZhiShan; Tan, HuiJuan; Gao, YanHong; Liu, LiChao; Wang, XingPing

    2014-05-01

    The main prevention and control area for wind-blown sand hazards in northern China is about 320000 km(2) in size and includes sandlands to the east of the Helan Mountain and sandy deserts and desert-steppe transitional regions to the west of the Helan Mountain. Vegetation recovery and restoration is an important and effective approach for constraining wind-blown sand hazards in these areas. After more than 50 years of long-term ecological studies in the Shapotou region of the Tengger Desert, we found that revegetation changed the hydrological processes of the original sand dune system through the utilization and space-time redistribution of soil water. The spatiotemporal dynamics of soil water was significantly related to the dynamics of the replanted vegetation for a given regional precipitation condition. The long-term changes in hydrological processes in desert areas also drive replanted vegetation succession. The soil water carrying capacity of vegetation and the model for sand fixation by revegetation in aeolian desert areas where precipitation levels are less than 200 mm are also discussed. PMID:24699917

  5. Aerosol emissions from biochar-amended agricultural soils

    NASA Astrophysics Data System (ADS)

    Ravi, S.; Sharratt, B. S.; Li, J. J.; Olshvevski, S.; Meng, Z.; Zhang, J.

    2015-12-01

    Agricultural production is a major contributor to anthropogenic greenhouse gas emissions and associated global warming. In this regard, novel carbon sequestration strategies such as large-scale biochar application may provide sustainable pathways to increase the terrestrial storage of carbon in agricultural areas. Biochar has a long residence time in the soil and hence understanding the soil properties affected by biochar addition needs to be investigated to identify the tradeoffs and synergies of large-scale biochar application. Even though several studies have investigated the impacts of biochar application on a variety of soil properties, very few studies have investigated the impacts on soil erosion, in particular wind (aeolian) erosion and subsequent particulate emissions. Using a combination of wind tunnel studies and laboratory experiments, we investigated the dust emission potential of biochar-amended agricultural soils. We amended biochar (unsieved or sieved to appropriate particle size; application rates ranging from 1 - 5 % of the soil by weight) to three soil types (sand, sandy loam, and silt loam) and estimated the changes in threshold shear velocity for wind erosion and dust emission potential in comparison to control soils. Our experiments demonstrate that emissions of fine biochar particles may result from two mechanisms (a) very fine biochar particles (suspension size) that are entrained into the air stream when the wind velocity exceeds the threshold, and (b) production of fine biochar particles originating from the abrasion by quartz grains. The results indicate that biochar application significantly increased particulate emissions and more interestingly, the rate of increase was found to be higher in the intermediate range of biochar application. As fine biochar particles effectively adsorb/trap contaminants and pathogens from the soil, the preferential erosion of fine biochar particles by wind may lead to concentration of contaminants in the

  6. Magnetic characteristics of aeolian and fluvial sediments and onset of dust accumulation at Lake Yoa (northern Chad) during the Holocene

    NASA Astrophysics Data System (ADS)

    Just, Janna; Kröpelin, Stefan; Karls, Jens; Rethemeyer, Janet; Melles, Martin

    2014-05-01

    The Holocene is a period of fundamental climatic change in North Africa. Humid conditions during the Holocene Humid Period have favored the formation of big lake systems (e.g. Lake Megachad) and are evident in terrestrial and marine archives. Only very few of these lakes persist until today. One of them is Lake Yoa (19°03'N/20°31'E) in the Ounianga Basin, Chad, which maintains its water level by ground water inflow. Here we present the magnetic characteristics of a continuous 16 m long sediment record (Co1240) from Lake Yoa, retrieved in 2010 within the framework of the Collaborative Research Centre 806 - Our Way to Europe (Deutsche Forschungsgemeinschaft). The sedimentary section covers the past 11,000 years. In an earlier core (Kröpelin et al. 2008), a humid climate during the Mid-Holocene is indicated by fresh-water conditions in the lake. At about 4,000 cal. years BP, a fresh-to-saline transition is reflected in the record. However, a major rise in magnetic susceptibility, interpreted as an increase in the accumulation of wind-blown material, is only visible after 3,000 cal. years BP. Beyond using the concentration of magnetic minerals (susceptibility), environmental magnetic proxies, e.g. magnetic grain size and the composition of the magnetic mineral fabric, are often used as paleoenvironmental indicators. The underlying assumption is that the formation of magnetic minerals during pedogenesis is catalyzed by precipitation and soil-temperature. The application of magnetic proxies as reliable climofunctions has, however, recently been challenged. Possible problems are that soil formation might not reach an equilibrium state if climate perturbations are too short (e.g. hundreds of years) or that other variables such as soil organic carbon and vegetation have varied. In this study, we will focus on the variability of magnetic parameters in Lake Yoa sediments and its implication for the regional environmental development throughout Holocene times. 400 discrete

  7. The National Wind Erosion Research Network: Building a standardized long-term data resource for aeolian research, modeling and land management

    USGS Publications Warehouse

    Webb, Nicholas P.; Herrick, Jeffrey E.; Van Zee, Justin W; Courtright, Ericha M; Hugenholtz, Ted M; Zobeck, Ted M; Okin, Gregory S.; Barchyn, Thomas E; Billings, Benjamin J; Boyd, Robert A.; Clingan, Scott D; Cooper, Brad F; Duniway, Michael C.; Derner, Justin D; Fox, Fred A; Havstad, Kris M.; Heilman, Philip; LaPlante, Valerie; Ludwig, Noel A; Metz, Loretta J; Nearing, Mark A; Norfleet, M Lee; Pierson, Frederick B; Sanderson, Matt A; Sharrat, Brenton S; Steiner, Jean L; Tatarko, John; Tedela, Negussie H; Todelo, David; Unnasch, Robert S; Van Pelt, R Scott; Wagner, Larry

    2016-01-01

    The National Wind Erosion Research Network was established in 2014 as a collaborative effort led by the United States Department of Agriculture’s Agricultural Research Service and Natural Resources Conservation Service, and the United States Department of the Interior’s Bureau of Land Management, to address the need for a long-term research program to meet critical challenges in wind erosion research and management in the United States. The Network has three aims: (1) provide data to support understanding of basic aeolian processes across land use types, land cover types, and management practices, (2) support development and application of models to assess wind erosion and dust emission and their impacts on human and environmental systems, and (3) encourage collaboration among the aeolian research community and resource managers for the transfer of wind erosion technologies. The Network currently consists of thirteen intensively instrumented sites providing measurements of aeolian sediment transport rates, meteorological conditions, and soil and vegetation properties that influence wind erosion. Network sites are located across rangelands, croplands, and deserts of the western US. In support of Network activities, http://winderosionnetwork.org was developed as a portal for information about the Network, providing site descriptions, measurement protocols, and data visualization tools to facilitate collaboration with scientists and managers interested in the Network and accessing Network products. The Network provides a mechanism for engaging national and international partners in a wind erosion research program that addresses the need for improved understanding and prediction of aeolian processes across complex and diverse land use types and management practices.

  8. [Effects of short-term fencing on organic carbon fractions and physical stability of sandy sierozem in desert steppe of Northwest China].

    PubMed

    Yang, Xin-Guo; Song, Nai-Ping; Li, Xue-Bin; Liu, Bing-Ru

    2012-12-01

    In order to explore the change patterns of organic carbon fractions and physical stability of sandy sierozem in desert steppe at the early stage of fencing, 0-40 cm soil samples were collected from a 5-year fenced desert steppe (inside the fence) and a free grazing steppe (outside the fence) in Yanchi County of Ningxia, Northwest China, with the soil organic carbon, labile organic carbon, and particulate organic carbon contents and soil particle composition analyzed. No significant differences were observed in the soil organic carbon content and soil particle composition inside and outside the fence. The average soil organic carbon inside and outside the fences was 3.25 g x kg(-1), the percentages of sand, silt, and clay were averagely 72%, 16%, and 12%, respectively, and the soil physical stability index was 1.30% -1.31%. The soil active organic carbon showed a significant change in 10-20 cm layer. The soil labile organic carbon content was 0.80 g x kg(-1) inside the fence, which was significantly higher than that outside the fence (0.62 g x kg(-1)). The percentage of soil particulate organic carbon was 50.9% inside the fence, which was also significantly higher than that outside the fence (31.7%). The soil texture inside the fence changed from sandy to loam, and the soil labile organic carbon content increased gradually; while the soil texture outside the fence was sandy, and its vertical change was relatively smooth. The organic carbon of sandy si- erozem in the desert steppe under the conditions of short-term fencing was still in a balance between consumption and accumulation, the soil texture was relatively stable, and the soil physical stability changed little. It was suggested that the soil active organic carbon content and its relative percentage in 10-20 cm layer could be used as the indicators of early soil quality change of desert steppe. PMID:23479873

  9. Element geochemical analysis of the contribution of aeolian sand to suspended sediment in desert stream flash floods.

    PubMed

    Jia, Xiaopeng; Wang, Haibing

    2014-01-01

    The interaction of wind and water in semiarid and arid areas usually leads to low-frequency flash flood events in desert rivers, which have adverse effects on river systems and ecology. In arid zones, many aeolian dune-fields terminate in stream channels and deliver aeolian sand to the channels. Although aeolian processes are common to many desert rivers, whether the aeolian processes contribute to fluvial sediment loss is still unknown. Here, we identified the aeolian-fluvial cycling process responsible for the high rate of suspended sediment transport in the Sudalaer desert stream in the Ordos plateau of China. On the basis of element geochemistry data analysis, we found that aeolian sand was similar to suspended sediment in element composition, which suggests that aeolian sand contributes to suspended sediment in flash floods. Scatter plots of some elements further confirm that aeolian sand is the major source of the suspended sediment. Factor analysis and the relation between some elements and suspended sediment concentration prove that the greater the aeolian process, the higher the suspended sediment concentration and the greater the contribution of aeolian sand to suspended sediment yield. We conclude that aeolian sand is the greatest contributor to flash floods in the Sudalaer desert stream. PMID:25089295

  10. Element Geochemical Analysis of the Contribution of Aeolian Sand to Suspended Sediment in Desert Stream Flash Floods

    PubMed Central

    Wang, Haibing

    2014-01-01

    The interaction of wind and water in semiarid and arid areas usually leads to low-frequency flash flood events in desert rivers, which have adverse effects on river systems and ecology. In arid zones, many aeolian dune-fields terminate in stream channels and deliver aeolian sand to the channels. Although aeolian processes are common to many desert rivers, whether the aeolian processes contribute to fluvial sediment loss is still unknown. Here, we identified the aeolian-fluvial cycling process responsible for the high rate of suspended sediment transport in the Sudalaer desert stream in the Ordos plateau of China. On the basis of element geochemistry data analysis, we found that aeolian sand was similar to suspended sediment in element composition, which suggests that aeolian sand contributes to suspended sediment in flash floods. Scatter plots of some elements further confirm that aeolian sand is the major source of the suspended sediment. Factor analysis and the relation between some elements and suspended sediment concentration prove that the greater the aeolian process, the higher the suspended sediment concentration and the greater the contribution of aeolian sand to suspended sediment yield. We conclude that aeolian sand is the greatest contributor to flash floods in the Sudalaer desert stream. PMID:25089295

  11. Desertification triggered by hydrological and geomorphological processes and palaeoclimatic changes in the Hunshandake Sandy Lands, Inner Mongolia, northern China

    NASA Astrophysics Data System (ADS)

    Yang, X.; Scuderi, L. A.; Wang, X.; Zhang, D.; Li, H.; Forman, S. L.

    2015-12-01

    Although Pleistocene and earlier aeolian sediments in the adjacent regions of deserts were used as indicators for the occurrence of the deserts in northern China, our multidisciplinary investigation in the Hunshandake Sandy Lands, Inner Mongolia, a typical landscape in the eastern portion of the Asian mid-latitude desert belt, demonstrates that this sandy desert is just ca. 4000 years old. Before the formation of the current sand dunes, Hunshandke was characterized with large and deep lakes and grasssland vegetation, as many sedimentary sections indicate. Optically Stimulated Luminescence (OSL) chronology shows that the three large former lakes where we have done detailed investigation, experienced high stands from early Holocene to ca. 5 ka. During the early and middle Holocene this desert was a temperate steppe environment, dominated by grasslands and trees near lakes and streams, as various palaeoenvironmental proxies suggest. While North Hemisphere's monsoonal regions experienced catastrophic precipitation decreases at ca. 4.2 ka, many parts of the presently arid and semi-arid zone in northern China were shifted from Green to Desert state. In the eastern portion of the Hunshandake, the desertification was, however, directly associated with groundwater capture by the Xilamulun River, as the palaeo-drainage remains show. The process of groundwater sapping initiated a sudden and irreversible region-wide hydrologic event that lowered the groundwater table and exacerbated the desertification of the Hunshandake, and further resulting in post-Humid period mass migration of northern China's Hongshan culture from that we think the modern Chinese civilization has been rooted.

  12. Characterizing subsurface complexity of aeolian morphotypes with georadar

    NASA Astrophysics Data System (ADS)

    Bentley, Andrew Phillip Keller

    Aeolian landforms are classified based on their plan morphology, which is a function of sediment transport volume, wind direction, and vegetation. In the case of compound landforms or two-dimensional exposures (outcrops), there is insufficient information for discriminating between 3D morphotypes (e.g., barchans vs. parabolic dunes). To characterize the dip-section architecture of near end-member morphologies (interacting barchans and sparsely vegetated parabolics), a series of axial transects were selected from >25 km of high-resolution (500 MHz) ground-penetrating radar (GPR) data from the gypsum dune field of White Sands National Monument, New Mexico. For dunes of comparable size (6-7 m high), a series of attributes were analyzed for unsaturated portions along the thickest (axial) radargram sections. Given the limitations in vertical resolution (7 cm in dry sand), the average measureable slipface thickness in barchans ranged between 10-22 cm, whereas parabolic slipfaces were thinner at 10-14 cm. High-amplitude diffractions produced by buried vegetation, semi-lithified pedestals, and bioturbation structures were rare within barchans (point-source diffraction density = 0.03/m2; hyperbolics per 1-m-wide cross-sectional area of the image), in contrast to a point-source density of 0.07/m2 in parabolics. An aeolian internal complexity threshold (pi) is proposed, which incorporates standardized scores of slipface thickness, point-source diffraction density, and continuity of major bounding surfaces at mesoscale range determined through semivariogram analysis. For the study region, these variables were sufficient for discriminating barchans (pi = -2.39 to -0.25; pib= -1.65) from parabolic (pi = 0.13 to 2.87; pip= 1.65) dunes. This threshold has the potential for differentiating dune morphotypes in areas where surface morphology is masked and for identifying compound landforms (e.g., a re-activated parabolic dune converted into a barchan in situ ). Ultimately

  13. Theoretical analysis of particle number density in steady aeolian saltation

    NASA Astrophysics Data System (ADS)

    Kang, Liqiang; Zou, Xueyong

    2014-01-01

    Particle number density or particle concentration in aeolian saltation is one important input parameter to calculate the sand flux, kinetic energy and mid-air collision probability in the aeolian saltation and particle concentration is also related to the wind erosion capacity, hence, in the present paper, the vertical distribution of particle number density in steady aeolian saltation is analyzed based on two different types of probability density functions of vertical lift-off velocity of saltating particles: one is the PDF (probability density function) of vertical velocity of lift-off particles in the three-dimensional space defined as a type-A PDF which considers the number of particles in various velocity bins per unit volume; and the other is the PDF of vertical velocity of lift-off particles ejected from the sand bed surface in a period of time as a type-B PDF which considers the number flux of particles in various velocity bins per unit surface area. These two types of PDFs are from two different perspectives (i.e., volume- and surface-based perspectives, respectively), and can be deduced from each other. The half-normal and exponential distributions are recommended for the type-A PDF, and the corresponding type-B PDF is expressed by Rayleigh and Gamma(2) distributions. The PDF distribution pattern of vertical velocity of lift-off particles has an important influence on the vertical profile of particle number density. If the type-A PDF of vertical velocity of ejected particles is a half-normal distribution, the particle number density decays exponentially with height. If the type-A PDF is an exponential distribution, the particle number density also decreases with height. If the type-A PDF is Gamma(3) and Rayleigh distributions, the particle number density first increases, then decreases with height. The type-A and type-B height parameters, which are calculated according to the mean vertical lift-off velocity from the type-A and type-B PDFs, respectively

  14. Biochar effects on soil hydrology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biochar has the potential to alter soil hydrology, and these alterations may lead to significant changes in water cycling and ecosystem processes mediated by water. Biochar soil amendment may change infiltration and drainage in both sandy and clay soils, may increase or decrease plant-available wate...

  15. MICROBIAL COMMUNITY STRUCTURE AND ENZYME ACTIVITIES IN SEMIARID AGRICULTURAL SOILS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of management on the microbial community structure and enzyme activities of three semiarid soils from Southern High Plains of Texas were investigated. The soils (sandy clay loam, fine sandy loam and loam) were under continuous cotton (Gossypium hirsutum L.) or in cotton -peanut (Arachis h...

  16. Factors controlling magnetism of reddish brown soil profiles from calcarenites in Southern Spain: Dust input or in-situ pedogenesis?

    NASA Astrophysics Data System (ADS)

    Liu, Qingsong; Zhang, Chunxia; Torrent, José; Barrón, Vidal; Hu, Pengxiang; Jiang, Zhaoxia; Duan, Zongqi

    2016-05-01

    Under aerobic conditions, the A and B horizons of soils are magnetically enhanced due to neoformation of ferrimagnets through pedogenesis. This study systematically investigated soils developed on calcarenites of Neogene age in southern Spain to determine the dominant factors controlling the soil magnetism. Geochemical and clay mineral analyses indicate that aeolian dust significantly contribute to the A and B horizon material of the Spanish soil. Nevertheless, the magnetic enhancement of soils can be simply attributed to the pedogenically produced ferrimagnets in-situ. Therefore, the magnetism of Spanish soils is still linked to paleoclimatic variations regardless of the complexities of aeolian inputs from the Northwestern Africa.

  17. Concentric crater fill on Mars - An aeolian alternative to ice-rich mass wasting

    NASA Technical Reports Server (NTRS)

    Zimbelman, J. R.; Clifford, S. M.; Williams, S. H.

    1989-01-01

    Concentric crater fill, a distinctive martian landform represented by a concentric pattern of surface undulations confined within a crater rim, has been interpreted as an example of ice-enhanced regolith creep at midlatitudes (e.g., Squyres and Carr, 1986). Theoretical constraints on the stability and mobility of ground ice limit the applicability of an ice-rich soil in effectively mobilizing downslope movement at latitudes poleward of + or - 30 deg, where concentric crater fill is observed. High-resolution images of concentric crater fill material in the Utopia Planitia region (45 deg N, 271 deg W) show it to be an eroded, multiple-layer deposit. Layering should not be preserved if the crater fill material moved by slow deformation throughout its thickness, as envisioned in the ice-enhanced creep model. Multiple layers are also exposed in the plains material surrounding the craters, indicating a recurrent depositional process that was at least regional in extent. Mantling layers are observed in high-resolution images of many other locations around Mars, suggesting that deposition occurred on a global scale and was not limited to the Utopia Planitia region. It is suggested that an aeolian interpretation for the origin and modification of concentric crater fill material is most consistent with morphologic and theoretical constraints.

  18. Aeolian features and processes at the Mars Pathfinder landing site

    USGS Publications Warehouse

    Greeley, Ronald; Kraft, Michael; Sullivan, Robert; Wilson, Gregory; Bridges, Nathan; Herkenhoff, Ken; Kuzmin, Ruslan O.; Malin, Michael; Ward, Wes

    1999-01-01

    The Mars Pathfinder landing site contains abundant features attributed to aeolian, or wind, processes. These include wind tails, drift deposits, duneforms of various types, ripplelike features, and ventifacts (the first clearly seen on Mars). Many of these features are consistant with formation involving sand-size particles. Although some features, such as dunes, could develop from saltating sand-size aggregates of finer grains, the discovery of ventifact flutes cut in rocks strongly suggests that at least some of the grains are crystalline, rather than aggregates. Excluding the ventifacts, the orientations of the wind-related features correlate well with the orientations of bright wind steaks seen on Viking Orbiter images in the general area. They also correlate with wind direction predictions from the NASA-Ames General Circulation Model (GCM) which show that the strongest winds in the area occur in the northern hemisphere winter and are directed toward 209°. Copyright 1999 by the American Geophysical Union.

  19. Microdunes and other aeolian bedforms on Venus - Wind Tunnel simulations

    NASA Astrophysics Data System (ADS)

    Greeley, R.; Marshall, J. R.; Leach, R. N.

    1984-10-01

    The development of aeolian bedforms in the simulated Venusian environment has been experimentally studied in the Venus Wind Tunnel. It is found that the development of specific bedforms, including ripples, dunes, and 'waves', as well as their geometry, are controlled by a combination of factors including particle size, wind speed, and atmospheric density. Microdunes are formed which are analogous to full-size terrestrial dunes and are characterized by the development of slip faces, internal cross-bedding, a low ratio of saltation path length to dune length, and a lack of particle-size sorting. They begin to develop at wind speeds just above saltation threshold and evolve into waves at higher velocities. At wind speeds of about 1.5 m/sec and higher, the bed is flat and featureless. This evolution is explained by a model based on the interaction of alternating zones of erosion and deposition and particle saltation distances.

  20. Microdunes and Other Aeolian Bedforms on Venus: Wind Tunnel Simulations

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Marshall, J. R.; Leach, R. N.

    1985-01-01

    The development of aeolian bedforms in the simulated Venusian environment has been experimentally studied in the Venus Wind tunnel. It is found that the development of specific bedforms, including ripples, dunes, and waves, as well as their geometry, are controlled by a combination of factors including particle size, wind speed, and atmospheric density. Microdunes are formed which are analogous to full-size terrestrial dunes and are characterized by the development of slip faces, internal cross-bedding, a low ratio of saltation path length to dune length, and a lack of particle-size sorting. They begin to develop at wind speeds just above saltation threshold and evolve into waves at higher velocities. At wind speeds of about 1.5 m/sec and higher, the bed is flat and featureless. This evolution is explained by a model based on the interaction of alternating zones of erosion and deposition and particle saltation distances.

  1. Microdunes and other aeolian bedforms on Venus - Wind Tunnel simulations

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Marshall, J. R.; Leach, R. N.

    1984-01-01

    The development of aeolian bedforms in the simulated Venusian environment has been experimentally studied in the Venus Wind Tunnel. It is found that the development of specific bedforms, including ripples, dunes, and 'waves', as well as their geometry, are controlled by a combination of factors including particle size, wind speed, and atmospheric density. Microdunes are formed which are analogous to full-size terrestrial dunes and are characterized by the development of slip faces, internal cross-bedding, a low ratio of saltation path length to dune length, and a lack of particle-size sorting. They begin to develop at wind speeds just above saltation threshold and evolve into waves at higher velocities. At wind speeds of about 1.5 m/sec and higher, the bed is flat and featureless. This evolution is explained by a model based on the interaction of alternating zones of erosion and deposition and particle saltation distances.

  2. Lidar measurements of Aeolian dust: Mars and Earth

    NASA Astrophysics Data System (ADS)

    Dickinson, C. S.; Davy, R.; Komguem, L.; Junkermann, W.; Whiteway, J. A.

    2009-12-01

    The Phoenix Lidar system was operated in 2008, beginning in Martian northern spring (L_s = 78) through mid summer (L_s = 147). During this period, nighttime observations of dust indicate both persistent background dust up to heights of approximately 15 km, and enhanced dust loading in the Boundary Layer up to heights of approximately 4 km. The magnitude of the optical extinction was observed to decrease within the Boundary Layer with time following summer solstice. This situation is similar to that observed in the Australian desert: a persistent dust layer up to heights of 6 km, with a daytime Convective Boundary Layer increasing up to heights of 4 km during local dust storm activity, and then decreasing during night. A comparative study was undertaken, with the results being augmented by both in situ measurements of the Australian desert dust, as made by over-flying aircraft, and modeled results of Aeolian dust in both environments.

  3. Downslope coarsening in aeolian grainflows of the Navajo Sandstone

    NASA Astrophysics Data System (ADS)

    Loope, David B.; Elder, James F.; Sweeney, Mark R.

    2012-07-01

    Downslope coarsening in grainflows has been observed on present-day dunes and generated in labs, but few previous studies have examined vertical sorting in ancient aeolian grainflows. We studied the grainflow strata of the Jurassic Navajo Sandstone in the southern Utah portion of its outcrop belt from Zion National Park (west) to Coyote Buttes and The Dive (east). At each study site, thick sets of grainflow-dominated cross-strata that were deposited by large transverse dunes comprise the bulk of the Navajo Sandstone. We studied three stratigraphic columns, one per site, composed almost exclusively of aeolian cross-strata. For each column, samples were obtained from one grainflow stratum in each consecutive set of the column, for a total of 139 samples from thirty-two sets of cross-strata. To investigate grading perpendicular to bedding within individual grainflows, we collected fourteen samples from four superimposed grainflow strata at The Dive. Samples were analyzed with a Malvern Mastersizer 2000 laser diffraction particle analyser. The median grain size of grainflow samples ranges from fine sand (164 μm) to coarse sand (617 μm). Using Folk and Ward criteria, samples are well-sorted to moderately-well-sorted. All but one of the twenty-eight sets showed at least slight downslope coarsening, but in general, downslope coarsening was not as well-developed or as consistent as that reported in laboratory subaqueous grainflows. Because coarse sand should be quickly sequestered within preserved cross-strata when bedforms climb, grain-size studies may help to test hypotheses for the stacking of sets of cross-strata.

  4. Boundary Conditions for Aeolian Activity in North American Dune Fields

    NASA Astrophysics Data System (ADS)

    Halfen, A. F.; Lancaster, N.; Wolfe, S.

    2014-12-01

    Geomorphic and chronological data for dune fields are evaluated for three contrasting areas of North America: 1) the Prairie-Parkland-Boreal ecozones of the northern Great Plains in Canada; 2) the Central Great Plains of the USA; and 3) the deserts of southwestern USA and northern Mexico. Luminescence and radiocarbon ages for periods of dune accumulation and stability are compared with palaeoenvironment proxies to provide an assessment of the boundary conditions of dune system response to changes in sediment supply, availability, and mobility. Dune fields in the northern Great Plains were formed from sediment originating from glaciofluvial or glaciolacustrine sediments deposited during deglaciation 16-11 ka. Subsequent aeolian deposition occurred in Parkland and Prairie dune fields as a result of mid-Holocene (8-5 ka) and late-Holocene (< 3.5 ka) activity related to drought conditions that reworked pre-existing aeolian sands. In the Central Great Plains, dune fields are closely linked to fluvial sediment sources. Sediment supply was high during deglaciation of the Rocky Mountains and resulted in widespread dune construction 16-10 ka. Multiple periods of Holocene reactivation are recorded and reflect increased sediment availability during drought episodes. Dune fields in the southwestern deserts experienced periods of construction as a result of enhanced supply of sediment from fluvial and lacustrine sources during the period 11.8-8 ka and at multiple intervals during the late Holocene. Despite spatial and temporal gaps in chronometric data as a result of sampling biases, the record from North American dune fields indicates the strong influence of sediment supply on dune construction, with changes in sediment availability as a result of drought episodes resulting in dune field reactivation and reworking of pre-existing sediment.

  5. Mean flow and Reynolds stress structure over aeolian ripples

    NASA Astrophysics Data System (ADS)

    Li, Bailiang; McKenna Neuman, Cheryl; Bédard, Otto; O'Brien, Patrick

    2015-04-01

    Mean flow and turbulence structure on transverse ripples have been well documented in hydrodynamic literature. However, very few studies have described the flow characteristics over aeolian ripples. This study adopted laser Doppler anemometry (LDA) to measure the wind field above granular ripples with different bimodal particle size distributions in a wind tunnel. Multiple runs were conducted to examine the vertical profiles of time-averaged horizontal and vertical velocities and Reynolds stress above four different locations: crest, lee slope, trough, and stoss slope. The rippled sand bed has a fine beige fraction with grain size smaller than 0.542 mm concentrated in the troughs and a coarse fraction dyed in red with grain size greater than 0.542 mm concentrated in the crests. The magnitude of the ripples at equilibrium is controlled by both wind velocity and the ratio of beige sand to red sand. Freestream velocity has a range between 8-11 m/s (above the saltation threshold of beige sand and below the threshold of red sand) and the percentage coarse by mass varies from 5.2% to 27.5% with median grain size from 0.289 mm to 0.399 mm. Experimental results indicate that the ripples have the wave length ranged between 20 mm and 140 mm with a characteristic ripple index (wave length/wave height) of 15. Flow streamlines are generally parallel to the bed surface, which is inconsistent with previous hydrodynamic observations that a return flow is usually found at the lee side of the ripples. Reynolds stress has demonstrated a strong spatial differentiation near the sand surface: greatest at crests and smallest at the troughs, however, this difference diminishes with elevation. This is an exploratory study on the turbulence characteristics of air flow above aeolian ripples, and we believe the finding of this research will enhance the understanding the interaction mechanisms between the air and bed morphology.

  6. Modeling aeolian transport in response to succession, disturbance and future climate: Dynamic long-term risk assessment for contaminant redistribution

    NASA Astrophysics Data System (ADS)

    Breshears, David D.; Kirchner, Thomas B.; Whicker, Jeffrey J.; Field, Jason P.; Allen, Craig D.

    2012-01-01

    Aeolian sediment transport is a fundamental process redistributing sediment, nutrients, and contaminants in dryland ecosystems. Over time frames of centuries or longer, horizontal sediment fluxes and associated rates of contaminant transport are likely to be influenced by succession, disturbances, and changes in climate, yet models of horizontal sediment transport that account for these fundamental factors are lacking, precluding in large part accurate assessment of human health risks associated with persistent soil-bound contaminants. We present a simple model based on empirical measurements of horizontal sediment transport (predominantly saltation) to predict potential contaminant transport rates for recently disturbed sites such as a landfill cover. Omnidirectional transport is estimated within vegetation that changes using a simple Markov model that simulates successional trajectory and considers three types of short-term disturbances (surface fire, crown fire, and drought-induced plant mortality) under current and projected climates. The model results highlight that movement of contaminated soil is sensitive to vegetation dynamics and increases substantially (e.g., > fivefold) when disturbance and/or future climate are considered. The time-dependent responses in horizontal sediment fluxes and associated contaminant fluxes were sensitive to variability in the timing of disturbance, with longer intervals between disturbance allowing woody plants to become dominant and crown fire and drought abruptly reducing woody plant cover. Our results, which have direct implications for contaminant transport and landfill management in the specific context of our assessment, also have general relevance because they highlight the need to more fully account for vegetation dynamics, disturbance, and changing climate in aeolian process studies.

  7. Modeling aeolian transport in response to succession, disturbance and future climate: Dynamic long-term risk assessment for contaminant redistribution

    USGS Publications Warehouse

    Breshears, D.D.; Kirchner, T.B.; Whicker, J.J.; Field, J.P.; Allen, C.D.

    2012-01-01

    Aeolian sediment transport is a fundamental process redistributing sediment, nutrients, and contaminants in dryland ecosystems. Over time frames of centuries or longer, horizontal sediment fluxes and associated rates of contaminant transport are likely to be influenced by succession, disturbances, and changes in climate, yet models of horizontal sediment transport that account for these fundamental factors are lacking, precluding in large part accurate assessment of human health risks associated with persistent soil-bound contaminants. We present a simple model based on empirical measurements of horizontal sediment transport (predominantly saltation) to predict potential contaminant transport rates for recently disturbed sites such as a landfill cover. Omnidirectional transport is estimated within vegetation that changes using a simple Markov model that simulates successional trajectory and considers three types of short-term disturbances (surface fire, crown fire, and drought-induced plant mortality) under current and projected climates. The model results highlight that movement of contaminated soil is sensitive to vegetation dynamics and increases substantially (e.g., > fivefold) when disturbance and/or future climate are considered. The time-dependent responses in horizontal sediment fluxes and associated contaminant fluxes were sensitive to variability in the timing of disturbance, with longer intervals between disturbance allowing woody plants to become dominant and crown fire and drought abruptly reducing woody plant cover. Our results, which have direct implications for contaminant transport and landfill management in the specific context of our assessment, also have general relevance because they highlight the need to more fully account for vegetation dynamics, disturbance, and changing climate in aeolian process studies. ?? 2011.

  8. Soil Types Effect on Grape and Wine Composition in Helan Mountain Area of Ningxia

    PubMed Central

    Wang, Rui; Sun, Quan; Chang, Qingrui

    2015-01-01

    Different soil types can significantly affect the composition of wine grapes and the final wine product. In this study, the effects of soil types on the composition of Cabernet Sauvignon grapes and wine produced in the Helan Mountains were evaluated. Three different representative soil types—aeolian, sierozem and irrigation silting soil were studied. The compositions of grapes and wines were measured, and in addition, the weights of 100-berry samples were determined. The grapes that grown on the aeolian and sierozem soils matured sooner than those grown on the irrigation silting soil. The highest sugar content, total soluble solids content, sugar to acid ratio and anthocyanin content were found in the grapes that grown on the aeolian soil. The wine produced from this soil had improved chroma and tone and higher-quality phenols. The grapes grown on the sierozem soil had the highest total phenol and tannin contents, which affected the wine composition. The grapes grown on the irrigation silting soil had higher acidities, but the remaining indices were lower. In addition, the grapes grown on the aeolian soil resulted in wines with better chroma and aroma. The sierozem soil was beneficial for the formation of wine tannins and phenols and significantly affected the wine composition. The quality of the grapes from the irrigation silting soil was relatively low, resulting in lower-quality wine. PMID:25706126

  9. Soil types effect on grape and wine composition in Helan Mountain area of Ningxia.

    PubMed

    Wang, Rui; Sun, Quan; Chang, Qingrui

    2015-01-01

    Different soil types can significantly affect the composition of wine grapes and the final wine product. In this study, the effects of soil types on the composition of Cabernet Sauvignon grapes and wine produced in the Helan Mountains were evaluated. Three different representative soil types--aeolian, sierozem and irrigation silting soil were studied. The compositions of grapes and wines were measured, and in addition, the weights of 100-berry samples were determined. The grapes that grown on the aeolian and sierozem soils matured sooner than those grown on the irrigation silting soil. The highest sugar content, total soluble solids content, sugar to acid ratio and anthocyanin content were found in the grapes that grown on the aeolian soil. The wine produced from this soil had improved chroma and tone and higher-quality phenols. The grapes grown on the sierozem soil had the highest total phenol and tannin contents, which affected the wine composition. The grapes grown on the irrigation silting soil had higher acidities, but the remaining indices were lower. In addition, the grapes grown on the aeolian soil resulted in wines with better chroma and aroma. The sierozem soil was beneficial for the formation of wine tannins and phenols and significantly affected the wine composition. The quality of the grapes from the irrigation silting soil was relatively low, resulting in lower-quality wine. PMID:25706126

  10. Evaluation of noise level and site response at Mt. Etna volcano and Aeolian Islands

    NASA Astrophysics Data System (ADS)

    D Amico, S.; Giampiccolo, E.; Maiolino, V.; Patanè, D.; Ursino, A.

    2003-04-01

    The aim of this work was to test the quality of the sites where the stations of the INGV-CT seismic network are installed. This because most of the installations will be soon improved with new broad-band sensors, which require a low level of background noise. Therefore, we investigated the noise level and estimated the site response at the seismic stations deployed at Mt. Etna and at Aeolian Islands, in order to evidence possible disturbs which can be related to anthropic activity, environmental factors and/or to the local soil conditions. Noise measurements were carried out using a portable digital seismic station equipped with a 3-component, 20 s sensor. The acquisition was performed both inside the vault structures where the remote stations are located and in proximity of them, on the outcropping terrain. The noise spectra were compared with the NLNM (New Low Noise Model) and NHNM (New High Noise Model) models described by Peterson (1993). A preliminary estimate of site response at each station, by applying the Nakamura (1989) technique, was also performed. The obtained results show, for some stations, higher noise levels mainly due to volcanic tremor and/or bad soil conditions. Moreover, in several cases, vault design need to be deeply reviewed and for some installations the substitution of the sites is required. References Nakamura, Y., (1989). A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. Quarterly R of Report RTRI, 30, 25-33. Peterson, J., (1993). Observations and modelling of background seismic noise. Open File Report 93-322, U. S. Geological Survey, Albuquerque, NM.

  11. Holocene aeolian sedimentation and episodic mass-wasting events recorded in lacustrine sediments on Langøya in Vesterålen, northern Norway

    NASA Astrophysics Data System (ADS)

    Nielsen, Pål Ringkjøb; Dahl, Svein Olaf; Jansen, Henrik Løseth; Støren, Eivind N.

    2016-09-01

    In this study, the frequency of mass-wasting events and past storminess has been reconstructed throughout the Holocene (11,500 cal yr BP to present) from lacustrine sediments in lake Trehynnvatnet (33 m a.s.l.), which is located in a glacially carved valley at Nykvåg on the outmost coast of western Langøya, Vesterålen, northern Norway. Sediment cores (∼2-5 m long) have been examined by use of high-resolution magnetic susceptibility and XRF-scanning as well as grain size and loss-on-ignition analysis. In total 35 episodic event layers have been identified throughout the Holocene. The majority of these events are characterized as discrete coarse-grained sediment layers followed by normal grading, and are related to past mass-wasting activity within the catchment. Periods with high mass-wasting activity are dated to 11,000-10,500, 5500-4500, 4000-3500, 3000-2500, 2000-1000 and 500-0 cal yr BP. The continuous input of sand grains (>250 μm) has been systematically investigated throughout the sediment cores. The sand grains are related to catchment samples from the sandy beach deposits in Sandvikbukta c. 750 m away in SW direction, and are suggested to indicate (niveo-) aeolian influx to the lake. The content of sand grains varies greatly throughout the record, although there is a clear increase in influx of sand during the last 2800 years. Periods with high aeolian influx are proposed to indicate increased storminess, which occurred between 1600 and 1550 (350-400 CE), 1400-1300 (450-550 CE), 750-550 (1200-1400 CE) and 250-20 cal yr BP (1700-1930 CE), which to some degree coincides with periods of increased storminess and winter precipitation recorded in other studies around the North Eastern Atlantic region.

  12. Quantifying accelerated soil erosion through ecological site-based assessments of wind and water erosion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This work explores how organising soil erosion assessments using established groupings of similar soils (ecological sites) can inform systems for managing accelerated soil erosion. We evaluated aeolian sediment transport and fluvial erosion rates for five ecological sites in southern New Mexico, USA...

  13. Source-to-sink cycling of aeolian sediment in the north polar region of Mars

    NASA Astrophysics Data System (ADS)

    Ewing, R. C.; Kocurek, G.

    2012-12-01

    Aeolian sand dunes are prominent features on the landscapes of Earth, Mars, Venus and Titan and sedimentary deposits interpreted as aeolian in origin are found in the rock records of Earth and Mars. The widespread occurrence of aeolian dunes on the surface of these worlds and within their deep-time depositional records suggests that aeolian systems are and likely have been a default depositional environment for the Solar System. Within an aeolian source-to-sink context, we hypothesize that planet-specific boundary conditions strongly impact production, transport, accumulation and preservation of aeolian sediment, whereas dunes and dune-field patterns remain largely similar. This hypothesis is explored within the north polar region of Mars, which hosts the most extensive aeolian dune fields and aeolian sedimentary deposits yet recognized on Mars and appears to be a region of dynamic source-to-sink cycling of aeolian sediments. The Planum Boreum Cavi Unit rests beneath north polar ice cap of Mars and is composed of several hundred meters of niveo-aeolian dune cross-stratification. The overall architecture of the unit consists of sets of preserved dune topography with an upward increase in the abundance of ice. Dune sets are defined by stabilized, polygonally fractured bounding surfaces, erosional bounding surfaces and typical internal lee foresets made of sediment and ice. The accumulation of the Cavi Unit is interpreted as occurring through freezing and serves as an example of a cold temperature boundary condition on aeolian sediment accumulation. Preservation of the Cavi Unit arises because of deposition of the overlying ice cap and contrasts with preservation of aeolian sediment on Earth, which is largely driven by eustasy and tectonics. The Cavi Unit is thought to be one source of sediment for the north polar Olympia Undae Dune Field. The region of Olympia Undae near the Cavi Unit shows a reticulate dune field pattern composed of two sets of nearly orthogonal

  14. Threats to sandy beach ecosystems: A review

    NASA Astrophysics Data System (ADS)

    Defeo, Omar; McLachlan, Anton; Schoeman, David S.; Schlacher, Thomas A.; Dugan, Jenifer; Jones, Alan; Lastra, Mariano; Scapini, Felicita

    2009-01-01

    We provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world's single largest type of open shoreline. Threats to beaches arise from a range of stressors which span a spectrum of impact scales from localised effects (e.g. trampling) to a truly global reach (e.g. sea-level rise). These pressures act at multiple temporal and spatial scales, translating into ecological impacts that are manifested across several dimensions in time and space so that today almost every beach on every coastline is threatened by human activities. Press disturbances (whatever the impact source involved) are becoming increasingly common, operating on time scales of years to decades. However, long-term data sets that describe either the natural dynamics of beach systems or the human impacts on beaches are scarce and fragmentary. A top priority is to implement long-term field experiments and monitoring programmes that quantify the dynamics of key ecological attributes on sandy beaches. Because of the inertia associated with global climate change and human population growth, no realistic management scenario will alleviate these threats in the short term. The immediate priority is to avoid further development of coastal areas likely to be directly impacted by retreating shorelines. There is also scope for improvement in experimental design to better distinguish natural variability from anthropogenic impacts. Sea-level rise and other effects of global warming are expected to intensify other anthropogenic pressures, and could cause unprecedented ecological impacts. The definition of the relevant scales of analysis, which will vary according to the magnitude of the impact and the organisational level under analysis, and the recognition of a physical-biological coupling at different scales, should be included in approaches to quantify impacts. Zoning strategies and marine reserves, which have not

  15. Late Amazonian aeolian features, gradation, wind regimes, and Sediment State in the Vicinity of the Mars Exploration Rover Opportunity, Meridiani Planum, Mars

    NASA Astrophysics Data System (ADS)

    Fenton, Lori K.; Michaels, Timothy I.; Chojnacki, Matthew

    2015-03-01

    The 2° × 2° region surrounding the landing site and traverse of Mars Exploration Rover (MER) Opportunity is richly blanketed with several generations and classes of aeolian features, including coarse-grained ripples, large dark dunes (LDDs), transverse aeolian ridges (TARs), erosional scars, depositional wind streaks of two types, and a new class of wind streak comprised entirely of coarse-grained ripples. The extensive observation campaigns from orbiting spacecraft in support of the MER and 2016 ExoMars missions, as well as in situ data from Opportunity, have provided unprecedented coverage of the region, permitting further interpretation of the local aeolian history than is typically possible on Mars. We present an analysis of bedform construction, sediment-transporting wind patterns, crater gradation and resulting erosion rate, sand provenance, and sediment state resulting from surficial mapping and geomorphic backstripping of aeolian features. Coarse-grained ripples on the intercrater plains formed from local sediments, with induration and low wind speeds preventing them from migrating more than roughly one bedform wavelength from their source region. Limited migration and a likely local, planar sand source of plains bedforms suggests their provenance is previously-eroded layers within the underlying Burns Formation. Although the bedform stabilization process is different from that of Earth, these ripples appear to be analogous to coarse-grained ripples that form and quickly stabilize on the Argentinean Puna. Some small craters (<100 m) exhibit inverted topography as high as ∼1 m, produced by an armoring effect of the indurated coarse-grained ripples. The erosion rate leading to this relief is ∼0.014 m/Myr over the past 71 ± 2 Ma, falling between values estimated for younger and older surfaces. Present-day winds are not represented uniformly in the region, with most active sandy wind streaks on the plains formed by a southeasterly wind and intracrater

  16. Granulometric profiling of aeolian dust deposits by automated image analysis

    NASA Astrophysics Data System (ADS)

    Varga, György; Újvári, Gábor; Kovács, János; Jakab, Gergely; Kiss, Klaudia; Szalai, Zoltán

    2016-04-01

    Determination of granulometric parameters is of growing interest in the Earth sciences. Particle size data of sedimentary deposits provide insights into the physicochemical environment of transport, accumulation and post-depositional alterations of sedimentary particles, and are important proxies applied in paleoclimatic reconstructions. It is especially true for aeolian dust deposits with a fairly narrow grain size range as a consequence of the extremely selective nature of wind sediment transport. Therefore, various aspects of aeolian sedimentation (wind strength, distance to source(s), possible secondary source regions and modes of sedimentation and transport) can be reconstructed only from precise grain size data. As terrestrial wind-blown deposits are among the most important archives of past environmental changes, proper explanation of the proxy data is a mandatory issue. Automated imaging provides a unique technique to gather direct information on granulometric characteristics of sedimentary particles. Granulometric data obtained from automatic image analysis of Malvern Morphologi G3-ID is a rarely applied new technique for particle size and shape analyses in sedimentary geology. Size and shape data of several hundred thousand (or even million) individual particles were automatically recorded in this study from 15 loess and paleosoil samples from the captured high-resolution images. Several size (e.g. circle-equivalent diameter, major axis, length, width, area) and shape parameters (e.g. elongation, circularity, convexity) were calculated by the instrument software. At the same time, the mean light intensity after transmission through each particle is automatically collected by the system as a proxy of optical properties of the material. Intensity values are dependent on chemical composition and/or thickness of the particles. The results of the automated imaging were compared to particle size data determined by three different laser diffraction instruments

  17. ON-SITE ENGINEERING REPORT FOR THE LOW-TEMPERATURE THERMAL DESORPTION PILOT-SCALE TEST ON CONTAMINATED SOIL

    EPA Science Inventory

    Performance of the thermal desorption process for removal of organic contaminants, mostly polynuclear aromatic hydrocarbons (PAHs), from soils was evaluated. The Superfund Site soil tested was a fine sandy soil contaminated with creosote. An optimum operating temperature of 550 C...

  18. ON-SITE ENGINEERING REPORT FOR THE LOW-TEMPERATURE THERMAL DESORPTION PILOT-SCALE TEST ON CONTAMINATED SOIL

    EPA Science Inventory

    Performance of the thermal desorption process for removal of organic contaminants, mostly polynuclear aromatic hydrocarbons (PAHs), from soils was evaluated. he Superfund Site soil tested was a fine sandy soil contaminated with creosote. n optimum operating temperature of 550 deg...

  19. Video monitoring of meso-scale aeolian activity on a narrow beach

    NASA Astrophysics Data System (ADS)

    Hage, Pam; Ruessink, Gerben

    2014-05-01

    The morphologic evolution of coastal dunes is inextricably linked to the neighbouring beach through the incessant exchange of sand. Intense storm-wave processes erode the foredune within a few hours and transport its sand sand seaward, while aeolian processes return the eroded sand from the beach into the dune system, although at a much lower pace (months to years, or meso scale). Here we use an 8-year long data set of half-hourly snapshot video images, collected from an ≡ 50 m high tower on Egmond Beach (The Netherlands), and a concurrent meteorological and water level data set, to examine which factors affect aeolian sand delivery into the dunes. Egmond is a north-south oriented, micro- to meso-tidal, wave-dominated site that faces the North Sea. Its beach is relatively narrow ( ~ 100 m at spring low tide) and mildly sloping (~ 1 : 30), and consists of quartz sand with a median diameter of about 300 μm. Aeolian activity is clearly visible on the images as sand streamers and, in particular, sand strips, defined as low-amplitude, large-wavelength and slipfaceless deposits that migrate slowly in the wind direction and, depending on wind direction, can have orientations from almost shore-parallel to shore-normal. Beach width in combination with wind direction appeared to be the dominant factors in controlling aeolian activity. Many high wind (>≡ 13 m/s) events, especially from the west and northwest, were associated with a storm surge that inundated almost the entire beach with, accordingly, no possibility for aeolian transport. In contrast, sand-strip fields covered the entire beach during medium wind (≡ 12 - 13 m/s) events, especially when the wind was nearly shore-parallel. Many sand-strip events were observed to be regulated by the tide. Prominent sand-strip fields on the intertidal and upper beach were largely limited to low-tide situations with a wide beach, with a rising tide obviously destroying the intertidal sand strips and sometimes also negatively

  20. Antimony release from contaminated mine soils and its migration in four typical soils using lysimeter experiments.

    PubMed

    Shangguan, Yu-Xian; Zhao, Long; Qin, Yusheng; Hou, Hong; Zhang, Naiming

    2016-11-01

    Antimony (Sb) can pose great risks to the environment in mining and smelting areas. The migration of Sb in contaminated mine soil was studied using lysimeter experiments. The exchangeable concentration of soil Sb decreased with artificial leaching. The concentrations of Sb retained in the subsoil layers (5-25cm deep) were the highest for Isohumosol and Ferrosol and the lowest for Sandy soil. The Sb concentrations in soil solutions decreased with soil depth, and were adequately simulated using a logarithmic function. The Sb migration pattern in Sandy soil was markedly different from the patterns in the other soils which suggested that Sb may be transported in soil colloids. Environmental factors such as water content, soil temperature, and oxidation-reduction potential of the soil had different effects on Sb migration in Sandy soil and Primosol. The high Fe and Mn contents in Ferrosol and Isohumosol significantly decreased the mobility of Sb in these soils. The Na and Sb concentrations in soils used in the experiments positively correlated with each other (P<0.01). The Sb concentrations in soil solutions, the Sb chemical fraction patterns, and the Sb/Na ratios decreased in the order Sandy soil>Primosol>Isohumosol>Ferrosol, and we concluded that the Sb mobility in the soils also decreased in that order. PMID:27395817

  1. Aeolian process-induced hyper-concentrated flow in a desert watershed

    NASA Astrophysics Data System (ADS)

    Ta, Wanquan; Wang, Haibin; Jia, Xiaopeng

    2014-04-01

    Ephemeral desert channels are characterized by very high rates of sediment transport during infrequent flood events. Here we show that aeolian process-induced hyper-concentrated (AHC) flows occur in the Sudalaer desert watershed in the Ordos Plateau of China, which primarily transport 0.08-0.25 mm non-cohesive aeolian sand and have a peak suspended sediment concentration of 1.1-1.4 × 106 mg l-3. Aeolian sand supply and storage in the channel play a crucial role in causing hyper-concentrated flow. Our results indicate that non-cohesive aeolian sand can be entrained from the bed and suspended in the turbulent flow when the channel bed slope exceeds a critical threshold (0.0003). We also show that if the frequency ratio of wind-blown sandstorms to rainstorms Tw/Tp exceeds β(γ - γ0)/α (P/V3) (A/L) (where α is the wind-blown sand transport coefficient, β is the runoff coefficient, γ - γ0 is the increase in suspension concentration caused by addition of aeolian sands, P is the density of rainstorms, V is the wind speed of sandstorms, A is the runoff-generating area, L is the aeolian sand-filled channel length), an AHC flow occurs during the passage of a flood in a desert channel. Since high-frequency aeolian processes provide an adequate quantity of transportable sediment and promote AHC flow, most of the infrequent rainfall-induced floods occurring in arid zones can develop as AHC flows.

  2. Evaluation of aeolian desertification from 1975 to 2010 and its causes in northwest Shanxi Province, China

    NASA Astrophysics Data System (ADS)

    Xue, Zhanjin; Qin, Zuodong; Li, Hongjian; Ding, Guangwei; Meng, Xianwen

    2013-08-01

    Efforts to control aeolian desertification in China have focused on the arid and semiarid regions. However, the direct dust emission rates, sediment characteristics and local-scale controls, as well as the measures needed to combat desertification, remain poorly understood in northwest Shanxi Province. Aeolian desertification is regarded as an obstacle to local sustainable socioeconomic development. This paper investigated changes in aeolian desertification between 1975 and 2010 on the northwestern Shanxi Plateau. In this study, remote sensing images were used to classify land suffering from aeolian desertification into four categories: light, moderate, severe, and extremely severe. To evaluate the evolution and status of aeolian desertification as well as its causes, we interpreted and analyzed Landsat multi-spectral scanner (MSS) image (acquired in 1975) and Landsat Thematic Mapper (TM) images (acquired in 1991, 2000, 2006, and 2010) as well as meteorological and socioeconomic data. Results revealed 11,866 km2, 13,362 km2, 14,051 km2, 13,613 km2, and 12,318 km2 of aeolian desertified land (ADL) in the above 5 periods, respectively. The spatial dynamics and patterns showed two stages: expansion during 1975-2000 at a rate of 87.37 km2 a- 1, and spatial transfer of affected areas during 2000-2010 with a net decrease of 173.27 km2 a- 1. During the evolution of aeolian desertification, areas of moderate ADL had the greatest dynamic response (11.45%). The factors controlling ADL dynamics were analyzed from the perspectives of two groups of factors: natural factors and human activities. Our results indicated that the climate-dominated natural factors contribute greatly to the occurrence and development of ADL. However, they are not the fundamental causes of its development. The human factors are the primary and direct driving forces responsible for the increase in ADL area. More thorough quantitative analysis, with more frequent remotely sensed data is needed to assess

  3. Aeolian Processes at the Mars Exploration Rover Opportunity Landing Site

    NASA Technical Reports Server (NTRS)

    Sullivan, R.; Bell, J. F., III; Calvin, W.; Fike, D.; Golombek, M.; Greeley, R.; Grotzinger, J.; Herkenhoff, K.; Jerolmack, D.; Malin, M.

    2005-01-01

    The traverse of the Mars Exploration Rover Opportunity across its Meridiani Planum landing site has shown that wind has affected regolith by creating drifts, dunes, and ubiquitous ripples, by sorting grains during aeolian transport, by forming bright wind streaks downwind from craters seen from orbit, and by eroding rock with abrading, wind-blown material. Pre-landing orbiter observations showed bright and dark streaks tapering away from craters