This paper examines the problem of the flexural interaction between a long-distance buried pipeline embedded in a soil medium that experiences differential frost heave. The modeling takes into consideration the interaction at a transition zone between a frozen region and a frost-susceptible region that experiences a time-dependent growth of a frost bulb around the buried pipeline. The heave that accompanies the development of a frost bulb induces the soil-pipeline interaction process. The analysis focuses on the development of a computational scheme that addresses the three-dimensional nature of the soil-pipeline interaction problem, the creep susceptibility of the frozen region, and a prescribed time- and stress-dependent heave in an evolving frost bulb zone. The numerical results presented in the paper illustrate the influence of the heave process and the creep behavior of the frozen soil on the displacements and stresses in the buried pipeline.

This paper describes restraint of frost heave in a test filling frost waste soil from construction using lime stabilization. The restraint of frost heave is significant for the road design in cold districts, and replacement has been conventionally adopted. However, due to the exhaustion of replacement materials which are a great amount of coarse grain materials and the treatment of waste soil, construction method using soil generated at original site has been required. The frost depth of stabilized soil using untreated soil and site soil is constant between 68 and 70 cm. The restraint effect of frost heave was enhanced with increasing the lime addition. The addition of 10% lime decreased the frost heave to 4 mm which was of the same order experienced in the sand replacement method. Through the lime stabilization, the frost heave can be suppressed by the reduction of permeability and by the increase in intergranular force due to pozzolanic reaction. Based on the relationship between the frost depth and frost heave, it was found that the frost heave of soil stabilized by lime concentrates on the surface part of improved layer. This was considered to be caused by the increase in the water content of upper layer with rain water and snowmelt water due to the uneven mixing of improving agent and the reduction of permeability of treated layer. 9 refs., 8 figs.

In cold districts, frost heave of ground in the winter and ground softening in the ice-melting period in the spring are problems. Volcanic cohesive soil is a soil liable to frost heave, and many frost heave damages occurred in ground of cohesive soil of low water content. However, it is considered that it is effective to use slaked lime and cement as well as raw lime which has been conventionally used for soil stabilization and frost heave protection of volcanic cohesive soil of low water content (natural water content 60% or less). This paper describes the results of the comparison and study on the application of raw lime, slaked lime, and cement as soil stabilizers to the cohesive soil of low water content. The results led to many new findings that if the non-immersion strength of the soil stabilized by lime and cement is known, the immersion strength can be estimated, that the water content has an effect on frost heave more than the immersion strength, and that the relationships between the water content and the frost heave amount of the three types of soil stabilizers are expressed by a single straight line, showing a similar tendency. 7 refs., 12 figs.

Pipes, especially buried pipes, in cold regions generally experience a rash of failures during cold weather snaps. However, the existing heuristic models are unable to explain the basic processes involving frost actions. This is because the frost action is not a direct load but one that causes variations in pipe-soil interactions resulting from the coupled thermohydro-mechanical process in soils. This paper developed and implemented a holistic multiphysics simulation model for freezing soils and extended it to the analysis of pipe-soil systems. The theoretical framework was implemented to analyze both static and dynamic responses of buried pipes subjected to frost actions. The multiphysics simulations reproduced phenomena commonly observed during frost actions, e.g., ice fringe advancement...

The purpose of this document is to evaluate the effect of frost heave on waste transfer lines with shallow depths in DST farms. Because of the insulation, well compacted sandy material around waste transfer lines, the type of sandy and gravel soil, and relatively low precipitation at Hanford site, it is concluded that waste transfer lines with one foot of soil covers (sandy cushion material and insulation) are not expected to undergo frost heave damaging effects.

This book covers basic information on proper, cost-effective design of buried-pipe systems for underground fluid transportation. Examines various pipe products available. Discusses soil engineering and piping mechanics. Specific topics include pipe-wall stresses and strains; design bases; rigid- and flexible-pipe analysis; soil pressure; and longitudinal, wheel, expansive-soil, and frost loading.

We studied the effects of artificial soil frost on cambial activity and xylem formation on 47-year-old Norway spruce [Picea abies (L.) Karst.] trees grown on medium fertile site type (with moraine soil) in eastern Finland (62?42?N; 29?45?E). Different soil frost treatments applied were: (1) natural snow accumulation and melting (control, CTRL); (2) artificial removal of snow from soil surface during two consecutive winters (OPEN); and (3) snow clearing and insulation (FROST), which was in other ways similar to OPEN, but the ground was insulated in early spring to delay soil thawing. Each treatment was replicated in three blocks, and two sample trees in each plot were repeatedly microcored during growing seasons of 2006?2007 for the analysis of the onset, cessation and the duration of xylem...

Soil temperature, surface heave and downslope movements were monitored continuously for one year (1998-99) within a solifluction lobe developed on seasonally frozen ground in the Daisetsu Mountains, northern Japan. Observations were also made of soil moisture and ice segregation. Seasonal freeze-thaw cycles produced both frost creep and gelifluction. In layers shallower than 60 cm, ice segregation during the freezing season induced seasonal frost heave, and ice melt at the same depths during the thaw season promoted gelifluction as well as seasonal frost creep. At greater depths, gelifluction did not occur even when the thaw plane reached the ice-rich layers. The results at the study site demonstrate that segregated ice plays an important role in gelifluction, but only at shallower depths....

Freezing and thawing may substantially influence the rates of C and N cycling in soils, and soil frost was proposed to induce NO Formula Not Shown losses with seepage from forest ecosystems. Here, we test the hypothesis that freezing and thawing triggers N and dissolved organic matter (DOM) release from a forest soil after thawing and that low freezing temperatures enhance the effect. Undisturbed soil columns were taken from a soil at a Norway spruce site either comprising only O horizons or O horizons + mineral soil horizons. The columns were subjected to three cycles of freezing and thawing at temperatures of -3degreeC, -8degreeC, and -13degreeC. The control columns were kept at constant +5degreeC. Following the frost events, the columns were irrigated for 20 d at a rate of 4 mm d-1. Per...

+ CICERO (Center for International Climate and Environmental Research , Oslo) .... to soil acidification, lack of other nutrients or increased sensitivity to other stress factors. ... effect of man-made and natural stress (e. g. drought, frost, and insects). .... Interestingly, while damages to aquatic and, in particular, forest ecosystems ...

The timing of life history traits is central to lifetime fitness and nowhere is this more evident or well studied as in the phenology of flowering in governing plant reproductive success. Recent changes in the timing of environmental events attributable to climate change, such as the date of snowmelt at high altitudes, which initiates the growing season, have had important repercussions for some common perennial herbaceous wildflower species. The phenology of flowering at the Rocky Mountain Biological Laboratory (Colorado, USA) is strongly influenced by date of snowmelt, which makes this site ideal for examining phenological responses to climate change. Flower buds of Delphinium barbeyi, Erigeron speciosus, and Helianthella quinquenervis are sensitive to frost, and the earlier beginning of the growing season in recent years has exposed them to more frequent mid-June frost kills. From 1992 to 1998, on average 36.1% of Helianthella buds were frosted, but for 1999-2006 the mean is 73.9%; in only one year since 1998 have plants escaped all frost damage. For all three of these perennial species, there is a significant relationship between the date of snowmelt and the abundance of flowering that summer. Greater snowpack results in later snowmelt, later beginning of the growing season, and less frost mortality of buds. Microhabitat differences in snow accumulation, snowmelt patterns, and cold air drainage during frost events can be significant; an elevation difference of only 12 m between two plots resulted in a temperature difference of almost 2 degrees C in 2006 and a difference of 37% in frost damage to buds. The loss of flowers and therefore seeds can reduce recruitment in these plant populations, and affect pollinators, herbivores, and seed predators that previously relied on them. Other plant species in this environment are similarly susceptible to frost damage so the negative effects for recruitment and for consumers dependent on flowers and seeds could be widespread. These findings point out the paradox of increased frost damage in the face of global warming, provide important insights into the adaptive significance of phenology, and have general implications for flowering plants throughout the region and anywhere climate change is having similar impacts. PMID:18409425

The distribution of frost table depths on a peat-covered permafrost slope was examined in a discontinuous permafrost region in northern Canada over 4 consecutive years at a variety of spatial scales, to elucidate the role of active layer development on runoff generation. Frost table depths were highly variable over relatively short distances (0.25-1 m), and the spatial variability was strongly correlated to soil moisture distribution, which was partly influenced by lateral flow converging to frost table depressions. On an interannual basis, thaw rates were temporally correlated to air temperature and the amount of precipitation input. Simple simulations show that lateral subsurface flow is governed by the frost table topography having spatially variable storage that has to be filled before water can spill over to generate flow downslope, in a similar manner that bedrock topography controls subsurface flow. However, unlike the bedrock surface, the frost table is variable with time and strongly influenced by the heat transfer involving water. Therefore, it is important to understand the feedback between thawing and subsurface water flow and to properly represent the feedback in hydrological models of permafrost regions.

During the past decade, important dieback has been observed in short-rotation forestry plantations of Salix viminalis and S. dasyclados in Sweden and Estonia, plantations from which the isolation of ice nucleation-active (INA) and pathogenic bacteria has also been reported. This thesis investigates the connection between bacterial infection and frost as a possible cause for such damage, and the role played by internal and external factors (e.g. plant frost sensitivity, fertilisation) in the dieback observed. Bacterial floras isolated from ten Salix clones growing on fertilised/unfertilised mineral soil or nitrogen-rich organic soil, were studied. Culturable bacterial communities present both in internal necrotic tissues and on the plant surface (i.e. epiphytes) were isolated on two occasions (spring and autumn). The strains were biochemically characterised (with gram, oxidase and fluorescence tests), and tested for ice nucleation-activity. Their pathogenic properties were studied with and without association to a freezing stress. Certain strains were eventually identified with BIOLOG plates and 16S rRNA analysis. A high number of culturable bacterial strains was found in the plant samplings, belonging mainly to Erwinia and Sphingomonas spp.; pathogenic and INA communities being mostly Erwinia-, Sphingomonas- and Xanthomonas-like. The generally higher plant dieback noted in the field on nutrient-rich soils and for frost sensitive clones was found connected to higher numbers of pathogenic and INA bacteria in the plants. We thus confirm Salix dieback to be related to a synergistic effect of frost and bacterial infection, possibly aggravated by fertilisation.

Icy Bay, in the Chugach-St.Elias mountains of southern Alaska, provides an excellent opportunity to 1) document exceptionally rapid breakdown of cobbles on surfaces recently exposed by glacial retreat, 2) examine frost-induced breakdown in light of recent advances in theory, and 3) explore the potential role of periglacial processes in limiting the height of mountain ranges. The latter adds to the current interest in the interactions between topography, tectonics and climate, and in particular, the so-called glacial buzzsaw (Egholm, et al. 2009. Nature, 460, p 884; doi:10.1038/nature08263). This is the notion that the growth of mountains is curtailed by erosion and related effects of glaciers with little or no dependence on the factors that are generally thought to control the height of mountains; height increases with the elevation of the snow line, with little or no influence of uplift and exhumation rates, rock type, and precipitation. A well-documented retreat of tidewater glaciers in Icy Bay has resulted in a succession of outwash surfaces on which cobbles of diverse lithology were exposed to atmospheric conditions sequentially. Following deposition, initial breakdown rates were determined for each of four distinct lithologies: siltstone, sandstone, greenschist, and granite/gneiss. These rates decrease to negligible values after 10-15 years of exposure. Breakdown is significantly enhanced adjacent to the current shoreline with the fraction of surface cobbles fractured after 30 years ranging from 20% for granite/gneiss to 90% for siltstone. Theoretical considerations suggest that the susceptibility of a rock type to frost weathering is dictated by its specific surface area and resistance to fracture. These parameters define a threshold zone for frost weathering specific to ambient thermal and moisture conditions in Icy Bay, a conclusion substantiated by independent experimental evidence. This result, coupled with the fact that this and other studies have shown enhanced rock breakdown under relatively mild climatic conditions, suggests the importance of unfrozen water migration in frost weathering under natural conditions and a significantly greater spatial importance of frost weathering than previously recognized. The rate of frost weathering should be maximized for temperatures between -3 to -10°C and in the presence of abundant moisture. These conditions ought to define an elevation interval in mountainous landscapes most conducive to frost weathering. Climatic fluctuations ought to drive large altitudinal changes in this interval causing variations in affected land area. Frost weathering appears to be significantly faster than other subaerial weathering mechanisms, and probably contributes significantly to the rapid exhumation documented in the Icy Bay region (Berger, A.L., et al. 2008. Nature Geoscience,1, 793-802.)

The observations of frost depth and snow water equivalent were carried out at Lhasa, Rikeze and Nagqu in the eastern part of the Tibetan Plateau from July 1993 to March 1999. Also, the routine data at the ten meteorological stations in the same part was analyzed, which covers the observation period. All the stations are located in the seasonally frozen ground region. The main results are as follows: The development of seasonally frozen ground was most remarkable at Nagqu, where the maximum frost depth was 160-200 cm. At Nagqu, the frost penetration began in October and continued until the middle of March. During the frost penetration, except in the midwinter, the soil layer near the surface froze in the night and melted in the daytime. At the thawing stage from April to May, the frozen ground melted from the surface and the frozen soil layer left underground became thin. The efficiency of frost penetration, ?, under certain temperature conditions tends to increase with the altitude and the precipitation in the preceding autumn, but ? is not influenced by the snow cover. Exceptionally, ? is large at Lingzi and Qamdo in spite of their low altitudes. This may be ascribed to the less solar radiation at these stations than other stations, which enhances the frost penetration. The maximum frost depth increases with the altitude except for Lingzi and Qamdo.The days of snow cover increases with the latitude, but long lasting snow cover is not usual. At Nagqu, where the days of snow cover is the second largest among the ten stations, the maximum snow water equivalent was 20 mm, the maximum snow depth was 9 cm and the mean snow density was about 0.2 g cm-3. inter-annual variation of the days of snow cover at Nagqu is almost similar to that at Sogxian. The localized negative correlation between the winter air temperature anomaly and the days of snow cover was found at Nagqu and Sogxian in the winter of 97/98, suggesting the albedo effect of snow cover. The correlation is positive between the precipitation is summer and the days of snow cover at Sogxian in the preceding winter, which apparently corresponds to the snow-hydrological effect. The warm (cold) winter tends to follow the wet (dry) summer with much (little) precipitation respectively. But the relationship between air temperature and precipitation in the summer is not clear.   

Majority of the existing gravel roads have low bearing capacity during spring and autumn, due to thaw and/or rain. Low bearing capacity leads often to bad road conditions. This situation results in higher costs for the lumber industry and the public. Management of gravel roads all the year around would traditionally require excavation of frost susceptible soils and replacement with natural materials. Fly ash (from bio fuels) has good technical properties as bearing layer in road constructions. Fly ash stabilised gravel roads have better function and longer life span with less maintenance than traditional gravel roads. The aim of this project is to show how fly ash stabilisation of gravel roads can increase bearing capacity and what its environmental impact is. The overall aim is to make it easier for entrepreneurs and consulting companies to use fly ash during gravel road renovation and/or constructing new gravel roads. This report targets fly ash producers and road constructors as well as environmental agencies. Two different pilot tests were investigated in this study, Norberg with fly ash from Stora Enso Fors AB, and Boerje (Uppsala) with fly ash from Vattenfall Uppsala AB. Both road sections with related reference section were investigated during a two year period. Only fly ash was used in the bearing layer at Norberg and fly ash gravel was used at Boerje. Bearing capacity was investigated twice, for both locations, November 2003 one month after the road renovation and during thawing, April 2004. Water samples from lysimeters, ground water and surface water were only collected and analysed from Norberg. Experience from the fly ash stabilised road sections show that curing and traffic load can with time compensate for less compaction. The same is noticed at Boerje, although deflection measurements show that there are small differences. Stabilisation of gravel roads increases the roads bearing capacity. Two years after stabilisation 90 timber loads were transported trough the road section stabilised at Norberg, without any stability problems. The stabilisation effect can be destroyed by the effect of water and frost, and results indicate that road ditches and are of great importance. After thawing the stabilised roads bearing capacity is decreased after the first year. Leaching and transport of heavy metals from the road construction is in the same level as from the reference section. However, leaching of Na, K and sulphate are increased. This report shows that fly ash stabilisation gives an increase of bearing capacity of gravel roads. Water in the road construction leads to an increase of leaching, a reduction in bearing capacity and decreased frost resistance. Drainage of fly ash stabilised roads are essential due to bearing capacity and environment. Fly ash production is limited and use of fly ash stabilised gravel is more efficient as less fly ash is required than when only fly ash is used.

Many properties of forest stands in the boreal main zone have means that are specific to each boreal zone (i.e. subzones of the main climatic zone). These properties are arranged in zonal systems, called forest vegetational zones. The paper examines the vegetative productivity using three climatic variables: the effective temperature sum, the duration of the vegetation period, and the maximum soil frost penetration; each of them means for the period 1961- 2000. Soil frost penetration was calculated mainly as a function of snow depth and frost sum. The productivity for each boundary between the boreal forest vegetational zones in Finland was obtained mainly from Ilvessalo, beginning with the boundary between the hemiboreal and southern boreal zones in the south and ending at the boundary between the middle and northern boreal zones in the north. The regional distribution of residuals reflects the regional variation of the soil fertility. A hypothesis that each boundary corresponds to a certain productivity from the western coast of Norway to western Siberia, was tested. The productivity for the boundary between the hemiboreal and temperate zones was found to be in accordance for the limit determined by vegetation. Some applications of the results are presented. (orig.)

The compaction of arable soils caused by driving over them with agricultural machinery poses a serious problem in numerous agricultural regions across temperate climate zones. The risk of compaction is particularly high in early spring or late autumn when soils are wet. This is why driving over soils frozen near the surface is recommended in some cases in temperate climate zones to prevent soil compaction. However, no findings have been available about the thickness of frozen soil required to effectively prevent compaction when the soil is driven over. In one experiment, soil physical measurements were carried out on the topsoil after a single pass with a tractor (4100kg wheel load, 80kPa inflation pressure) over an unfrozen variant, a variant with 2-3cm frost covering and a variant with 5...

Spring snowmelt is an important period of mercury (Hg) export from watersheds; contributing a large portion of the annual Hg flux. The export of mercury and dissolved solutes such as sulphate and dissolved organic carbon in meltwaters from upland soils may affect Hg methylation rates in low-lying wetlands and subsequent methylmercury (MeHg) export. Given the toxicological and teratological effects associated with mercury and methylmercury to ecosystem and human health, understanding hydrological controls on mercury mobility, especially under a changing climate, warrants further study. However, the impact of global climate change on snowpack accumulation and spring runoff intensity, and its subsequent influence on mercury and solute mobility in forested watersheds are not fully understood. In order to assess the potential effects of climate change, inter-annual climate variability was used as a proxy by comparing hydrological flows and mercury and solute mobility in spring following winters with: 1) a severely diminished snow accumulation with an early melt (2009-10) and 2) a significantly greater winter snow accumulation with average to late melt timing (2010-11). To additionally assess spatial variability, spring runoff samples were collected from three replicate instrumented, forested hillslope plots delineated in an upland-peatland watershed at the Marcell Experimental Forest in north-central Minnesota. Installed in each plot is a shallow subsurface runoff trench equipped with digital flow datalogging. Total mercury (THg) analysis of the spring 2010 runoff period revealed an average overall THg freshet yield of approximately 520 ng m-2 upland forest area from each of the three replicate plots. For the 2011 spring snowmelt period, an average THg yield of approximately 1480 ng m-2 upland forest area was observed; nearly three times greater than that observed in 2010. Enhanced snow accumulation and a subsequently greater magnitude of runoff significantly enhances THg yield. The spring snowmelt period for 2009-2010 highlighted the important contribution of the melting of soil frost following snowmelt in the export of THg from the hillslope, with nearly 30% of the THg mobilized as a result of soil frost melt. This effect of soil frost was not observed in spring 2011, due to greater snow accumulation. Melting of soil frost may play a key role in Hg export from hillslope environments when minimal snow accumulation allows for deeper frost development; significantly delaying about 1/4 of the total upland Hg export during spring snowmelt.

Dielectric sensors have been widely used for determining soil water content, but until now few have been effectively applied for observing the freeze-thaw cycle in soil at the field scale. With this intention we tested a frequency domain (FD) probe designed for use in access tubes installed into the ground at five sites. For accurate depth-referenced measurements, a series of magnetism-sensing Hall-switches was used. The experiment was carried out over the winter of 2009-2010. The temperature-dependent dielectric response was interpreted using a mixing model to fit four soil components, solid, air, liquid water and ice. To illustrate the soil frost dynamics over time, the measured liquid water content of frozen soil (LWCFS) was transformed into different expressions including frozen soil p...

Little is known of the microclimate differences in orchards posed by different floor management systems. Comparisons were made of microclimatic factors on eight radiation frost nights in the spring of 1986 between two adjacent. 1.4 ha peach (Prunus persica (L.) Batsch) plots in the Shenandoah Valley of West Virginia. The two plots were under different floor management systems; one plot with a complete grass cover (grass plot) and the other plot consisted of alternating 3-m-wide soil, 3-m-wide grass strips with coal dust applied to the soil strip of the tree row (coal dust plot). The net radiative flux (R/sub n/) on radiation frost nights from the coal dust plot was 10-15 W m/sup -2/ lower (greater radiative loss) than from the grass plot. Only 50% of this R/sub n/ difference in the early morning hours at the beginning of this study was accounted for by the soil heat flux (G) difference. However, G accounted for an increased percentage of the R/sub n/ difference in the early morning hours as the study progressed, reaching 100% at approximately 30 days from the commencement of this study. Because the differences in R/sub n/ and G were nearly equal during radiation frost nights, it is apparent that little of the energy liberated by the soil was intercepted by the canopy. Provided a means of trapping the energy from the soil in the canopy can be devised, a potential 2-3 degrees C difference in canopy temperature may be realized between these floor management systems for the site studied. These differences in canopy temperature, however would be site-specific due to the effect of aspect, slope, relative position on slope, and vegetation on solar energy partitioning. 12 refs.

The freezing of ground for the containment of subsurface hazardous waste is a promising method that is environmentally friendly and offers a safe alternative to other methods of waste retention in many cases. The frozen soil method offers two concepts for retaining waste. One concept is to freeze the entire waste area into a solid block of frozen soil thus locking the waste in situ. For small areas where the contaminated soil does not include vessels that would rupture from frost action, this concept may be simpler to install. A second concept, of course, is to create a frozen soil barrier to confine the waste within prescribed unfrozen soil boundaries; initial research in this area was funded by EPA, Cincinnati, OH, and the Army Corps of Engineers. The paper discusses advantages and limitations, a case study from Oak Ridge, TN, and a mesh generation program that simulates the cryogenic technology.

Shifts in community composition of soil protozoa in response to climate change may substantially influence microbial activity and thereby decomposition processes. However, effects of climate and vegetation on soil protozoa remain poorly understood. We studied the distribution of soil testate amoebae in herbaceous and shrubby vegetation along an altitudinal gradient (from below the treeline at 500m to the mid-alpine region at 900m a.s.l.) in subarctic tundra. To explain patterns in abundance, species diversity and assemblage composition of testate amoebae, a data set of microclimate and soil chemical characteristics was collected. Both elevation and vegetation influenced the assemblage composition of testate amoebae. The variation was regulated by interactive effects of summer soil moisture, winter soil temperature, soil pH and nitrate ion concentrations. Besides, soil moisture regulated non-linear patterns in species richness across the gradient. This is the first study showing the effects of winter soil temperatures on species composition of soil protozoa. The effects could be explained by specific adaptations of testate amoebae such as frost-resistant cysts allowing them to survive low winter temperatures. We conclude that the microclimate and soil chemical characteristics are the main drivers of changes in protozoan assemblage composition in response to elevation and vegetation. PMID:23022310

Two 9-year old Estonian Salix plantations suffering from dieback were studied: one situated on poor mineral soil and divided into fertilised and unfertilised plots (Saare plantation) and another growing on a well-decomposed and nitrogen-rich organic soil, without fertiliser application (Kambja plantation). Bacteria from internal tissues of visually damaged shoots from seven clones were isolated in spring and autumn. The strains were subsequently biochemically characterised and tested for ice nucleation activity and pathogenicity on Salix. Some strains were also analysed with 16S rRNA. High numbers of culturable bacteria were found, belonging mainly to Erwinia, Sphingomonas, Pseudomonas and Xanthomonas spp. Fertilised plots were significantly more colonised by bacteria than unfertilised plots and also more extensively damaged, showing a lower density of living plants after 7 years of culture. More ice nucleation active (INA) strains were found in Saare fertilised plots and at Kambja than in Saare unfertilised plots. Likewise, most pathogenic strains were isolated from Saare fertilised plots and from Kambja. For some of the willow clones studied, dieback appeared to be related to both clonal frost sensitivity and abundance of INA and pathogenic bacteria. The plantations probably suffered from the presence of high amounts of pathogens and from frost related injuries aggravated by INA bacteria. Most probably the fertilisation at Saare and the nitrogen-rich soil at Kambja created a favourable environment for bacterial development and led to high dieback levels after the first harvest. (author)

Our main objective was to elucidate how snow cover and soil frost influenced CO2 dynamics over agricultural land. We observed the CO2 flux above the soil or snow surface continuously using the commonly used static-chamber method and the CO2 concentration in the soil on snow-removal plot and untreated control plot over agricultural land in northern Japan from September 25, 2009, to May 31, 2010. The recorded largest CO2 flux was 3.9 ?mol m-2 s-1 and CO2 concentration in soil was 390-5000 ppm. Little CO2 flux was observed during the soil-freezing and snow-covered periods. The CO2 concentration had been increasing about 10 ppm day-1 during the soil-freezing period at the snow-removal plot. At the beginning of April, the CO2 flux increased temporarily up to 0.19 ?mol m-2 s-1 after the snow melted entirely at the untreated control plot and up to 0.52 ?mol m-2 s-1 after the soil had thawed at the snow-removal plot. Snow-melting and soil-thawing largely influenced on CO2 flux, irrespective of soil temperature. The data were not explained by conventionally used temperature response functions for CO2 fluxes in these periods.   

A field trial was carried out in 1995 to study the effect of fertilization at planting on the survival, growth, and nutrition of tree seedlings planted on Andisol soils at two sites in South Iceland. Nine fertilizer treatments were tested on three tree species Betula pubescens Ehrh., Larix sibirica Ledeb. and Picea sitchensis (Bong.) Carr. After six growing seasons, seedlings provided with controlled-release-fertilizer (Osmocote®: 25 g per seedling) or smaller amounts of easily soluble nitrogen–phosphorus fertilizer (e.g. 1.2 g N per seedling and 1.4 g P per seedling) showed significantly improved survival and growth. Larger amounts of N increased mortality during the first year. Fertilized trees were less subject to frost heaving than untreated trees. In the year following application of NPK fertilizer the effect was insignificant on the foliar concentration of macronutrients of the fertilized seedlings, compared to control seedlings. It is concluded that fertilization during afforestation in Iceland and other areas in the world with similar climatic and soil properties could make the difference between plantation success or failure. Growth; Survival; Foliar nutrient concentration; Frost heaving; Betula pubescens Ehrh.; Larix sibirica Ledeb.; Picea sitchensis (Bong.) Carr.; Fertilizer; Containerized seedlings

Forests in the Upper Lakes States region, composed predominantly of sugar maple and red maple with a large number of stems in small diameter classes, were evaluated for conversion to biomass/energy plantations. The study included examining the use of black locust as an interplant species to improve maple productivity. Available water and phosphorus were found to be highly correlated with site index and biomass on the sites. Skidding of trees with tops intact caused widespread disruption of forest floor horizons. Natural coppice regrowth on all sites was poor. Results indicate it is not feasible to coppice natural stands of northern hardwoods on a 4-year rotation. Survival of interplanted black locust was very poor due to susceptibility to frost. The potential of black locust as a biomass species for SRIC plantations was demonstrated by the exceptional growth of surviving individuals. A provenance trial of 20 seed sources showed variability in frost resistance among seed sources. Data is presented on the wood characteristics of seven northern hardwoods species show that young sprouts have higher moisture content, seasonal moisture content variation, higher extractive and ash content, a lower specific gravity and lower thermal stability. All species evaluated are comparable in terms of major chemical composition, caloric values, and extent of gasification. 111 refs., 11 figs., 35 tabs.

Rooted cuttings of Chrysanthemum morifolium 'Yellow Delaware' (Fusarium-susceptible) and 'White Iceberg' (Fusarium-resistant) were greenhouse-grown in: (i) non-infested soil; (ii) soil infested with Fusarium oxysporum alone; (iii) soil infested with Meloidogyne incognita, M. javanica or M. hapla; an...

The ubiquitous presence of frozen ground in cold regions creates a unique dynamic boundary issue for subsurface water movement and storage. We examined the relationship between ground thaw and spatiotemporal soil moisture patterns at three sites (peatland, wetland and valley) near Yellowknife NT. Thaw depth and near-surface soil moisture were measured along a systematic grid at each site. Energy and water budgets were computed for each site to explain the soil moisture patterns. At the peatland, overall soil moisture decreased through the summer and became more spatially homogeneous with deepened thaw, increased subsurface storage capacity, and drying from evapotranspiration. In the peatland and wetland, accumulated water in depressions maintained soils at higher soil moistures for a longer duration than the hummock tops. The depressions had deeper frost tables than the drier hummock tops because the organic mats covering the hummocks insulated the ground and retarded ground thaw. The wettest soils were often locations of deepest thaw depth due to surface ponding and the transfer of latent heat accompanying surface runoff from upslopes. For example, the 3.3 ha wetland received 3.08x105 m3 of surface inflow from a lake with 2.32 kJm-2 of convective heat available to be transferred into the frozen ground over the study period. Soil moisture patterns also revealed preferential surface and subsurface flow routes. The findings indicate that the presence of frozen ground and differential thawing have a diverse and dynamic relationship with near-surface soil moisture content. When the impermeable boundary is dynamic, and controlled by water and energy fluxes, thicker soil layers are associated with higher moisture. This contrasts findings from temperate regions with a fixed impermeable boundary which show that surface soil moisture content can be lower in areas with thick soil.

Runoff production is strongly dependent on the ground-thawing process in most arctic and subarctic permafrost regions covered by taiga and tundra, where the ground contains a relatively thin (i.e. 0.05-1.0 m) organic layer, overlying mineral sediment. The organic layer is characterized by high hydraulic conductivity, in contrast to the lower hydraulic conductivity of the underlying mineral sediment. As a consequence, hillslope drainage occurs predominantly below the ground surface, and, in particular, between the relatively impermeable frost table and the ground surface. In addition, in the first 0.2-0.3 m below the surface, the saturated hydraulic conductivity of the organic soil decreases by approximately 2 orders of magnitude with increasing depth. Early in the thaw period, when the frost table is still relatively close to the ground surface, lateral flow therefore occurs in the portion of the active layer with highest hydraulic conductivity. Later in the thaw season, as a result of the deepening of the frost table, the lateral flow rate is substantially lower since horizontal drainage occurs through the portion of soil with low hydraulic conductivity. This process has been conceptualized as the energy-based theory of runoff, and can only be investigated with a model that couples the heat and water flow equations in the soil. The GEOtop distributed hydrological model is a grid-based model with a complete surface energy balance scheme that accounts for variations in both the turbulent fluxes of sensible and latent heat, as well as for variations in radiant fluxes. The model also has a coupled subsurface heat and water flux scheme that is able to route water and energy both vertically between a large number of soil layers, and horizontally between grids. The model has been applied and tested with satisfying results in 3 different basins in the Canadian Arctic: Trail Valley Creek (NWT) located just North of treeline in the Mackenzie delta, Big Lake (NWT) in vicinity of the Arctic Ocean, and Wolf Creek (YT) in the mountainous Southern Yukon Territory. The different runoff responses during the summer are analyzed, and related to the different climate and surface properties. This is essential for considering the complex interactions of climate, vegetation, permafrost and hydrology in a warming climate.

The following report contributes to our knowledge of how to economically produce wildlife-friendly grass mixtures for future fuel feedstocks in the northern plains. It investigates northern-adapted cultivars; management and harvest regimes that are good for yields, soils and wildlife; comparative analysis of monocultures and simple mixtures of native grasses; economic implications of growing grasses for fuel feedstocks in specific locations in the northern plains; and conversion options for turning the grasses into useful chemicals and fuels. The core results of this study suggest the following: ? Native grasses, even simple grass mixtures, can be produced profitably in the northern plains as far west as the 100th meridian with yields ranging from 2 to 6 tons per acre. ? Northern adapted cultivars may yield less in good years, but have much greater long-term sustainable yield potential than higher-yielding southern varieties. ? Grasses require very little inputs and stop economically responding to N applications above 56kg/hectare. ? Harvesting after a killing frost may reduce the yield available in that given year but will increase overall yields averaged throughout multiple years. ? Harvesting after a killing frost or even in early spring reduces the level of ash and undesirable molecules like K which cause adverse reactions in pyrolysis processing. Grasses can be managed for biomass harvest and maintain or improve overall soil-health and carbon sequestration benefits of idled grassland ? The carbon sequestration activity of the grasses seems to follow the above ground health of the biomass. In other words plots where the above ground biomass is regularly removed can continue to sequester carbon at the rate of 2 tons/acre/year if the stand health is strong and yielding significant amounts of biomass. ? Managing grasses for feedstock quality in a biomass system requires some of the same management strategies as managing for wildlife benefit. We believe that biomass development can be done in such a way that also maximizes or improves upon conservation and other environmental goals (in some cases even when compared to idled land). ? Switchgrass and big bluestem work well together in simple mixture plots where big bluestem fills in around the switchgrass which alone grows in bunches and leaves patches of bare soil open and susceptible to erosion. ? Longer-term studies in the northern plains may also find that every other year harvest schemes produce as much biomass averaged over the years as annual harvests ? Grasses can be grown for between $23 and $54/ton in the northern plains at production rates between 3 and 5 tons/acre. ? Land costs, yields, and harvest frequency are the largest determining factors in the farm scale economics. Without any land rent offset or incentive for production, and with annual harvesting, grass production is likely to be around $35/ton in the northern plains (farm gate). ? Average transportation costs range from $3 to $10/ton delivered to the plant gate. Average distance from the plant is the biggest factor - $3/ton at 10 miles, $10/ton at 50 miles. ? There is a substantial penalty paid on a per unit of energy produced basis when one converts grasses to bio-oil, but the bio-oil can then compete in higher priced fuel markets whereas grasses alone compete directly with relatively cheap coal. ? Bio oil or modified bio-oil (without the HA or other chemical fraction) is a suitable fuel for boiler and combustion turbines that would otherwise use residual fuel oil or number 2 diesel. ? Ensyn has already commercialized the use of HA in smokey flavorants for the food industry but that market is rather small. HA, however, is also found to be a suitable replacement for the much larger US market for ethanolamines and ethalyne oxides that are used as dispersants. ? Unless crude oil prices rise, the highest and best use of grass based bio-oil is primarily as a direct fuel. As prices rise, HA, phenol and other chemical fractions may become more attractive ? Although we were able to create available glucose from the AHG fraction in the bio-oil it proved recalcitrant to fermentation by yeast. Although fermentation results were much more positive with wood based bio-oil sugars, ethanol does not appear to be a likely product from grass based bio-oil. ? A package of policy recommendations has been developed with roughly 75 key stakeholders from throughout the region that would support the transition to greater development of advanced biofuels and products in the region, as well as a strong role for native grass agriculture to support those industries.

The technical properties and general state of permafrost in Greenland is not well documented. A new coordinated investigation has been initiated, for ground temperature measurements and permafrost mapping in Greenlandic towns in sporadic, discontinuous and continuous permafrost zones. We present investigation results from one of the sites, located at Ilulissat, in an area of discontinuous saline permafrost. We have established ground temperature measurement stations and conducted a shallow geoelectrical study. Our results show that the sediments in the studied area mainly consist of very frost susceptible silty clays. The area has permafrost with a maximum active layer thickness between 0.9 and 1 m. In spite of low permafrost temperatures a considerable part of the pore water is unfrozen, due to high residual salt concentrations. Consequently, the unfrozen water content dominates the technical properties, and the sediments have a limited heat capacity available, should the temperature conditions change.

In this study of the behaviour of the fractions of unretted and frost-retted fibre straws in damp air, a production scale method to separate fibre and shive from fibre plants was introduced and tested on bast fibre plants (Linum usitatissimum L. and Cannabis sativa L.). The method consists of optional drying of stalks, unloading bales, milling the straws with a hammer mill, separating the fractions from air stream with a cyclone and finally separating fibres from shives with a screening drum. Fractions were characterized focusing on technologically indicative properties such as equilibrium moisture content, ash and microbiological quality. Unretted fractions of the bast fibre plant stem reached higher equilibrium moisture contents than the retted fractions, and hemp fibres absorbed more moisture from air than did the Linum fibres. In very humid air, all fractions began to lose weight due to moulding. The weight decrease during the first week was lower in frost-retted than in unretted fractions. The frost-retted fractions appeared to be more resistant to humidity in the short term. The total number of microbes and especially the numbers of yeasts and moulds can be used as a criterion of hygienic level. For green fractions, the mould level was similar in fibres and in shives, but frost-retted shives contained more moulds than the unretted shives. The mould content of a fraction had no direct correlation with the moulding tendency of the fraction. The ash contents of fibres were somewhat higher than those of shives, due to a probable soil contamination. Ash content did not have significant correlation with microbiological quality, although ash is a possible risk factor for hygienic quality. According to the results of this study it is highly important to study the quality of the production chain of bast fibre plants to ensure the quality of industrial products. From the producer's point of view, raw material with defined quality can be directed to the most suitable application. The behaviour of fractions in various ambient atmospheres, and other quality aspects such as hygienic level can be used as criteria for defining the most appropriate product applications. PMID:15081488

Peniocereus striatus (Brandegee) Buxb. (Cactaceae) is an endemic Sonoran Desert cactus that reaches its northern range limit in southwestern Arizona. One U.S. population occupies a small area of Organ Pipe Cactus National Monument near the U.S./Mexico international boundary, which has been monitored since 1939. An extensive survey conducted in 2002, covering 177 ha, resulted in the discovery of 88 new plants, in addition to the relocation of 57 plants found in previous surveys. Despite potential increases in population size and spatial distribution, mean plant height and number of basal stems has not significantly changed in recent years. Bud scars revealed that a majority of the population was sexually mature. Peniocereus striatus occurrence increased with decreasing slope, spanned every slope aspect, and was highest on rocky soils, but was noticeably low on west and northwest slopes and areas where severe land degradation had previously occurred. Over half of P. striatus plants were nursed by shrubs and subshrubs, while 40% occurred under leguminous trees. A severe frost in January 2002 top-killed 19% of the population, with the greatest damage in drainage bottoms. However, long-term (1944–2002) climate records show that there has been an overall increase in the number of frost free days in the region, which, coupled with land use change, has implications for the future health of this population.

Appendix 3. Soil and land types with high susceptibility to hydrophobic layer. -- ..... mudstone), and Quaternary marine terrace deposits (weakly consolidated sandstones and ..... Air Force Civil Engineering Center, Tyndall. Air Force Base ...

We investigated the effects of nitrogen (N) availability and spraying trees with urea, copper chelate (CuEDTA), and phosphonate-containing fungicides on tree N status and susceptibility to infection by Phytophthora syringae. Increasing soil N availability increased susceptibility and increased N and...

The transmission dynamics of the human-pig zoonotic cestode Taenia solium are explored with both deterministic and stochastic versions of a modified Reed-Frost model. This model, originally developed for microparasitic infections (i.e. bacteria, viruses and protozoa), assumes that random contacts occur between hosts and that hosts can be either susceptible, infected or 'recovered and presumed immune'. Transmission between humans and pigs is modelled as susceptible roaming pigs scavenging on human faeces infected with T. solium eggs. Transmission from pigs to humans is modelled as susceptible humans eating under-cooked pork meat harbouring T. solium metacestodes. Deterministic models of each scenario were first run, followed by stochastic versions of the models to assess the likelihood of infection elimination in the small population modelled. The effects of three groups of interventions were investigated using the model: (i) interventions affecting the transmission parameters such as use of latrines, meat inspection, and cooking habits; (ii) routine interventions including rapid detection and treatment of human carriers or pig vaccination; and (iii) treatment interventions of either humans or pigs. It is concluded that mass-treatment can result in a short term dramatic reduction in prevalence, whereas interventions targeting interruption of the life cycle lead to long-term reduction in prevalence. PMID:17250839

This study on wind turbine foundation systems considers a system using a Howden HWP60 horizontal axis machine, operating in conditions typical of northern Ontario. The design wind load corresponds to a maximum steady wind speed of 58 m/s at 20 m height. There are 3 main variables to be considered in selecting the appropriate design: the soil conditions, the frost conditions, and the availability of materials and skilled labor. The load bearing capabilities of muskeg, weak cohesive soils, stiff cohesive soils, granular soils, weathered rock, and sound rock are discussed. Precautions necessary for conditions of seasonal freezing, discontinuous permafrost, and continuous permafrost are described. The installation procedures in this study take into account the difficulties of transporting materials to remote areas where heavy equipment cannot be used and where local labor is generally unskilled. The types of foundations are the shallow concrete footing, steel grillage, timber grillage, piles, screw anchors, rock anchors, and ring beam foundations. Each type of foundation is appropriate for certain kinds of soil conditions, and the need for insulation has to be assessed for each individual site in conjunction with the selection of the type of footing. 21 refs., 11 figs., 2 tabs.

Performance of heat exchangers in appliances such as air-conditioners, showcase coolers and unit coolers can deteriorate under frosting conditions. To address this issue, the mechanism of frost deposition needs to be investigated. To achieve this goal, the frost formations process was observed and properties of frost were measured at air and cooling surface temperatures less than 0 °C using a refrigeration apparatus. Frost crystals formed on the cooling surface had a needle-like structure under the chilled condition, which represents an air temperature of 0 °C and cooling surface temperature of -10°C. On the other hand, frost crystals formed on cooling surface had a block shaped structure under the frozen condition, which represents an air temperature of -15°C and cooling surface temperature of -29°C. This work examined the relationship between density and thermal conductivity of frost, and calculated Nusselt number and Sherwood number.

Various crops were tested in greenhouse and field trials for their potential utility in the rotation sequence in the potato cropping system in Meloidogyne chitwoodi-infested soils of the Klamath Basin in northeastern California and southern Oregon. Two Solarium accessions from the International Potato Center in Peru were potential sources of resistance to M. chitwoodi. Cultivars of barley, oat, rye, wheat, and white lupine were maintenance hosts, supporting the nematode population at its current level without substantial increase or decline. Poor to nonhosts to race 1 of the nematode included cultivars of alfalfa, amaranth, oilseed radish, oilseed rape, and safflower. These crops have potential for inclusion in the cropping system but are subject to various constraints, including frost sensitivity and availability of markets. Sugarbeet, a new crop in the area, is a maintenance or better host of M. chitwoodi. Potato, tomato, and sunflower are excellent hosts. PMID:19279852

In studies near Rhinelander, Wisconsin, unrooted cuttings of two poplar clones (Populus Tristis No. 1 and P. NC-9922) were planted throughout the period when soil was frost free during 1979-1982. Cuttings were grown with or without (1) soaking for 6 days before planting; (2) irrigation; and (3) weed control by hand-hoeing. Survival at the end of the first season was generally greater than 90% for all planting dates. After a second season, cuttings planted before 16 July had greater than 90% survival, while cuttings planted during 30 July - 27 August showed a major decline in survival. Trees planted in early to mid May were taller than those planted earlier. This optimum planting time was not affected by clone, soaking, irrigation or weed treatment. 9 references.

During the three stages of production, construction and demolition, approximately 15 million tons of gypsum waste plasterboard is generated annually in the world. It is considered a serious problem due to scarcity of land-filling space, increasing the cost of disposal and increasing environmental regulations. Investigations of using recycled gypsum ?bassanite? which is derived from gypsum waste plasterboard and waste plastic trays for ground improvement were studied. Recycled gypsum was used as a stabilizing agent to improve the compressive strength while the waste plastic trays were used to improve the tensile strength. Recycled gypsum content, curing time and frost heave property throughout capillary rise test were investigated to determine the behavior of treated soil with recycled gyps...

The US Army Engineer Waterways Experiment Station (WES) and the US Army Engineer Division, Huntsville (HNDED) have developed general design criteria and specific design review criteria for the below-ground vault (BGV) alternative method of low-level radioactive waste (LLW) disposal. A BGV is a reinforced concrete vault (floor, walls, and roof) placed underground below the frost line, and above the water table, surrounded by filter blanket and drainage zones and covered with a low permeability earth layer and top soil with vegetation. Eight major review criteria categories have been developed ranging from the loads imposed on the BGV structure through material quality and durability considerations. Specific design review criteria have been developed in detail for seven of the eight major categories. 59 refs., 14 figs., 2 tabs.

OBJECTIVE: To simulate the probability of HCV transmission from HCV a seropositive index patient to susceptible household contacts through non-sexual exposures. METHODS: A modified Reed-Frost stochastic simulation model was used to assess the probability of HCV transmission from an HCV seropositive index patient to susceptible household contacts through non-sexual exposures. This mathematical model used does not require the specification of infection onset times for individual, nor is it necessary to identify the chains of household infections. Therefore, this model can be used with serologic data on detected asymptomatic infections. The HCV serological data on 341 non-sexual household contacts of 86 HCV seropositive index patients were used in this simulation study. The frequency distribution of HCV infection of susceptibles for each household size of 4-8 initial susceptibles was calculated. A maximum likelihood procedure was used to estimate the non-sexual household transmission parameter for HCV infection for the range of household sizes studied and was used in 1000 stochastic iterations. The goodness-of-fit test was carried out to compare the observed number of households where HCV transmission occurred to one or more initial susceptible with mean expected simulated number of such households with varying sizes ranging from 4 to 8 initial susceptibles. RESULTS: The maximum likelihood estimates (90% probability interval (PI)) of binomial probability of HCV transmission within households with varying number of initial susceptible non-sexual household contacts ranged from 0.248 (90%PI: 0.031, 0.560) to 0.164 (90%PI: 0.011, 0.440) for household size of 4 and 8 respectively. The ?(2) goodness-of-fit test of observed and mean expected simulated proportions of households wherein at least one of the susceptibles was infected revealed good fit for households of all sizes examined (P ? 0.96). In a household, the probability of HCV transmission from the index HCV seropositive patient to susceptible via non-sexual contacts tended to decrease linearly as the household size increased from four to seven. CONCLUSION: Intra-household HCV transmission through non-sexual contacts may have substantial impact on HCV transmission and needs to be considered in an HCV control program. PMID:23103288

Seedling Paradox (Juglans hindsii x J. regia) has been the rootstock of choice for English walnut in California because of its vigor and greater tolerance of wet soil conditions. However, seedling Paradox rootstock is highly susceptible to crown gall, a disease caused by the soil-borne bacterium Agr...

Presents a laboratory exercise that uses a simple imaging technique to illustrate the profound effects that living roots exert on the pH of the surrounding soil environment. Achieves visually stimulating results that can be used to reinforce lectures on rhizosphere pH, nutrient availability, plant tolerance of soil acidity, microbial activity, and plant susceptibility to diseases. (Author/JRH)

Surface hydrophilicity has a strong influence on frost nucleation according to phase transition theory. To study this effect, a close observation of frost formation and deposition processes on a vertical plate was made under free convection conditions. The formation and shape variation of frost crystals during the initial period are described and the frost thickness variation with time on both hydrophobic and plain copper cold surfaces are presented. The various influencing factors are discussed in depth. The mechanism of surface hydrophilicity influence on frost formation was analyzed theoretically. This revealed that increasing the contact angle can increase the potential barrier and restrain crystal nucleation and growth and thus frost deposition. The experimental results show that the initial water drops formed on a hydrophobic surface are smaller and remain in the liquid state for a longer time compared with ones formed on a plain copper surface. It is also observed that the frost layer deposited on a hydrophobic surface is loose and weak. Though the hydrophobic surface can retard frost formation to a certain extent and causes a looser frost layer, our experimental results show that it does not depress the growth of the frost layer. (author)

Two field trials were conducted to investigate different herbage grasses and cereals for their susceptibility to the disease take-all, for their impact on concentrations of the pathogen, Gaeumannomyces graminis var. tritici (Ggt), in soil and for their effect on development of take-all in a subsequent wheat crop. In the herbage grass trial, Bromus willdenowii was highly susceptible to Ggt, produced the greatest post-senescence Ggt concentrations in soil and highest incidence of take-all in following wheat crop. Lolium perenne, Lolium multiflorum and Festuca arundinacea supported low Ggt soil concentrations and fallow the least. The relationship between susceptibility to Ggt and post-senescence concentrations in soil differed between pasture grasses and cereals. In a trial in which Ggt was ...

This homepage of Dr. Richard A. McLaughlin at North Carolina State University includes a four-part tutorial about soil erosion and mitigation. Slide presentations include an introduction to the factors that lead to soil erosion, a general discussion of soil characteristics and susceptibility to erosion, an overview of the formation of rills and gullies, and some examples of sediment transport dynamics and erosion reduction techniques. The site also features short videos that show tests of erosion control methods in an artificial environment.

Traffic intensities have a significant influence on a range of crop and soil parameters (Hamza & Anderson, 2005; Raper, 2005). For grass and especially clover, the yield response is negative as a function of traffic intensity (e.g. Frost, 1988).  During the growing season, conventional grass-clover production for silage experience high traffic intensities due to operations like fertilizing with slurry, cutting the grass, rolling the grass into swaths, and collecting and chopping the grass into trailers with a forage harvester.  Normally, the traffic is distributed all over the field area during the growth season. In this way, the track impacts formed by the machines will influence the grass and clover growth and yield differently.  As clover is known to have a higher feed value[1], the evaluation of the quantitative and qualitative affects on the combined clover-grass entity, the individual components must be determined.   The objective of this paper was to measure yield affects on clover-grass as a consequence of different traffic intensities. The experiments were carried out in the context of a full scale field trial. A 14 hectare full scale grass-clover field trial with 24 different traffic intensities and 35 replicates was established. Each net parcel measured 9 x 1.3 m and the 24 treatments were randomized onto the 840 net parcels. The grass clover was established in spring 2007 using RTK-GPS auto steered tractors and implements. A Claas Axion tractor equipped with AutoFarm RTK AutoSteer and a 15 m3 Kimadan slurry tanker on two axels, was used to perform the simulated traffic treatment on the parcels. The different traffic intensities are combinations of different tire pressure (1,0 and 2,5 bar), tire load (3000 and 6000 kg), time of year and number of passes (variating from 0 to 8). The harvesting procedure was preformed with a Haldrup plot harvester modified with RTK-GPS. This paper shows the initial results from measuring the yield affects References M.A. Hamza, M.A.; Anderson, W.K 2005. Soil compaction in cropping systems: A review of the nature, causes and possible solutionsRaper , R.L. 2005. Agricultural traffic impacts on soil. Journal of Terramechanics, Volume 42, Issues 3-4, July-October 2005, Pages 259-280 Frost, J.P. 1988. Effects on crop yield of machinery traffic and soil loosening. 1. Effects on grass yield of      traffic frequency and date of loosening. Journal of Agricultural Engineering Research, 39 (4): 301-31. Soil and Tillage Research, Volume 82, Issue 2, June 2005, Pages 121-145   [1] http://www.ruralni.gov.uk/index/publications/press_articles/dairy-2/role-of-clover.htm

This paper deals with the heat and mass transfer characteristics of humid air-flow under frosting conditions. A slit fin bundle was used for the simulation of fins of a heat exchanger. The effects of the cooling block temperature, air humidity and air velocity on the frosting characteristics were experimentally investigated. The frosted mass was affected considerably by the cooling block temperature and air humidity. However, the effect of air velocity on it was not so large. The pressure drop was affected remarkably by all experimental parameters in this study. Local heat flux distribution and frost thickness distribution on each fin were predicted from the measured fin temperatures and the mass and energy conservation equations on the frost surface and inside the frost layer.

We investigated differential susceptibility of lady beetles to entomopathogenic nematodes, for two reasons: (1) to estimate potential nontarget effects on natural lady beetle populations, (2) to compare the susceptibility of exotic versus native lady beetle species. We hypothesize that successful establishment of some exotically introduced arthropods may be due, in part, to a lower susceptibility relative to competing native species. In laboratory studies, we compared the pathogenicity, virulence, and reproductive capacity of Heterorhabditis bacteriophora and Steinernema carpocapsae among two native (Coleomegilla maculata and Olla v-nigrum) and two successfully established exotic (Harmonia axyridis and Coccinella septempunctata) lady beetles, and a known susceptible lepidopteran host, Agrotis ipsilon. After 1 and 2 days of exposure to either nematode species, mortality of A. ipsilon was higher than in all lady beetles. Thus, we predict that nematode field applications would have significantly less impact on lady beetle populations than on a susceptible target pest. Additionally, the impact of soil-applied nematodes may be lower on lady beetles than on soil-dwelling hosts because the former spends relatively less time on the soil. Exotic lady beetles were less susceptible to nematode infection than native species. Reproductive capacity data also indicated lower host suitability in H. axyridis, but not in C. septempunctata. Overall, the hypothesis that low susceptibility to pathogens in certain exotic lady beetles may have contributed to competitive establishment was supported (especially for H. axyridis). Additional studies incorporating different hosts and pathogens from various geographic locations will be required to further address the hypothesis. PMID:15913642

The amount of soil organic carbon (SOC) in the high Arctic is generally poorly constrained. Because of periglacial processes such as frost churning and sequestration in frozen soils, a substantial amount of SOC is typically not inventoried. This study provides a detailed study of SOC content by depth in 55 soil pits in a high Arctic ecosystem of northwest Greenland. Sampling sites spanned ecosystems from mires to polar deserts, from sea level to the margins of the Greenland Ice Sheet, and across various periglacial features. The amount of SOC in the various ecosystems was mapped using a correlation of SOC with high-resolution ASTER satellite imagery and the normalized difference vegetation index (NDVI) classes from the Circumpolar Arctic Vegetation Map. On the basis of this correlation, the total carbon was extrapolated to greater areas of the high Arctic. Our study found the amount of SOC in the high Arctic has typically been grossly underestimated, remarkably by the greatest amount in the most barren environments of the polar desert. We estimate that the high Arctic contains about 12 Pg SOC, a factor of over 5 times greater the most cited values previously reported. Since our estimate was only assessed in seasonally frozen ground, additional carbon frozen in the permafrost is likely present and potentially available in the event of permafrost thawing due to warming of the Arctic.

The state of health of 30 Norway spruce (Picea abies L. Karst.) stands located on the uplifting coast of western Finland was examined in 1992. Relationships between crown condition, elemental concentrations of the needles, organic layer properties and soil type were studied using sitewise data. The site scores along the first axis of the Principal Component Analysis for certain needle and organic layer variables were used as the site fertility index. The spruces in the study area showed a higher level of defoliation and this occurred in younger stands than elsewhere in southern Finland. Defoliation and discoloration correlated positively with stand age, and negatively with the site fertility index. Low N and Cu concentrations of the needles were found in older stands where spruces were highly defoliated and discolored. Boron concentrations of the needles were highest in these stands. Total N of organic layer and extractable S concentrations were negatively correlated with stand age, defoliation and discoloration. The results suggest that poor crown condition of the coastal spruce stands is related to natural soil factors such as periodic water-logging and low fertility. Long-lasting soil frost as a consequence of thin snow cover might be an additional stress factor impeding water and mineral nutrient uptake in the beginning of the growing season 46 refs, 4 figs, 3 tabs

In 2000-2002 the retention of {sup 137}Cs in various types of andosols, which are the most abundant soils in Iceland, was investigated. This is the first comprehensive attempt to determine radiocaesium levels and retention characteristics of Icelandic soils. Soils were sampled at 29 sites located near meteorological stations covering variation in precipitation and environmental conditions. Samples were obtained from 0- 5, 5-10, and 10-15 cm depths. Several physical and chemical parameters were measured, such as organic carbon, cation exchange capacity, pH and clay mineral content. The radiocaesium activity is quite variable and ranges between 300 and 4800 Bq/m{sup 2} and correlates closely to total annual precipitation (r{sup 2}=0.9). Most of the radiocaesium is retained in the uppermost 5 cm of the soil, or 83% on average. The greatest penetration was observed for organic Histo-sols, where 6% of the total {sup 137}Cs was found at 10-15 cm depth compared to less than 3% for Andosols types. The Icelandic Vitrisols (barren, poorly developed Andosols) are coarse grained with low clay content and contain little organic matter (<1%). Yet these soils retained 74% of {sup 137}Cs in the top 5 cm in our study. The results clearly indicate that radioactive fallout caesium is strongly retained by colloidal materials characteristic of Andosols, such as allophane and ferri-hydrite. Winter frost, snow melt, crack flow, and animal activity seem to have little effect on the {sup 137}Cs distribution at the present sampling sites. However, erosion and aeolian activity can markedly influence the aerial activity and vertical distribution of radiocaesium in Icelandic soils. (author)

The Phoenix Mission operated in the northern plains of Mars for 5 months starting May 25, 2008 spanning solar longitudes from 78 to 143 (summer). Throughout this period a diverse set of atmospheric measurements were taken and analyzed. The data sets provide information on the diurnal temperatures at 2 m above the surface, diurnal pressure, wind vectors, cloud properties, dust devils, the boundary layer, and humidity. In addition, coordinated observations were obtained with orbital instruments from Mars Reconnaissance Orbiter, Odyssey, and Mars Express. The measurements have been compared with predictions from Global Climate Models and found to agree in most regards. Taken as a whole this represents a unique description of the summer weather in a heretofore unexplored region of Mars. The Canadian LIDAR experiment gives us the first direct measurement of the boundary layer height. The first 90 sols of the mission were conducted under dusty conditions and the height of the dust layer was determined as 4-5 km above the surface. After 90 sols, the dust dispersed and water ice clouds were seen at ever lower altitudes and the boundary layer dropped to as low as 3 km. Snowfall was observed and frost imaged on the surface. Winds swirled around the lander completing a full circle each sol; typical wind speeds were 5-10 m/s. From near surface humidity measurements, a diurnal cycle sublimates ice and adsorbed water from the surface soil as the Sun heats it forming water ice clouds at the boundary layer. As temperatures cool in the night the water is returned as snow and frost to the soil. Temperatures ranged from -30 C to -90 C, but never exceed the melting point; even though atmospheric pressures are always above the triple point, liquid water is not allowed at this time. The lack of dune forms and the presence of dust devils suggest that wind erosion is a strong force despite the constant dust fall observed on the spacecraft deck. Local dust storms are often seen by the MARCI instrument on Odyssey and the dust optical depth above Phoenix testifies to rapid variations. The microscopic examination of the soil by the MECA instrument reveals two size modes: larger particles rounded by saltation and a clay-sized mode likely transported by atmospheric winds. Even so, the crusted surface and cobbles perched on the surface make it likely that the soil particles have been emplaced for long periods. Atmospheric data sets are still being analyzed and the latest results will be presented at the conference.

An experimental study was reported earlier on the development of frost formation by humid flow passing over the cylinder. In this study, dimensionless correlations based on previous experimental data and reported empirical correlations of others for frost properties are proposed. The frost conduction coefficient is determined by using an analytical equation. Subsequently, correlations are sought for the heat conduction coefficient, dimensionless temperature, dimensionless thickness and density. The advantages of these correlations to any other proposed correlations are their explicit and dependency on time. Furthermore, an estimation of characteristics of the frost is followed by using the same approach and the established correlations.

Purpose: To describe a case of frosted branch angiitis in a patient with tuberculous meningitis. Methods: Case report. Results: A 27-year-old woman of tuberculous meningitis was referred to us complaining of blurred vision for 2 days. Prominent white sheathing of the retinal venules and, to a much lesser extent, arterioles, consistent with frosted branch angiitis were also observed in both eyes. And after treatment with systemic anti-tuberculosis medications and steroid, frosted branch angiitis showed resolution. Conclusions: Frosted branch angiitis can be caused by Mycobacterium tuberculosis. Systemic anti-tubercular therapy and steroids were effective.

Mumbai city is the economical capital of India and is situated about midway on the western coast of stable continental region of Peninsular India. Major part of the city being of reclaimed land, the soil type is of alluvium, sand, and recent conglomerate. There are some bigger water bodies within the city range. In this study, an attempt has been made to study the susceptibility of soil liquefaction using simplified empirical procedure based on number of blow counts (N values) of the soil layers from standard penetration test. The liquefaction susceptibility is quantified in terms of factor of safety along the borehole depths at available borehole locations using earthquake-induced cyclic stress on the soil and the cyclic resistance of the soil to withstand the load. The factor of safety a...

Landslides are a common phenomenon within the Ecuadorian Andes and have an impact on soil-landscape formation. Landslide susceptibility was determined in a steep mountain forest region in Southern Ecuador. Soil mechanical and hydrological properties in addition to terrain steepness were hypothesised to be the major factors in causing soil slides. Hence, the factor of safety (FS) was calculated as the soil shear ratio that is necessary to maintain the critical state equilibrium on a potential sliding surface. Regression tree (RT) and Random Forest (RF) models were compared in their predictive force to regionalise the depth of the failure plane and soil bulk density based on terrain parameters. The depth of the failure plane was assumed at the lower boundary of the stagnic soil layer or soil...

Several lines of evidence indicate the presence of nearly pure, segregated ground ice in the martian high latitudes. In particular, shallow ice containing only 1-2% soil was excavated by Phoenix. One hypothesis for the excess ice is that it developed in situ, via a mechanism analogous to terrestrial ice lenses. Problematically, terrestrial soil-ice segregation is driven by freeze/thaw cycles, which have not occurred recently on Mars. Here we investigate ice lens formation at T model that applies premelting physics to track phase partitioning and lens growth on Mars. The model balances forces arising from intermolecular interactions against gravity and overburden pressure. Thin films of premelted ice minimize the interfacial free energy between ice and soil particles, leading to strong repulsive forces that are ultimately responsible for frost heave. In a freezing soil, gravity and the repulsive intermolecular forces are balanced by the force transmitted vertically between soil grains. Integrating the force balance equation downward from the surface, we identify layers in which interparticle pressures become negative. At those depths the interparticle forces unload, initiating lens formation. Then, given circumstances in which lens initiation is indicated, we ask how quickly lenses grow, how long growth accumulates, and how rapidly lenses are destroyed. We have modeled the last 106 years, assuming two different soils (silt and clay), ice depth determined by vapor-phase equilibration, and, (initially), salt-free liquid phases. Although intermolecular forces are frequently capable of unloading soil grains, rates of vertical H2O transport typically limit lens growth to exchange with the atmosphere would be expected to outstrip and prevent in situ segregated ice lens formation in a salt-free soil. (Earlier in Mars' history however, we find that warmer temperatures frequently lead to macroscopic lens development.) The soils measured by Phoenix of course were not salt-free; in particular the presence of per-chlorate argues that our model must be expanded. The inclusion of even a single salt has multiple complicating effects. For saturated Mg(ClO4)2 solutions, the eutectic temperature is as low as 206 K. The resulting decrease in pore ice at low T leads to higher hydraulic permeability which would enhance growth rates. Liquid phase density increases, which increases the buoyancy forces on soil grains. Conversely, dynamic viscosity also increases, inhibiting lens growth. Both the heat capacity and thermal conductivity of the melt are also affected. At high concentrations, osmotic potentials begin to play a role in determining the movement of melt. Finally, all of these properties evolve continually with temperature, as the composition of the liquid phase changes. Understanding the ways in which these processes might affect in situ segregation of martian ground ice is a challenging and exciting undertaking.

Rural agriculture in the Bolivian Altiplano is vulnerable to climate related shocks. Projections of eight precipitation and temperature extreme indices for the Altiplano are examined. Increases in observed warm nights and warm spells are consistent with increasing temperatures in the tropical Andes. Projections of warm nights, frost days, and heat waves are consistent with projected annual cycle temperature increases. Projected increases in precipitation extremes are consistent with trends at Patacamaya and annual cycle projections indicating a later rainy season characterized by less frequent, more intense precipitation. PDFs of Patacamaya precipitation suggest that precipitation changes may occur earlier than projected. The observed increase in frost days can be understood within the context of precipitation changes and increased radiative cooling. Consistencies between simulated and observed extremes suggest the projected directions of change are reliable. The ability of the CMIP3 models to simulate relationships between Altiplano precipitation anomalies and large-scale atmospheric variables for spring and summer is examined. A majority of models simulate an easterly/wet-westerly/dry relationship between upper-level winds and Altiplano precipitation in spring and summer, consistent with observations. Examination of future precipitation variability under conditions of greenhouse warming suggests the requirement of moisture transport from the east will not change. Atmospheric circulation changes associated with expansion of the Hadley circulation reduces the frequency of upper-level easterly winds, explaining springtime drying. Increased tropical tropospheric warming reduces the frequency of summertime upper-level easterly winds, explaining less frequent summertime rainfall. Springtime soil moisture is expected to decrease throughout the 21 st century, consistent with projections for increased temperature and decreased precipitation. Reductions in springtime soil moisture are likely to affect sowing times and plant survival. Reductions in summertime soil moisture are expected from the mid-century onward because small precipitation increases may not offset increased evapotranspiration related to higher temperatures. Consistencies between the results and expected large-scale changes in atmospheric circulation provide confidence in the projections. The results have serious implications for water resources and food security in the Altiplano, and provide a first step toward providing the critical information necessary to reduce the effects of changing climate in the Altiplano.

The overall aim of the Department of Short Rotation Forestry is to carry out research for development of basic, theoretical and practical knowledge in the related disciplines of biology, ecology and cultivation techniques in order to reach a high and sustainable production of woody biomass for energy purposes using environmentally acceptable methods. This report gives summaries of nine research programs within the Department, and the reports were prepared for the evaluation of the research during the period 1993-1996. The projects are: 1. Competition in short rotation forests (Theo Verwijst); 2. Carbon allocation as a function of nutrient and water availability (Lars Rytter, Tom Ericsson); 3. States and fluxes of water and carbon dioxide in the soil-plant-atmosphere system (Anders Lindroth); 4. Root dynamics of fast growing deciduous trees (Rose-Marie Rytter); 5. Accumulation and mobilization of root reserves in coppice growth (Lisa Sennerby-Forsse, Lars Bollmark, Yuehua von Fircks); 6. Effects of nutrient supply on frost resistance in fast growing Salix clones (Heinrich von Fircks); 7. Optimizing water and nutrients in poplar and willow plantations for maximum growth (Sune Elowson); 8. Soil biology in relation to energy forestry (Ulf Granhall); and 9. Plant protection in short rotation forestry against fungi and bacteria (Mauritz Ramstedt)

This paper summarizes and evaluates the main findings of 14 preceding papers related to the joint 14-month tree-exposure experiment carried out by the 'Munich Working Party on Air Pollution' at the GSF, Munich, FRG, from July 1986 to September 1987. The experiment tested the hypothesis that an interaction of ozone/acid mist/soil/extreme climatic conditions is the cause of decline of Norway spruce (Picea abies (L.) Karst.) at higher altitudes of the Inner Bavarian Forest. The main findings of the individual studies are presented and their implications for the hypothesis are discussed. Clear effects of soil and genetic factors (differences between clones), for example on growth and frost resistance were found. Treatment with O(3)/acid mist was shown to have effects on plant biochemistry, physiology, histology/ cytology, and growth. The wide scattering of these effects, and the lack of a consistent pattern of response across all clones does not permits a firm conclusion on the validity of the experimental hypothesis. These effects were not confounded by the nutrient stresses imposed during the initial exposure period and were not found to be cumulative during repeated treatments, as was proposed by the hypothesis. It is concluded that the experimental evidence does not indicate that ozone/acid mist are major factors to explain the Norway spruce decline on acidic sites at higher altitudes of the Inner Bavarian Forest and probably similar forest areas. PMID:15092294

Plant survivability and stormwater management have been studied at NRC's Institute for Research in Construction. For the plant survivability study different types of sedum plants were planted in boxes containing 4 inches, 5 inches, and 6 inches of growing medium respectively, with thermocouples installed in each box to monitor soil temperature at different depths. The objective was to study how well these species of plants survived through winter in different soil depths. Results showed that thus far, the plants have survived several extensive frosts. Stormwater runoff was measured from a 6-inch thick green roof and compared with runoff from a reference roof at the NRC's Ottawa green roof research site. By comparing the runoff from green roof and the reference roof it was shown that the green roof affected the runoff in three different ways: (1) it delayed the runoff for 35 minutes from the start of the rain event; (2) it reduced runoff rate from the initial rainfall of 1.8 mm/h to 0.8 mm/h; and (3) it reduced runoff volume, inasmuch as the green roof retained at least 8 mm out of the total of 33 mm rain that fell during the study period.

Satellite estimates of worldwide bromine levels and sea ice coverage were analyzed. Results indicate a correlation between frost flowers and ozone depletion. Researchers suggest that trace gases produced by frost flowers may explain the huge amounts of aerosols seen in the polar troposphere and the thinning of the ozone layer during the polar sunrise.

9 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a south polar scene, covered by bright, seasonal, carbon dioxide frost. The dark patches are areas where the frost has begun to sublime away. Location near: 80.0oS, 334.0oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

Spring and autumn frost tolerance was measured using material from a range-wide (50-67° N, 38-158° E) provenance trial of four Russian larch species (Larix sukaczewii Dyl., L. sibirica Ledeb., L. gmelinii Rupr. and L. cajanderi Mayr.) growing in northern Sweden. Shoots were collected in early May and late September and frozen at -8, -12, -16 and -20°C. Cambial damage was assessed visually after development under ideal conditions for 2 weeks. Differences in frost damage among provenances were highly significant in both spring and autumn. Autumn frost damage was significantly correlated with provenance latitude and longitude and spring frost damage was significantly correlated with provenance longitude but not latitude. Frost damage was not correlated with provenance elevation...

The present paper deals with a new method of defrosting using the frost sublimation phenomenon, which occurs below the triple point of water (273.16K, 610.5Pa). The present experimental study examines the mass transfer of the annular frost layer developed on a cooling pipe exposed to an impinging jet flow. The morphology of the frost layer during sublimation was observed using a digital video recorder. It was understood that the mass flux of the frost layer increased with increasing the jet flow velocity and the difference in the mass concentration of water vapor between the frost surface and the impinging jet flow. The non-dimensional correlation equations of mass transfer of defrosting were derived as functions of various parameters.   

The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically. (author)

Plasma membranes were isolated from both unfrozen and frozen tissues of Jerusalem artichoke tubers (Helianthus tuberosus L.) in high purity utilizing an aqueous two-polymer phase partition system. Although the recovery of the plasma membranes was decreased significantly by freezing of tissues even at the nonlethal temperature (-5 degrees C), the isolated plasma membrane samples were considered to be representative of the plasma membranes in situ. Freezing of the tissues at sublethal temperatures resulted in marked changes in the chemical composition of the plasma membrane. Those are losses of sterols and phosphatidylethanolamine from the plasma membranes, and a change of specific proteins with relatively high molecular weights into low molecular weight peptides. These specific proteins were designated as frost susceptible proteins. The properties of the plasma membrane ATPase seem to be not affected so much by the in vivo freezing of cells. However, inhibition of the plasma membrane ATPase by N,N'-dicyclohexylcarbodiimide (DCCD) was relatively low before and after freezing in vivo at the nonlethal temperature at -5 degrees C, but was markedly enhanced by freezing in vivo at sublethal temperatures below -10 degrees C. From the results, it is assumed either that the enzyme molecule was partially modified, especially at the presumed DCCD binding sites or that the DCCD had become more accessible to the enzyme as a result of increased permeability of the plasma membranes. These observed changes are discussed in connection with the mechanism of cell injury. PMID:16664579

The foliar-acting, post-emergence herbicides Agil (active ingredient propaquizafop) and Tell (active ingredient primisulfuronmetyl) were tested in two different Salix plantations during the first and second growing seasons. The residual effects on Salix plants and weeds in the year after application were also assessed in one plantation. Overall-spraying of Agil did not result in any visible damage to Salix plants, and stool weight was not negatively affected. Couch grass was controlled by Agil. The use of Tell resulted in severe damage to Salix plants when applied during the first growing season. The damage was expressed by an abnormally high sprouting frequency from the leading shoots as well as retarded growth in the leading shoots. Treatment with Agil combined with Tell resulted in very good weed control, but it increased the growth disturbances to Salix plants compared to Agil or Tell by themselves when applied early during the year of planting, as well as the one-year-old plantation. An additional effect of the treatment with Agil in combination with Tell in the established Salix plantation was an increased susceptibility to frost damage in the year after application. (author)

Cereals have evolved chelation systems to mobilize insoluble iron in the soil, but in rice this process is rather inefficient, making the crop highly susceptible to alkaline soils. We therefore engineered rice to express the barley iron-phytosiderophore transporter (HvYS1), which enables barley plants to take up iron from alkaline soils. A representative transgenic rice line was grown in standard (pH 5.5) or alkaline soil (pH 8.5) to evaluate alkaline tolerance and iron mobilization. Transgenic plants developed secondary tillers and set seeds when grown in standard soil although iron concentration remained similar in leaves and seeds compared to wild type. However, when grown in alkaline soil transgenic plants exhibited enhanced growth, yield and iron concentration in leaves compared to th...

Soil erosion is one of most widespread process of degradation. The erodibility of a soil is a measure of its susceptibility to erosion and depends on many soil properties. Soil erodibility factor varies greatly over space and is commonly estimated using the revised universal soil loss equation. Neglecting information about estimation uncertainty may lead to improper decision-making. One geostatistical approach to spatial analysis is sequential Gaussian simulation, which draws alternative, equally probable, joint realizations of a regionalised variable. Differences between the realizations provide a measure of spatial uncertainty and allow us to carry out an error analysis. The objective of this paper was to assess the model output error of soil erodibility resulting from the uncertainties ...

The potential for carbon (C) sequestration in soils depends on the rate of humification of C inputs to soils in relation to the decomposition of old soil organic matter. Recent results indicate a close connection between the input of fresh organic matter and the decomposition of old organic matter through soil priming. We conducted a tree girdling experiment in order to better understand the interdependence of soil microbial communities and plant belowground C allocation. A girdling experiment in a mature Western Hemlock (Tsuga heterophylla) stand near York (NE England) confirms the pattern observed in other girdling studies, with a reduction in total soil CO2 efflux (RS) to about 60% of control plots following a delay of about 2 weeks. High frequency measurements of RS immediately after girdling show a short-lived significant increase in RS in girdled plots between 3 and 8 hours after tree girdling, which have not been observed previously. The autotrophic flux contribution (calculated as the difference in RS between the control and girdled plots) declined throughout autumn, but in contrast to most girdling studies, remained significantly greater than zero throughout during December and January. This result indicates that tree belowground allocation continues throughout winter, despite regular night-time frosts in the period measurement were taken. Dominant mesofauna invertebrates (Enchytraeid worms) showed a positive response to girdling and higher abundances were recorded in the girdled plots when compared to the control ones, although differences were only significant on one sampling occasion. These results suggest that, in contrast to other components of the soil food-web, these organisms appear to be underpinned by detrital decomposition rather than by recent photosynthate-C deposition. Litterbag incubations showed no significant short-term treatment effect over the 4 months period following girdling, indicating no measurable interaction of decomposition and plant activity by this method. The results emphasise the strong influence of plants on the composition and activity of microbial soil communities. This has clear implications for our ability to predict ecosystem response to environmental change, including shifts in land use managements, and we discuss the need of incorporating these effects into current ecosystem models.

This study was undertaken to determine sorption coefficients of eight herbicides (alachlor, amitrole, atrazine, simazine, dicamba, imazamox, imazethapyr, and pendimethalin) to seven agricultural soils from sites throughout Lithuania. The measured sorption coefficients were used to predict the susceptibility of these herbicides to leach to groundwater. Soil-water partitioning coefficients were measured in batch equilibrium studies using radiolabeled herbicides. In most soils, sorption followed the general trend pendimethalin > alachlor > atrazine approximately amitrole approximately simazine > imazethapyr > imazamox > dicamba, consistent with the trends in hydrophobicity (log K(ow)) except in the case of amitrole. For several herbicides, sorption coefficients and calculated retardation factors were lowest (predicted to be most susceptible to leaching) in a soil of intermediate organic carbon content and sand content. Calculated herbicide retardation factors were high for soils with high organic carbon contents. Estimated leaching times under saturated conditions, assuming no herbicide degradation and no preferential water flow, were more strongly affected by soil textural effects on predicted water flow than by herbicide sorption effects. All herbicides were predicted to be slowest to leach in soils with high clay and low sand contents, and fastest to leach in soils with high sand content and low organic matter content. Herbicide management is important to the continued increase in agricultural production and profitability in the Baltic region, and these results will be useful in identifying critical areas requiring improved management practices to reduce water contamination by pesticides. PMID:17701699

Coastal Plain soils in Georgia are susceptible to runoff, sediment, and chemical losses from short duration-high intensity, runoff producing storms at critical times during the growing season. We quantified runoff and sediment losses from a Tifton loamy sand managed under conventional- (CT) and stri...

Insect-damaged peanut seeds are highly susceptible to contamination by carcinogenic aflatoxins produced by A. flavus and A. parasiticus, fungi belonging to Aspergillus section Flavi. A laboratory procedure was developed in which viable peanut seeds were wounded and inoculated with field soil contai...

Little is known about the natural oxidant demand (NOD) that soil matrix interactions exhibit on modified Fenton's reagent. Some studies indicate that the susceptibility of chemical oxidation of PAH is a function of total organic carbon in high carbon systems (>5%). However, there is also evidence ...

As a first step towards the development of an ecologically rational control strategy against western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte, Coleoptera: Chrysomelidae) in Europe, we compared the susceptibility of the soil living larvae and pupae of this maize pest to infec...

This paper presents a landslide susceptibility analysis in Jeju Island, South Korea using AHP (Analytic Hierarchy Process) and ANN (Artificial Neural Network) methods. To assess the landslide susceptibility, seven factors which affect the landslide occurrence were selected as: slope, aspect, soil type, geological type, rainfall intensity, forest and land cover. According to the relation between the above factors and landslide distribution, the weight value and rating value of each factor were calculated using AHP and ANN. Finally, we get two susceptibility maps using AcrView software through weighted overlay GIS (Geographic Information System) method. The comparative analysis reveals that the slope, rainfall intensity, soil and forest play important roles in landslide occurrence. From the ...

We present a procedure for monitoring heavy metals in soil based on the integration of satellite and ground-based techniques, tested in an area affected by high anthropogenic pressure. High resolution multispectral satellite data were elaborated to obtain information on vegetation status. Magnetic susceptibility measurements of soils were collected as proxy variable for monitoring heavy metal presence. Chemical analyses of heavy metals were used for supporting and validating the integrated monitoring procedure. Magnetic and chemical measurements were organized in a GIS environment to be overlapped to satellite-based elaborations and to analyze the pattern distribution. Results show the presence of correlation between anomalies in vegetation activity and soil characteristics. The relationsh...

Io's sublimation atmosphere is inextricably linked to the SO2 surface frost temperature distribution which is poorly constrained by observations. We constrain Io's surface thermal distribution by a parametric study of its thermophysical properties in an attempt to better model the morphology of Io's sublimation atmosphere. Io's surface thermal distribution is represented by three thermal units: sulfur dioxide (SO2) frosts/ices, non-frosts (probably sulfur allotropes and/or pyroclastic dusts), and hot spots. The hot spots included in our thermal model are static high temperature surfaces with areas and temperatures based on Keck infrared observations. Elsewhere, over frosts and non-frosts, our thermal model solves the one-dimensional heat conduction equation in depth into Io's surface and includes the effects of eclipse by Jupiter, radiation from Jupiter, and latent heat of sublimation and condensation. The best fit parameters for the SO2 frost and non-frost units are found by using a least-squares method and fitting to observations of the Hubble Space Telescope's Space Telescope Imaging Spectrograph (HST STIS) mid- to near-UV reflectance spectra and Galileo PPR brightness temperature. The thermophysical parameters are the frost Bond albedo, ?F, and thermal inertia, ?F, as well as the non-frost surface Bond albedo, ?NF, and thermal inertia, ?NF. The best fit parameters are found to be ?F ? 0.55 ± 0.02 and ?F ? 200 ± 50 J m-2 K-1 s-1/2 for the SO2 frost surface and ?NF ? 0.49 ± 0.02 and ?NF ? 20 ± 10 J m-2 K-1 s-1/2 for the non-frost surface.These surface thermophysical parameters are then used as boundary conditions in global atmospheric simulations of Io's sublimation-driven atmosphere using the direct simulation Monte Carlo (DSMC) method. These simulations are unsteady, three-dimensional, parallelized across 360 processors, and include the following physical effects: inhomogeneous surface frosts, plasma heating, and a temperature-dependent residence time on the non-frost surface. The DSMC simulations show that the sub-jovian hemisphere is significantly affected by the daily solar eclipse. The simulated SO2 surface frost temperature is found to drop only ˜5 K during eclipse due to the high thermal inertia of SO2 surface frosts but the SO2 gas column density falls by a factor of 20 compared to the pre-eclipse column due to the exponential dependence of the SO2 vapor pressure on the SO2 surface frost temperature. Supersonic winds exist prior to eclipse but become subsonic during eclipse because the collapse of the atmosphere significantly decreases the day-to-night pressure gradient that drives the winds. Prior to eclipse, the supersonic winds condense on and near the cold nightside and form a highly non-equilibrium oblique shock near the dawn terminator. In eclipse, no shock exists since the gas is subsonic and the shock only reestablishes itself an hour or more after egress from eclipse. Furthermore, the excess gas that condenses on the non-frost surface during eclipse leads to an enhancement of the atmosphere near dawn. The dawn atmospheric enhancement drives winds that oppose those that are driven away from the peak pressure region above the warmest area of the SO2 frost surface. These opposing winds meet and are collisional enough to form stagnation point flow.The simulations are compared to Lyman-? observations in an attempt to explain the asymmetry between the dayside atmospheres of the anti-jovian and sub-jovian hemispheres. Lyman-? observations indicate that the anti-jovian hemisphere has higher column densities than the sub-jovian hemisphere and also has a larger latitudinal extent. A composite "average dayside atmosphere" is formed from a collisionless simulation of Io's atmosphere throughout an entire orbit. This composite "average dayside" atmosphere without the effect of global winds indicates that the sub-jovian hemisphere has lower average column densities than the anti-jovian hemisphere (with the strongest effect at the sub-jovian point) due primarily to the diurn

Deposition rates and growth rates of frost on cooled surfaces under reduced pressure were obtained by using a freezing apparatus to reproduce natural convection where an upper surface was cooled at constant temperature and water was evaporated from a lower surface. It was designed for a basic study of a cryogenic freezer proposed for a fuel clean-up system of a fusion reactor. The experiment was carried out in the ranges of 6{times}l0{sup 2}Pa to 1{times}10{sup 5}Pa of total pressure and 77 K to 261 K of the cooling temperature. Sh numbers at the initial stage of frosting could be fitted to values evaluated using a conventional correlation of natural convection multiplied by a factor based on the critical supersaturation model. Frost thickness and average frost density under reduced pressure grew with the square root of time. In addition, frost thickness increased with [(T{sub S1}-T{sub W1})t]{sup 0.5} over all the ranges of the experimental conditions except where frost melted on the interface. The difference in frost thickness with the total pressure was qualitatively correlated by a parameter which was defined by the ratio of latent heat flux to sensitive heat flux. 21 refs., 8 figs.

A quantitative study recorded measurements of creep and heave taken during a 40-day period in the fall of 1991 on a partially vegetated northwest facing hillslope located behind the Power Station on Cortland College Campus. The hillslope is under scrutiny due to the construction of a parking lot sited at the top of the hillslope resulting in runoff directed toward the slope. Nine stakes hammered into the slope topsoil at various elevations all recorded forward and backward slope movement. Six stakes totalled movement < 1.0 cm. Three stakes totalled movement > 1.0 cm. Average movement of creep for the nine stakes totalled 0.85 cm. A creep rate of 0.5 m/yr is acceptable on uncovered talus slopes affected by frost action. The average movement of 0.85 cm over the course of the 40-day study would predict a total of 0.08 m/yr. Movement of stake no. 2 measured 2.23 cm or 0.2 m/yr and stake no. 3 measured 1.80 cm or 0.16 m/yr. Both measurements are within reason on an uncovered talus slope. These two stakes were positioned in a vegetated area just below the parking lot. Possible high erosion could be developing at the top of the hillslope under the edge of the parking lot. Analysis of the slope topsoil indicated a high degree of permeability. The soil horizon consists of > 70% coarse permeable sand grains. The amount of clay in the samples analyzed proved negligible. A soil layer of low permeability to account for the backward movement of the stakes proved absent. Low permeable shale bedrock, as little as 10.0 cm below the top soil is inferred to be the cause of a saturated condition which builds above the shale bedrock resulting in lateral flow causing the stakes to tip backwards towards the top of the hillslope.

Iron deficiency chlorosis (IDC) and soybean cyst nematode (SCN; Heterodera glycines) infestation are major factors that contribute to soybean (Glycine max Merr.) yield reduction in the Midwest. The IDC is often associated with soybean grown on high pH, calcareous soils. In addition, it was documented that SCN population density is higher in high pH soils. The objectives of this paper were to assess the proportion of within-field soybean yield and SCN variability that could be explained by soil pH, calcium carbonate equivalent (CCE), and a previously defined alkalinity stress index (ASI). Aerial images from 21 fields planted to SCN-resistant or susceptible soybean varieties were collected from 2001 through 2005 and used as a guide for soil and grain sampling. Ten to 16 sampling sites were selected on each field. Regression analyses within and across sites were used to study relationships between the measured variables. The SCN population density increased and yield decreased with increasing pH, CCE, and ASI across the fields. The percentage of yield variability across fields explained by soil pH, CCE, ASI, and SCN was 13%, 15%, 18%, and 1%, respectively, for resistant soybean varieties and 37%, 24%, 39%, and 10%, respectively, for susceptible varieties. The yield reduction due to high pH, CCE, and ASI was greater for SCN-susceptible varieties in field areas heavily infested with SCN.

From four Danish pig farms, bacteria of Pseudomonas spp. and the Bacillus cereus group were isolated from soil and susceptibility towards selected antimicrobials was tested. From each farm, soil samples representing soil just before and after spread of animal waste and undisturbed agricultural soil, when possible, were collected. Soil from a well-characterized Danish farm soil (Hojbakkegaard) was collected for comparison. The Psudomonas spp. and B. cereus were chosen as representative for Gram-negative and Gram-positive indigenous soil bacteria to test the effect of spread of animal waste on selection of resistance among soil bacteria. No variations in resistance levels were observed between farms; but when the four differently treated soils were compared, resistance was seen for carbadox, chloramphenicol, nalidixan (nalidixic acid), nitrofurantoin, streptomycin and tetracycline for Pseudomonas spp., and for bacitracin, erythromycin, penicillin and streptomycin for the B. cereus group. Variations in resistance levels were observed when soil before and after spread of animal waste was compared, indicating an effect from spread of animal waste.

We present a procedure for monitoring heavy metals in soil based on the integration of satellite and ground-based techniques, tested in an area affected by high anthropogenic pressure. High resolution multispectral satellite data were elaborated to obtain information on vegetation status. Magnetic susceptibility measurements of soils were collected as proxy variable for monitoring heavy metal presence. Chemical analyses of heavy metals were used for supporting and validating the integrated monitoring procedure. Magnetic and chemical measurements were organized in a GIS environment to be overlapped to satellite-based elaborations and to analyze the pattern distribution. Results show the presence of correlation between anomalies in vegetation activity and soil characteristics. The relationship between the distribution of normalized difference vegetation index anomalies and magnetic susceptibility values provides hints for adopting the integrated procedure as preliminary screening to minimize monitoring efforts and costs by supporting the planning activities of field campaigns. PMID:23044196

Abstract Plague, an often-fatal zoonotic disease caused by Yersinia pestis, is characterized by epizootic and quiescent periods. How Y. pestis is maintained during inter-epizootic periods is poorly understood, but soil has been implicated as a potential reservoir. Although previous studies have suggested that Y. pestis is able to survive in soil for weeks or months, it is unclear whether or not it is infectious to susceptible hosts. Here we investigate the potential for Y. pestis to infect mice through close contact with contaminated soil under laboratory conditions. In an attempt to approximate the natural conditions under which animals would be exposed to Y. pestis-contaminated soil, mouse cages filled with soil from a plague-endemic region were held at temperature and humidity ranges ob...

Some clay soils are highly susceptible to erosion and piping because of dispersion or deflocculation in pore water. These soils, called ''dispersive clay soil'' in geotechnical engineering, are structurally unstable, easily dispersive and, thus, highly erodible. There are many tests to determine dispersibility both physically and chemically. However, these tests can give different results for the same soil sample. Therefore, more than one test should be used to identify dispersive soils more accurately. In previous research, the discriminant method was used to combine these test results. In this study, a fuzzy logic approximation method was developed to combine the different results of the double hydrometer, pinhole, Na(%)-TDS and ESP-CEC methods into a single value. This new method was ap...

MSWI fly ash is susceptible to contain high amount of polychlorinated dibenzo-dioxins and polychlorinated dibenzo-furans. However, the use of MSWI residue for road construction started in France at a period when MSWI Bottom Ash and MSWI fly ash were not separated. From four old road sites, MSWI residue, road soils, reference soils and geo-textiles were sampled and their PCDD/F contents were analyzed. MSWI residue show a great heterogeneity but also high amounts of PCDD/F (14-2960 ng I-TEQ kg(-1)dm). Soils underlying the road show less heterogeneity and PCDD/F contents between 0.57 and 7.23 ng I-TEQ kg(-1)dm, lower than ordinary soils. Moreover, the specific analysis of the 17 toxic PCDD/F congeners (notably the 2,3,7,8-TetraCDD) indicates the very low harmfulness of road soils. The study also allows to assert the relation between the MSWI residue particle size and the PCDD/F content. PMID:18986676

Se-79 is a long-lived radionuclide of potential radiological significance in relation to the deep geological disposal of solid radioactive wastes. In the context of release to the terrestrial environment, its main radiological impact is delivered through food chain pathways. Therefore, its accumulation in soils and uptake by plants is an important consideration in post-closure safety assessment studies. However, representation of its behaviour in the soil-plant system requires consideration of the multiple valence states that it can exhibit under different redox conditions and its susceptibility to volatilisation. A simple model is described that includes seasonal variations in soil hydrology and their effects on the mobility and root uptake of Se-79. Illustrative calculations are undertaken with the model, to demonstrate its capabilities for interpreting experimental data on the behaviour of Se-79 in soils and plants, and for making projections on the long-term behaviour of Se-79 transported to soils. PMID:22327104

This study evaluated the efficacy of soil washing with a nonionic surfactant (Brij98) in combination with a complexing reagent (ethylenediaminedisuccinic acid, [S,S]-EDDS) for the simultaneous mobilization of macro- and trace elements (MTEs) and PAH compounds from a field-contaminated soil. Soil fractionation studies indicated that an appreciable fraction of the Al, Ca, Cu, Fe and Mn was associated with the residual fraction but that much of the other trace elements (As, Cd, Cr, Ni, Pb and Zn) might be susceptible to soil washing. Ultrasonically aided mixing of the field contaminated soil with Brij98 and a sparing quantity (2mmol) of [S,S]-EDDS, simultaneously mobilized virtually all of the benzo[a]pyrene {B(a)P} and chrysene (CRY) and appreciable quantities of the trace elements (Cd, Cr, ...

2 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a patch of frost-covered, dark sand that, at the time the picture was acquired in June 2005, had begun to defrost. The frost is carbon dioxide. Dunes and other patches of sand are usually the first polar features to develop dark spots as the frost begins to sublime away. Location near: 78.9oS, 80.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

8 May 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dunes in the north polar region of Mars. The dunes in this scene are covered by a layer of carbon dioxide frost that accumulated during the winter in 2005. Dark spots indicate areas where frost has begun to sublime away. In summer, the dune field will be dark, as all of the frost will be gone and the iron- and magnesium-bearing silicate sands will be exposed. Location near: 81.9oN, 226.1oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Spring

Although of great interest for science and resource utilization, the Moon's permanently shadowed regions (PSRs) near each pole present difficult targets for remote sensing. The Lyman Alpha Mapping Project (LAMP) instrument on the Lunar Reconnaissance Orbiter (LRO) mission is able to map PSRs at far-ultraviolet (FUV) wavelengths using two faint sources of illumination from the night sky: the all-sky Ly? glow produced as interplanetary medium (IPM) H atoms scatter the Sun's Ly? emissions, and the much fainter source from UV-bright stars. Since the reflected light from these two sources produces only a few hundred events per second in the photon-counting LAMP instrument, building maps with useful signal-to-noise (SNR) ratios requires the careful accumulation of the observations from thousands of individual LRO orbits. In this talk we present the latest FUV albedo maps obtained by LAMP of the Moon's southern and northern polar regions. The results show that 1) most PSR regions are darker at all FUV wavelengths, consistent with their surface soils having much larger porosities than non-PSR regions (e.g., P~0.9 or so), and 2) most PSRs are somewhat "redder" (i.e., more reflective at the longer FUV wavelengths) than non-PSR regions, consistent with the presence of ~1-2% water frost at the surface.

The phenomenon of interaction of particles with solid-liquid interfaces that results in particle engulfment or pushing (PEP) has been Studied since mid 1960's. While the original interest stemmed from geology applications (frost heaving in soil), it was recognized early that understanding particle behavior at solidifying interfaces mi ht yield 9 practical benefits in other fields. In metallurgical applications the issue is the location of particles with respect to grain boundaries at the end of solidification. Considerable amount of experimental and theoretical research was lately focused on applications to metal matrix composites produced by casting; or spray forming techniques. Another application of PEP is in the growing of Y1Ba2CU3O7-delta(123) superconductor crystals from an undercooled liquid. The oxide melt contains Y2Ba1CU1O5 (211) precipitates, which act as flux pinning sites. The paper presents results of PEP micro-gravity research performed by the authors on two shuttle missions using metallic and polymeric materials. In addition. a discussion on the theoretical aspects of the physics of PEP is offered. Analytical and numerical models for planar solidification interfaces developed by the authors are used to explain the experimental results. Shortcomings of steady-state models are emphasized. A numerical model that includes the effect of the solutal field and of natural convection is introduced. A discussion of phenomena associated with dendritic solidification based on experimental observations is also offered. A mechanism of engulfment is proposed.

An innovative method of transporting heavy oil without diluent is described. The method involves heat conservation, and is used by the East Central Heavy Oil (ECHO) Pipeline in Alberta. The 153 km pipeline between Elk Point and Hardisty is buried two meters underground to minimize the impact of frost and is protected by two inches of insulation to prevent heat loss and thawing of surface soils. The system uses elevated temperatures to reduce viscosity and induce flow. The pipeline has transported 30,000 bbls of crude oil per day prior to the drop in world oil prices. The ultimate capacity of ECHO is 50,000 bbls per day. The 12-inch insulated line, complete with heater and booster station, allows producers to deliver hot oil of up to 90 degrees C. Savings accrue from the elimination of the need to transport condensate to the battery site for blending and then move the blended crude back to the delivery point for injection. Another advantage is the possibility of choice of condensates that producers ultimately want added to their crude at the Hardisty terminal before the crude enters the Interprovincial Pipe Line system.

A simple method of analysis was proposed to characterize the impact of climatic conditions of a wide region of Argentina (from 27°05'S to 35°48'S, from 61°5'W to 64°21'W) on potential maize ( Zea mays L.) grain yield, and the occurrence of various climatic constraints (low temperatures and low soil water content, frost, drought stress and heat stress) along the cycle. The analysis was based on previous studies of the eco-physiology of maize crops and the use of climatic records of six locations in the region under study. Results were analyzed using a probabilistic method, later organized as a checklist to consider when deciding on sowing date in a location of the region. Thus, for each production scenario (combination of location and sowing date), farmers would have a tool enabling them to pay particular attention to the restrictions more likely to occur, to include some cultural practices to avoid or mitigate the most severe climatic constraint to maize production.

After land abandonment for five decades (Arnáez et al., 2010; Belmonte Serrato et al., 1999) as a widespread process in Spain, agriculture intensification is taken place. This is changing the nature of the soil erosion processes as they were known (Cerdà, 1997; Cammeraat and Imeson, 1999; Ruiz Sinoga et al., 2010; Zavala et al., 2010). Citrus production are being reallocated on slopes due to the new irrigation systems (drip-irrigation), the thermic inversion on the bottom of the valley and then the frost affecting the plantations, the high prices of the bottom valley lands and the investment in agriculture from other economic sectors such as tourism and industry. Those new plantations are based on intense pesticides and herbicides use, and erosion processes are triggered due to the sloping surface developed (Cerdà et al., 2010). Five study sites were selected in the Montesa Municipality research zone, where an increase in the orange and clementines plantations were found during the last 20 years. Measurements were perfomed by a simple method, which consist in measuring the surface characteristics: stoniness, crust, herbs, bare soil, sheet flow, rills and gullies. One thousand meters were monitored at each of the study sites and measurements were done in January and August with a precision of 1 cm. The results show that the erosion rates are controlled by the sheet erosion (78,4 %), although rill and gullies exist (citrus plantations results in low infiltration rates, and high erosion rates. This is contributing to a non-sustainable agriculture production due to the high erosion rates. And also a lack in soil services as the surface runoff and then the soil erosion is enhanced; and soil infiltration reduce. The economical value of the land and water lost is making this new intense chemically managed new citrus plantation non sustainable. The intensification of agriculture is triggering new soil erosion processes to be added to the traditional ones (García Ruiz and López Bermúdez, 2009). This research study is being supported by the the research project CGL2008-02879/BTE

Abstract in portuguese Avaliaram-se 18 linhagens e duas cultivares de trigo, em experimentos instalados em condição de irrigação por aspersão, solo corrigido e adubado, na Estação Experimental de Agronomia de Tatuí (SP), em 1999 e 2000. Determinaram-se as seguintes características agronômicas: produção de grãos, altura das plantas, ciclo - em dias - da emergência ao florescimento, número de grãos por espiga, massa de cem grãos e comprimento, largura e espessura dos grãos. Corr (more) elações simples entre todas essas características foram estimadas para os dois experimentos. As geadas ocorridas na época de enchimento dos grãos, em 2000, ocasionaram em todos os genótipos de trigo redução nas produção de grãos e, na maioria dos genótipos, no número de grãos por espiga e na massa de cem grãos. Os genótipos mais altos tenderam ser menos afetados pela ação das geadas. Destacaram-se, em 1999, o genótipo 9 (BANACORA T 88) pelo porte baixo; os genótipos 2 (KAUZ*2/MNV//KAUZ), 9 e 14 (WH 542) pelo maior número de grãos por espiga e, o genótipo 3 (SAWGAI) pela maior massa de cem grãos, constituindo-se em fontes genéticas dessas características para programas de cruzamentos de trigo. Abstract in english Eighteen wheat lines and two cultivars were evaluated in trial carried out under sprinkler irrigation, limed and fertilized soils, at the Tatuí Agronomy Experimental Station, State of São Paulo, Brazil during 1999 and 2000. Grain yield, plant height, number of days from emergence to flowering, number of grains per spike, 100 grain weight, grain length, width and thickness were evaluated. Simple correlations between these characteristics were estimated. The occurrence of (more) frosts at grain filling period, in 2000, resulted in grain yield reduction in all genotypes, reduction in the number of grains per spike, and also in 100 grain weight for the majority of the genotypes. The highest genotypes showed a tendency to be less affected by the frosts. The genotype 9 (BANACORA T 88) exihibited short plants; the genotypes 2 (KAUZ*2/MNV//KAUZ), 9 and 14 (WH 542) presented high number of grains per spike and the genotype 3 (SAWGAI) high 100 grain weight, in the experiment seeded in 1999. These genotypes could be used as genetic sources in crossing programs, where these traits would be desired.

Abstract in portuguese O conhecimento das relações entre propriedades físicas e mecânicas do solo pode contribuir no desenvolvimento de funções de pedotransferência, que permitam estimar outras propriedades do solo de difícil mensuração. Neste trabalho, objetivou-se avaliar a relação entre a susceptibilidade à compactação e o suporte de carga com propriedades físicas de solos do sul do Brasil. Foram avaliadas a resistência à penetração, a umidade, a densidade e a compressibi (more) lidade de seis solos. A resistência à penetração pode ser estimada pelo modelo que considera a umidade e densidade do solo. Solos com maior densidade inicial apresentaram menor susceptibilidade à compactação e menor deformação, quando submetidos a pressões externas. Quanto maior a resistência do solo à penetração, menor é a deformação e maior é a capacidade de suporte de carga, embora isso não indique solos com qualidade física adequada para as culturas; quanto maior a deformação do solo, maior a susceptibilidade à compactação e menor a capacidade de suporte de carga. A susceptibilidade de um solo à compactação e sua capacidade de suporte de carga podem ser estimadas, respectivamente, pela densidade inicial e pela resistência do solo à penetração. Abstract in english Quantifying the relationship between physical and mechanical soil properties can contribute to the development of pedotransfer functions that allow estimating hard-to-measure soil properties. The objective of this study was to evaluate the interrelations between susceptibility to compaction and load support with some physical properties of soils from Southern Brazil. Penetration resistance, moisture, bulk density and compressibility of six soils were evaluated. In a model (more) including soil moisture and bulk density as independent variables, the relation with penetration resistance values obtained in the field was high. Soils with higher initial bulk density were less susceptible to compaction and exhibited less deformation under external loads. With increasing soil penetration resistance, less deformation and greater load support were observed, which does not necessarily indicate a satisfactory soil physical quality for crop cultivation. The greater the soil deformation, the higher is the susceptibility to compaction and the lower is its load support. The compaction susceptibility and load support of a soil can be estimated, respectively, by its initial bulk density and resistance to penetration.

The content of water-dispersible colloids (WDC) in a soil can have a major impact on soil functions, such as permeability to water and air, and on soil strength, which can impair soil fertility and workability. In addition, the content of WDC in the soil may increase the risk of nutrient loss and of colloid-facilitated transport of strongly sorbing compounds. In the present study, soils from the Bad Lauchstädt long-term static fertilizer experiment with different management histories were investigated to relate basic soil properties to the content of WDC, the content of water-stable aggregates (WSA), and aggregate tensile strength. Our studies were carried out on soils on identical parent material under controlled management conditions, enabling us to study the long-term effects on soil physical properties with few explanatory variables in play. The content of WDC and the amount of WSA were measured at a series of time steps giving a colloid release and aggregate disaggregation rate and a quantification of the content of WDC and WSA at a given time for each of the six investigated experimental field plots. The content of WDC in the moist soil was linearly correlated (r = 0.82* [P < 0.05]) to the part of the total clay not associated with organic matter. No significant difference in release rate was found for air-dry aggregates. The low-carbon soils initially had a higher content of WSA but were more susceptible to disaggregation than the high-carbon soils. Furthermore, the application of NPK fertilizer had a destabilizing effect on the WSA and also caused a decrease in the cation exchange capacity of the soils. The mean tensile strength was positively correlated to the colloid release rate and the content of WDC after 2 min of shaking and therefore to the amount of clay not associated with organic carbon

Water treeing problems encountered in the Netherlands in some medium voltage cables prompted the authors to develop a test with which the degradation of the insulation of extruded cable could be characterized. The test method is described. It was demonstrated to be effective. It revealed that 20% of the network cables examined were defective and needed replacement. In evaluating the results, it is shown that the water tree susceptibility of some cables can be correlated to specific manufacturers or unknown parameters in their production process. However, it was not possible to isolate the cause of this susceptibility to any of the following parameters along: crosslinking process, conductor shields or wet soils.

Ground-penetrating radar (GPR) has been used to study the variations in the depth of the frost table throughout a complete thaw-freeze season in Kangerlussuaq Airport, western Greenland. In autumn 2000, three test areas were painted white on the parking area of the airport in order to reduce further development of depressions in the asphalt pavement. One of these areas has been used in the GPR investigations to compare the variations of the frost table underneath a normal dark asphalt surface to that below a more reflective surface. The GPR results have shown a clear correlation between the use of the reflective surface and a reduced depth to frost table. In late summer the difference in the depths to the frost table is approximately 0.9 m. The results should promote the interest in the development and use of light colored pavement materials in order to reduce the effect of a warming climate on arctic infrastructures.

...Export Trade Certificate of Review to Northwest Fruit Exporters on August 12, 2011. The Certificate...Chief Orchards LLC (Yakima, WA), Dovex Fruit Co. (Wenatchee, WA), and Jack Frost Fruit Co. (Yakima, WA); and 3. Change the...

This paper uses high-order categorical non-stationary Markov chains to model the occurrence of extreme temperature events, in particular frost days. These models can be applied to estimate: the probability that a given day in the future is a frost day (below zero); the probability that a given period is frost-free; the distribution of the length of the frost-free period. These quantities then can be used for pricing of weather derivatives. Several stationary and non-stationary high-order (yet parsimonious) Markov models are proposed and compared using AIC and BIC. Partial likelihood theory is used to estimate the parameters of these models. We show that optimal (in terms of AIC/BIC) non-stationary Markov models that have constant ?Markov coefficients? (across the year) are not adequate to ...

Radiant frost is a major abiotic stress, particularly at the reproductive stage, in field pea (Pisum sativum L.) grown in Mediterranean environments. Here, response to frost was studied for flowering stage (FS) organs (buds, flowers and set pods) and pod development stage (PDS) organs (flat, swollen and mature pods) under controlled conditions, with plants exposed to a minimum temperature of ?4.8?C for 4?h. This frost treatment adversely affected seed yield through (i) abortion of buds, flowers and set pods (ii) death of pods and (iii) reduction in seed size. FS organs were more sensitive to frost than PDS organs. Genetic variation was observed among 83 accessions collected from 34 countries worldwide for survival of FS buds, flowers and set pods. In 60 of 83 accessions, no buds, flowers o...

MGS MOC Release No. MOC2-532, 2 November 2003As seasonal polar frosts sublime away each spring, winds may re-distribute some of the frost or move sediment exposed from beneath the frost. This action creates ephemeral wind streaks that can be used by scientists seeking to study the local circulation of the martian [missing text] surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of wind streaks created in subliming carbon dioxide frost. These dark streaks appear to conform to the shape of the slopes on which they occur, suggesting that slope winds play a dominant role in creating and orienting these streaks. This picture is located near 73.8oS, 305.7oW. The image is illuminated by sunlight from the upper left and covers an area 3 km (1.9 mi) wide. Winds responsible for the streaks generally blew from the bottom/right (south/southeast) toward the top/upper left (north/northwest).

Compact tube-fin evaporators have been extensively used in refrigeration cassettes for light commercial applications. Such refrigeration systems are space constrained and, therefore, the heat exchangers (condenser and evaporator) must have a large area-to-volume ratio. In addition, such applications require a subfreezing evaporating temperature that induces the growth of a frost layer on the finned surface, which may block the evaporator if a proper defrost strategy is not used. Before completely blocking the evaporator, the frost layer depletes the heat exchanger performance by adding an extra thermal resistance and also by reducing the fan-supplied air flow rate. Understanding the way the frost forms on these compact heat exchangers and also the way the fan is affected by frost clogging ...

In this thesis I studied responses of three biennial, monocarpic plants Erysimum strictum, Gentianella amarella, and G. campestris, to various aspects in resource availability (i.e. competition, mineral nutrition, neighbor removal) and environmental stress (early frost) at adult or rosett...

An 11-month-old boy presented with bilateral vision loss following upper respiratory tract infection. Extensive perivascular sheathing resembling frosted branch angiitis and severe macular edema was noted in both eyes. All tests for etiological diagnosis were negative. Treatment with systemic corticosteroids and antibiotics caused resolution of perivascular infiltrates. Macular edema resolved with improvement in visual acuity following consecutive bilateral intravitreal triamcinolone acetonide injections. To our knowledge, this is the youngest reported case of frosted branch angiitis.

Abstract in portuguese O objetivo deste trabalho foi determinar, pelo uso do modelo de capacidade de suporte de carga, o efeito do tráfego das operações de colheita florestal na pressão de preconsolidação (sigmap), durante um ciclo do eucaliptus. O trabalho foi realizado com amostras indeformadas, coletadas na superfície do horizonte A e no topo do horizonte B de um Argissolo Amarelo, de um Plintossolo e de um Latossolo Amarelo. As amostras indeformadas foram usadas nos ensaios de compre (more) ssão uniaxial. A amostragem foi realizada antes e depois das operações de colheita. As operações realizadas com o Forwarder causaram maior compactação do solo do que as operações realizadas com o Feller Büncher e o Harvester. A porcentagem de amostras de solo, na região onde ocorre compactação adicional, indicou que o Argissolo Amarelo foi mais suscetível à compactação, seguido do Plintossolo e do Latossolo Amarelo. Apesar de o Argissolo Amarelo ser a classe de solo mais suscetível à compactação, a regeneração da estrutura nesta classe de solos foi mais evidente do que no Plintossolo. As porcentagens de amostras de solo com sigmap situados na região em que ocorreu compactação adicional em 1996, 1998 e 2004, após as operações de colheita, indicaram uma exploração sustentável da floresta nesse período. Abstract in english The objective of this work was to determine, through the use of the bearing capacity model, the traffic effects of the forest harvest operations on the preconsolidation pressure (sigmap), during one cycle of the eucalyptus plantation. The work was conducted using undisturbed soil samples, collected at the surface of the A horizon and in the top of the B horizon of an Udult (PA), Aquox (FX) and Udox (LA) soils. The undisturbed soil samples were used in the uniaxial compres (more) sion tests. The soil sampling was done before and after the harvest operations. The operations performed with the Forwarder caused greater soil compaction than the ones done with the Feller Büncher and Harvester. The percentage of soil samples, in the region with additional soil compaction, indicated that the Udult was the soil class more susceptible to soil compaction, followed by the Aquox and Udox. Despite Udult is the more susceptible to soil compaction, the regeneration of the soil structure in this soil class was more efficient than in Aquox. The percentage of soil samples with sigmap values in the region with additional soil compaction in 1996, 1998 and 2004, after harvest operations, indicated a sustainable forest exploration in this period.

This paper reviews the potential of trace/heavy metal-induced stress to reduce plant frost hardiness at northern high latitudes. The scientific questions are first outlined prior to a brief summary of heavy metal tolerance. The concepts of plant capacity and survival adaptation were used to formulate a hypothesis, according to which heavy metal stress may reduce plant frost hardiness for the following reasons: (1) Heavy metals change membrane properties through impaired resource acquisition and subsequent diminution of the cryoprotectant pool. (2) Heavy metals change membrane properties directly through oxidative stress, i.e. an increase of active oxygen species. (3) The involved co-stress may further increase oxidative stress. (4) The risk of frost injury increases due to membrane alterations. An opposite perspective was also discussed: could metal stress result in enhanced plant frost hardiness? This phenomenon could be based on the metabolism (i.e. glutathione, polyamines, proline, heat shock proteins) underlying a possible general adaptation syndrome of stress (GAS). As a result of the review it was suggested that metal-induced stress seems to reduce rather than increase plant frost hardiness. - Metal stress may reduce plant frost hardiness.

Residual soils are products of chemical weathering and thus their characteristics are dependent upon environmental factors of climate, parent material, topography and drainage, and age. These conditions are optimized in the tropics where well-drained regions produce reddish lateritic soils rich in iron and aluminum sesquioxides and kaolinitic clays. Conversely, poorly drained areas tend towards montmorillonitic expansive black clays. Andosols develop over volcanic ash and rock regions and are rich in allophane (amorphous silica) and metastable halloysite. The geological origins greatly affect the resulting engineering characteristics. Both lateritic soils and andosols are susceptible to property changes upon drying, and exhibit compaction and strength properties not indicative of their classification limits. Both soils have been used successfully in earth dam construction, but attention must be given to seepage control through the weathered rock. Conversely, black soils are unpopular for embankments. Lateritic soils respond to cement stabilization and, in some cases, lime stabilization. Andosols should also respond to lime treatment and cement treatments if proper mixing can be achieved. Black expansive residual soils respond to lime treatment by demonstrating strength gains and decreased expansiveness. Rainfall induced landslides are typical of residual soil deposits.

This study evaluated the efficacy of soil washing with a nonionic surfactant (Brij98) in combination with a complexing reagent (ethylenediaminedisuccinic acid, [S,S]-EDDS) for the simultaneous mobilization of macro- and trace elements (MTEs) and PAH compounds from a field-contaminated soil. Soil fractionation studies indicated that an appreciable fraction of the Al, Ca, Cu, Fe and Mn was associated with the residual fraction but that much of the other trace elements (As, Cd, Cr, Ni, Pb and Zn) might be susceptible to soil washing. Ultrasonically aided mixing of the field contaminated soil with Brij98 and a sparing quantity (2 mmol) of [S,S]-EDDS, simultaneously mobilized virtually all of the benzo[?]pyrene {B(a)P} and chrysene (CRY) and appreciable quantities of the trace elements (Cd, Cr, Mn, Ni, Pb, Zn) burdens. The recovery of both PAHs and trace elements were increased from the soil organic matter (SOM)-rich soil. This report concerns the fate of MTEs during soil washing. Multiple ultra-sonically aided washes (five or nine) with the same dosage of reagents mobilized virtually all of PAHs and decreased the levels of Cd, Cr, Ni, Pb and Zn to comply with recommended maxima. By contrast, the levels of As and Cu remained excessive after the treatments. PMID:22023908

Although the virgin soil has a high organic matter content that reduces the soil's susceptibility to compaction, the high weight of the tractors used for land clearing cause a high degree of soil compaction. This study was performed in the Calden (Prosopis Caldenia Burkart) forest at La Pampa State, in West Argentina. The object of this study was to assess the soil compaction during mechanical land clearing with heavy machinery. Variables measured were (CI) cone index, (BD) dry bulk density, tractor rut depth (TRD) and Proctor test. The land clearing was performed with a Caterpillar tractor D6, with 0.7x2.3m metallic tracks. The engine power was 300kW and the weight was 18 Mg. The relevant results were as follows: in topsoil (0-0.2m) 1 and 2 passes of a tractor caused mean CI values of 183...

Low available phosphorus (P) is a serious constraint for crop production in acidic tropical soils. Economical yields in these environments require application of large amounts of costly nitrogen (N) and P fertilizers. Although phosphate rock (PR) has been proposed as a less expensive P source, the slow P release to the soil limits its use for annual crops. The objective of this work was to examine the effect of inoculating a nonsterile acidic soil with vesicular arbuscular mycorrhizal (VAM) Gigaspora margarita on PR dissolution and P uptake by aluminum (Al)-tolerant maize inbreds. Three maize inbreds from CIMMYT, at Cali, Colombia, ranked as Al-tolerant and one local breed ranked as Al-susceptible were seeded in 4-kg pots filled with a soil of pH 4.1 and 2.5 mg kg-1 availabl...

Soils in tropical montane cloud forests contain large amounts of organic carbon but few data are available on the flux of carbon dioxide (CO2) from them. Routine methods used to measure soil CO2 efflux, however, may be susceptible to measurement artifact in these ecosystems due to the high porosity and low bulk density of their soils. Here, we measured soil CO2 efflux in two tropical montane cloud forests, one lowland tropical forest and a garden lawn in the Peruvian Andes-Amazon and used 'swap tests' (repeated alternating measurements) to explore sources of measurement artifact when using two different closed-dynamic chamber systems (made by LI-COR Biosciences, NE, USA): a 'multiplexed system', consisting of 104-long term chambers, 8150-multiplexer and 8100-infra-red-gas analyzer (IRGA); ...

Understanding how environmental variables affect the processes that regulate the carbon flux over grassland is critical for large-scale modeling research, since grasslands comprise almost one-third of the earth's natural vegetation. To address this issue, fluxes of CO{sub 2} (F{sub c}, flux toward the surface is negative) were measured over a Mediterranean, annual grassland in California, USA for 2 years with the eddy covariance method. To interpret the biotic and abiotic factors that modulate F{sub c} over the course of a year we decomposed net ecosystem CO{sub 2} exchange into its constituent components, ecosystem respiration (R{sub eco}) and gross primary production (GPP). Daytime R{sub eco} was extrapolated from the relationship between temperature and nighttime F{sub c} under high turbulent conditions. Then, GPP was estimated by subtracting daytime values of F{sub c} from daytime estimates of R{sub eco}. Results show that most of carbon exchange, both photosynthesis and respiration, was limited to the wet season (typically from October to mid-May). Seasonal variations in GPP followed closely to changes in leaf area index, which in turn was governed by soil moisture, available sunlight and the timing of the last frost. In general, R{sub eco} was an exponential function of soil temperature, but with season-dependent values of Q{sub 10}. The temperature-dependent respiration model failed immediately after rain events, when large pulses of R{sub eco} were observed. Respiration pulses were especially notable during the dry season when the grass was dead and were the consequence of quickly stimulated microbial activity. Integrated values of GPP, R{sub eco}, and net ecosystem exchange (NEE) were 867, 735, and -132g C m{sup -2}, respectively, for the 2000-2001 season, and 729, 758, and 29g C m{sup -2} for the 2001-2002 season. Thus, the grassland was a moderate carbon sink during the first season and a weak carbon source during the second season. In contrast to a well-accepted view that annual production of grass is linearly correlated to precipitation, the large difference in GPP between the two seasons were not caused by the annual precipitation. Instead, a shorter growing season, due to late start of the rainy season, was mainly responsible for the lower GPP in the second season. Furthermore, relatively higher R{sub eco} during the non-growing season occurred after a late spring rain. Thus, for this Mediterranean grassland, the timing of rain events had more impact than the total amount of precipitation on ecosystem GPP and NEE. This is because its growing season is in the cool and wet season when carbon uptake and respiration are usually limited by low temperature and sometimes frost, not by soil moisture.

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

Previous studies have demonstrated that microcosms with field collected soil nematode and microarthropod communities are suitable model systems to detect effects of toxins on soil food web structure and function. The authors investigated the toxicity of copper, cadmium, malathion, and Aroclor 1254 to nematodes (total, bacterivores, fungivores, herbivores, omnivore-predators, hatchlings) and microarthropods (Prostigmata, Mesostigmata, Oribatida, Collembola, other arthropods). Nematodes were sensitive indicators of copper application, and total numbers were reduced at 100 {micro}g g{sup {minus}1}. Fungivore, bacterivore and omnivore-predators were the most susceptible trophic groups. Cadmium had no effects on either nematode or microarthropod communities. Microarthropods were more sensitive to malathion than nematodes, and total microarthropod abundance was lower than controls at 320 {micro}g g{sup {minus}1}. Prostigmatid mites and other arthropods were the most affected groups. Only the herbivore nematode trophic group was affected by malathion, and numbers did not decline until 1,280 {micro}g g{sup {minus}1}. Aroclor 1254 also had a greater negative impact on microarthropods than on nematodes. Total microarthropod abundance declined at 2,500 {micro}g g{sup {minus}1}, while there was no effect on nematodes. Prostigmatid and oribatid mites were the most susceptible groups to PCB application. Strong differential sensitivity between nematode and microarthropod communities indicates that both groups need to be examined to fully evaluate the impact of chemicals on soil systems. The authors conclude that microcosms with field-collected communities of soil microfauna offer high resolution of the ecotoxicological effects of chemicals in complex soil systems.

The role of fire in shaping steep, forested landscapes depends on a suite of hydrologic, biologic, and geological characteristics, including the propensity for hydrophobic soil layers to promote runoff erosion during subsequent rainfall events. In the Oregon Coast Range, several studies postulate that fire primarily modulates sediment production via root reinforcement and shallow landslide susceptibility, although few studies have documented post-fire geomorphic response. Here, we describe field observations and topographic analyses for three sites in the central Oregon Coast Range that burned in 1999, 2002, and 2003. The fires generated strongly hydrophobic soil layers that did not promote runoff erosion because the continuity of the layers was interrupted by pervasive discontinuities tha...

Mumbai metropolitan region (MMR) in India represents one of the most industrialized and thickly populated areas of the monsoon dominated Asian region. We present here pre- and post-monsoon magnetic susceptibility variations in the top-soils representing sampling domains of industrial, heavy traffic and forested areas within MMR. The rock magnetic studies (including isothermal and anhysteric remanent magnetization and hysteresis loop analysis) infer predominant pseudo single domain to multi domain grains in an overall ferrimagnetic dominant mineralogy of the soils. The susceptibility-temperature variations (from ?190 to 700?C) infer maghemite (?-Fe2O3) as the chief mineral component of pedogenic origin, and the pure magnetite (Fe3O4) is of anthropogenic nature. Spatial distribution of ferri...

The antimicrobial susceptibility of 50 Clostridium difficile isolates, 36 of them from horse feces and 14 from environmental sites, was determined by broth microdilution. The antimicrobial agents tested were avilamycin, cephalothin, chloramphenicol, clindamycin, erythromycin, gentamicin, neomycin, oxacillin, oxytetracycline, penicillin, spiramycin, streptomycin, trimethoprim/sulfamethoxazole, vancomycin, and virginiamycin. All isolates were susceptible to vancomycin (MIC 16 microg/ml), oxytetracycline (MIC >/=32 microg/ml), spiramycin (MIC > 16 microg/ml), and virginiamycin (MIC 8-16 microg/ml) were higher for 18 isolates. Those were mainly isolated from horses at animal hospitals and further from environmental sites at a stud farm. In contrast, all isolates, except one, from healthy foals had low MICs of erythromycin, spiramycin, virginiamycin, and oxytetracycline. The isolates from soil in public parks had also low MICs of these antimicrobial agents. Broth microdilution appeared both reliable and reproducible for susceptibility testing of C. difficile. The method was also readily performed and the MIC endpoints were easily read. PMID:15140395

In the course of the 21st century, thawing of permafrost is expected to occur in large areas as a consequence of climate change, which could trigger a number of climatic feedback mechanisms on the local to global scale. As the vast and remote permafrost areas cannot be sufficiently covered by ground-based monitoring of soil temperatures in boreholes alone, it is desirable to exploit the wealth of multi-sensor-multi-source data to assess the thermal ground conditions on large scales. In Norway, permafrost conditions range from mountain permafrost over organic-rich wetlands to high-arctic permafrost in Svalbard. Furthermore, the availability of gridded data sets from various sources makes it a well-suited test region to evaluate the performance of soil thermal models run with different input data, which facilitates comparing and benchmarking requirements on data quality. Soil temperatures can be modeled using Fourier's law of heat conduction, so that the key challenge is to supply accurate time series of three key input variables at suitable spatial and temporal resolutions: 1. land surface temperature, 2. snow depth, and 3. soil and snow thermal properties. We developed a framework for transient and distributed modeling the ground thermal regime in Norway, CryoGRID 2.0. In the model, the subsurface heat flow is treated in terms of 1D heat conduction using the land or snow surface temperature as upper boundary condition. The model features a dynamical representation of the snow cover and explicitly accounts for the heat flux through the snow pack. The spatio-temporal distribution of ground temperatures is calculated for a spatial resolution of 1 km for mainland Norway. The model is driven by operationally gridded data of daily air temperature and snow depth available at http://senorge.no. These datasets are available for the period 1957 to date having a spatial resolution of 1 km2. Spatial distributions of the ground thermal properties (e.g. heat conductivity), surface cover (e.g. vegetation, block fields) were derived from geological maps, borehole measurements and remotely-sensed data. We present preliminary results from model runs to demonstrate the capacity of the approach to simulate permafrost distribution, and duration of seasonal frost and discuss strategies to reduce computational cost, hence to make the model applicable to large datasets.

Measures preventing an earthquake-induced soil liquefaction are of significant importance to mitigate the liquefaction hazards. An air-injection technique may be a simple, inexpensive method - this leads the saturated soils to the desaturated by injecting pressurized air, resulting in a higher liquefaction strength and lower susceptibility. The objective of this study is to investigate the evolution of desaturation process during air injection into saturated soil deposits and verify the validity of a multiphase flow simulator if it is capable of being applied for predicting the process as well as the distribution of degree of saturation after the air injection ceased. In this study simplified model tests that simulate the air injection into saturated soils using air-injection probes, are conducted using two different sizes of soil containers. The experiments using the small container are aimed to examine the nominal rates and magnitudes of the soil desaturation driven by air injection, whilst those with the large container are performed to obtain not only the rates and magnitudes but also the distributions of the desaturated zones within the soil. The results obtained indicate, although clearly depending on the physical properties of targeted soils, that the evolution of desaturation is strongly controlled by the air pressures injected and the soil permeabilities. Numerical analyses are also conducted using a multiphase flow simulator to describe the evolution of the soil desaturation, and to examine the applicability of the model as a prediction tool enabling an evolution of desaturation in situ to be followed with time and space. Predictions show a relatively good agreement with the experimental measurements regarding the rates, magnitudes, and distribution of desaturation specifically for the small-container experiments although predictions of desaturated domain slightly overestimate the measurements for the large-container experiments. Thus, this study indicates that the numerical model described is applicable to field problems when the soil properties in terms of flow transport are well-constrained.   

In steep mountainous regions, landslides may include both soil and underlying weathered bedrock (hereafter, —deep catastrophic landslides•). The method for assessing susceptibility to deep catastrophic landslides, originally developed for landslides caused by heavy rain, was tested in this study against historical landslides caused by the Iwate and Miyagi inland earthquake of 2008. The method proved to be capable of independently identifying catchments in which deep catastrophic landslides occurred with fair accuracy.   

Winter wheat - summer fallow is the crop rotation used on more than 1.5 million ha in the Pacific Northwest United States. Land maintained using conventional summer fallow is susceptible to wind erosion because multiple tillage operations during the fallow period expose the soil to high winds. Alternative management strategies are needed that protect the soil surface from erosion during summer fallow. Surface characteristics were examined after subjecting the loessial soil to seven (conventional), five (reduced), three (minimum), and zero (no) tillage operations during the fallow period. Surface residue biomass and roughness and soil crust, aggregation, strength, and water content were measured after tillage and sowing operations. No tillage resulted in a more persistent and thicker soil crust and greater residue cover, silhouette area index (SAI), and penetration resistance than conventional and reduced tillage. For those treatments subject to tillage, minimum tillage resulted in a thicker soil crust and greater residue cover, SAI, ridge roughness, mean aggregate diameter, and penetration resistance as compared to conventional or reduced tillage after primary tillage. Near the end of the fallow period, minimum tillage resulted in 15% greater residue cover than conventional tillage. Soil loss from minimum tillage is expected to be 50% of conventional tillage based upon these differences in residue cover. This study suggests that minimum tillage is an alternative strategy to conventional tillage for reducing wind erosion in the wheat-fallow region of the Pacific Northwest.

The objectives of this work were: to chemically characterize samples of the Los Angeles sewage sludge, the Domino soil which had been continuously amended with this sludge over a 7-year period (90 Mg.ha/sup -1/.yr/sup -1/) and the unamended Domino soil using neutron activation, inductively coupled argon plasma, and atomic absorption spectroscopy analyses; to physicochemically fractionate sewage sludge and amended soil samples into particle size, density, and magnetic susceptibility fractions so as to concentrate trace metallic element-bearing solids into a few subsamples; and to characterize the sewage sludge and amended soil separates for the characterization and identification of trace metallic element bearing solids. Multi-elemental chemical analyses resulted in elemental concentration data for 35 elements. The Los Angeles sewage sludge was found to contain 7 of these in concentrations exceeding their previously reported sewage sludge concentration ranges. Sludge-amended Domino soil was found to have elevated concentrations of 13 elements in the zone of sludge incorporation. However, only Ce, La, Nd, and Sb were found to accumulate in the Domino soil to concentrations that greatly exceeded their concentration ranges in uncontaminated soils.

Pipelines, fuel storage tanks and other metallic structures are in permanent contact and exposed to different types of soils, of horizons or layers, or of soil aggressiveness. This interaction may cause expressive damages to the environment and to the planned work. Contamination may occur due to leakage of stored products, splitting during transportation, accidents caused by pipelines without extensive maintenance. The result of these accidents could be, among others, some financial losses. In order to recognize the dynamic interactions between metallic surfaces and the environment it is crucial to have preventive actions and to develop better-applied materials. API steel 5L X70 has been used in structures of low and high pressure with high mechanical strength and corrosion and, even so, it is susceptible to etching corrosion since it is in contact with different environments from mangrove regions to industrial environments. The present case evaluated the role of 5L X70 API steel in contact with different soil horizons representative of the Brazilian soil. This investigation correlated chemical species with solute ions in soil solution, secondary and primary phase minerals besides physical and chemical characteristics as pH, electric conductivity, total dissolved solids, among others, to the results of corrosion resistance and ways of corrosion. The evaluation was carried out using x-ray diffractometry, scanning electron microscopy, total reflection x-ray fluorescence, fuel injection flow besides texture and gravimetric analyses to soil characterization and mineralogy, identification of corrosion products, soil solution analyses, evaluation of tested materials and classification of ways and types of corrosion. This was an attempt to integrate the data to a better understanding of the process involving reagents and products. The results showed that different soil horizons such as different types of analyzed soils produce specific etching in metallic structures showing this selectivity. The study also shows that these results can be readily obtained with soil solution as an analytical means in comparison with nowadays evaluations. (author)

Nuclear testing at and around the Nevada Test Site (NTS) resulted in plutonium (Pu) contamination of the soil over an area of several thousands of acres. The objective of this project was to evaluate the potential of five different processes to reduce the volume of Pu-contaminated soil from three different areas, namely Areas 11, 13, and 52. Volume reduction was to be accomplished by concentrating the Pu into a small but highly contaminated soil fraction, thereby greatly reducing the volume of soil requiring disposal. The processes tested were proposed by Paramag Corp. (PARAMAG), Advanced Processing Technologies Inc. (APT), Lockheed Environmental Systems and Technologies (LESAT), Nuclear Remediation Technologies (NRT), and Scientific Ecology Group (SEG). Because of time and budgetary restraints, the NRT and SEG processes were tested with soil from Area 11 only. These processes typically included a preliminary soil conditioning step (e.g., attrition scrubbing, wet sieving), followed by a more advanced process designed to separate Pu from the soil, based on physiochemical properties of Pu compounds (e.g., magnetic susceptibility, specific gravity). Analysis of the soil indicates that a substantial fraction of the total Pu contamination is typically confined in a relatively narrow and small particle size range. Processes which were able to separate this highly contaminated soil fraction (using physical methods, e.g., attrition scrubbing, wet sieving), from the rest of the soil achieved volume (mass) reductions on the order of 70%. The advanced, more complex processes tested did not enhance volume reduction. The primary reason why processes that rely on the dependence of settling velocity on density differences failed was the very fine grain size of the Pu-rich particles.

This paper introduces a series of publications referring to a single 14-month laboratory study testing the hypothesis that the recent decline of Norway spruce (Picea abies (L.) Karst.) at higher elevations of the Bavarian Forest and comparable forests in medium-range mountains and in the calcareous Alps is caused by an interaction of elevated ozone concentrations, acid mist and site-specific soil (nutritional) characteristics. The effect of climatic extremes, a further important factor, was not included as an experimental variable but was considered by testing of the frost resistance of the experimental plants. Results of these individual studies are presented and discussed in the following 14 papers. Plants from six pre-selected clones of 3-year-old Norway spruce (Picea abies (L.) Karst.) were planted in April 1985 in an acidic soil from the Bavarian Forest, or a calcareous soil from the Bavarian Alps. After a transition period, plants were transferred, in July 1986, into four large environmental chambers and exposed for 14 months to an artificial climate and air pollutant regime based on long-term monitoring in the Inner Bavarian Forest. The climatic exposure protocol followed realistic seasonal and diurnal cycles (summer maximum temperature, 26 degrees C; total mean temperature, 9.8 degrees C; winter minimum, -14 degrees C; mean relative humidity, 70%; maximum irradiance, 500 W m(-2); daylength summer maximum, 17 h; winter minimum, 8 h). Plants were fumigated with ozone, generated from pure oxygen (control: annual mean of 50 microg m(-3); pollution treatment: annual mean of 100 microg m(-3) with 68 episodes of 130-360 microg m(-3) lasting 4-24 h), and background concentrations of SO(2) (22 microg m(-3)) and NO(2) (20 microg m(-3)); windspeed was set at a constant 0.6 m s(-1). Plants were additionally exposed to prolonged episodes of misting at pH 5.6 (control) and pH 3.0 (treatment). Simulation of the target climatic and fumigation conditions was highly reliable and reproducible (temperature +/-0.5 degrees C; rh+/-10%; ozone+/-10 microg m(-3);SO(2) and NO(2)+/-15 microg m(-3)). PMID:15092280

Although GIS models have been developed to map alpine permafrost occurrence, their results are often generalized and in some instances have been validated based on limited field data. A field monitoring network of 30 HOBO temperature data loggers were installed at unique sites along Trail Ridge Road during the summer of 2008. Each logger contains a temperature sensor at 10 cm below the surface and a second sensor at depths ranging from 30 to 80 cm. Temperatures were recorded at 2-hour intervals over the course of a year. The Mean Annual Soil Temperature (MAST) at 10 cm was below freezing for 28 of the 30 sites. At 10 cm depth, the MAST was -1.1°C for all sites; at secondary depths ranging from 30 to 80 cm, the MAST was also -1.1°C but had a lower standard deviation. December to February means were -8°C at 10 cm and -6°C at depth. Frost indices averaged 0.56 at the surface, which indicates that sporadic permafrost is present. The active layer likely extends some 1 - 3 m below the surface where permafrost is present. During the early autumn, several sites had “zero curtain” signatures where temperatures at each probe remained at 0°C for an extended period. This suggests convergence of the upward (from the permafrost below) and downward (from the atmosphere above) freezing fronts; constant 0°C temperatures are produced as large quantities of latent heat are released. Some sites exhibited a spring snowmelt signature in which deeper probes have extended period during which the temperature is constant at 0°C after the near surface probe rises above freezing. This likely indicates the flow of snowmelt groundwater at a depth along a "wet line" on the permafrost surface. An example of the Zero Curtain effect for Site 18 during the fall. Field photograph of site 18 at 3,700m.

The tropical leguminous shrub/tree, leucaena (Leucaena spp. mainly leucocephala), and perennial tropical tall grasses such as elephantgrass (Pennisetum purpureum), sugarcane, and energycane (Saccharum spp.) are well adapted to the long growing seasons and high rainfall of the humid lower South. In much of the area the topgrowth is killed by frost during winter and plants regenerate from underground parts in spring. Selected accessions from a duplicated 373 accession leucaena nursery had an average annual woody stem dry matter production of 31.4 Mg ha{sup -1}. Average oven dry stem wood yields from selected accessions adjusted for environmental enrichment over the 4 growth seasons were 78.9 Mg ha{sup -1} total and average annual yield of 19.7 Mg ha{sup -1}. The tall perennial grasses have linear growth rates of 18 to 27 g m{sup 2}d{sup -1} for long periods (140 to 196 d and sometimes longer) each season. Oven dry biomass yields of tall grasses have varied from 20 to 45 Mg ha{sup -1} in mild temperature locations to over 60 Mg ha{sup -1} yr{sup -1} in warm subtropics of the lower Florida peninsula. Tall grasses and leucaena, once established, may persist for many seasons. A map showing the possible range of the crops in lower South is shown. Highest biomass yields of tall grasses have been produced when irrigated with sewage effluent or when grown on phosphatic clay and muck soils of south Florida. Several companies are considering using leucaena and/or tall grasses for bioenergy in the phosphatic mining area of Polk County, Florida.

Devastating weather-related events recorded in recent years have captured the interest of the general public in Belgium. Extreme weather events such as droughts, heat stress, rain storms and floods are projected to increase both in frequency and magnitude with climate change. Since more than half of the Belgian territory is managed by the agricultural sector, extreme events have significant impacts on agro-ecosystem services and pose severe limitations to sustainable agricultural land management. The perspective of rising risk-exposure is exacerbated further by more limits to aid received for agricultural damage (amendments to EC Regulation 1857/2006) and an overall reduction of direct income support to farmers. Current knowledge gaps related to the occurrence of extreme events and the response of agro-ecosystems need to be addressed in conjunction with their vulnerability, resilience and adaptive possibilities. A chain of risks approach starts with assessing the likely frequency and magnitude of extreme meteorological events by means of probability density functions. Impacts are subsequently based on physically based models that provide information on the state of the damage at any given time and assist in understanding the links between different factors causing damage and in determining bio-physical vulnerability. The output of regional bio-physical models is compared with remote sensing based algorithms applied on SPOT-VGT temporal data. Crop damage and risk indicators are derived from remote sensing, meteorological records, crop modelling and agricultural statistics and compared to damage statistics obtained from the government-based agricultural disaster funds. Damages due to adverse meteorological events are strongly dependent on crop type, crop stage and soil type. Spatio-temporal indicators of drought during the growing season and waterlogging at harvest showed the highest agreement with damage, followed by hail and frost. In general potatoes, flax and rape seed are the most vulnerable crops, followed by cereals and sugar beets.

There are several million hectares of marginal agricultural lands available for afforestation in Canada. A fully implemented afforestation program could sequester as much as 28.6 megatons (Mt) of carbon per year (C/y) in above ground biomass alone. Opportunities for carbon storage or, ultimately, feedstock for biofuel production, are likely to be greatest in intensively managed stands of rapidly growing tree species. To achieve high rates of C sequestration, climate and soil conditions in our northern temperate and boreal regions favor poplar and willow. Hybrid poplars, in particular, can reach very high rates of growth. Unfortunately, most available hybrids are adapted to relatively mild climates. Our native forests, however, support four of the five native North American poplar species. Prospects for developing stress-resistant, cold-climate adapted, fast-growing hybrids or intra-species crosses are thus very good. Appropriate selections could greatly increase the potential area that can be successfully planted to poplar. Associated with afforestation using poplar will be a reduced reliance on old-growth and ancient natural forests (and the carbon already banked there) to supply wood fiber for conventional uses. Our aim is to contribute to a national afforestation effort through the development of rapid, cost-effective analyses to identify native poplar genotypes for purposes of carbon sequestration and/or biofuel production. We are investigating plant hormone profiles, carbon isotopic composition, photosynthesis, frost hardiness, and several other physiological parameters in native clones and populations of poplar and cottonwood to form a basis for selecting stock and developing breeding strategies. Experimental crosses will be field tested and successful genotypes entered into field progeny trials. (author)

The average coefficient of performance (COP) of air/water heat pumps shall be further improved over the next decade. Its success will strongly depend on two measures: by altering the characteristic of the heat pump through continuous operation instead of on/off operation, and further, by reducing the formation of frost and ice. Frost significantly reduces the air flow, and consequently also the heat and mass transfer in the fin tube evaporator. The formation of frost and ice is influenced by a complex interaction between the fin tube evaporator, the characteristic of the fan and of the heat pump itself. An accurate prediction of these processes is required to optimize the design of the fin tube evaporator in combination with fan and heat pump to further improve the overall efficiency. Based on the theory of simultaneous heat and mass transfer combined with partial condensation and desublimation, a simulation program for the prediction of frost and ice formation has been developed, being valid over the wide range of the ambient air (from -10 {sup o}C to 15 {sup o}C and dry to saturated air). The humidity is deposited either as condensate, frost, ice or as a combination of them on the fins and tubes of the evaporator. It was a major challenge to create a correlation for the physical properties of the frost and ice layer in the unsteady processes. By numerous experiments, four regions of physical properties are distinguished, depending on the temperature at the boundary layer between air and frost or ice: condensate above -2.7 {sup o}C, condensate and ice between -3.5 {sup o}C to -2.7 {sup o}C, ice and frost between -5.2 {sup o}C to -3.5 {sup o}C and frost formed directly by desublimation below -5.2 {sup o}C. A high reliability has been obtained with the mathematical-physical simulation program proven over the entire applicable range of air temperature and humidity, temperature difference for heat transfer, air velocity and geometry of the fin tube evaporator. (author)

Purposes of this study are unsteady evaluation of thermal performance of heat exchanger with frosting and decision of optimal defrosting cycle. Thermal performance characteristics were examined. The density distribution in the height direction of the frost layer on the flat plate exists under the forced convection. The structure of the frost can't be regarded as homogeneous. The friction coefficients can be arranged by Reynolds number and the equivalent diameter ratio within ±12%.Dependence of Reynolds number is different on the experiment condition, but there are no relations in the experiment condition, and equivalent diameter ratios are almost arranged by the constant value. As for the time variation of the mass and heat transfer, reverse tendency is shown, and analogy isn't concluded. The reason is that: 1) The leading edge becomes the quadrant-shaped projection caused by the frost growth, that is made to enhance heat transfer. 2) Due to the temperature rise and partial melting of the leading edge, the infiltration of the water vapor into frost is blocked, and mass transfer doesn't increase.

Guidance is provided for geotechnical engineers designing civil engineering works in silty soils based on a detailed characterisation of a glaciomarine silt from Os in western Norway. It was found that these soils are susceptible to disturbance by good quality fixed piston tube sampling and care needs to be taken when using laboratory derived design parameters, particularly for consolidation and shear strength properties. A technique for assessing sample disturbance using shear wave velocity and suction measurements proved promising. Conventional techniques for determining soil strength from triaxial tests in silt are inappropriate due to the dilational nature of the material and more reliable and logical strength estimates can be made from a limiting strain criterion. Field vane data shou...

This paper discusses the challenges that occur when performing Cone Penetration Tests (CPT) in silty soil due to changes in drainage conditions. In this paper, CPT results from various papers and researchers are collected and interpreted. Results from cone penetrations tests with various penetration rates is analysed, and it is shown how the changes in drainage condition, caused by the change in penetration rate, affects the plot in the soil classification charts. In addition, the effect on changes in penetration rate is compared for clay and silt, respectively, where the silty soil is more susceptible towards change in penetration rate. A normalized penetration rate is implemented in order to compare various cone resistance results, and hence investigate the changes from undrained to partially drained and from partially drained to fully drained.

The physicochemical properties and the contamination levels of mercury and arsenic in roadway dust from Baoji, NW China were investigated using an Atomic Fluorescence Spectrophotometer. Contamination levels were assessed based on the geoaccumulation index and the enrichment factor. The results show that magnetic susceptibilities of roadway dust were higher than Holocene loess-soil of central Shaanxi Loess Plateau. The mean contents of organic matter, PM10 and PM100 were 8.8%, 21.8% and 98.6%, respectively. Mercury concentration ranged from 0.48 to 2.32 mg g-1, with a mean value of 1.11 mg g-1, 17.1 times the Chinese soil mercury background value and 37 times the Shaanxi soil mercury background value. Arsenic concentration ranged from 9.0 to 42.8 mg g-1, with a mean value of 19.8 mg g-1, 1....

Measurements of the dissolved (<0.4 ..mu..m) major element water chemistry of 10 lakes and reservoirs situated in the southern Appalachian Mountain and Carolina Piedmont regions are used to examine effects of acidic atmospheric deposition inputs on water chemistry. In the mountain region, lakes with low alkalinity and small watershed/lake area ratio appear to be most susceptible to, and may be undergoing, pH reduction. In the Piedmont region, watershed soils, especially those exposed by man's activities, appear to be effectively neutralizing acid inputs. Weathering of rocks and soils accelerated beyond that expected from carbonic acid alone is probably occurring in the mountain and Piedmont systems. Our analysis suggests that reduction of lake water pH, mobilization of soil chemical constituents, and subsequent changes in the chemical composition of aquatic systems may be a more widespread and potentially serious environmental problem in this area than previous analyses have suggested.

The goal of this project is the in situ immobilization and detoxification of specific metal contaminants by changing their chemical state. The injection of a gas mixture containing low concentrations of hydrogen sulfide into soil can change the oxidation state of some metals. Chromium, which is present at the test site in an oxidation state of VI can be reduced to chromium III, through this method. Chromium VI is highly mobile and highly toxic, whereas, in its lower oxidation state it is immobile and virtually harmless. Other metals which are susceptible to this type of treatment are; lead, copper, cadmium, uranium, technetium and arsenic. TSS: Diluted mixtures of hydrogen sulfide in air can treat soils contaminated with heavy metals and radionuclides. The reactive gas is injected directly into the contaminated soil causing a redox reaction where Chromium(VI) is transformed to Chromium(III) - an insoluable and more stable form of Chromium.

Black carbon (BC) produced during slash and burn agriculture on tropical soils may enhance the soils organic matter content and hence their biological properties. However, once deposited on the soil surface, BC may be subject to erosion and/or microbial decomposition and thus not be preserved on site. Up to now, few studies have been carried out to assess the contribution of BC to the soils stable carbon pool on sites under slash and burn agriculture. The aim of the study was to assess the survival potential of BC in sloping tropical soils of clayey texture. The study was carried out in Northern Laos, where the soils are subjected to addition of black carbon produced by burning of agricultural crop residues. Our conceptual approach included the characterisation of (a) morphologically distinct BC forms and (b) chemical soil fractions. The samples were analysed for elemental content, chemical composition by 13C CPMAS NMR spectroscopy, carbon resistant to acid hydrolysis with HCl, carbon resistant to oxidation with acid dichromate solution and 14C activity. Our results indicated that BC produced by slash and burn agriculture was highly aromatic in nature. Its elemental composition as well as its susceptibility to be lost by chemical oxidation was dependent on its morphology. Acid hydrolysis did not lead to carbon loss from any BC form. We thus hypothesised that BC should be present in the hydrolysis resistant fraction isolated from soil. The charactersation of the chemical composition by 13C CPMAS NMR spectroscopy showed that the hydrolysis residue was composed of highly aromatic carbon. Considering the low lignin content of these soils and the good recovery of bulk soil aromatic carbon signal (80-100%) in the hydrolysis residue, we consider that this fraction may be suitable to assess BC contribution to clayey soils. We suggest that BC isolated as hydrolysis resistant C may represent up to 25% of the soils C as compared to 8% as isolated by acid dichromate oxidation. The 14C age of this fraction was older than that of the untreated soil and increased to more than 1000 years in B horizons. These observations suggest that BC may be preserved for long time, once incorporated into the mineral soil.

Restricted area from the most south-eastern part of Bulgaria at the Bulgarian-Turkish border is characterized by continental Mediterranean climate. Peculiarity of the area is determined by the proved absence of Quaternary glaciations and predominance of Mediterranean flora (mainly oak (Fagus orientalis) with widely distributed rhododendron (Rhododendron ponticum)). Under these conditions, characteristic red colored Luvisols are developed. We have studied two profiles - Ferric Luvisol and Rhodic Luvisol - with the aim to characterize the iron oxides' mineralogy and their depth distribution. According to the carried out grain size analyses clay content varies between 11-19% in Rhodic Luvisol and between 24-34% in Ferric Luvisol, while silt content ranges between 60-80% for both profiles. Extended set of magnetic measurements includes: magnetic susceptibility and its frequency dependence, hysteresis properties, isothermal- and anhysteretic remanences; thermomagnetic analyses of magnetic susceptibility. Strong magnetic enhancement is observed in the upper soil horizons, while parent material (presented by metamorphosed sediments) is weakly magnetic. Notable difference between the two profiles is the obtained high percent frequency dependent susceptibility (10-14%) for Ferric Luvisol, while Rhodic Luvisol has only 1-2% frequency dependent susceptibility. Thermomagnetic analyses of magnetic susceptibility imply that strongly magnetic fraction is represented by maghemite and magnetite. Hematite presence anticipated by the intense red-brown colouring of the soils cannot be identified by magnetic measurements, suggesting that most probably it exists in superparamagnetic state. Instead, remanence-carrying hematite is identified in nodules from the iluvial horizon of Ferric Luvisol. Additional information from SEM observations and chemical analyses will be utilized to better constrain the mineralogy. This study is carried out in the frame of the project DO 02-193/2008 funded by the Bulgarian National Science Fund and bilateral cooperation between NIGGG - Inst. Geophys. (Czech Republic)

Soil organic carbon (SOC) plays a vital role in ecosystem function determining soil fertility, water holding capacity and susceptibility to land degradation. In addition, SOC is related to atmospheric CO2 levels with soils having the potential for C release or sequestration, depending on land use, land management, and climate. The Mediterranean region is expected to be highly affected by climate change, and it is expected that SOC decreases under climate warming conditions. Estimates of soil organic carbon stocks and changes under different climate scenarios and land use systems can also help to determine the vulnerability to land degradation. In this work an assessment of changes in soil organic carbon for Sardinia, the second largest island of the Mediterranean Basin, is presented. The carbon dynamics were estimated for the whole island using the Rothamsted Carbon model and the A1b emission scenario provided by the Euro-Mediterranean Centre for Climate Change (CMCC). Almost 200 soil analysis data were used to calibrate and validate the model output for different land use typologies. After the calibration, a good agreement between soil C estimated from the model with the current climate and observed SOC data was found. Preliminary results show a general reduction in the soil C content with the A1b scenario projection (-18% in the 2100 vs 2000). The SOC reduction in the soils was higher in the forested and semi-natural ecosystems than agricultural areas. In addition, an increase of 4.3% in the CO2 fluxes is expected at the end of the 21th century. The work allowed an estimation of the SOC projections for the current century under climate warming conditions, identifying the potential contribution of the several land use typologies. The methodological approach constitutes a first exercise where other processes, such as changes in land use, and in the net primary production need to be accounted for a more comprehensive approach in the SOC dynamics estimations and projections for the future.

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.

Five clones of 3-year old Norway spruce (Picea abies [L.] Karst), planted in a soil from the Bavarian Forest (pH 4.4) or a soil from the Calcareous Bavarian Alps (pH 6.9), were exposed for two successive vegetation periods, in closed environmental chambers, to a pollution treatment consisting of acidic mist (pH 3.0) plus ozone levels of 100 microg m(-3) with episodes of 130-360 microg m(-3); control trees were exposed to mist of pH 5.6 and ozone levels of 50 microg m(-3). Climatic and pollution protocols followed the diurnal and seasonal pattern characteristic for the Inner Bavarian Forest in Southern Germany, an area affected by the new-type forest decline. Biometric parameters were strongly related to clone and soil. Pollution treatment had a limited effect on only a few growth parameters. The stem diameter growth increment of two clones was reduced by pollution treatment in both soils, a third clone was affected in the acidic soil only. Two other clones were not affected at all. Stem volume increment of three clones, calculated as D(2)H, was reduced by pollution treatment in the neutral soil, a fourth clone was affected in the acidic soil only. Bud break was either delayed (two clones) or accelerated (two other clones) by treatment. Depending on soil and clone, needle yellowing was observed in previous years' needles in both treatment and control trees exposed to increased light intensities. The 'spotted' yellowing was not identical to symptoms found in forest decline areas and was most likely a consequence of nutrient deficiencies during the vegetation period preceding the experiment. The results of this experiment are discussed with regard to field observations and forest productivity. The complex pattern of growth responses resulting from interactions between air pollution, soil and genetic factors is considered to reflect different susceptibilities of trees to air pollutants. PMID:15092281

Decomposer fungi are primary decomposing agents in terrestrial soils. Their mycelial networks play an important role in nutrient mineralisation and distribution, but are also nutritious resources for various soil invertebrates. Global climate change is predicted to alter the diversity and community composition of these soil fauna. To understand whether changes in invertebrate species diversity are likely to affect fungal-mediated decomposition, this study compared the grazing potentials of different invertebrate taxa and functional groups. Specifically, the grazing impacts of seven invertebrate taxa on the growth and spatial distribution of six basidiomycete fungi growing from beech wood blocks in soil microcosms were explored. Wood decay rates by fungi were also compared. The consequences of grazing were both taxon- and species-specific. Generally, macro-invertebrates caused the greatest damage, while meso- and micro-invertebrates often stimulated mycelial growth. Invertebrate size, preferences and population dynamics are likely to influence grazing potentials. Effects of grazing varied between fungi, with mycelial morphology and biochemistry possibly influencing susceptibility. Heavy grazing indirectly increased fungal-mediated wood decomposition. Changes in invertebrate community composition are predicted to have consequences for fungal growth, activity and community structure in woodland soils. Abiotic climate change factors including CO(2) and temperature affect mycelial productivity directly, but the indirect effects, mediated through changes in the soil invertebrate community, may be equally important in controlling ecosystem functioning. PMID:21562866

Switchgrass (Panicum virgatum L.) is considered to be a valuable bioenergy crop with significant potential to sequester soil organic carbon (SOC). A study was conducted to evaluate soil carbon stocks within established switchgrass stands and nearby cultivated cropland on farms throughout the northern Great Plains and northern Cornbelt. Soil from 42 paired switchgrass/cropland sites throughout MN, ND, and SD was sampled to a depth of 120 cm and analyzed for soil carbon in depth increments of 0-5, 5-10, 10-20, 20-30, 30-60, 60-90, and 90-120 cm. SOC was greater (P<0.1) in switchgrass stands than cultivated cropland at 0-5, 3-60, and 60-90 cm. Differences in SOC between switchgrass stands and cultivated cropland were especially pronounced at deeper soil depths, where treatment differences were 7.74 and 4.35 Mg ha{sup -1} for the 30-60 and 60-90 cm depths, respectively. Greater root biomass below 30 cm in switchgrass likely contributed to trends in SOC between switchgrass stands and cultivated cropland. Switchgrass appears to be effective at storing SOC not just near the soil surface, but also at depths below 30 cm where carbon is less susceptible to mineralization and loss. (Author)

Lunar regolith contains important materials that can be used for in-situ resource utilization (ISRU) on the Moon, thereby providing for substantial economic savings for development of a manned base. However, virtually all activities on the Moon will be affected by the deleterious effects of the adhering, abrasive, and pervasive nature of lunar dust (<20 {micro}m portion of regolith, which constitutes {approx}20 wt% of the soil). In addition, the major impact-produced glass in the lunar soil, especially agglutinitic glass (60-80 vol% of the dust), contains unique nanometer-sized metallic Fe (np-Fe{sup 0}), which may pose severe pulmonary problems for humans. The presence of the np-Fe0 imparts considerable magnetic susceptibility to the fine portion of the lunar soil, and dust mitigation techniques can be designed using these magnetic properties. The limited availability of Apollo lunar soils for ISRU research has made it necessary to produce materials that simulate this unique np-Fe{sup 0} property, for testing different dust mitigation methods using electromagnetic fields, and for toxicity studies of human respiratory and pulmonary systems, and for microwave treatment of lunar soil to produce paved roads, etc. A method for synthesizing np-Fe{sup 0} in an amorphous silica matrix is presented here. This type of specific simulant can be used as an additive to other existing lunar soil simulants.

The 813-mm-diameter China-Russia Crude Oil Pipeline enters northeastern China at Lianyin, Mo'he County, Heilongjiang Province and crosses 441km of warm discontinuous, sporadic and isolated patches of permafrost and 512km of seasonally frozen ground before reaching Daqing, China. It is inevitable that the buried pipeline is subject to frost heave and/or thaw settlement when it passes through regions of permafrost and seasonally frozen ground with available moisture. Therefore, stress and deformation analyses of the pipe subject to frost action or thaw settlement are important for the safety, long-term stability and economic feasibility of the buried oil pipeline system. Based on the (empirical) frost heave and/or thaw settlement coefficients, a simple thermal elasto-plastic finite element c...

Triton, Neptune's largest moon, has been predicted to undergo significant seasonal changes that would reveal themselves as changes in its mean frost temperature. But whether this temperature should at the present time be increasing, decreasing or constant depends on a number of parameters (such as the thermal properties of the surface, and frost migration patterns) that are unknown. Here we report observations of a recent stellar occultation by Triton which, when combined with earlier results, show that Triton has undergone a period of global warming since 1989. Our most conservative estimates of the rate of temperature and surface-pressure increase during this period imply that the atmosphere is doubling in bulk every 10 years, significantly faster than predicted by any published frost model for Triton. Our result suggests that permanent polar caps on Triton play a c dominant role in regulating seasonal atmospheric changes. Similar processes should also be active on Pluto.

Using mechanical ventilation with highly efficient heat-recovery in northern European or arctic climates is a very efficient way of reducing the energy use for heating in buildings. However, it also presents a series of problems concerning condensation and frost formation in the heat-exchanger. Developing highly efficient heat-exchangers and strategies to avoid/remove frost formation implies the use of detailed models to predict and evaluate different heat-exchanger designs and strategies. This paper presents a quasi-steady-state model of a counter-flow air-to-air heat-exchanger that takes into account the effects of condensation and frost formation. The model is developed as an Excel spreadsheet, and specific results are compared with laboratory measurements. As an example, the model is used to determine the most energy-efficient control strategy for a specific heat-exchanger under northern European and arctic climate conditions. (C) 2007 Elsevier Ltd. All rights reserved.

Observations of the 4-micron SO2 band on Jupiter's satellite Io and laboratory measurements of SO2 frost are presented. The observations confirm the existence of a large longitudinal variation in band strength, but show no evidence of temporal changes. Comparison of the band position and shape in Io's spectrum with those in the laboratory frost's suggests that the bulk of the absorption on Io is due to frost, not adsorbed gas. The derived SO2 coverage is large enough to require that SO2 be present in most terrain types on Io and not just in the white plains unit. To reconcile the infrared observations that indicate large amoutns of SO2 with the ultraviolet observations of Voyager and IUE that show little, the SO2 must be mixed intimately with the sulfur (or other material) so that at each wavelength the darker component dominates the spectrum.

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection.

17 August 2004 This July 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of aligned barchan sand dunes in the martian north polar region. At the time, the dunes were covered with seasonal frost, but the frost had begun to sublime away, leaving dark spots and dark outlines around the dunes. The surrounding plains exhibit small, diffuse spots that are also the result of subliming seasonal frost. This northern spring image, acquired on a descending ground track (as MGS was moving north to south on the 'night' side of Mars) is located near 78.8oN, 34.8oW. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the upper left.

The development of sapphire tips, coupled to the distal end of silica fibers, introduced the use of a new surgical power delivery system known as contact tip surgery. An alternative medium to sapphire tips is the use of silica optical fibers with molded distal ends. We investigated a number of possible approaches for the fabrication of a variety of distal end configurations on silica fibers using an oxy-propane gas torch, arc fusion, Nd:YAG radiation, and CO2 radiation. We fabricated seven silica contact tips that included a clear and frosted microlens, a clear and frosted ball lens, a clear and frosted conical lens, and a flat end lens. The most reliable method found to fabricate silica contact tips used a CO2 laser because it offered complete control over the manufacturing process.

The effect of antifreeze solution liquid film on the frost prevention is experimentally investigated. It is desirable that the antifreeze solution spreads widely on the heat exchanger surface forming thin liquid film to prevent frost nucleation while having small thermal resistance across the film. A porous layer coating technique is adopted to improve the wettability of the antifreeze solution on heat exchanger surface. The antifreeze solution spreads widely on the heat exchanger surface with 100 µm thickness by the capillary force resulted from the porous structure. It is observed that the antifreeze solution liquid film prevents a heat exchanger from frosting. The reductions of heat and mass transfer rate caused by the thin liquid film are only 1-2% compared with those for non-liquid film surface.