Loose Surface Material Research Articles

Comparative Soil Analysis from Different Crime Prone Areas of Kottayam and Kollam Districts of Kerala for Forensic Characterization

Soil is the loose surface material that covers land on which plants grow. It consists of a mixture of organic remains, clay, and rock particles, which gives it its uniqueness from place to place. Because of the uniqueness of soil, it has a high evidential value in the field of forensic science. In the present study, research has been conducted to check the range of variations in the soil collected from different crime-prone areas of Kottayam and Kollam districts of Kerala by physical, chemical, microscopic, and instrumental examination. In physical examination, soil colour, texture, consistency, and density were measured, and in chemical examination, pH and total soluble sulphate of the soil were measured. In instrumental examination, Heavy metal analysis was done by using Atomic Absorption Spectrometry (AAS), which helps to measure the amount of trace elements present in the soil. The study found that each soil has some significant variations that make it unique. In the field of forensic science, this can be highly helpful in determining the origin of soil by examining its colour, texture, structure, content, etc.

The challenges of commercial mountaineering on the highest Volcanic Seven Summit, the Ojos del Salado

Commercial mountaineering has gained widespread popularity in recent decades. Global mountaineering challenges – e.g., the Seven Summits challenge to climb the highest summit of each continent – amplify this process, and also raise the profile of individual destinations. The highest volcano on the Earth, the Ojos del Salado in the Dry Andes (Chile/Argentina) is featured in two of the major challenges (Seven Second Summits, Volcanic Seven Summits). Thus, it is a prime extreme outdoor tourism destination. The relative ease of access and the non-technical nature of the ascent have also contributed to the increasing volume of tourism. However, our observations about commercial mountaineering practices reveal surprisingly low success rates on the summit. Based on data from our decade-long environmental monitoring programme and our field experiences,, we attribute this to the extreme environment and landscape of the mountain (e.g., cold and dry climate, strong winds, topographical situation, loose surface material), scarce mountaineering facilities, and potential misjudgements by inexperienced climbers.

A controlled field experiment to investigate the deterioration of earthen heritage by wind and rain

Earthen heritage constitutes 10% of sites on the World Heritage List and many of these sites are experiencing extensive deterioration caused by environmental forces, such as wind and rain. This study used a well-established test wall to investigate the impact of environmental conditions on the deterioration of earthen heritage at the remote and under-studied site of Suoyang Ancient City, Gansu Province, China, which is exhibiting widespread deterioration. Test walls have previously been used in earthen heritage research as they allow controlled experiments to be undertaken on complex, realistic structures without risking damage or loss of value to the historic material. This study used portable wind and rain erosion simulation devices to investigate experimentally (i) the comparative effect of wind, sediment-laden wind and wind-driven rain in causing deterioration to earthen heritage and (ii) how the incipient deterioration features produced by wind, sediment-laden wind and wind-driven rain on the test wall relate to the deterioration features recorded on the historic city walls. The test wall was subjected to low, medium and high intensities of clean wind, sediment-laden wind and wind-driven rain. The extent of deterioration produced was measured using repeat, high resolution laser scans before and after each test run. The deterioration features caused by each environmental force were notably different with clean wind removing the loose surface material, sediment-laden wind causing pitting and wind-driven rain causing incipient gullying. These incipient features compare well with more developed features seen on the historic walls. Wind-driven rain caused the greatest amount of deterioration while clean wind caused the least. However, as the frequency and duration of wind events at Suoyang is much greater than those of rain events, wind is likely to play an important role in the deterioration of earthen heritage over annual timescales. These findings show that conservation strategies at rammed earth sites like Suoyang need to address the impact of multiple environmental forces, such as clean wind, sediment laden wind and wind-driven rain.

SMART‐1 end of life shallow regolith impact simulations

AbstractThe SMART‐1 end‐of‐life impact with the lunar surface was simulated with impacts in a two stage light‐gas gun onto inclined basalt targets with a shallow surface layer of sand. This simulated the probable impact site, where a loose regolith will have overlaid a well consolidated basaltic layer of rock. The impact angles used were at 5° and 10° from the horizontal. The impact speed was ~2 km s−1 and the projectiles were 2.03 mm diameter aluminum spheres. The sand depth was between approximately 0.8 and 1.8 times the projectile diameter, implying a loose lunar surface regolith of similar dimensions to the SMART‐1 spacecraft. A crater in the basement rock itself was only observed in the impact at 10° incidence, and where the depth of loose surface material was less than the projectile diameter, in which case the basement rock also contained a small pit‐like crater. In all cases, the projectile ricocheted away from the impact site at a shallow angle. This implies that at the SMART‐1 impact site the crater will have a complicated structure, with exposed basement rock and some excavated rock displaced nearby, and the main spacecraft body itself will not be present at the main crater.

HiRISE observations of gas sublimation-driven activity in Mars’ southern polar regions: III. Models of processes involving translucent ice

Enigmatic surface features, known as ‘spiders’, found at high southern martian latitudes, are probably caused by sublimation-driven erosion under the seasonal carbon dioxide ice cap. The Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE) has imaged this terrain in unprecedented details throughout southern spring. It has been postulated [Kieffer, H.H., Titus, T.N., Mullins, K.F., Christensen, P.R., 2000. J. Geophys. Res. 105, 9653–9700] that translucent CO 2 slab ice traps gas sublimating at the ice surface boundary. Wherever the pressure is released the escaping gas jet entrains loose surface material and carries it to the top of the ice where it is carried downslope and/or downwind and deposited in a fan shape. Here we model two stages of this scenario: first, the cleaning of CO 2 slab ice from dust, and then, the breaking of the slab ice plate under the pressure built below it by subliming ice. Our modeling results and analysis of HiRISE images support the gas jet hypothesis and show that outbursts happen very early in spring.

Dust emissions from undisturbed and disturbed supply‐limited desert surfaces

Aeolian sediment transport systems have been treated frequently as transport limited, where transport is governed by the force of the wind, or as supply limited, where sediment transport is controlled by the availability of surface grains. Although many arid environments are dominated by supply‐limited surfaces, almost all available dust emission and sand transport models are restricted to transport‐limited conditions. To examine the emission of PM10 (particulate matter ≤10 μm aerodynamic diameter) and horizontal sand transport from supply‐limited environments, a series of wind tunnel tests were conducted in the Mojave Desert, California. In situ testing was conducted with an open‐floored, portable wind tunnel (12 × 1 × 0.75 m) on a variety of natural soils having disturbed and undisturbed surface conditions. Results indicate that for these supply‐limited environments, PM10 emissions are primarily driven by the aerodynamic resuspension of loose surface material as opposed to the dynamic entrainment mechanisms associated with saltating grains. Emission rates were directly influenced by wind shear and mechanical disturbance and indirectly influenced by soil texture. In addition, disturbance of the surface was found to increase the potential for multiple emission events, which may affect the temporal accumulation of atmospheric dust.

The need for enemy-free space: The impact of an invasive gecko on island endemics

How introduced reptiles cause the loss of endemic reptiles is poorly understood and currently there are no available techniques for dealing with this major conservation issue. We addressed both these problems by investigating the role of the introduced house gecko Hemidactylus frenatus in causing the catastrophic decline and extinction of the endemic night gecko Nactus populations of the Mascarene Islands and how this introduced species can be excluded from habitats on the basis of morphology. Competition for enemy free space was tested in experimental enclosures and showed that H. frenatus displace the endemic Nactus coindemirensis and Nactus durrelli from favoured positions close to and from refugia, thus increasing the risk of predation and exposure to stochastic events. The ability of H. frenatus to grip substrates with their pad-bearing toes was examined, and we demonstrated that naturally occurring substrates with a greater amount of loose surface material of a higher particulate concentration and size excludes H. frenatus, but not Nactus. These findings support the hypothesis that H. frenatus led to the fragmentation and extinction of the endemic Nactus populations and demonstrate that artificial refugia made of a crumbly substrate may be used to limit future disturbances by this gecko and others like it in the Mascarene Islands and elsewhere.

Surface deformation associated with the March 1996 earthquake swarm at Akutan Island, Alaska, revealed by C-band ERS and L-band JERS radar interferometry

In March 1996, an intense earthquake swarm beneath Akutan Island, Alaska, was accompanied by extensive ground cracking but no eruption of Akutan volcano. Radar interferograms produced from L-band JERS-1 and C-band ERS-1/2 images show uplift associated with the swarm by as much as 60 cm on the western part of the island. The JERS-1 interferogram has greater coherence, especially in areas with loose surface material or thick vegetation. It also shows subsidence of similar magnitude on the eastern part of the island and displacements along faults reactivated during the swarm. The axis of uplift and subsidence strikes about N70°W, which is roughly parallel to a zone of fresh cracks on the northwest flank of the volcano, to normal faults that cut the island and to the inferred maximum compressive stress direction. A common feature of models that fit the deformation is the emplacement of a shallow dike along this trend beneath the northwest flank of the volcano. Both before and after the swarm, the northwest flank was uplifted 5–20 mm/year relative to the southwest flank, probably by magma intrusion. The zone of fresh cracks subsided about 20 mm during 1996–1997 and at lesser rates thereafter, possibly because of cooling and degassing of the intrusion.

X-RAY MICROANALYSIS OF APPLES TREATED WITH KAOLIN INDICATES WAX-EMBEDDED PARTICULATE IN THE CUTICLE

Gala' apples trees were treated with kaolin (Surround) in mid-July, and fruit were sampled 1 and 7 days after treatment. Apples were gently rinsed with cold deionized water to remove loose surface material. Small sections of cuticle tissue were shaved from the fruit surface with a razor blade and flash frozen on an aluminum block held at -190oC with liquid N2. The tissue was freeze-dried, coated with a thin film of carbon, and examined using a field emission scanning electron microscope coupled with an energy dispersive x-ray microanalysis system capable of light element detection. Qualitative secondary electron imaging combined with quantitative elemental compositional analyses indicated kaolin particles may become embedded in the cuticle between individual wax platelets. INTRODUCTION Sun-induced injury (solar injury, SI) can be a costly problem in some years for tree fruit growers, especially in hot, arid regions. Although the injury to the fruit appears to be a combination of heat and solar radiation exposure (Lipton and O’Grady, 1980), synergistic thresholds for temperature, and radiation wavelength and intensity have not been clearly defined. To reduce this type of injury, therefore, either temperature or radiation, or both, must be reduced or regulated. Lipton and Matoba (1971) reduced the surface temperature of ‘Crenshaw’ melons (Cucumis melo, L.) by as much as 8 °C by applying a mineral whitewash material to the fruit surface, and thus reduced SI damage. Lipton (1972) also demonstrated that mineral whitewash applied to the melon fruit surface reduced internal tissue temperature and, as a result, improved fruit quality. (Mineral whitewash contains kaolinite, bentonite, attapulgite, as well as spreading and sticking agents). More recently, Glenn et al. (2002) reported kaolin alone reduced solar injury to apple fruit. Kaolin, also known as kaolinite, is a clay mineral with the chemical composition Al 4(OH)5O2Si2. The basic building blocks are layers of silica tetrahedra and layers of alumina octahedra in a 1:1 relationship. The unit cell repeats in the x and y direction to form extensive sheets in the xy plane, and in the z direction to form stacks of sheets (Barak and Nater, 2002). When placed in water the platelets shift apart, each plate attracting water to its negative face. Kaolin particulate may absorb 7 to 10 times its own weight, consequently swelling up to 18 times its dry volume. Because of these characteristics, we wanted to know first, whether small particles would lodge in the micro-cracks of the fruit cuticle surface, second, whether the particles would become an integral part of the cuticle as the micro-cracks continued to ‘heal’ with new growth of wax platelet, and third, because of the marketability of appearance, whether the integration of clay particles within the cuticle matrix would alter the properties of the cuticle itself. MATERIALS AND METHODS Mature 'Gala'/EMLA MM.106 apples trees in northcentral Washington were treated with a single application of kaolin (Surround) in mid-July. Fruit were sampled 1 and 7 days after treatment, placed in a cooler held at 34oC and transported to the Proc. XXVI IHC – Deciduous Fruit and Nut Trees

Surface runoff and soil erosion on unpaved forest roads from rainfall simulation tests in northeastern Spain

The generation of surface runoff and transport of sediment were studied on unpaved forest roads in the Iberian Range (Spain). To this end, a mobile rainfall simulator was used so that information could be compared. Twenty-eight rainfall simulations were carried out on the cutslope (12), sidecast fill (6) and roadbed (10). Under low soil moisture conditions, cutslopes had runoff coefficients of 58%, and overland flow was generated in 3 min. On the sidecast fill and the roadbed, the runoff coefficients were 34% and 46%, respectively. The part of the road that showed the greatest erosion was the cutslope (161 g m −2), where mass wasting and freeze–thaw processes supply loose material to be transported by overland flow. The cutslope soil loss rates exceed those from the sidecast fill and the roadbed by 16 and 11 times, respectively. In these tests, the maximum sediment concentration was recorded in the first few minutes. The concentration reduces with time as a consequence of the exhaustion of loose surface material. Correlation coefficients and regression analysis showed that the gradient, plant cover density and stone cover of the cutslopes, fill areas and roadbeds had statistically significant effects on runoff and erosion. A comparison of these data with others obtained on different land-uses allowed us to conclude that some parts of forest roads have similar hydromorphological behaviour to abandoned fields in mountainous areas and to cereal fields.

Improved method for modelling sediment transport on unpaved roads using KINEROS2 and dynamic erodibility

AbstractOne difficulty in modelling sediment transport on unpaved road surfaces stems from the inability of physically based models to simulate the flush of loose surface material that is deposited on the road surface prior to the onset of a storm. This work builds upon a prior modelling methodology (referred to as dynamic erodibility) to simulate time‐varying sediment transport on unpaved mountain roads by loosely coupling a continuous, exponential decay disturbance model with the erosion algorithm in KINEROS2. The method is tested against sediment transport time‐series observed on small‐scale rainfall simulation plots for various slope, antecedent soil wetness and pre‐storm sediment availability conditions. The new method generally improves prediction errors of total sediment output, peak sediment output and fit of the sediment output time‐series. However, for some validation events, the method fails to simulate high initial sediment spikes. This limitation may be a side‐effect of using data from small‐scale plots, but also may signify the need for additional calibration of the disturbance model subcomponent with data from surfaces having a greater variety of pre‐event surface material. Nevertheless, this road erosion modelling approach provides a realistic ‘description’ of time‐varying sediment transport, which is controlled both by the baseline erodibility of the underlying road surface, and importantly, by the removal of a loose, surficial sediment layer by overland flow. Copyright © 2002 John Wiley & Sons, Ltd.

Interstorm surface preparation and sediment detachment by vehicle traffic on unpaved mountain roads

Road survey and field rainfall simulation experiments have shown that the erodibility of a road surface is dynamic. In the absence of extreme runoff events, dynamic erodibility results from the generation and removal of easily entrained surface material by human road surface maintenance activities, vehicular detachment and overland flow events. Maintenance activities introduce easily transportable material to the road surface where it can be entrained by overland flow. Traffic in dry conditions detaches material that is quickly removed during subsequent overland flow events. The pre-storm erodibility of a road is therefore largely a function of maintenance and vehicle activity since the last overland flow event. During rainstorms, vehicle passes increase sediment production by detaching/redistributing surface material and creating efficient overland flow pathways for sediment transport. However, if incision of tracks by overland flow does not occur, post-pass sediment transport quickly returns to pre-pass rates. Field rainfall simulation data suggest that sediment transport resulting from during-storm vehicle passes is greatly influenced by the presence of existing loose material, which again is a function of prior road usage and maintenance activities. Incorporation of vehicular effects into physically based road erosion models may be possible by parameterizing both during-storm and inter-storm changes in the supply of loose surface material as changes in surface erodibility. Copyright © 2001 John Wiley & Sons, Ltd.

Runoff generation and sediment production on unpaved roads, footpaths and agricultural land surfaces in northern Thailand

Rainfall simulation was used to examine runoff generation and sediment transport on roads, paths and three types of agricultural fields in Pang Khum Experimental Watershed (PKEW), in mountainous northern Thailand. Because interception of subsurface flow by the road prism is rare in PKEW, work focused on Horton overland flow (HOF). Under dry antecedent soil moisture conditions, roads generated HOF in c. 1 min and have event runoff coefficients (ROCs) of 80 per cent, during 45 min, c. 105 mm h−1 simulations. Runoff generation on agricultural fields required greater rainfall depths to initiate HOF; these surfaces had total ROCs ranging from 0 to 20 per cent. Footpaths are capable of generating erosion-producing overland flow within agricultural surfaces where HOF generation is otherwise rare. Paths had saturated hydraulic conductivity (Ks) values 80–120 mm h−1 lower than those of adjacent agricultural surfaces. Sediment production on roads exceeded that of footpaths and agricultural lands by more than eight times (1·23 versus < 0·15 g J−1). Typically, high road runoff volumes (owing to low Ks, c. 15 mm h−1) transported relatively high sediment loads. Initial road sediment concentrations exceeded 100 g l−1, but decayed with time as loose surface material was removed. Compared with the loose surface layer, the compacted, underlying road surface was resistant to detachment forces. Sediment concentration values for the road simulations were slightly higher than data obtained from a 165 m road section during a comparable natural event. Initial simulation concentration values were substantially higher, but were nearly equivalent to those of the natural event after 20 min simulation time. Higher sediment concentration in the simulations was related to differences in the availability of loose surface material, which was more abundant during the dry-season simulations than during the rainy season natural event. Sediment production on PKEW roads is sensitive to surface preparation processes affecting the supply of surface sediment, including vehicle detachment, maintenance activities, and mass wasting. The simulation data represent a foundation from which to begin parameterizing a physically based runoff/erosion model to study erosional impacts of roads in the study area. Copyright © 2000 John Wiley & Sons, Ltd.

Runoff generation and sediment production on unpaved roads, footpaths and agricultural land surfaces in northern Thailand

Rainfall simulation was used to examine runoff generation and sediment transport on roads, paths and three types of agricultural fields in Pang Khum Experimental Watershed (PKEW), in mountainous northern Thailand. Because interception of subsurface flow by the road prism is rare in PKEW, work focused on Horton overland flow (HOF). Under dry antecedent soil moisture conditions, roads generated HOF in c. 1 min and have event runoff coefficients (ROCs) of 80 per cent, during 45 min, c. 105 mm h−1 simulations. Runoff generation on agricultural fields required greater rainfall depths to initiate HOF; these surfaces had total ROCs ranging from 0 to 20 per cent. Footpaths are capable of generating erosion-producing overland flow within agricultural surfaces where HOF generation is otherwise rare. Paths had saturated hydraulic conductivity (Ks) values 80–120 mm h−1 lower than those of adjacent agricultural surfaces. Sediment production on roads exceeded that of footpaths and agricultural lands by more than eight times (1·23 versus < 0·15 g J−1). Typically, high road runoff volumes (owing to low Ks, c. 15 mm h−1) transported relatively high sediment loads. Initial road sediment concentrations exceeded 100 g l−1, but decayed with time as loose surface material was removed. Compared with the loose surface layer, the compacted, underlying road surface was resistant to detachment forces. Sediment concentration values for the road simulations were slightly higher than data obtained from a 165 m road section during a comparable natural event. Initial simulation concentration values were substantially higher, but were nearly equivalent to those of the natural event after 20 min simulation time. Higher sediment concentration in the simulations was related to differences in the availability of loose surface material, which was more abundant during the dry-season simulations than during the rainy season natural event. Sediment production on PKEW roads is sensitive to surface preparation processes affecting the supply of surface sediment, including vehicle detachment, maintenance activities, and mass wasting. The simulation data represent a foundation from which to begin parameterizing a physically based runoff/erosion model to study erosional impacts of roads in the study area. Copyright © 2000 John Wiley & Sons, Ltd.

Downslope movement of material on Deimos

Viking Orbiter images have shown downslope movement of loose material to be an important surface process on Deimos. Loose surface material moves downslope from prominent ridges and accumulates in topographic lows. In some areas, up to 10 m of surface material have been removed; in others, craters up to 200 m in diameter have been filled completely by material moving downslope. Brighter material associated with, and probably derived from crater rims, also moves downslope and forms tapered streamers up to 3 km in length which appears as prominent features on the satellite. The mechanism for downslope movement is uncertain, but thermal creep, micrometeroroid bombardment and impact-related seismic shaking may be involved. Certain craters show conspicuous unfilling even though their prominent rims should prevent material moving downslope from reaching their interiors. Such fill must have been emplaced ballistically—the amounts of sediment suggest that over half of all ejecta produced on Deimos are retained on the satellite. Phobos appears to retain little ejecta and shows little evidence of downslope movement of debris.

Saltation and Martian sandstorms

A brief topical review of current knowledge available for predicting the characteristics of sandstorms is presented. Particular emphasis is placed on extrapolations to Mars where saltation of loose surface material appears to be a necessary condition for initiation of observed dust storms. Considerable data are now available to predict threshold winds under earth's environmental conditions, but techniques for predicting the quantity of material transported and the height and velocity to which it travels are still crude. Extrapolation of current knowledge to Mars is probably sufficient only for estimating purposes and landing craft design. The upcoming Viking landing mission on Mars will, it is hoped, shed additional light on the problem.