Environmental Volunteering: motivations,modes and outcomes     

Thomas G. Measham  Guy B. Barnett 《The Australian geographer》2008,39(4):537-552

Volunteers play a key role in natural resource management: their commitment, time and labour constitute a major contribution towards managing environments in Australia and throughout the world. From the point of view of environmental managers, much interest has focused on defining tasks suitable to volunteers. However, we argue that an improved understanding of what motivates volunteers is required to sustain volunteer commitments to environmental management in the long term. This is particularly important given that multiple government programs rely heavily on volunteers in Australia, a phenomenon also noted in the UK, Canada, and the USA. Whilst there is considerable research on volunteering in other sectors (e.g. health), there has been relatively little attention paid to understanding environmental volunteering. Drawing on the literature from other sectors and environmental volunteering where available, we present a set of six broad motivations underpinning environmental volunteers and five different modes through which environmental volunteering is manifested. We developed and refined the sets of motivations and modes through a pilot study involving interviews with volunteers and their coordinators from environmental groups in Sydney and Bass Coast. The pilot study data emphasise the importance of promoting community education as a major focus of environmental volunteer groups and demonstrate concerns over the fine line between supporting and abusing volunteers, given their role in delivering environmental outcomes.  相似文献   

Seismic time‐lapse effects of solution salt mining – a feasibility study     

Guy Drijkoningen  Guus van Noort  Rob Arts  Joren Bullen  Jan Thorbecke 《Geophysical Prospecting》2012,60(2):239-254

This article addresses the question whether time‐lapse seismic reflection techniques can be used to follow and quantify the effects of solution salt mining. Specifically, the production of magnesium salts as mined in the north of the Netherlands is considered. The use of seismic time‐lapse techniques to follow such a production has not previously been investigated. For hydrocarbon production and CO₂ storage, time‐lapse seismics are used to look at reservoir changes mainly caused by pressure and saturation changes in large reservoirs, while for solution mining salt is produced from caverns with a limited lateral extent, with much smaller production volumes and a fluid (brine) replacing a solid (magnesium salt). In our approach we start from the present situation of the mine and then study three different production scenarios, representing salt production both in vertical and lateral directions of the mine. The present situation and future scenarios have been transformed into subsurface models that were input to an elastic finite‐difference scheme to create synthetic seismic data. These data have been analysed and processed up to migrated seismic images, such that time‐lapse analyses of intermediate and final results could be done. From the analyses, it is found that both vertical and lateral production is visible well above the detection threshold in difference data, both at pre‐imaging and post‐imaging stages. In quantitative terms, an additional production of the mine of 6 m causes time‐shifts in the order of 2 ms (pre‐imaging) and 4 ms (post‐imaging) and amplitude changes of above 20% in the imaged sections. A laterally oriented production causes even larger amplitude changes at the edge of the cavern due to replacement of solid magnesium salt with brine introducing a large seismic contrast. Overall, our pre‐imaging and post‐imaging time‐lapse analysis indicates that the effects of solution salt mining can be observed and quantified on seismic data. The effects seem large enough to be observable in real seismic data containing noise.  相似文献   

Laboratory scale study of an industrial phosphate and thermal treatment for polluted dredged sediments   总被引：1，自引：0，他引：1  

Souhila KRIBI  Jocelyn RAMAROSON  Ange NZIHOU  Patrick SHARROCK  Guy DEPELSENAIRE 《国际泥沙研究》2012,27(4):538-546

Dredged sediments are being chemically treated with phosphoric acid on an industrial scale.The effectiveness of the treatment was evaluated by performing the chemical reaction in a tubular reactor, followed by convective drying and maturation of the treated sediment at ambient temperature and finally thermal destruction of the organic matter by calcinations(500℃-900℃).The influence of acid concentration and calcination temperature on the specific surface area of the sediment was investigated. The stabilization of the heavy metals was evaluated by leaching tests and sequential extraction procedures.The phosphoric acid treatment is effective in reducing heavy metal mobility,a prerequisite for recycling the sediments in various construction materials.  相似文献   

Observing Global Surface Water Flood Dynamics   总被引：3，自引：2，他引：1  

Paul D. Bates  Jefferey C. Neal  Douglas Alsdorf  Guy J.-P. Schumann 《Surveys in Geophysics》2014,35(3):839-852

Flood waves moving along river systems are both a key determinant of globally important biogeochemical and ecological processes and, at particular times and particular places, a major environmental hazard. In developed countries, sophisticated observing networks and ancillary data, such as channel bathymetry and floodplain terrain, exist with which to understand and model floods. However, at global scales, satellite data currently provide the only means of undertaking such studies. At present, there is no satellite mission dedicated to observing surface water dynamics and, therefore, surface water scientists make use of a range of sensors developed for other purposes that are distinctly sub-optimal for the task in hand. Nevertheless, by careful combination of the data available from topographic mapping, oceanographic, cryospheric and geodetic satellites, progress in understanding some of the world’s major river, floodplain and wetland systems can be made. This paper reviews the surface water data sets available to hydrologists on a global scale and the recent progress made in the field. Further, the paper looks forward to the proposed NASA/CNES Surface Water Ocean Topography satellite mission that may for the first time provide an instrument that meets the needs of the hydrology community.  相似文献   

Estimating azimuthal stress‐induced P‐wave anisotropy from S‐wave anisotropy using sonic log or vertical seismic profile data          下载免费PDF全文

Olivia Collet  Boris Gurevich  Guy Duncan 《Geophysical Prospecting》2016,64(5):1305-1317

Most sedimentary rocks are anisotropic, yet it is often difficult to accurately incorporate anisotropy into seismic workflows because analysis of anisotropy requires knowledge of a number of parameters that are difficult to estimate from standard seismic data. In this study, we provide a methodology to infer azimuthal P‐wave anisotropy from S‐wave anisotropy calculated from log or vertical seismic profile data. This methodology involves a number of steps. First, we compute the azimuthal P‐wave anisotropy in the dry medium as a function of the azimuthal S‐wave anisotropy using a rock physics model, which accounts for the stress dependency of seismic wave velocities in dry isotropic elastic media subjected to triaxial compression. Once the P‐wave anisotropy in the dry medium is known, we use the anisotropic Gassmann equations to estimate the anisotropy of the saturated medium. We test this workflow on the log data acquired in the North West Shelf of Australia, where azimuthal anisotropy is likely caused by large differences between minimum and maximum horizontal stresses. The obtained results are compared to azimuthal P‐wave anisotropy obtained via orthorhombic tomography in the same area. In the clean sandstone layers, anisotropy parameters obtained by both methods are fairly consistent. In the shale and shaly sandstone layers, however, there is a significant discrepancy between results since the stress‐induced anisotropy model we use is not applicable to rocks exhibiting intrinsic anisotropy. This methodology could be useful for building the initial anisotropic velocity model for imaging, which is to be refined through migration velocity analysis.  相似文献   

寒区路面   总被引：1，自引：0，他引：1  

GuyDore 《冰川冻土》2002,24(5):593-600

The article mainly discusses several essential problems of cold region pavement, including thermal cracking of asphalt concrete, cracking deterioration and heaving, frost heave, seasonal and long term roughness induced by different frost heave, frost heave cracking, bearing capacity loss during spring thaw. The reason for these problems is that cold region pavements are subjected to intense solicitation by climatic and environmental factors. The author offers several models corresponding to the solicitation. Furthermore in conclusion of the article the author indicates future research for cold region.  相似文献   

Earthquake loss estimation for the New York City Metropolitan Region   总被引：1，自引：0，他引：1  

Michael W. Tantala  Guy J.P. Nordenson  George Deodatis  Klaus Jacob 《Soil Dynamics and Earthquake Engineering》2008,28(10-11):812

This study is a thorough risk and loss assessment of potential earthquakes in the NY–NJ–CT Metropolitan Region. This study documents the scale and extent of damage and disruption that may result if earthquakes of various magnitudes occurred in this area. Combined with a detailed geotechnical soil characterization of the region, scenario earthquakes were modeled in HAZUS (Hazards US), a standardized earthquake loss estimation methodology and modeling program. Deterministic and probabilistic earthquake scenarios were modeled and simulated, which provided intensities of ground shaking, dollar losses associated with capital (the building inventory) and subsequent income losses. This study has also implemented a detailed critical (essential) facilities analysis, assessing damage probabilities and facility functionality after an earthquake. When viewed in context with additional information about regional demographics and seismic hazards, the model and results serve as a tool to identify the areas, structures and systems with the highest risk and to quantify and ultimately reduce those risks.  相似文献   

Slurry-flow deposits in the Britannia Formation (Lower Cretaceous), North Sea: a new perspective on the turbidity current and debris flow problem   总被引：9，自引：1，他引：8  

Donald R. Lowe  & Martin Guy 《Sedimentology》2000,47(1):31-70

The Lower Cretaceous Britannia Formation (North Sea) includes an assemblage of sandstone beds interpreted here to be the deposits of turbidity currents, debris flows and a spectrum of intermediate flow types termed slurry flows. The term ‘slurry flow’ is used here to refer to watery flows transitional between turbidity currents, in which particles are supported primarily by flow turbulence, and debris flows, in which particles are supported by flow strength. Thick, clean, dish‐structured sandstones and associated thin‐bedded sandstones showing Bouma T_b–e divisions were deposited by high‐ and low‐density turbidity currents respectively. Debris flow deposits are marked by deformed, intraformational mudstone and sandstone masses suspended within a sand‐rich mudstone matrix. Most Britannia slurry‐flow deposits contain 10–35% detrital mud matrix and are grain supported. Individual beds vary in thickness from a few centimetres to over 30 m. Seven sedimentary structure division types are recognized in slurry‐flow beds: (M₁) current structured and massive divisions; (M₂) banded units; (M₃) wispy laminated sandstone; (M₄) dish‐structured divisions; (M₅) fine‐grained, microbanded to flat‐laminated units; (M₆) foundered and mixed layers that were originally laminated to microbanded; and (M₇) vertically water‐escape structured divisions. Water‐escape structures are abundant in slurry‐flow deposits, including a variety of vertical to subvertical pipe‐ and sheet‐like fluid‐escape conduits, dish structures and load structures. Structuring of Britannia slurry‐flow beds suggests that most flows began deposition as turbidity currents: fully turbulent flows characterized by turbulent grain suspension and, commonly, bed‐load transport and deposition (M₁). Mud was apparently transported largely as hydrodynamically silt‐ to sand‐sized grains. As the flows waned, both mud and mineral grains settled, increasing near‐bed grain concentration and flow density. Low‐density mud grains settling into the denser near‐bed layers were trapped because of their reduced settling velocities, whereas denser quartz and feldspar continued settling to the bed. The result of this kinetic sieving was an increasing mud content and particle concentration in the near‐bed layers. Disaggregation of mud grains in the near‐bed zone as a result of intense shear and abrasion against rigid mineral grains caused a rapid increase in effective clay surface area and, hence, near‐bed cohesion, shear resistance and viscosity. Eventually, turbulence was suppressed in a layer immediately adjacent to the bed, which was transformed into a cohesion‐dominated viscous sublayer. The banding and lamination in M₂ are thought to reflect the formation, evolution and deposition of such cohesion‐dominated sublayers. More rapid fallout from suspension in less muddy flows resulted in the development of thin, short‐lived viscous sublayers to form wispy laminated divisions (M₃) and, in the least muddy flows with the highest suspended‐load fallout rates, direct suspension sedimentation formed dish‐structured M₄ divisions. Markov chain analysis indicates that these divisions are stacked to form a range of bed types: (I) dish‐structured beds; (II) dish‐structured and wispy laminated beds; (III) banded, wispy laminated and/or dish‐structured beds; (IV) predominantly banded beds; and (V) thickly banded and mixed slurried beds. These different bed types form mainly in response to the varying mud contents of the depositing flows and the influence of mud on suspended‐load fallout rates. The Britannia sandstones provide a remarkable and perhaps unique window on the mechanics of sediment‐gravity flows transitional between turbidity currents and debris flows and the textures and structuring of their deposits.  相似文献   

Ground penetrating radar application in a shallow marine Oxfordian limestone sequence located on the eastern flank of the Paris Basin, NE France   总被引：5，自引：0，他引：5  

Guy Dagallier  Ari I. Laitinen  Fabrice Malartre  Ignace P. A. M. Van Campenhout  Paul C. H. Veeken   《Sedimentary Geology》2000,130(3-4):149-165

A Ground Penetrating Radar (GPR) survey has been carried out in Upper Jurassic limestones located on the eastern flank of the Paris Basin (NE France). The potential of the investigation method is assessed for delineating geologically meaningful stratifications in the shallow subsurface. The fundamentals of the GPR technique are described. Penetration depth and vertical resolution depends on the soil conditions, the characteristics of input signal and the configuration of the transmitter–receiver assembly. In the studied carbonates the penetration level is rather good and the electromagnetic signal reaches up to 1000 nanoseconds maximum (i.e. approximately 55 m). Several depositional units are outlined on the GPR profiles. Six different lithological units are recognised with distinct GPR reflection characteristics. The profiles illustrate the internal 3D organisation of the carbonate platform and its geometry. They provide detailed insight into the nature of an Oxfordian reefal build-up. The high-resolution subsurface model is directly calibrated with geological field observations and it results in a predictive 3D depositional working model. The GPR method is a non-destructive remote sensing technique that is cost effective. The method is considered complementary to other conventional high-resolution reservoir characterisation studies. It represents a powerful investigation tool in earth science studies concerning the imaging of the structure of the shallow subsurface.  相似文献   

From community planning to partnership planning. Urban regeneration and shifting power geometries on the South Bank, London     

Guy Baeten 《GeoJournal》2000,51(4):293-300

This paper seeks to explain the persistence of inner-city deprivation in spite of sustained regeneration efforts, through demonstrating how urban regeneration policies are embedded in peculiar political-institutional power dynamics that actually contribute to the further disempowerment of the already disempowered groups in inner cities. The reconstruction of the post-war planning history of one specific urban neighbourhood, the South Bank in central London, will allow to demonstrate how the constantly reworked urban regeneration models comprise specific power relations that have important repercussions for the success and failure of regeneration programmes. The focus here will particularly be on how the fall of the South Bank's prominent era of community-based development in the 1970s is firmly embedded in changing political-institutional frameworks that, after a spell of `community power', were soon to restore the power of the local cultural, political and business elites over the local regeneration agenda.  相似文献