Vulnerability and its discontents: the past,present, and future of climate change vulnerability research     

James D. Ford  Tristan Pearce  Graham McDowell  Lea Berrang-Ford  Jesse S. Sayles  Ella Belfer 《Climatic change》2018,149(2):189-204

The agri-food sector must adapt to changes in climate variability, while also helping to mitigate climate change. Measures termed ‘triple-win’ mitigate and adapt to climate change, while also improving soil health, thereby increasing yields. These measures might appear to be the easiest to implement, but in practice, barriers prevent full realisation. This study aims to move beyond previous research efforts that identify and categorise barriers by (i) revealing hidden barriers, (ii) understanding the interactions between barriers and (iii) exploring ways to address barriers. A case study focusing on crop rotation as a triple-win strategy in Ukraine demonstrates how a participant-driven iterative research approach can achieve these objectives. During semi-structured interviews with farmers and stakeholders, crop rotation emerged as an area of considerable dissensus with stakeholders commonly citing the greedy behaviour of producers as the problem. Further discussion indicated that the political economy of Ukraine caused financial constraints for producers and Q methodology allowed for additional clarity on the opposing views of crop rotation. Three factors emerged: producer insecurity, national insecurity and business insecurity. These three perspectives reveal contrasting priorities with producer insecurity and business insecurity concerned with the conditions under which producers must operate, while national insecurity has a focus on improving agricultural production to benefit the nation. Consensus statements across all factors could provide first steps to addressing barriers and an opportunity to open discussions amongst stakeholders. Finally, barriers arising from political processes demonstrate that climate policy needs to be integrated with other sector-specific policy decisions.  相似文献   

Electromagnetic Studies Of The Lithosphere And Asthenosphere   总被引：3，自引：0，他引：3  

Graham Heinson 《Surveys in Geophysics》1999,20(3-4):229-255

In geodynamic models of the Earth's interior, the lithosphere and asthenosphere are defined in terms of their rheology. Lithosphere has high viscosity, and can be divided into an elastic region at temperatures below 350 °C and an anelastic region above 650 °C. Beneath the lithosphere lies the ductile asthenosphere, with one- to two-orders of magnitude lower viscosity. Asthenosphere represents the location in the mantle where the melting point (solidus) is most closely approached, and sometimes intersected. Seismic, gravity and isostatic observations provide constraints on lithosphere-asthenosphere structure in terms of shear-rigidity, density and viscosity, which are all rheological properties. In particular, seismic shear- and surface-wave analyses produce estimates of a low-velocity zone (LVZ) asthenosphere at depths comparable to the predicted rheological transitions. Heat flow measurements on the ocean floor also provide a measure of the thermal structure of the lithosphere.Electromagnetic (EM) observations provide complementary information on lithosphere-asthenosphere structure in terms of electrical conductivity. Laboratory studies of mantle minerals show that EM observations are very sensitive to the presence of melt or volatiles. A high conductivity zone (HCZ) in the upper mantle therefore represents an electrical asthenosphere (containing melt and/or volatile) that may be distinct from a rheological asthenosphere and the LVZ. Additionally, the vector propagation of EM fields in the Earth provides information on anisotropic conduction in the lithosphere and asthenosphere. In the last decade, numerous EM studies have focussed on the delineation of an HCZ in the upper mantle, and the determination of melt/volatile fractions and the dynamics of the lithosphere-asthenosphere. Such HCZs have been imaged under a variety of tectonic zones, including mid-ocean ridges and continental rifts, but Archaean shields show little evidence of an HCZ, implying that the geotherm is always below the mantle solidus. Anisotropy in the conductivity of oceanic and continental lithosphere has also been detected, but it is not clear if the HCZ is also anisotropic. Although much progress has been made, these results have raised new and interesting questions of asthenosphere melt/volatiles porosity and permeability, and lithosphere-upper mantle heterogeneity. It is likely that in the next decade EM will continue to make a significant contribution to our understanding of plate tectonic processes.  相似文献   

An experimental study of phase equilibria in the system H2O-CO2-NaCl at 800 °C and 9 kbar     

Kirill I. Shmulovich  Colin M. Graham 《Contributions to Mineralogy and Petrology》1999,136(3):247-257

Phase equilibria in the ternary system H₂O-CO₂-NaCl were studied at 800 °C and 9 kbar in internally heated gas pressure vessels using a modified synthetic fluid inclusion technique. The low rate of quartz overgrowth along the `b' and `a' axes of quartz crystals was used to avoid fluid inclusion formation during heating, prior to attainment of equilibrium run conditions. The density of CO₂ in the synthetic fluid inclusions was calibrated using inclusions in the binary H₂O-CO₂ system synthesised by the same method and measured on the same heating-freezing stage. In the two-phase field, two types of fluid inclusions with different densities of CO₂ were observed. Using mass balance calculations, these inclusions are used to constrain the miscibility gap and the orientation of two-phase tie-lines in the H₂O-CO₂-NaCl system at 800 °C and 9 kbar. The equation of state of Duan et al. (1995) approximately describes the P-T section of the ternary system up to about 40 wt% of NaCl. At higher NaCl concentrations the measured solubility of CO₂ in the brine is much smaller than predicted by the EOS. A “salting out” effect must be added to the equation of state to include coulomb interaction in the model of Anderko and Pitzer (1993) and Pitzer and Jiang (1996). The new experimental data together with published data up to 5 kbar (Shmulovich et al. 1995) encompass practically all subsolidus crustal P-T conditions. A feature of the new experimental results is the large compositional range in the H₂O-CO₂-NaCl system occupied by the stability fields of halite + CO₂-rich fluid ± H₂O-NaCl brine. The prediction of halite stability in equilibrium with CO₂-rich fluid in deep-crustal rocks is supported by recent petrological and fluid inclusion studies of granulites. Received: 29 June 1998 / Accepted: 17 March 1999  相似文献   

Sediment and nutrient storage in a beaver engineered wetland          下载免费PDF全文

Alan Puttock  Hugh A. Graham  Donna Carless  Richard E. Brazier 《地球表面变化过程与地形》2018,43(11):2358-2370

Beavers, primarily through the building of dams, can deliver significant geomorphic modifications and result in changes to nutrient and sediment fluxes. Research is required to understand the implications and possible benefits of widespread beaver reintroduction across Europe. This study surveyed sediment depth, extent and carbon/nitrogen content in a sequence of beaver pond and dam structures in South West England, where a pair of Eurasian beavers (Castor fiber) were introduced to a controlled 1.8 ha site in 2011. Results showed that the 13 beaver ponds subsequently created hold a total of 101.53 ± 16.24 t of sediment, equating to a normalised average of 71.40 ± 39.65 kg m². The ponds also hold 15.90 ± 2.50 t of carbon and 0.91 ± 0.15 t of nitrogen within the accumulated pond sediment. The size of beaver pond appeared to be the main control over sediment storage, with larger ponds holding a greater mass of sediment per unit area. Furthermore, position within the site appeared to play a role with the upper‐middle ponds, nearest to the intensively‐farmed headwaters of the catchment, holding a greater amount of sediment. Carbon and nitrogen concentrations in ponds showed no clear trends, but were significantly higher than in stream bed sediment upstream of the site. We estimate that >70% of sediment in the ponds is sourced from the intensively managed grassland catchment upstream, with the remainder from in situ redistribution by beaver activity. While further research is required into the long‐term storage and nutrient cycling within beaver ponds, results indicate that beaver ponds may help to mitigate the negative off‐site impacts of accelerated soil erosion and diffuse pollution from agriculturally dominated landscapes such as the intensively managed grassland in this study. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

Impacts of Methane on Carbon Dioxide Storage in Brine Formations          下载免费PDF全文

Mohamad R. Soltanian  Mohammad A. Amooie  David R. Cole  Thomas H. Darrah  David E. Graham  Susan M. Pfiffner  Tommy J. Phelps  Joachim Moortgat 《Ground water》2018,56(2):176-186

In the context of geological carbon sequestration (GCS), carbon dioxide (CO₂) is often injected into deep formations saturated with a brine that may contain dissolved light hydrocarbons, such as methane (CH₄). In this multicomponent multiphase displacement process, CO₂ competes with CH₄ in terms of dissolution, and CH₄ tends to exsolve from the aqueous into a gaseous phase. Because CH₄ has a lower viscosity than injected CO₂, CH₄ is swept up into a ‘bank’ of CH₄‐rich gas ahead of the CO₂ displacement front. On the one hand, this may provide a useful tracer signal of an approaching CO₂ front. On the other hand, the emergence of gaseous CH₄ is undesirable because it poses a leakage risk of a far more potent greenhouse gas than CO₂ if the cap rock is compromised. Open fractures or faults and wells could result in CH₄ contamination of overlying groundwater aquifers as well as surface emissions. We investigate this process through detailed numerical simulations for a large‐scale GCS pilot project (near Cranfield, Mississippi) for which a rich set of field data is available. An accurate cubic‐plus‐association equation‐of‐state is used to describe the non‐linear phase behavior of multiphase brine‐CH₄‐CO₂ mixtures, and breakthrough curves in two observation wells are used to constrain transport processes. Both field data and simulations indeed show the development of an extensive plume of CH₄‐rich (up to 90 mol%) gas as a consequence of CO₂ injection, with important implications for the risk assessment of future GCS projects.  相似文献   

One Million Years tephra record at IODP Sites U1436 and U1437: Insights into explosive volcanism from the Japan and Izu arcs          下载免费PDF全文

Julie Christin Schindlbeck  Steffen Kutterolf  Susanne M. Straub  Graham D. M. Andrews  Kuo‐Lung Wang  Maryline J. Mleneck‐Vautravers 《Island Arc》2018,27(3)

The 1 Myr tephra records of IODP (International Ocean Discovery Program) Holes U1436A and U1437B in the Izu‐Bonin fore‐ and reararc were investigated in order to assess provenance and eruptive volumes, respectively. In total, 304 tephra samples were examined and 260 primary tephra layers were identified. Tephra provenance was determined by means of major and trace element compositions of glass shards and distinguished between Japan and Izu‐Bonin arc origin of the tephra layers. A total of 33 marine tephra compositions were correlated to the Japan arc and 227 to the Izu arc. Twenty marine tephra layers were correlated between the two drilling sites. Additionally, we defined eleven correlations of marine tephra deposits to major widespread Japanese eruptions; from the 1.05 Ma Shishimuta‐Pink Tephra to the 30 ka Aira‐Tn Tephra, both from Kyushu Island. These eruptions provide independent time markers within the sediment record and six correlations were used to date tephra layers from Japan in Hole U1436A to establish an alternative age model for this hole. Furthermore, the minimum distal tephra volumes of all detected events were calculated, which enabled the comparison of the tephra volumes that derived from the Japan and the Izu‐Bonin arcs. For some of the major Japanese eruptions these are the first volume estimations that also include distal deposits. All of the Japanese tephras derived from events with eruption magnitude M_v ≥ 5.6 and three of the investigated eruptions reach magnitudes M_v ≥ 7. Volcanic events of the Izu‐Bonin arc have mostly eruption magnitudes M_v ≤ 5.  相似文献   

Coupled consolidation of a porous medium with a cylindrical or a spherical cavity     

Y. Zhou  R. K. N. D. Rajapakse  J. Graham 《国际地质力学数值与分析法杂志》1998,22(6):449-475

This paper presents a theoretical approach to analyse coupled, linear thermoporoelastic fields in a saturated porous medium under radial and spherical symmetry. The governing equations account for compressibility and thermal expansion of constituents, heat sink due to thermal dilatation of water and thermal expansion of the medium, and thermodynamically coupled heat–water flow. It has been reported in the literature that thermodynamically coupled heat–water flows known as thermo-osmosis and thermal filtration have the potential to significantly alter the flow fields in clay-rich barriers in the near field of a underground waste containment scheme. This study presents a mathematical model and examines the effects of thermo-osmosis and thermal-filtration on coupled consolidation fields in a porous medium with a cavity. Analytical solutions of the governing equations are presented in the Laplace transform space. A numerical inversion scheme is used to obtain the time-domain solutions for a cylindrical cavity in a homogeneous or a non-homogeneous medium. A closed form time-domain solution is presented for a spherical cavity in a homogeneous medium. Selected numerical solutions for homogeneous and non-homogeneous media show a significant increase in pore pressure and displacements due to the presence of thermodynamically coupled flows and a negligible influence on temperature. © 1998 John Wiley & Sons, Ltd.  相似文献   

Use of Sonication for Enhanced Sampling of Attached Microbes from Groundwater Systems     

Murray Close  Phil Abraham  Judith Webber  Eliza Cowey  Bronwyn Humphries  Graham Fenwick  Simon Howard  Kimberly Huynh  Travis Grace  Pierre-Yves Dupont  Louise Weaver 《Ground water》2020,58(6):901-912

The vast majority of microorganisms in aquifers live as biofilms on sediment surfaces, which presents significant challenges for sampling as only the suspended microbes will be sampled through normal pumping. The use of a down-well low frequency sonicator has been suggested as a method of detaching microbes from the biofilm and allowing rapid sampling of this community. We developed a portable, easy to use, low-frequency electric sonicator and evaluated its performance for a range of well depths (tested up to 42 m below ground level) and casing types. Three sonicators were characterized in laboratory experiments using a 1 m long tank filled with pea gravel. These included a commercially available pneumatic sonicator, a rotating flexible shaft sonicator, and the prototype electric sonicator. The electric sonicator detached between 56 and 74% of microbes grown on gravel-containing biobags at distances ranging between 2 and 50 cm from the sonicator. The field testing comprises of a total of 55 sampling events from 48 wells located in 4 regions throughout New Zealand. Pre- and post-sonication samples showed an average 33 times increase in bacterial counts. Microbial sequence data showed that the same classes are present in pre- and post-sonicated samples and only slight differences were seen in the proportions present. The sampling process was rapid and the significant increases in bacterial counts mean that microbial samples can be quickly obtained from wells, which permits more detailed analysis than previously possible.  相似文献   

The ductility reduction factor in the seismic design of buildings     

Nelson Lam  John Wilson  Graham Hutchinson 《地震工程与结构动力学》1998,27(7):749-769

This paper presents new trends in the relationship between the ductility reduction factor and the ductility demand in the seismic design of buildings. A total of 4860 inelastic time-history analyses were carried out to study this relationship using 60 single-degree-of-freedom models excited by an ensemble of 81 earthquake accelerogram records from around the world. The asymmetrical distribution of the results highlighted the inaccuracies associated with assuming a normal distribution simply described by the mean and standard deviation to represent the data. A probability of exceedence approach has been used based on counting the number of occurrences the ductility demand exceeds a specified level. The ductility reduction factors developed in this study are consistent with other studies in the long-period range but are different in the short-period range. The ductility reduction factor for very short period buildings of limited ductility has been found to be greater than previously predicted. © 1998 John Wiley & Sons, Ltd.  相似文献   

The history and dynamics of a welded pyroclastic dam and its failure     

Graham D. M. Andrews  James K. Russell  Martin L. Stewart 《Bulletin of Volcanology》2014,76(4):1-16

Igneous intrusions in coal seams are found in 80 % of coal mines in the Huaibei coalfield, China, and coal and gas outburst accidents have occurred 11 times under a 120-m-thick sill in the Haizi mining field. The magma’s heat had a significant controlling effect on coal seam gas occurrence. Based on theoretical analysis, experimental tests and site validation, we analyzed the temperature distribution following magma intrusion into coal measure strata and the variations in multiple physical parameters and adsorption/desorption characteristics between the underlying coal seams beneath the sill in the Haizi mining field and coal seams uninfluenced by magma intrusion in the adjacent Linhuan mining field. The research results show that the main factors controlling the temperature distribution of the magma and surrounding rocks in the cooling process include the cooling time and the thickness and initial temperature of the magmatic rock. As the distance from sill increases, the critical effective temperature and the duration of sustained high temperatures decrease. The sill in the Haizi mining field significantly promoted coal seam secondary hydrocarbon generation in the thermally affected area, which generated approximately 340 m³/t of hydrocarbon. In the magma-affected area, the metamorphic grade, micropore volume, amount of gas adsorption, initial speed of gas desorption, and amount of desorption all increase. Fluid entrapment by sills usually causes the gas pressure and gas content of the underlying coal seams to increase. As a result, the outburst risks from coal seams increases as well.  相似文献