Framing and communicating climate change: The effects of distance and outcome frame manipulations     

Alexa Spence  Nick Pidgeon 《Global Environmental Change》2010,20(4):656-667

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伊犁京希—伊尔曼德金矿床的热液蚀变及成矿流体演化特征   总被引：10，自引：1，他引：10  

肖龙  王方正等 《地质学报》2001,75(4):518-526

京希－伊尔曼德金矿床的热液蚀变在空间上有明显的分带性，中心蚀变带以强烈的硅化为主，典型的蚀变矿物组合为石英或玉髓和地开石，中间带为高级泥化带，以地开石－高岭石－石英或玉髓为特征；外带为以蒙脱石－高岭石－伊利石－其他粘土矿物等矿物组合为主的泥化带，蚀变强度和矿物组合的分带性是温度、压力和化学梯度的反映，是流体在不断的水或流体－岩石反应和成分交换的产物。该矿床成矿流体演化过程为：早期酸性（pH=2-3)含矿流体在沿断裂上升过程中，受围岩灰岩中的流体（pH为中性）缓冲，在其进入高渗透性的碎屑岩层时，流速和水－岩石或流休－岩石反应大大加快，并在与大气降水的混合作用下，pH值逐步升高（3－5），产生了流体的温度及成分梯度，在温度和压力迅速下降的条件下，金及蚀变矿物沉淀、结晶生长，形成了蚀变空间分带，中心带保存完好的多孔状石英和地开石等高级泥化矿物组合说明该矿床是高硫化热液体系作用下的产物。  相似文献   

The inner city: In search of the problem     

Ray Forrest  John Lloyd  Nick Rogers  Peter Williams 《Geoforum》1979,10(1):109-116

This paper explores the theoretical content of the inner-city debate in Britain and seeks to examine the extent to which the ‘problem’ is either new or primarily economic. It is argued that the inner-city issue, while subject to specific political and ideological forces, is associated with the general processes of uneven capitalist development. In this sense, metropolitan decline is a further manifestation of the relationship between the built environment, the transience of economic activity and social change. More specifically the decline of the inner city relates to the incipient role of Britain in the development of capitalism and its current position in the world economy. The emergence of this as a ‘problem’ for the British state is combined with a convenient spatial determinism, which isolates the inner city as an anomaly even as the search for palliatives is erected to the status of a major social task.  相似文献   

Evaluation of lead movement from the abiotic to biotic at a small-arms firing range     

Michael P. Labare  Michael A. Butkus  Dawn Riegner  Nick Schommer  Jason Atkinson 《Environmental Geology》2004,46(6-7):750-754

An investigation to characterize the extent and speciation of lead contamination in water, soil, and surrounding biota was conducted at a small-arms firing and skeet range in West Point, New York. Specifically, lead concentrations were examined in sediment, soil, water, plants, fish and invertebrates. There is an elevated concentration of lead in the soil and sediment up to 11,000 g/g and 340 g/g and also evidence of bioconcentration of the lead by the surrounding biota. Earthworms had up to 90% higher concentrations of lead while tadpoles showed 20% higher concentrations compared with their controls. Lead uptake by indigenous plants gave varying results. Two species bioconcentrated lead 20 and 55 times greater than the control plants. These differences were significant (P <0.05 level) when tested by the students t test. Further studies show that the total leachable lead was highest in the invertebrates and vertebrates but not in the plants.  相似文献   

Retrieval of atmospheric reflectivity profiles in case of long radar pulses     

Nick Schutgens  David P. Donovan 《Atmospheric Research》2004,72(1-4):187

Future space-borne cloud profiling radars (CPR) will employ longer pulse lengths than ground-based systems. As a consequence, reflectivity profiles observed from space will be more strongly convoluted with the radar pulse shape. Here we describe a constrained linear inverse technique that reduces the effects of this convolution. We apply the technique to simulated data, based on actual observations from the ground, and show that significant improvements in the reflectivity profile can be obtained. Average Z errors (dBz) are halved, while cloud boundaries are substantially better retrieved. The results in this paper are relevant to space-borne missions like CloudSat and EarthCARE.  相似文献   

U and Th concentrations and isotope ratios in modern carbonates and waters from the Bahamas   总被引：1，自引：0，他引：1  

Laura F Robinson  Nick S Belshaw 《Geochimica et cosmochimica acta》2004,68(8):1777-1789

The short residence times of Th and Pa in seawater make them very responsive to changes in the ocean environment. We use a new multi-ion-counting technique to make Th and Pa isotope measurements in seawaters from a near-shore environment in which oceanic chemical tracers are not overwhelmed by terrestrial inputs (the Bahamas). An unusual feature of the Bahamas setting is the shallow depth of water residing on the bank tops. These waters have significantly lower ²³²Th/²³⁰Th (∼10,000) than those immediately adjacent to the banks (24,000-31,000) and a (²³¹Pa/²³⁰Th) near the production ratio (∼0.1). The change in ²³²Th/²³⁰Th and (²³¹Pa/²³⁰Th) on the bank tops is explained by almost quantitative removal of Th and Pa by scavenging, and their replacement with a mixture of ²³⁰Th and ²³¹Pa alpha-recoiled from the underlying carbonates, together with Th from dust dissolution. Analysis of a water profile in the Tongue of the Ocean, which separates the Great and Little Bahama Banks, allows us to trace the movement of bank-top water to depth. A distinct minimum in both ²³²Th/²³⁰Th (∼13,000) and (²³¹Pa/²³⁰Th) (∼0.5) is observed at ∼430 m and is interpreted to reflect density cascading of bank-top water with entrained carbonate sediment. These results suggest that Th and Pa can be used as water-mass tracers in near-shore environments. Uranium concentration measurements on the same waters demonstrate that U is conservative across a range in salinity of 2 psu, with a concentration of 3.33 ppb (at a salinity of 35).The incorporation of U and Th isotopes into marine carbonates has also been assessed by analyzing carbonate samples from the same location as these Bahamas waters. Such incorporation is critical for U-Th geochronology. U isotope analyses demonstrate that seawater δ²³⁴U averages 146.6 and does not vary by more than 2.5%o, and that carbonates capture this value. Additional high precision measurements (≈±1%o) on modern carbonates confirm that all oceans have identical δ²³⁴U. Modern marine carbonates are shown to have ²³²Th/²³⁰Th ratios that reflect the local seawater in which they formed.  相似文献   

Contrasting flow pathways within tropical forest slopes of Ultisol soils     

Nick A. Chappell  Mark D. Sherlock 《地球表面变化过程与地形》2005,30(6):735-753

There are very few experimental studies identifying hydrological pathways within rain forest slopes. Such knowledge is, however, necessary to understand why forest disturbance affects rainfall–riverflow response and nutrient migration. This study examines flow pathways within lowland rain forest slopes comprising Udults of the Ultisol soil order. Experimentation was conducted on four SE Asian hillslope units (each 5 × 5 m in plan) in the Bukit Timah catchment (Singapore Island), and in the W8S5 catchment (Sabah, Borneo Island). The flow pathways were identified by artificial tracer experiments. We evaluated how well hydrometric calculations based on tensiometry and permeametry measurements predicted the tracer patterns. The tracer work indicated much faster subsurface flows at Bukit Timah than W8S5 for the storms studied. Some explanation of the greater subsurface waterflows at Bukit Timah in comparison to W8S5 is afforded by the less steep moisture release curves which maintain hydraulic conductivity as the soil dries. Vertical flow of the tracer through the upper 1 m of soil predominated (>90 per cent of percolation) in the Bukit Timah slopes. In some contrast, a major component (approximately 60 per cent) of the tracer percolation was directed laterally within the W8S5 slopes. The flow vectors calculated using the hydrometric methods did, however, grossly under‐estimate the degree of lateral deflection of waterflow generated at W8S5 and to a lesser extent over‐estimated it at Bukit Timah. In part, these errors may relate to the inability of traditional hydrometric techniques to fully characterize the effect of the large and small ‘natural soil pipes’ present within both catchments. In conclusion, the study indicates that marked variations in flow vectors exist within the Udult great group of SE Asian soils and hydrometric calculations may be poor predictors of these dominant pathways. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Oceanic electromagnetic studies: A review   总被引：3，自引：0，他引：3  

Nick A. Palshin 《Surveys in Geophysics》1996,17(4):455-491

The review covers the main results of the oceanic electromagnetic studies presented during last 4–5 years. Seafloor electromagnetic observations are dedicated to studies in solid Earth geophysics and oceanography. Thus, a large range of objectives and targets are under investigation. Technological and theoretical advances provide an increase of quantity and quality of the collected seafloor data. The host conductivity models for oceanic crust and mantle are being developed; the possibility of obtaining useful structural constraints in heterogeneous environment are discussed. Significant oceanographic results were derived from electromagnetic field observations; these appeared to be a new powerful method for study of long-term large-scale ocean variability.  相似文献   

Book review     

Nick Oliver  H. J. Turin  Robert D. Cicerone  Andrea Lini 《Pure and Applied Geophysics》1996,146(1):195-205

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Field measurements of shear strength of an underconsolidated marine clay   总被引：1，自引：0，他引：1  

Moses Karakouzian  B. Bur  in Avar  Nick Hudyma  Jeffrey A. Moss 《Engineering Geology》2003,67(3-4):233-242

This paper presents the observations of cone penetration testing (CPT), in situ vane shear testing and undrained triaxial testing of underconsolidated marine clay in the Craney Island Dredged Material Management Area (CIDMMA), Norfolk, VA. Comparison of vane shear measurements, taken during 1981–1983, to CPT measurements, taken during 1993, indicates a change in undrained shear strength. Both the vane shear and cone penetration resistances are lowest at the mid-heights of the clay layers and the excess pore water pressures are highest at the mid-height of the clay layers, indicating that the clay layer is underconsolidated.  相似文献