Dawsonite as a daughter mineral in hydrothermal fluid inclusions   总被引：10，自引：0，他引：10  

Raymond M. Coveney  William C. Kelly 《Contributions to Mineralogy and Petrology》1971,32(4):334-342

Traces of dawsonite (NaAlCO₃(OH)₂) are extremely common as a daughter product in fluid inclusions in gold-quartz veins and altered wallrock of the Oriental mine, Alleghany district, California. A very similar daughter salt occurs in hydrothermal inclusions in quartz from 19 other mining localities of worldwide distribution.Vein fluids of the Oriental mine were probably CO₂-rich sodium bicarbonate brines that contained at least 1 weight percent dissolved aluminum. These fluids precipitated quartz and oligoclase in the veins and adjacent altered rocks. The precipitation of dawsonite rather than albite or oligoclase in the cooled inclusion brines suggests either that sodic plagioclase gives way to dawsonite plus quartz as the stable pair at low temperatures or that the dawsonite is a metastable daughter mineral. The rarity of dawsonite as a separate vein mineral or alteration product at the Oriental mine and elsewhere is attributed to its high solubility under normal conditions of mineralization.Dawsonite contributes 190 ppm or more to the aluminum content of some Oriental mine quartz. Large errors would result if the dawsonite were overlooked and the aluminum geothermometer of Dennen et al. (1970) were applied to this quartz. The combination of high primary inclusion filling temperatures and very low aluminum contents of optically clear quartz indicate that major revisions are needed in the published thermometer curve.  相似文献   

Seismic response of base-isolated structures with vertical-rocking coupling     

Tso-Chien Pan  James M. Kelly 《地震工程与结构动力学》1984,12(5):681-702

A base-isolated building is liable to have a small horizontal eccentricity between the centre of mass of the superstructure and the centre of rigidity of the supporting bearings. In seismic analysis, the structure is modelled as a rigid block with tributary masses supported on massless elastomeric rubber bearings placed at a constant elevation below the centre of mass. This simplified system has three degrees of freedom: two translations and one rotation in the vertical plane. The investigation of the dynamic behaviour of a base-isolated building is carried out for both the detuned and the perfectly tuned cases. In the detuned case, the natural frequencies of the system are assumed to be well separated. In the perfectly tuned case, the uncoupled rocking frequency is assumed to be identical to the vertical translational frequency, which may result from an unusual mass distribution and/or an extreme aspect ratio of the superstructure. Perturbation methods are implemented in finding the dynamic characteristics for both cases. However, the dynamic response of the perfectly tuned case is the major concern in this investigation. The Green's functions for the displacement response of the three-degree-of-freedom system are derived for both the undamped and damped conditions. The response spectrum modal superposition method is used in estimating the maximum acceleration response. A simple method, accounting for the effect of closely spaced modes, is proposed for combining modal maxima and results in an approximate solution corresponding to a single-degree-of-freedom system. This approximate solution may be used for the preliminary design of a base-isolated structure. Numerical results for a base-isolated building subjected to the vertical component of the El Centro earthquake of 1940 were carried out for comparison with these analytical results. The proposed modal combination method showed superiority over the conventional Square Root of the Sum of the Squares method in estimating maximum responses. The results also indicated that the approximate single-degree-of-freedom system yields accurate estimations. It is shown that the effect of rocking coupling on the vertical response of base-isolated structures subjected to transient loadings, such as earthquake motions, can generally be neglected as a result of the combined effects of the time lag between the maximum translational and rotational responses and the influence of damping in the isolation system, which for elastomeric bearings can be as high as 8 to 10 per cent of critical.  相似文献   

On the Temperature and Humidity Dissimilarity in the Marine Surface Layer     

Xiaoli Guo Larsén  Mark Kelly  Anna Maria Sempreviva 《Boundary-Layer Meteorology》2014,151(2):273-291

The dissimilarity of temperature and humidity transfer in the marine surface layer (MSL) is investigated through the relative transport efficiency and correlation coefficient of these two scalars. We examine their variability and relationship with mean values, as well as spectral characteristics. It is shown that the dissimilarity between these two scalars in the MSL is a function of stability, the boundary-layer depth, and flow steadiness. In general the temperature and humidity are less correlated in shallow marine boundary layers compared to deep marine boundary layers, due to the stronger impact of the boundary-layer scale in breaking the “same source, same sink” assumption for scalar similarity. This is supported by the combination of our spectral analysis of scalar fluxes and corresponding measured and modelled boundary-layer depth. This assumption is also broken in near-neutral conditions, when there is an efficient latent heat transfer but negligible sensible heat transfer. Our data suggest that parametrization of humidity fluxes via similarity theory could still be reliable when the correlation coefficient $>$ 0.5, and in near-neutral conditions the humidity flux can be estimated without use of the sensible heat flux.  相似文献   

A reassessment of the soil sink for atmospheric carbon tetrachloride based upon static flux chamber measurements     

James D. Happell  Yudania Mendoza  Kelly Goodwin 《Journal of Atmospheric Chemistry》2014,71(2):113-123

Static flux chamber measurements of CCl₄ uptake by soils in boreal, subtropical and tropical forests have been used to reassess the sink strength for this ozone depleting chemical. Happell and Roche (Geophys. Res. Lett. 30(2), 1088–1091, 2003) used flux estimates from soil concentration gradients to calculate a partial CCl₄ atmospheric lifetime (τ_soil) of 90 years. More recently, it is has been assumed that a better estimate of τ_soil is 195 years (Montzka et al. 2011). In the work here, the rate of CCl₄ uptake was calculated from 453 flux chamber measurements using an exponential fit to the chamber CCl₄ concentration change with time. This analysis indicated that the flux rate estimate in Happell and Roche (Geophys. Res. Lett. 30(2) 1088–1091, 2003) was overestimated by 2.75, yielding a new estimate of τ_soil for CCl₄ of 245 years. Significant correlations of CCl₄ uptake to temperature, soil moisture, or time of year were not observed. This work provides additional evidence that CCl₄ uptake by soils is a common process and needs to be considered when developing an atmospheric budget for this compound.  相似文献   

Adapting agriculture to climate change: a review   总被引：2，自引：0，他引：2  

Muhuddin Rajin Anwar  De Li Liu  Ian Macadam  Georgina Kelly 《Theoretical and Applied Climatology》2013,113(1-2):225-245

The agricultural sector is highly vulnerable to future climate changes and climate variability, including increases in the incidence of extreme climate events. Changes in temperature and precipitation will result in changes in land and water regimes that will subsequently affect agricultural productivity. Given the gradual change of climate in the past, historically, farmers have adapted in an autonomous manner. However, with large and discrete climate change anticipated by the end of this century, planned and transformational changes will be needed. In light of these, the focus of this review is on farm-level and farmers responses to the challenges of climate change both spatially and over time. In this review of adapting agriculture to climate change, the nature, extent, and causes of climate change are analyzed and assessed. These provide the context for adapting agriculture to climate change. The review identifies the binding constraints to adaptation at the farm level. Four major priority areas are identified to relax these constraints, where new initiatives would be required, i.e., information generation and dissemination to enhance farm-level awareness, research and development (R&D) in agricultural technology, policy formulation that facilitates appropriate adaptation at the farm level, and strengthening partnerships among the relevant stakeholders. Forging partnerships among R&D providers, policy makers, extension agencies, and farmers would be at the heart of transformational adaptation to climate change at the farm level. In effecting this transformational change, sustained efforts would be needed for the attendant requirements of climate and weather forecasting and innovation, farmer’s training, and further research to improve the quality of information, invention, and application in agriculture. The investment required for these would be highly significant. The review suggests a sequenced approach through grouping research initiatives into short-term, medium-term, and long-term initiatives, with each initiative in one stage contributing to initiatives in a subsequent stage. The learning by doing inherent in such a process-oriented approach is a requirement owing to the many uncertainties associated with climate change.  相似文献   

Emerging transitions in organic waste infrastructure in Aotearoa New Zealand     

Gradon Diprose  Kelly Dombroski  Emma Sharp  Amanda Yates  Bailey Peryman  Martine Barnes 《New Zealand geographer》2023,79(1):15-26

Aotearoa New Zealand is at a critical juncture in reducing and managing organic waste. Research has highlighted the significant proportion of organic waste sent to landfills and associated adverse effects such as greenhouse gas emissions and loss of valuable organic matter. There is current debate about what practices and infrastructure to invest in to better manage and use organic waste. We highlight the diversity of existing organic waste practices and infrastructures, focusing on Auckland, Wellington and Christchurch. We show how debates about organic waste practices and infrastructure connect across three themes: waste subjectivities, collective action in place and language.  相似文献   

Sorption of yttrium and rare earth elements by amorphous ferric hydroxide: Influence of solution complexation with carbonate     

Kelly A. Quinn  Johan Schijf 《Geochimica et cosmochimica acta》2006,70(16):4151-4165

The influence of solution complexation on the sorption of yttrium and the rare earth elements (YREEs) by amorphous ferric hydroxide was investigated at 25 °C over a range of pH (4.0-7.1) and carbonate concentrations . Distribution coefficients, defined as , where [MS_i]_T is the total concentration of sorbed YREE, M_T is the total YREE concentration in solution, and [S_i] is the concentration of amorphous ferric hydroxide, initially increased in magnitude with increasing carbonate concentration, and then decreased. The initial increase of is due to sorption of YREE carbonate complexes , in addition to sorption of free YREE ions (M³⁺). The subsequent decrease of , which is more extensive for the heavy REEs, is due to the increasing intensity of YREE solution complexation by carbonate ions. The competition for YREEs between solution complexation and surface complexation was modeled via the equation: