磷处理粉煤灰可作农业土壤磷源   总被引：2，自引：0，他引：2  

申俊峰  M.A.Powell  D.B.Hayden 《地学前缘》2008,15(6):112

粉煤灰(简称CCP或ash)具有改良土壤,增加植物产量的功能。此外,由于它特殊的多孔结构,也可用作吸纳并承载植物养分的载体。用NaH2PO4配制成含磷0.10mol/L浓度的溶液,对采自加拿大西安大略省Sarnia地区Lambton电厂的底灰(bottomash)进行振荡浸渍处理。结果表明,振荡浸渍66h后的粉煤灰中磷含量可达784×10-6。以磷处理粉煤灰、未进行磷处理的粉煤灰和石英砂按比例混合,作为基本生长介质进行玉米种植实验,其中实验配方设计为生长介质中含磷量分别为标准含磷浓度(50×10-6)的10%、25%、50%、75%和100%。生长26、34和46d后分别与不含磷的空白配方、施加含氮-磷-钾为0-20-0标准磷肥并控制磷含量为标准浓度(50×10-6)配方进行生物产量对比。生长实验结果表明,以磷处理粉煤灰供磷的生长介质,当含磷量为标准浓度的25%至100%时,其植物生长量就比添加标准浓度磷肥的配方好。种植46d后的生物生长量统计结果显示,含磷分别为标准浓度50%、75%和100%的实验介质中,玉米杆的鲜重较施标准磷肥介质中玉米分别增长39.46%、42.73%和46.13%;玉米杆干重依次增加29.71%、13.39%和28.87%;根鲜重平均增加16.62%;根干重平均增加14.03%。上述实验结果启示,粉煤灰可以很好地吸纳承载磷养分,并持续供给植物吸收生长,如果采用吸纳磷(或其他养分)的粉煤灰改良砂质土壤将有重要意义。  相似文献   

Editorial: Putting philosophies of geography into practice   总被引：1，自引：1，他引：1  

Hayden Lorimer  & Nick Spedding 《Area》2002,34(3):227-228

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Large-Eddy Simulation of Turbulent Flow Over a Rough Surface     

Zhengtong Xie  Peter R. Voke  Paul Hayden  Alan G. Robins 《Boundary-Layer Meteorology》2004,111(3):417-440

A family of wall models is proposed that exhibits moresatisfactory performance than previousmodels for the large-eddy simulation (LES) of the turbulentboundary layer over a rough surface.The time and horizontally averaged statistics such asmean vertical profiles of windvelocity, Reynolds stress, turbulent intensities, turbulentkinetic energy and alsospectra are compared with wind-tunnel experimental data.The purpose of the present study is to obtain simulatedturbulent flows that are comparable with wind-tunnelmeasurements for use as the wind environment for thenumerical prediction by LES of source dispersion in theneutral atmospheric boundary layer.  相似文献   

Revolution or evolution? New Zealand agriculture since 1984     

Willie Smith  Hayden Montgomery 《GeoJournal》2004,59(2):107-118

Agriculture was the primary target of moves to deregulate the New Zealand economy in 1984. Within twelve-months all production subsidies had been removed, including those for fertiliser and other inputs, as well as funding for drought relief, floods and other natural weather disasters. Whereas at the start of 1984, subsidies were estimated to represent as much as 33% of farm income, by 2003 this had fallen to less than 2% with most of this spent on agricultural research. The anticipated shift of thousands of people off the land did not appear to occur, and by conventional measures at least New Zealand agriculture in 2003 is a major success story. At the core of the changes imposed on agriculture was a commitment to remove all state or government distortions from the system and to fully expose the agricultural sector to market forces. This included wide-ranging and fundamental changes in the broad institutional context within which agriculture must operate. All this was achieved at great social cost and with a significant impact on the environment. In many respects New Zealand agriculture is now very different from that in 1984. Some sectors, such as dairying, have grown and become increasingly industrialised. On the other hand, sheep farming, particularly for wool has struggled to maintain its market share, while other enterprises have emerged as significant sources of income, including horticulture, viticulture and fruit. It is argued here that the trends evident in New Zealand agriculture since 1984 pre-existed the reform period and that the apparent success of the reforms evident at a national scale have not addressed or removed the fundamental problems which face New Zealand agriculture, just as they do modern agricultural systems elsewhere. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Cone-penetrometer exploration of Sinkholes: Stratigraphy and soil properties     

D. Bloomberg  S. B. Upchurch  M. L. Hayden  R. C. Williams 《Environmental Geology》1988,12(2):99-105

Four sinkholes with varying surficial expressions were subjected to detailed stratigraphic and soil analysis by means of Standard Penetration Tests (SPT) and Electric Friction Cone Penetration Tests (CPT) in order to evaluate applications of CPT to sinkhole investigations. Although widely used, SPT data are of limited value and difficult to apply to sinkhole mapping. CPT is sensitive to minor lithologic variability and is superior to SPT as a cost-effective technique for determining geotechnical properties of sinkholes. The effectiveness of CPT data results from the force measurements made along the sleeve of the cone. The friction ratio (ratio of sleeve to tip resistance) is a good indicator of soil stratigraphy and properties. By smoothing the friction-ratio data, general stratigraphy and changes in soil properties are easily identified. Stratigraphy of the sinks has been complicated by intense weathering, karstification and marine, transgressions. The resulting deposits include five stratigraphic units. I and II represent Plio-Pleistocene marine sediments with Unit II being the zone of soil clay accumulation. III and IV are horizons residual from Miocene strata and indicate an episode of karstification prior to deposition of Units I and II. Conduit fill is a mixture of materials with low cohesion. The fill materials indicate centripetal and downward movement of insoluble sediments derived from the surrounding strata. Loss of cohesion results in near-zero friction ratios. Very low friction ratios, coupled with materials with little cohesion, indicate potentially-liquefiable soils in the immediate vicinity of zones where piping failure may be imminent. SPT does not provide sufficient data to predict these zones of potential, failure. CPT provides sufficient information for recognition of sinkhole stratigraphy and geotechnical properties. When coupled with laboratory soil analysis, CPT provides unique information about sinkhole geometry and dynamics. In contrast, SPT data fail to produce consistent indicators of sinkhole stratigraphy or properties. With laboratory soil data, SPT indicates general, inconclusive trends.  相似文献   

Vortex shedding behind tapered obstacles in neutral & stratified flow     

Ian Castro  Simon Vosper  Martin Paisley  Paul Hayden 《Dynamics of Atmospheres and Oceans》2001,34(2-4)

Results of laboratory and numerical experiments on both homogeneous and density-stratified flow over single, bluff obstacles of various shapes are presented. The obstacle height is in most cases of the same order as the base diameter and the major controlling (flow) parameter is the Froude number, defined here as F_h=U/Nh, where U is the (uniform) upstream velocity, h the obstacle height and N is the buoyancy frequency. Attention is concentrated, firstly, on the case of homogeneous flows over rather weakly tapered obstacles and, secondly, for bodies whose height is similar to their base width, on the case F_h=0.1, representing stratification sufficiently strong that lee-wave motions do not play a significant role in the flow dynamics. For right-circular cones it is shown that the sectional contributions to the total fluctuating side force (lift) show significant phase variations up the height of the obstacle, which are not always reflected in the developed vortex street further downstream. For some obstacle shapes, the vortex lines linking the von Karman eddies at different heights can be significantly tilted, particularly in the upper part of the wake. Vortex convection speeds do not appear generally to vary greatly with height and, as found in previous work, the shedding frequency remains constant with height, despite the strong variation of cross-stream obstacle width. By comparison with the homogeneous results, it is suggested that the stratification enhances the shedding instability, which would otherwise be very weak for squat obstacles, but does not annihilate the ability of the flow at one level to influence that at another.  相似文献   

Global climatic change,hurricanes, and a tropical forest     

Sean T. O'Brien  Bruce P. Hayden  Herman H. Shugart 《Climatic change》1992,22(3):175-190

Most, if not all forests in the Caribbean are subject to occasional disturbances from hurricanes. If current general circulation model (GCM) predictions are correct, with doubled atmospheric CO₂ (2 × CO₂), the tropical Atlantic will be between 1 °C and 4 °C warmer than it is today. With such a warming, more than twice as many hurricanes per year could be expected in the Caribbean. Furthermore, Emanuael (1987) indicates that in a warmed world the destructive potential of Atlantic hurricanes could be increased by 40% to 60%. While speculative, these increases would dramatically change the disturbance regimes affecting tropical forests in the region and might alter forest structure and composition. Global warming impacts through increased hurricane damage on Caribbean forests are presented.An individual tree, gap dynamics forest ecosystem model was used to simulate the range of possible hurricane disturbance regimes which could affect the Luquillo Experimental Forest in Puerto Rico. Model storm frequency ranged from no storms at all up to one storm per year; model storm intensity varied from no damage up to 100% mortality of trees. The model does not consider the effects of changing temperature and rainfall patterns on the forest. Simulation results indicate that with the different hurricane regimes a range of forest types are possible, ranging from mature forest with large trees, to an area in which forest trees are never allowed to reach maturity.  相似文献   

ROAD DRAINAGE AND EQUILIBRIUM IN SMALL STREAM BASINS*     

Robert S. Hayden 《The Professional geographer》1981,33(4):429-435

Roads and road drainage accompany the development of the physical landscape for cultural purposes. The addition of a road network to a small stream basin creates a situation of geomorphic disequilibrium by adding to the length of surface drainage channels. Effects of road drainage on the geomorphic equilibrium of small stream basins are analyzed using Horton's Law of Stream Lengths. The effects of different types of road networks are analyzed using an hypothetical stream basin and eight hypothetical road networks, suggesting a method of predicting the location and extent of disequilibrium in a stream basin system as a result of road drainage.  相似文献   

Freshwater reserves of mid-atlantic coast barrier Islands     

Thomas H. Bolyard  George M. Hornberger  Robert Dolan  Bruce P. Hayden 《Environmental Geology》1979,3(1):1-11

A multiple regression model was constructed for the purpose of predicting barrier island hydrology from easily measureable island characteristics. The model was developed using data obtained from 17 sites on the Outer Banks of North Carolina. The accuracy of the model for predicting key hydrologic variables was evaluated by statistical and graphic procedures. In general, agreement between observed and predicted values of the hydrologic variables was very good, suggesting that the quantity of potable water at various island sites can be estimated without resorting to extensive field investigations. The model was then applied to Assateague Island, a barrier island located off the coasts of Maryland and Virginia. Results indicate that the original model developed for the Outer Banks may be applied to other barrier islands but that errors involved may necessitate corrections in detailed studies. Correction for bias in predictions for Assateague was shown to be possible with limited field data from surface resistivity surveys.  相似文献   

Scalar Fluxes Near a Tall Building in an Aligned Array of Rectangular Buildings     

Vladimír Fuka  Zheng-Tong Xie  Ian P. Castro  Paul Hayden  Matteo Carpentieri  Alan G. Robins 《Boundary-Layer Meteorology》2018,167(1):53-76

Scalar dispersion from ground-level sources in arrays of buildings is investigated using wind-tunnel measurements and large-eddy simulation (LES). An array of uniform-height buildings of equal dimensions and an array with an additional single tall building (wind tunnel) or a periodically repeated tall building (LES) are considered. The buildings in the array are aligned and form long streets. The sensitivity of the dispersion pattern to small changes in wind direction is demonstrated. Vertical scalar fluxes are decomposed into the advective and turbulent parts and the influences of wind direction and of the presence of the tall building on the scalar flux components are evaluated. In the uniform-height array turbulent scalar fluxes are dominant, whereas the tall building produces an increase of the magnitude of advective scalar fluxes that yields the largest component. The presence of the tall building causes either an increase or a decrease to the total vertical scalar flux depending on the position of the source with respect to the tall building. The results of the simulations can be used to develop parametrizations for street-canyon dispersion models and enhance their capabilities in areas with tall buildings.  相似文献