Microbiological characterisation of a diesel contaminated beach site     

Paton GI  Iroegbu CO  Dawson JJ 《Marine pollution bulletin》2003,46(7):903-906

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The most-cited works in Geomorphology     

Martin W. Doyle  Jason P. Julian 《Geomorphology》2005,72(1-4):238-249

We conducted a review and analysis of the references cited in articles published (1995–2004) in the journal Geomorphology and also solicited comments from the authors of the most-cited works on their major influences. Of the 31,696 unique works cited in the journal, only 22 were referenced at least 20 times, with the vast majority (92%) cited only once or twice. We divided the citations into the 10 most-cited books (i.e., complete volumes) and 10 most-cited papers (i.e., journal articles, book chapters, reports). A total of 23 different researchers were responsible for the 20 works, with one (Wolman) being an author or co-author of a quarter of them. Seven of the ten most-cited papers were based on work in the USGS in the mid-twentieth century, indicating a particularly fruitful time of geomorphic research and a particularly important cohort of scientists. Based on our citation analysis and author commentaries, we suggest that classic works in geomorphology are most likely to be those that provide useful knowledge and those that incorporate interdisciplinary perspectives.  相似文献   

Gamma-ray bursts and Swift     

Paul O'Brien  Julian Osborne  Keith Mason 《Astronomy& Geophysics》2005,46(3):3.18-3.22

Now that the Swift satellite is up and running, Paul O'Brien, Julian Osborne and Keith Mason report on the ideas and observations that this fast-moving autonomous observatory is investigating.  相似文献   

Effect of macrophyte spatial variability on channel resistance     

Julian C. Green 《Advances in water resources》2006

Aquatic macrophytes can severely retard flow rates in the river channels that they occupy. Consequently, there is a need to improve our ability to model vegetation resistance, to aid flood prediction and allow for better-informed channel management. An empirical model is developed to calculate flow resistance (Manning’s resistance coefficient) of channels containing the submergent macrophyte Ranunculus (water-crowfoot). Blockage factors (the proportion of a cross-section blocked by vegetation) were determined for up to nine cross-sections at each of 35 river sites. These were used to create blockage-factor percentiles, which were regressed against vegetation resistance. An exponential best-fit relation involving the 69th blockage-factor percentile gave the best results. A parameter relating the length of the vegetated/solid boundary in contact with the open channel to the length of the conventionally-defined wetted perimeter improved the model fit by acting as a pseudo-measure of the turbulent-energy losses generated within the unvegetated stream by the macrophytes. The model was tested on three additional sites containing different macrophyte species and much higher vegetation blockages, and was found to work well.  相似文献   

Challenging assumptions of future coastal habitat development around the UK     

Julian D. Orford  John Pethick 《地球表面变化过程与地形》2006,31(13):1625-1642

One habitat management requirement forced by 21st century relative sea‐level rise (RSLR), will be the need to re‐comprehend the dimensions of long‐term transgressive behaviour of coastal systems being forced by such RSLR. Fresh approaches to the conceptual modelling and subsequent implementation of new coastal and peri‐marine habitats will be required. There is concern that existing approaches to forecasting coastal systems development (and by implication their associated scarce coastal habitats) over the next century depend on a certain premise of orderly spatial succession of habitats. This assumption is shown to be questionable given the possible future rates of RSLR, magnitude of shoreline retreat and the lack of coastal sediment to maintain the protective morphologies to low‐energy coastal habitats. Of these issues, sediment deficiency is regarded as one of the major problem for future habitat development. Examples of contemporary behaviour of UK coasts show evidence of coastal sediment starvation resulting from relatively stable RSLR, anthropogenic sealing of coastal sources, and intercepted coastal sediment pathways, which together force segmentation of coastal systems. From these examples key principles are deduced which may prejudice the existence of future habitats: accelerated future sediment demand due to RSLR may not be met by supply and, if short‐ to medium‐term hold‐the‐line policies predominate, long‐term strategies for managed realignment and habitat enhancement may prove impossible goals. Methods of contemporary sediment husbandry may help sustain some habitats in place but otherwise, instead of integrated coastal organization, managers may need to consider coastal breakdown, segmentation and habitat reduction as the basis of 21st century coastal evolution and planning. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Principles of Geographical Information Systems by Peter A.     

Julian Cone 《New Zealand geographer》1998,54(2):56-57

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珠海市水文地质与工程地质特征初探     

张举兼 《地质灾害与环境保护》1997,8(3):6-12

从地形地貌，气候特征和地表水三方面简述了珠海市的自然地理概况，论核实 珠海市基础地 中的地层，岩层分布情况以及构造特征。重点对珠海市地下水的类型，形成，赋存条件，水理性质，以及岩土的居因类型，分布规律，海岸类型和工程地质特征等作了初探讨  相似文献   

Al/Si interdiffusion in albite: effect of pressure and the role of hydrogen   总被引：1，自引：0，他引：1  

Julian R. Goldsmith 《Contributions to Mineralogy and Petrology》1987,95(3):311-321

The effect of pressure on the rate of Al/Si disorder in albite has been determined at temperatures from 800° C to 1050° C and at pressures up to 24 kbar, using dried samples in welded Pt containers, in piston-cylinder devices and internally-heated gas apparatus. In the piston-cylinder device with NaCl medium, the effect of pressure is profound. A pure low albite from Clear Creek, California reaches the equilibrium state of disorder at 850° C and 22 kbar in 10 h, whereas at 6 kbar it has not equilibrated in three weeks, and at one bar it probably cannot be disordered at 850° C in the laboratory. The enhancement of Al/Si interdiffusion takes place under dry conditions: any H₂O penetrating the samples would have produced melting, and none was observed. Hydrogen, however, is produced by dissociation of moisture in the pressure medium and can penetrate the Pt sample capsules. If the samples are deprived of hydrogen by replacing NaCl with glass or by embedding the samples in a hydrogen getter such as Fe₂O₃ or ZnO, the order-disorder reaction is greatly inhibited.A mechanism is suggested in which OH^– groups are formed by hydrogen hopping in albite. The smaller charge on the tetrahedral complex induces transient coordination of Al greater than four at elevated pressures, facilitating Al/Si interchange during the bond-breaking process. This results in an exponential pressure dependence of diffusion. It is also suggested that the presence of hydrogen at high pressures can greatly effect the mechanical properties and reactivity of deep crustal and mantle rocks. In nature, as well as in the laboratory, equilibration at elevated pressures may be as much dependent on the availability of hydrogen as on time or temperature.  相似文献   

Comments on Spaulding's report on overkill     

Julian D. Hayden 《Quaternary Research》1984,22(1):140-141

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Earthquake-induced landslides in Central America   总被引：11，自引：0，他引：11  

Julian J. Bommer  Carlos E. Rodríguez   《Engineering Geology》2002,63(3-4):189-220

Central America is a region of high seismic activity and the impact of destructive earthquakes is often aggravated by the triggering of landslides. Data are presented for earthquake-triggered landslides in the region and their characteristics are compared with global relationships between the area of landsliding and earthquake magnitude. We find that the areas affected by landslides are similar to other parts of the world but in certain parts of Central America, the numbers of slides are disproportionate for the size of the earthquakes. We also find that there are important differences between the characteristics of landslides in different parts of the Central American isthmus, soil falls and slides in steep slopes in volcanic soils predominate in Guatemala and El Salvador, whereas extensive translational slides in lateritic soils on large slopes are the principal hazard in Costa Rica and Panama. Methods for assessing landslide hazards, considering both rainfall and earthquakes as triggering mechanisms, developed in Costa Rica appear not to be suitable for direct application in the northern countries of the isthmus, for which modified approaches are required.  相似文献