Encyclopedia of caves D. C. Culver and W. B. White (eds) Publisher Elsevier Academic Press, 2004 (654 pp) ISBN 0 12 198651 9 (hardback)     

Andy Baker 《第四纪科学杂志》2005,20(5):509-510

  相似文献   

Continuous fluorescence assessment of organic matter variability on the Bournbrook River,Birmingham, UK     

Elfrida M. Carstea  Andy Baker  Gabriela Pavelescu  Ian Boomer 《水文研究》2009,23(13):1937-1946

Continuous monitoring of dissolved organic matter (DOM) character and concentration at hourly resolution is rare, despite the importance of analysing organic matter variability at high‐temporal resolution to evaluate river carbon budgeting, river water health by detecting episodic pollution and to determine short‐term variations in chemical and ecological function. The authors report a 2‐week experiment performed on DOM sampled from Bournbrook, Birmingham, UK, an urban river for which spectrophotometric (fluorescence, absorbance), physiochemical (dissolved organic carbon [DOC], electrical conductivity, pH) and isotopic (D/H) parameters have been measured at hourly frequency. Our results show that the river had sub‐daily variations in both organic matter concentration and characteristics. In particular, after relatively high‐magnitude precipitation events, organic carbon concentration increased, with an associated increase in intensity of both humic‐like and tryptophan‐like fluorescence. D/H isotopic ratio demonstrates different hydrological responses to different rainfall events, and organic matter character reflects this difference. Events with precipitation < 2 mm typically yielded isotopically heavy water with relatively hydrophilic DOM and relatively low specific absorbance. Events with precipitation > 2 mm had isotopically lighter water with higher specific absorbance and a decrease in the proportion of microbially derived to humic‐like fluorescence. In our heavily urbanized catchment, we interpret these signals as one where riverine DOM is dominated by storm sewer‐derived ‘old’ organic matter at low‐rainfall amounts and a mixed signal at high‐precipitation amounts where ‘event’ surface runoff‐derived organic matter dominate during storm sewer and combined sewer overflow routed DOM. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Mechanical Study of Shear Failure of Vertical Goaf Drainage Hole     

Khanal  Manoj  Adhikary  Deepak  Balusu  Rao  Wilkins  Andy  Belle  Bharath 《Geotechnical and Geological Engineering》2022,40(4):1899-1920

Geotechnical and Geological Engineering - Most of the published research on goaf-hole failures are performed using 2D numerical analyses. However, 2D analyses of the goaf-hole failure mechanism,...  相似文献   

Funding low carbon cities: local perspectives on opportunities and risks     

Rory Sullivan  Andy Gouldson  Phil Webber 《Climate Policy》2013,13(4):514-529

There are compelling reasons for policy makers to be interested in the low-carbon agenda. More than half of the world's population lives in, and more than half of the world's economic output comes from, cities. Up to 70% of global carbon emissions can also be attributed to consumption that takes place in cities. Recent research has shown that cost-effective investments in low-carbon options could deliver a 40% reduction in GHG emissions from cities by 2020, while also providing wider economic benefits such as enhanced competitiveness and increased employment. As yet, however, investments in low-carbon cities have not been made at scale due mainly to the scale of the finance required, local government budgetary constraints, and perceptions about their costs and benefits. With a focus on the UK, a contemporary account is provided of what local authorities see as the major financial risks associated with funding low-carbon cities. Practical proposals – which also have more general relevance to the future financing of low-carbon cities around the world – are offered on how local authorities, in conjunction with central government, the private sector, and institutional investors, can effectively manage these risks.

Policy relevance

Cities house more than half of the world's population, generate more than half of the world's economic output, and produce between 40% and 70% of all anthropogenic GHG emissions. In the UK, 70% of such emissions are under the influence of its local authorities. Thus, one of the key public policy challenges for the low-carbon transition is how it should be financed. There are several obstacles and related risks to this transition, including financial and legal obstacles and the differing views and perceptions of stakeholders. These can be attenuated, somewhat, by national government support at scale, local authority leadership, and cooperation between other authorities and the private sector, and the development of tools and guidance to reduce transaction costs.  相似文献   

Suspended sediment and phosphorus in proglacial rivers: bioavailability and potential impacts upon the P status of ice‐marginal receiving waters     

Andy Hodson  Paul Mumford  Debbie Lister 《水文研究》2004,18(13):2409-2422

This paper adopts standard tests developed in temperate catchment research to determine the total phosphorus (TP) and the algal available (base‐extractable) phosphorus (NaOH–P) content of a wide range of glaciofluvial sediments from the Northern Hemisphere. We find that the TP content of these sediments is broadly similar to the P content of major rock types in Earth's crust (230–670 µgP/g) and so the TP yields of glacier basins may be high owing to the efficacy of suspended sediment evacuation by glacial meltwaters. We show that this is best achieved where subglacial drainage systems are present. The NaOH–P pool of the sediments is found to be low (1–23 µgP/g) relative to the TP pool and also to the NaOH–P pool of suspended sediments in temperate, non‐glacierized catchments. This most probably reflects the restricted duration of intimate contact between dilute meltwaters and glacial suspended sediments during the ablation season. Thus, despite the high surface‐area:volume ratio of glacial suspended sediments, the potential for P adsorption to mineral surfaces following release by dissolution is also low. Further, sorption experiments and sequential extraction tests conducted using glacial suspended sediments from two Svalbard catchments indicate that the generation of reactive secondary minerals (e.g. Fe‐ and other hydroxides) with a strong capacity to scavenge P from solution (and thereby promote the continued dissolution of P) may also be limited by the short residence times. Most P is therefore associated with poorly weathered, calcite/apatite‐rich mineral phases. However, we use examples from the Svalbard glacier basins (Austre Brøggerbreen and Midre Lovénbreen) to show that the high sediment yields of glaciers may result in appreciable NaOH–P loading of ice‐marginal receiving waters. Again, the importance of subglacial drainage is highlighted, as it produces a major, episodic release of NaOH–P at Midre Lovénbreen that results in a yield (8·2 kg NaOH–P/km²/year) more than one order of magnitude greater than that at Austre Brøggerbreen (where subglacial drainage is absent and the yield is 0·48 kg NaOH‐P/km²/year). Therefore, as since both detrimental and beneficial effects of sediment‐bound P loading in ice marginal receiving waters are possible (i.e. either reduced primary productivity owing to increased turbidity or P fertilization following desorption) there is a pressing need to assess the ambient P status of such environments and also the capacity for ice‐marginal ecosystems to adapt to such inputs. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Bedform topography and basal conditions beneath a fast-flowing West Antarctic ice stream     

Andy M. Smith  Tavi Murray 《Quaternary Science Reviews》2009,28(7-8):584-596

A grid of seismic reflection lines has been used to image basal topography and infer basal conditions and flow processes beneath ～140 km² of Rutford Ice Stream, West Antarctica. The subglacial topography in this region consists of two troughs flanking a central high and the bed is composed of water-saturated sediments. The two troughs are filled with deforming sediment, whereas the bed in the central region appears to undergo a transition from largely deforming conditions upstream to basal sliding downstream. The deforming bed is very flat along flow, but undulates across flow. Sliding areas show rougher bed topography. Cross-stream bed topography is characterised by streamlined mounds of deforming sediment aligned in the ice flow direction. These bedforms occur superimposed on the bed in regions of both basal sliding and sediment deformation. In places, they form finger-like mounds of material, which extend into the sliding region further downstream. Mean bedform height is 22 m, mean width is 267 m, and many of them extend for at least 1–2 km along flow. We interpret most of these bedforms as drumlins and one as a mega-scale glacial lineation. The juxtaposition of different basal conditions is consistent with models proposed from terrestrial studies in which the glacier bed is a mosaic of stable and deforming bed areas, variable both spatially and temporally. Any theory of subglacial sediment rheology must also be able to account for our conclusion that, at any given time, pervasive deformation extends at least a few metres into the bed and can persist over a considerable area (many km²). Bedform geometry and basal conditions concur with interpretations of former ice streams, with evidence for increasing elongation ratio with distance downstream. However, those studies also identified bedrock cropping out at the ice-bed interface, for which there is no evidence on Rutford Ice Stream.  相似文献   

What's new with CUASHI?     

Toran L  Hooper R 《Ground water》2004,42(5):638-640

  相似文献   

A late Lake Minong transgression in the Lake Superior basin as documented by sediments from Fenton Lake, Ontario     

Andy Breckenridge  Thomas V. Lowell  Timothy G. Fisher  Shiyong Yu 《Journal of Paleolimnology》2012,47(3):313-326

The evolution of the early Great Lakes was driven by changing ice sheet geometry, meltwater influx, variable climate, and isostatic rebound. Unfortunately none of these factors are fully understood. Sediment cores from Fenton Lake and other sites in the Lake Superior basin have been used to document constantly falling water levels in glacial Lake Minong between 9,000 and 10,600 cal (8.1–9.5 ka) BP. Over three meters of previously unrecovered sediment from Fenton Lake detail a more complex lake level history than formerly realized, and consists of an early regression, transgression, and final regression. The initial regression is documented by a transition from gray, clayey silt to black sapropelic silt. The transgression is recorded by an abrupt return to gray sand and silt, and dates between 9,000 and 9,500 cal (8.1–8.6 ka) BP. The transgression could be the result of increased discharge from Lake Agassiz overflow or the Laurentide Ice Sheet, and hydraulic damming at the Lake Minong outlet. Alternatively ice advance in northern Ontario may have blocked an unrecognized low level northern outlet to glacial Lake Ojibway, which switched Lake Minong overflow back to the Lake Huron basin and raised lake levels. Multiple sites in the Lake Huron and Michigan basins suggest increased meltwater discharges occurred around the time of the transgression in Lake Minong, suggesting a possible linkage. The final regression in Fenton Lake is documented by a return to black sapropelic silt, which coincides with varve cessation in the Superior basin when Lake Agassiz overflow and glacial meltwater was diverted to glacial Lake Ojibway in northern Ontario.  相似文献   

Corrections for Wind-Speed Errors from Sodar and Lidar in Complex Terrain     

Stuart Bradley  Yvette Perrott  Paul Behrens  Andy Oldroyd 《Boundary-Layer Meteorology》2012,143(1):37-48

The quality of lidar and sodar wind estimates is generally judged through comparisons with mast-mounted instruments, and the resulting regressions. Evaluation of the relative merits of lidars versus sodars is complicated by the fact that lidars are generally placed close to a mast whereas sodars are generally placed some distance from a mast so that acoustic reflections off the mast are reduced. This leads to the two technologies, lidar and sodar, not being compared in similar situations. Differences arising from the two geometries can be expected to be larger in complex terrain, where the wind regime can vary significantly spatially. The current work explores these differences in moderately complex terrain. Lidar–mast comparisons are performed with the lidar close to an 80 m mast, and sodar–mast comparisons performed with the sodar 300 m from the mast. Systematic variations in estimated wind speed are found to occur with height, consistent with predictions from a simple flow model. When the lidar was moved to the sodar location, further from the mast, there were significant changes in the estimated wind speeds and a reduction in correlation with the mast-based wind speeds, as expected. However, the correlation between collocated lidar and sodar winds was high. This finding emphasizes that any comparison of two remote sensing instruments needs to be through similar experiments, and that differences in accuracy often reported for the lidar and sodar technologies are likely to be contaminated due to poor comparison configurations. A method was devised to simulate the sodar being collocated with the mast, by using the lidar–sodar measurements and the lidar–mast measurements. It was found that there was then no statistically detectable difference between lidar–mast regressions and sodar–mast regressions for the particular lidar and sodar tested. Both remote sensing instruments were also found to be good estimators of Weibull parameters, as compared with those derived from mast data. The conclusion is that the sodar measured the winds above the sodar with a similar accuracy to the lidar measuring winds above the lidar.  相似文献   

Palaeolithic and Quaternary research in the Trent Valley (UK): contributions by early collectors     

Tom S. White  Mark J. White  Andy J. Howard 《Proceedings of the Geologists' Association. Geologists' Association》2009,120(4):223-232

A brief history is presented here of the activities of the three most notable collectors of Lower and Middle Palaeolithic artefacts from Quaternary river terrace deposits in the Trent Valley, derived from archival material that has been largely ignored by previous research. Two, Mr. Fred W.G. Davey and Mr. George F. Turton, were local amateur collectors who did not publish the results of their work themselves and were reliant on collaboration with established archaeologists. The third, Mr. A. Leslie Armstrong, was an archaeologist best known for his work at Creswell Crags and Grimes Graves. Armstrong also made many Palaeolithic discoveries in the Trent Valley but published few details of his own material. Although such details of early Palaeolithic research in the Midlands and North of Britain are predominantly of historical interest only, they nonetheless provide a number of insights into the apparent lack of interest shown in areas north of the ‘Severn-Wash Line’ by collectors of Palaeolithic artefacts. Importantly, the dataset assembled by the Trent Valley Palaeolithic Project (TVPP) and summarized here is the only complete record of the known artefacts and archival material from the Trent, a proportion of which is now unavailable to the research community, having entered unknown private ownership since being studied. The second part of the paper relates this early research to current knowledge of the British Palaeolithic at its most northern fringes and to recent developments in reconstructing the Quaternary evolution of the River Trent.  相似文献