Communities as the agents of commodification: The Kumbo Water Authority in Northwest Cameroon     

Ben Page 《Geoforum》2003,34(4):483-498

In 1991 the people of the town of Kumbo in Northwest Cameroon expelled the national water corporation from town by force. They claimed to be retrieving a network that the community rightfully owned and they began to run the system along community lines. The paper tells the story of that water supply twice. First it reproduces the popular accounts that circulated in the 1990s that emphasize the role played by the community in the development and operation of the water supply and portray recent events as a triumph of community management. Then it retells the story using archive evidence that puts a quite different light on some of the events. It is argued that the emphasis on community management has a tendency to obscure other important aspects of the story, for example its political context and consequences. It is suggested that the widespread admiration for any initiative that is community based often results in an uncritical analysis of this form of development project. In this case the commodification of water accelerates after the community has wrested control of this public service from the state.  相似文献   

Are peatlands in different states with respect to their thermodynamic behaviour? A simple test of peatland energy and entropy budgets     

Fred Worrall  Ross Morrison  Chris Evans  Joerg Kaduk  Susan Page  Alex Cumming  Mark Rayment  Nicholas Kettridge 《水文研究》2021,35(12):e14431

Whilst all ecosystems must obey the second law of thermodynamics, these physical bounds and controls on ecosystem evolution and development are largely ignored across the ecohydrological literature. To unravel the importance of these underlying restraints on ecosystem form and function, and their power to inform our scientific understanding, we have calculated the entropy budget of a range of peat ecosystems. We hypothesize that less disturbed peatlands are ‘near equilibrium’ with respect to the second law of thermodynamics and thus respond to change by minimizing entropy production. This ‘near equilibrium’ state is best achieved by limiting evaporative losses. Alternatively, peatlands ‘far-from-equilibrium’ respond to a change in energy inputs by maximizing entropy production which is best achieved by increasing evapotranspiration. To test these alternatives this study examined the energy balance time series from seven peatlands across a disturbance gradient. We estimate the entropy budgets for each and determine how a change in net radiation (ΔR_n) was transferred to a change in latent heat flux (ΔλE). The study showed that: (i) The transfer of net radiation to latent heat differed significantly between peatlands. One group transferred up to 64% of the change in net radiation to a change in latent heat flux, while the second transferred as little as 27%. (ii) Sites that transferred the most energy to latent heat flux were those that produced the greatest entropy. The study shows that an ecosystem could be ‘near equilibrium’ rather than ‘far from equilibrium’.  相似文献   

Constraining sequence stratigraphy in north Australian basins: SHRIMP U–Pb zircon geochronology between Mt Isa and McArthur River     

R. W. Page  M. J. Jackson  A. A. Krassay 《Australian Journal of Earth Sciences》2013,60(3):431-459

Fifty‐five new SHRIMP U–Pb zircon ages from samples of northern Australian ‘basement’ and its overlying Proterozoic successions are used to refine and, in places, significantly change previous lithostratigraphic correlations. In conjunction with sequence‐stratigraphic studies, the 1800–1580 Ma rock record between Mt Isa and the Roper River is now classified into three superbasin phases—the Leichhardt, Calvert and Isa. These three major depositional episodes are separated by ～20 million years gaps. The Isa Superbasin can be further subdivided into seven supersequences each 10–15 million years in duration. Gaps in the geological record between these supersequences are variable; they approach several million years in basin‐margin positions, but are much smaller in the depocentres. Arguments based on field setting, petrography, zircon morphology, and U–Pb systematics are used to interpret these U–Pb zircon ages and in most cases to demonstrate that the ages obtained are depositional. In some instances, zircon crystals are reworked and give maximum depositional ages. These give useful provenance information as they fingerprint the source(s) of basin fill. Six new ‘Barramundi’ basement ages (around 1850 Ma) were obtained from crystalline units in the Murphy Inlier (Nicholson Granite and Cliffdale Volcanics), the Urapunga Tectonic Ridge (‘Mt Reid Volcanics’ and ‘Urapunga Granite’), and the central McArthur Basin (Scrutton Volcanics). New ages were also obtained from units assigned to the Calvert Superbasin (ca 1740–1690 Ma). SHRIMP results show that the Wollogorang Formation is not one continuous unit, but two different sequences, one deposited around 1730 Ma and a younger unit deposited around 1722 Ma. Further documentation is given of a regional 1725 Ma felsic event adjacent to the Murphy Inlier (Peters Creek Volcanics and Packsaddle Microgranite) and in the Carrara Range. A younger ca 1710 Ma felsic event is indicated in the southwestern McArthur Basin (Tanumbirini Rhyolite and overlying Nyanantu Formation). Four of the seven supersequences in the Isa Superbasin (ca 1670–1580 Ma) are reasonably well‐constrained by the new SHRIMP results: the Gun Supersequence (ca 1670–1655 Ma) by Paradise Creek Formation, Moondarra Siltstone, Breakaway Shale and Urquhart Shale ages grouped between 1668 and 1652 Ma; the Loretta Supersequence (ca 1655–1645 Ma) by results from the Lady Loretta Formation, Walford Dolomite, the upper part of the Mallapunyah Formation and the Tatoola Sandstone between ca 1653 and 1647 Ma; the River Supersequence (ca 1645–1630 Ma) by ages from the Teena Dolomite, Mt Les and Riversleigh Siltstones, and Barney Creek, Lynott, St Vidgeon and Nagi Formations clustering around 1640 Ma; and the Term Supersequence (ca 1630–1615 Ma) by ages from the Stretton Sandstone, lower Doomadgee Formation and lower part of the Lawn Hill Formation, mostly around 1630–1620 Ma. The next two younger supersequences are less well‐constrained geochronologically, but comprise the Lawn Supersequence (ca 1615–1600 Ma) with ages from the lower Balbirini Dolomite, and lower Doomadgee, Amos and middle Lawn Hill Formations, clustered around 1615–1610 Ma; and the Wide Supersequence (ca 1600–1585 Ma) with only two ages around 1590 Ma, one from the upper Balbirini Dolomite and the other from the upper Lawn Hill Formation. The Doom Supersequence (<1585 Ma) at the top of the Isa Superbasin is essentially unconstrained. The integration of high‐precision SHRIMP dating from continuously analysed stratigraphic sections, within a sequence stratigraphic context, provides an enhanced chronostratigraphic framework leading to more reliable interpretations of basin architecture and evolution.  相似文献   

Preventing groundwater contamination is possible     

G. William Page PhD 《Environmental Geology》1990,15(3):163-163

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太行山—五台山区前寒武纪变质岩系同位素地质年代学研究   总被引：2，自引：0，他引：2  

刘敦一  R.W.佩吉  W.康普斯顿  伍家善 《地球学报》1984,6(1):57-84

<正> 中国北方河北、山西两省交界地带的太行—五台山区,早前寒武纪变质岩系十分发育,分布面积达20,000平方公里,为华北地块的重要组成部分。在这一地区内,保留了早前寒武纪不同发展阶段的种种地质作用的记录。深入研究其地质历史,将对阐明华北地块的形成和演化具有重要的典型意义。作者正是基于这一目的,在该区进行了同位素地质年代学的研究。  相似文献   

The fraction of galaxies that contain active nuclei and their accretion rates     

M.J. Page 《Monthly notices of the Royal Astronomical Society》2001,328(3):925-930

We investigate the relationship between the present-day optical luminosity function of galaxies and the X-ray luminosity function of Seyfert 1s to determine the fraction of galaxies that host Seyfert 1 nuclei and their Eddington ratios. The local type 1 active galactic nuclei (AGN) X-ray luminosity function is well reproduced if ∼1 per cent of all galaxies are type 1 Seyferts which have Eddington ratios of ∼10⁻³. However, in such a model the X-ray luminosity function is completely dominated by AGN in E and S0 galaxies, contrary to the observed mix of Seyfert host galaxies. To obtain a plausible mix of AGN host galaxy morphologies requires that the most massive black holes in E and S0 galaxies accrete with lower Eddington ratios, or have a lower incidence of Seyfert activity, than the central black holes of later-type galaxies.  相似文献   

Opening address-14th ESLAB symposium     

D. Edgar Page 《Solar physics》1981,74(1):9-9

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Meso-scale testing and development of test procedures to maintain mass balance     

Bonner J  Page C  Fuller C 《Marine pollution bulletin》2003,47(9-12):406-414

The Conrad Blucher Institute for Surveying and Science (Texas A&M University––Corpus Christi) has conducted numerous petroleum experiments at the Shoreline Environmental Research Facility (Corpus Christi, Texas, USA). The meso-scale facility has multiple wave tanks, permitting some control in experimental design of the investigations, but allowing for real-world conditions. This paper outlines the evolution of a materials balance approach in conducting petroleum experiments at the facility. The first attempt at a materials balance was during a 1998 study on the fate/effects of dispersant use on crude oil. Both water column and beach sediment samples were collected. For the materials balance, the defined environmental compartments for oil accumulation were sediments, water column, and the water surface, while the discharge from the tanks was presumed to be the primary sink. The “lessons learned” included a need to quantify oil adhesion to the tank surfaces. This was resolved by adhering strips of the polymer tank lining to the tank sides that could be later removed and extracted for oil. Also, a protocol was needed to quantify any floating oil on the water surface. A water surface (oil slick) quantification protocol was developed, involving the use of solid-phase extraction disks. This protocol was first tested during a shoreline cleaner experiment, and later refined in subsequent dispersant effectiveness studies. The effectiveness tests were designed to simulate shallow embayments which created the need for additional adjustments in the tanks. Since dispersant efficacy is largely affected by hydrodynamics, it was necessary to scale the hydrodynamic conditions of the tanks to those expected in our prototype system (Corpus Christi Bay, Texas). The use of a scaled model permits the experiment to be reproduced and/or evaluated under different conditions. To minimize wave reflection in the tank, a parabolic wave dissipater was built. In terms of materials balance, this design reduced available surface area as a sink for oil adsorption.  相似文献   

Modelling the chloride signal at Plynlimon,Wales, using a modified dynamic TOPMODEL incorporating conservative chemical mixing (with uncertainty)     

T. Page  K. J. Beven  Jim Freer  Colin Neal 《水文研究》2007,21(3):292-307

The application of a modified version of dynamic TOPMODEL for two subcatchments at Plynlimon, Wales is described. Conservative chemical mixing within mobile and immobile stores has been added to the hydrological model in an attempt to simulate observed stream chloride concentrations. The model was not fully able to simulate the observed behaviour, in particular the short‐ to medium‐term dynamics. One of the primary problems highlighted by the study was the representation of dry deposition and cloud‐droplet‐deposited chloride, which formed a significant part of the long‐term chloride mass budget. Equifinality of parameter sets inhibited the ability to determine the effective catchment mixing volumes and coefficients or the most likely partition between occult mass inputs and chloride mass inputs determined by catchment immobile‐store antecedent conditions. Some success was achieved, in as much as some aspects of the dynamic behaviour of the signal were satisfactorily simulated, although spectral analysis showed that the model could not fully reproduce the 1/f power spectra of observed stream chloride concentrations with its implications of a wide distribution of residence times for water in the catchment. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Comments on the misuse of SPMDs in recent articles by Springman et al. (2008a,b) and Short et al. (2008)     

Paul D. Boehm  David S. Page  Jerry M. Neff 《Marine environmental research》2009,67(4-5):262-267

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