The population-environment nexus and vulnerability assessment in Africa     

Robert E. Ford  Kim T. Adamson 《GeoJournal》1995,35(2):207-216

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The effect of shell infestation byPolydora sp. and infection byHaplosporidium nelsoni (MSX) on the tissue condition of oysters,Crassostrea virginica     

Robert N. Wargo  Susan E. Ford 《Estuaries and Coasts》1993,16(2):229-234

A number of stressors, including the endoparasiteHaplosporodium nelsoni (MSX), reduce metabolic condition of oysters; however, previous studies of the effect of the shell-boring polychaetePolydora sp. on condition have produced conflicting results. To assess the effects of both symbionts, singly and in combination, we examined 214 oysters for shell infestation byPolydora sp. mud blisters (by image analysis), intensity of infection byH. nelsoni (by histology), and nutritional state (estimated by soft tissue gravimetric condition index). Among all oysters tested, condition index was negatively (p <0.05) correlated withPolydora sp. infestation, although the explained variance (r²) was only about 5%. When oysters withoutH. nelsoni were considered alone, the variance explained byPolydora sp. rose to approximately 30%, indicating that the presence of one deleterious symbiont can confound the effect of another. In oysters withoutH. nelsoni, a 36% loss in tissue condition was associated withPolydora sp. blister infestation covering 45% of the shell. After a single season's exposure to both symbionts, oysters withH. nelsoni had significantly (p<0.05) greaterPolydora sp. infestation than did animals withoutH. nelsoni, but the difference disappeared after a second year, when nearly all shells were infested. The mean condition index for oysters with bothPolydora sp. andH. nelsoni was 13% lower than that for individuals with neither; oysters with only one symbiont had intermediate values. The interaction between percent blister coverage andH. nelsoni intensity on tissue condition was significant (p<0.002), verifying that the effect of the two symbionts was not additive. We conclude thatPolydora sp. reduces the ability of oysters to accumulate nutritional reserves, but that this effect may be obscured by other deleterious influences.  相似文献   

Isostatic geoid anomalies over trenches and island arcs     

Glyn M. Jones 《Tectonophysics》1983,99(2-4)

Altimeter geoid profiles crossing trenches and island arcs typically exhibit a long-wavelength increase in geoidal height approaching the trench which, in many cases, reaches a maximum over the back-arc area. Bathymetry profiles across trenches show a similar regional increase in the mean depth of the ocean floor behind the trench. Filters corresponding to Airy and Pratt models of isostatic compensation were applied to bathymetry profiles crossing seven different trench systems in order to estimate how much of the observed geoid variation in these regions could be attributed to isostatically-compensated ocean-floor topography. The results indicate that short-wavelength, high-amplitude variations in the geoid, which in some cases account for over 50% of the total observed amplitude variation, can be reasonably reproduced assuming a Pratt model of isostatic compensation. An additional component of the geoid arises from the uncompensated outer rise seaward of the trench. It is therefore concluded that a large part of the geoid signal over trenches and island arcs may be related to variations in sea-floor topography. This topographic component should be removed from altimeter geoid profiles before using the data to infer details of the deeper structure of subduction zones.  相似文献   

Postcolonial environmental justice: Government and governance in India   总被引：1，自引：0，他引：1  

Glyn Williams  Emma Mawdsley 《Geoforum》2006,37(5):660-670

In this paper, we investigate the context within which struggles for environmental justice are taking place in India. We explore the ways in which postcolonial patterns of government and governance in India affect the ends, the means and the representation of these struggles, focusing on three particular areas: state reform, the judiciary and public interest litigation, and environmental social movements. We argue that India differs from west in the ambitious yet incomplete and contradictory nature of government-sponsored intervention in the environment, and in the particular nature of its public sphere, both of which have been important in shaping struggles for environmental justice. Our wider intention is not merely to catalogue these differences, but to use the Indian material to raise questions about the emphases and implicit assumptions of western environmental justice literature, and reflect on how these may be need reconsideration when working in postcolonial contexts.  相似文献   

Accurately measuring volcanic plume velocity with multiple UV spectrometers     

Glyn Williams-Jones  Keith A. Horton  Tamar Elias  Harold Garbeil  Peter J. Mouginis-Mark  A. Jeff Sutton  Andrew J. L. Harris 《Bulletin of Volcanology》2006,68(4):328-332

A fundamental problem with all ground-based remotely sensed measurements of volcanic gas flux is the difficulty in accurately measuring the velocity of the gas plume. Since a representative wind speed and direction are used as proxies for the actual plume velocity, there can be considerable uncertainty in reported gas flux values. Here we present a method that uses at least two time-synchronized simultaneously recording UV spectrometers (FLYSPECs) placed a known distance apart. By analyzing the time varying structure of SO₂ concentration signals at each instrument, the plume velocity can accurately be determined. Experiments were conducted on Kīlauea (USA) and Masaya (Nicaragua) volcanoes in March and August 2003 at plume velocities between 1 and 10 m s⁻¹. Concurrent ground-based anemometer measurements differed from FLYSPEC-measured plume speeds by up to 320%. This multi-spectrometer method allows for the accurate remote measurement of plume velocity and can therefore greatly improve the precision of volcanic or industrial gas flux measurements. Editorial responsibility: A. Woods  相似文献   

Jovan Cvijić and the founding of karst geomorphology     

Derek Ford 《Environmental Geology》2007,51(5):675-684

Jovan Cviji? was born in western Serbia and studied widely in the Dinaric Kras. His publication of Das Karstphänomen (1893) established that rock dissolution was the key process and that it created most types of dolines, “the diagnostic karst landforms”. The Dinaric Kras thus became the type area for dissolutional landforms and aquifers; Germanicised as “karst”, the regional name is now applied to modern and paleo-dissolutional phenomena worldwide. Cviji? related the complex behaviour of karstic aquifers to development of solutional conduit networks and linked it to a cycle of landform evolution. He is recognized as “the father of karst geomorphology”.  相似文献   

A technique for computing geoid height anomalies over two-dimensional earth models     

Glyn M. Jones 《Geophysical Journal International》1982,69(2):329-337

Summary A technique is presented for calculating geoid height anomalies over two-dimensional models of Earth structure. The method consists of convolving gravity anomalies over the structure with filters which take into account the finite size of the structure in the third dimension and the curvature of the Earth. Similar filters are also developed for a flat earth case. The method is applied to a sea-surface gravity profile crossing the Tonga-Kermadec trench and is found to give good agreement with a Geos-3 radar altimetry profile in the same region. The example demonstrates that introducing arbitrary offsets in computing gravity anomalies can result in spurious long-wavelength effects in the computed geoid. Comparison of the results obtained using flat earth and spherical earth filters suggests that the effects of the curvature of the Earth only become significant for wavelengths in the gravity field greater than about 1000 km.  相似文献   

Vulnerability and adaptive capacity of community food systems in the Peruvian Amazon: a case study from Panaillo   总被引：1，自引：1，他引：0  

Mya Sherman  James Ford  Alejandro Llanos-Cuentas  María José Valdivia  Alejandra Bussalleu  Indigenous Health Adaptation to Climate Change Research Group 《Natural Hazards》2015,77(3):2049-2079

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Preliminary results of a field study on some stress-related parameters in Tapes philippinarum naturally infected by the protozoan Perkinsus sp.     

L. Da Ros  M. G. Marin  N. Nesto  S. E. Ford 《Marine environmental research》1998,46(1-5)

The aim of the present work was to investigate the possible use of the clam Tapes philippinarum—a filter-feeding bivalve living on soft bottoms—in the monitoring of sediment pollution in the Lagoon of Venice (North-East Italy). To this end, two clam populations, exposed to different environmental conditions (a relative clean site and an industrial polluted area), have been monitored for the prevalence of the protozoan parasite Perkinsus sp. as well as for several biological parameters commonly used as determinants of contaminants exposure. First results showed a low prevalence, higher in the clean site, but a very diffuse distribution of the parasite throughout the two populations. Nevertheless, greater digestive cells height and longer lysosomal latency time were observed in clams from the clean area. As for the physiological stress-related parameters, even if clearance rates were always higher in these clams, scope for growth values indicated a more complicated biological response.  相似文献   

Tertiary foreland sedimentation in the Southern Subalpine Chains, SE France: a geodynamic appraisal   总被引：2，自引：0，他引：2  

Ford  Lickorish  & Kusznir 《Basin Research》1999,11(4):315-336

Tertiary foreland sedimentation in SE France occurred along the western sidewall of the Alpine orogen during collision of the Apulian indentor with the European passive margin. A detailed reappraisal of the stratigraphy and structure of the Southern Subalpine Chains (SSC) in SE France shows that Tertiary depocentres of differing character developed progressively toward the foreland during ongoing SW-directed shortening. The geodynamic controls on each of four stages of basin development are evaluated using a flexural isostatic modelling package of thrust sheet emplacement and foreland basin formation. (1) The initial stage (mid to late Eocene) can be explained as a flexural basin that migrated toward the NW, closing off to the SW against the uplifting Maures–Esterel block. This broad, shallow basin can be reproduced in forward modelling by loading a lower lithospheric plate with an effective elastic thickness of 20 km. (2) The end of detectable flexural subsidence in the early Oligocene coincides with the emplacement of the internally derived Embrunais–Ubaye (E-U) nappes, which caused 11 km of SW-directed shortening in the underlying SSC. The lack of Oligocene flexural subsidence dictates that the E-U units were emplaced as gravitational nappes. Within the SSC, Oligocene sedimentation was restricted to small thrust-sheet-top basins recording mainly continental conditions and ongoing folding. Further west, Oligocene to Aquitanian NNW–SSE extension generated the Manosque half-graben as part of the European graben system that affected an area from the Gulf of Lion to the Rhine graben. (3) Following the Burdigalian breakup of the Gulf of Lion rift, a marine transgression migrated northward along the European graben system. Subsequent thermal subsidence allowed 1 km of marine sediments to be deposited across the Valensole and Manosque blocks, west of the active SSC thrust belt. (4) Mio-Pliocene conglomeratic deposits (2 km thick) were trapped within the Valensole basin by the uplifting Vaucluse block to the west and the advancing Alpine thrust sheets to the east. Late Pliocene thrusting of the SSC across the Valensole basin (approx. 10.5 km) can be linked along a Triassic detachment to the hinterland uplift of the Argentera basement massif.  相似文献