Otolith chemistry: an aid to stock separation of Helicolenus dactylopterus (bluemouth) and Merluccius merluccius (European hake) in the Northeast Atlantic and Mediterranean   总被引：1，自引：0，他引：1  

Swan  S.C.; Geffen  A.J.; Morales-Nin  B.; Gordon  J.D.M.; Shimmield  T.; Sawyer  T.; Massuti  E. 《ICES Journal of Marine Science》2006,63(3):504-513

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Pleistocene forest on Tenerife's southern coast: a case study of Montaña Negra     

Claire L. Pannell  Alan Gray  Jan A. Zalasiewicz  Michael J. Branney  Gordon B. Curry 《第四纪科学杂志》2011,26(5):485-490

Montaña Negra is a 121 m cinder cone in the Bandas del Sur region of southern Tenerife. Formed in the Middle Pleistocene, it comprises alternating phonolitic pumice deposits and scoria layers; the latter are extremely fossiliferous with good taphonomical fidelity. ⁴⁰Ar/³⁹Ar age determination provides new dates of 302 ± 7.6 ka and 299.9 ± 11.4 ka for the Lower and Upper Aldea Blanca pumice fall deposits, respectively. This chronological constraint allows comparison of the palaeo‐habitat with the global climate at the time of pyroclastic activity. Abundant terrestrial gastropod species and rare disarticulated Coleoptera fragments are to be found. The occurrence of the endemic semi‐slug genus Plutonia (Family Vitrinidae) is significant in indicating a woodland habitat in the region during the Middle Pleistocene. We suggest that this may have been forest, possibly dominated by laurel, which is in stark contrast to the present‐day semi‐desert. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Characteristics, development and utilization of geothermal resources- a Nordic perspective     

John W. Lund Leif Bjelm Gordon Bloomquist Anette K. Mortensen 《《幕》》2008,31(1):140-147

Geothermal energy is classified as a renewable energy source and it utilizes the heat generated in the earth primarily from the natural radioactive decay of isotopes of uranium, thorium and potassium. Heat is extracted from the earth to generate geothermal energy via a carrier, usually water occurring either in the liquid or steam phase. In the late 19th century and the early 20th century, the first developments of geothermal resources for power generation and household heating got underway successfully. Many of these geothermal fields are still being utilized today, proving their sustainability. Today geothermal energy is being utilized in more than 72 countries around the world and of the Nordic countries Iceland and Sweden have been in the forefront in each of their respective fields. While geothermal heat pumps are widely used for space heating in Sweden, geothermal energy covers 55% of the primary energy consumption in Iceland where it is used for space heating, power generation and industrial purposes. Future developments aim at expanding the range of viable geothermal resources by improving the capabilities to generate electricity from geothermal resources at temperatures as low as 100℃, as well as developing geothermal resources where water needs to be introduced, so-called hot dry rock resources. But the biggest expansion is expected to continue to be in the installations of geothermal heat pumps.  相似文献   

Clear‐sky closure studies of lower tropospheric aerosol and water vapor during ACE‐2 using airborne sunphotometer, airborne in‐situ, space‐borne, and ground‐based measurements     

Beat Schmid  John M. Livingston  Philip B. Russell  Philip A. Durkee  Haflidi H. Jonsson  Donald R. Collins  Richard C. Flagan  John H. Seinfeld  Santiago Gassó  Dean A. Hegg  Elisabeth Öström  Kevin J. Noone  Ellsworth J. Welton  Kenneth J. Voss  Howard R. Gordon  Paola Formenti  Meinrat O. Andreae 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):568-593

We report on clear‐sky column closure experiments (CLEARCOLUMN) performed in the Canary Islands during the second Aerosol Characterization Experiment (ACE‐2) in June/July 1997. We present CLEARCOLUMN results obtained by combining airborne sunphotometer and in‐situ (optical particle counter, nephelometer, and absorption photometer) measurements taken aboard the Pelican aircraft, space‐borne NOAA/AVHRR data and ground‐based lidar and sunphotometer measurements. During both days discussed here, vertical profiles flown in cloud‐free air masses revealed 3 distinctly different layers: a marine boundary layer (MBL) with varying pollution levels, an elevated dust layer, and a very clean layer between the MBL and the dust layer. A key result of this study is the achievement of closure between extinction or layer aerosol optical depth (AOD) computed from continuous in‐situ aerosol size‐distributions and composition and those measured with the airborne sunphotometer. In the dust, the agreement in layer AOD (λ=380–1060 nm) is 3–8%. In the MBL there is a tendency for the in‐situ results to be slightly lower than the sunphotometer measurements (10–17% at λ=525 nm), but these differences are within the combined error bars of the measurements and computations.  相似文献   

Comparison of excavation-induced wall deflection using top-down and bottom-up construction methods in Taipei silty clay   总被引：2，自引：0，他引：2  

Gordon Tung-Chin Kung 《Computers and Geotechnics》2009

This paper compares the excavation-induced wall deflection caused by the top-down method (TDM) and the bottom-up method (BUM). First, a total of 26 quality excavation case histories in Taipei silty clay were collected and analyzed. The field observations show that the maximum lateral wall deflection (δ_hm) induced by the TDM were 1.28 times as large as that induced by the BUM. Factors affecting wall deflection are investigated and four of them are selected for further numerical experimentation to investigate the discrepancy of δ_hm caused by the two methods. Analysis results showed that the average ratio of δ_hm induced by the TDM over that induced by the BUM is approximately equal to 1.1, excluding the effect of thermal shrinkage of concrete floor slabs. Both observed data and analysis results revealed that greater δ_hm is generally induced by the TDM despite its use of floor slabs with higher support stiffness.  相似文献   

Effect of the cyanide-producing bacterium Chromobacterium violaceum on ultraflat gold surfaces     

Lintern Fairbrother  Joseph G. Shapter  Joël Brugger  Gordon Southam  Allan Pring  Frank Reith 《Journal of Geochemical Exploration》2009

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Diel vertical migration and interaction of zooplankton and juvenile walleye pollock (Theragra chalcogramma) at a frontal region near the Pribilof Islands, Bering Sea   总被引：1，自引：0，他引：1  

Schabetsberger  R.; Brodeur  R. D.; Ciannelli  L.; Napp  J. M.; Swartzman  G. L. 《ICES Journal of Marine Science》2000,57(4):1283-1295

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DMSP and DMS dynamics and microzooplankton grazing in the Labrador Sea: application of the dilution technique     

Gordon V. Wolfe  Maurice Levasseur  Guy Cantin  Sonia Michaud 《Deep Sea Research Part I: Oceanographic Research Papers》2000,47(12):687

We adapted the dilution technique to study microzooplankton grazing of algal dimethylsulfoniopropionate (DMSP) vs. Chl a, and to estimate the impact of microzooplankton grazing on dimethyl sulfide (DMS) production in the Labrador Sea. Phytoplankton numbers were dominated by autotrophic nanoflagellates in the Labrador basin, but diatoms and colonial Phaeocystis pouchetii contributed significantly to phytomass at several high chlorophyll stations and on the Newfoundland and Greenland shelfs. Throughout the region, growth of algal Chl a and DMSP was generally high (0.2–1 d⁻¹), but grazing rates were lower and more variable, characteristic of the early spring bloom period. Production and consumption of Chl a vs. DMSP followed no clear pattern, and sometimes diverged greatly, likely because of their differing distributions among algal prey taxa and size class. In several experiments where Phaeocystis was abundant, we observed DMS production proportional to grazing rate, and we found clear evidence of DMS production by this haptophyte following physical stress such as sparging or filtration. It is possible that grazing-activated DMSP cleavage by Phaeocystis contributes to grazer deterrence: protozoa and copepods apparently avoided healthy colonies (as judged by relative growth and grazing rates of Chl a and DMSP), and grazing of Phaeocystis was significant only at one station where cells were in poor condition. Although we hoped to examine selective grazing on or against DMSP-containing algal prey, the dilution technique cannot differentiate selective ingestion and varying digestion rates of Chl a and DMSP. We also found that the dilution method alone was poorly suited for assessing the impact of grazing on dissolved sulfur pools, because of rapid microbial consumption and the artifactual release of DMSP and DMS during filtration. Measuring and understanding the many processes affecting organosulfur cycling by the microbial food web in natural populations remain a technical challenge that will likely require a combination of techniques to address.  相似文献   

Thermokarst lakes and ponds on Mars in the very recent (late Amazonian) past   总被引：1，自引：0，他引：1  

Richard J. Soare  Gordon R. Osinski  Charlotte L. Roehm 《Earth and Planetary Science Letters》2008,272(1-2):382-393

The history of water is fundamental to understanding the geological evolution of Mars and to questions concerning the possible development of life on the Red Planet. Today, Mars is cold and dry; its regolith is permanently frozen and except under highly localised and transient conditions, liquid water is unstable at the surface. Intriguingly, we have identified geological features that could be markers of very late-Amazonian “wet” or ice-rich periglacial processes in Utopia and western Elysium Planitiae: 1. rimless, flat-floored and lobate, sometimes scalloped, depressions that are suggestive of terrestrial alases (evaporated/drained thermokarst lakes); 2. small-sized polygonal patterned-ground (perhaps formed by thermal-contraction cracking and possibly underlain by ice wedges); and, 3. circular/near-circular raised-rim depressions (consistent in morphology and scale with pingo-scars) that are nested in rimless depressions. In terrestrial cold-climate, non-glacial environments, landscape assemblages of this type occur only in the presence of ice-rich permafrost.Commenting upon the origin of the putative periglacial features on Mars, most workers have suggested that sublimation and not evaporation has been the dominant process. By contrast, we propose that two key characteristics of the rimless depressions – inner terraces and orthogonally-oriented polygons – are markers of stable, ponded water and its slow loss by evaporation or drainage. If the raised-rim landforms are pingo scars, then this also points to boundary conditions that are supportive of stable liquid water.With regard to the relative age of the features described above, previous work identified some lobate depressions superposed on crater-rim gullies in the region (Soare et al., 2007). Gullies could be amongst the youngest geological features on Mars; superposed depressions point to an origin that is more youthful than the gullies. In turn, as some raised-rim landforms are superposed on rimless depressions, this is indicative of an origin that is even more recent than that of the depressions. Together with the geological evidence showing that the rimless depressions could have been formed by ponded water, the stratigraphy of the putative periglacial-landscape in this region suggests that the very late Amazonian period could have been warmer and wetter than had been thought hitherto.  相似文献   

Seismic anisotropy in granite at the Underground Research Laboratory, Manitoba   总被引：2，自引：0，他引：2  

Gordon M. Holmes  Stuart Crampin  & R. Paul Young 《Geophysical Prospecting》2000,48(3):415-435

The Shear-Wave Experiment at Atomic Energy of Canada Limited's Underground Research Laboratory was probably the first controlled-source shear-wave survey in a mine environment. Taking place in conjunction with the excavation of the Mine-by test tunnel at 420 m depth, the shear-wave experiment was designed to measure the in situ anisotropy of the rockmass and to use shear waves to observe excavation effects using the greatest variety of raypath directions of any in situ shear-wave survey to date. Inversion of the shear-wave polarizations shows that the anisotropy of the in situ rockmass is consistent with hexagonal symmetry with an approximate fabric orientation of strike 023° and dip 35°. The in situ anisotropy is probably due to microcracks with orientations governed by the in situ stress field and to mineral alignment within the weak gneissic layering. However, there is no unique interpretation as to the cause of the in situ anisotropy as the fabric orientation agrees approximately with both the orientation expected from extensive-dilatancy anisotropy and that of the gneissic layering. Eight raypaths with shear waves propagating wholly or almost wholly through granodiorite, rather than granite, do not show the expected shear-wave splitting and indicate a lower in situ anisotropy, which may be due to the finer grain size and/or the absence of gneissic layering within the granodiorite. These results suggest that shear waves may be used to determine crack and mineral orientations and for remote monitoring of a rockmass. This has potential applications in mining and waste monitoring.  相似文献