Near-infrared imaging of 222 nearby Hδ-strong galaxies from the Sloan Digital Sky Survey     

Michael L. Balogh  Chris Miller  Robert Nichol  Ann Zabludoff  Tomo Goto 《Monthly notices of the Royal Astronomical Society》2005,360(2):587-609

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High Arctic sea ice conditions influence marine birds wintering in Low Arctic regions     

Laura McFarlane Tranquilla  April Hedd  Chantelle Burke  William A. Montevecchi  Paul M. Regular  Gregory J. Robertson  Leslie Ann Stapleton  Sabina I. Wilhelm  David A. Fifield  Alejandro D. Buren 《Estuarine, Coastal and Shelf Science》2010

Ocean climate change is having profound biological effects in polar regions. Such change can also have far-reaching downstream effects in sub-polar regions. This study documents an environmental relationship between High Arctic sea ice changes and mortality events of marine birds in Low Arctic coastal regions. During April 2007 and March 2009, hundreds of beached seabird carcasses and moribund seabirds were found along the east and northeast coasts of Newfoundland, Canada. These seabird “wrecks” (i.e. dead birds on beaches) coincided with a period of strong, persistent onshore winds and heavily-accumulated sea ice that blocked bays and trapped seabirds near beaches. Ninety-two percent of wreck seabirds were Thick-billed Murres (Uria lomvia). Body condition and demographic patterns of wreck murres were compared to Thick-billed Murres shot in the Newfoundland murre hunt. Average body and pectoral masses of wreck carcasses were 34% and 40% lighter (respectively) than shot murres, indicating that wreck birds had starved. The acute nature of each wreck suggested that starvation and associated hypothermia occurred within 2–3 days. In 2007, first-winter murres (77%) dominated the wreck. In 2009, there were more adults (78%), mostly females (66%). These results suggest that spatial and temporal segregation in ages and sexes can play a role in differential survival when stochastic weather conditions affect discrete areas where these groups aggregate. In wreck years, southward movement of Arctic sea ice to Low Arctic latitudes was later and blocked bays longer than in most other years. These inshore conditions corresponded with recent climate-driven changes in High Arctic ice break-up and ice extent; coupled with local weather conditions, these ice conditions appeared to be the key environmental features that precipitated the ice-associated seabird wrecks in the Low Arctic region.  相似文献   

Spatial scale and habitat-dependent diversity patterns in nematode communities in three seepage related sites along the Norwegian Sea margin     

Saskia Van Gaever  Maarten Raes  Francesca Pasotti  & Ann Vanreusel 《Marine Ecology》2010,31(1):66-77

Assessing the relative contribution of local diversity to regional biodiversity may be the key to understanding large-scale and even global patterns in species diversity. Here, the contribution of habitat heterogeneity of cold seeps at three spatial scales [micro-scale (ms), macro-scale (10 to 100s of ms), and mega-scale (10 to 100s of km)] to the total nematode biodiversity (genus level) along the Norwegian continental margin is evaluated. Due to the development of higher resolution bathymetry and increased bottom sampling in recent years, continental margins, once regarded as monotonous landscapes, are now acknowledged to have a high degree of habitat complexity and diversity. By calculating the additive partitioning of gamma diversity in alpha and beta fractions, we examined to what extent habitat diversity of seep sites significantly increases the nematode genus composition and diversity at different spatial scales. Siboglinidae patches and control sediments yielded comparably high levels of nematode genus richness. They exhibited low turnover rates within and across the different seep sites. In contrast, the bacterial mats at Håkon Mosby Mud Volcano (HMMV) and the reduced sediments at the Nyegga pockmarks harboured genus-poor nematode communities with an equally high dominance of one or two species, which were different for each seep. Different habitats, in particular at the HMMV, contributed significantly to the seep nematode richness. This study demonstrates that the presence of distinct habitat types within multiple seep sites contributes to the high diversity of nematode communities inhabiting the seeps in the Norwegian deep sea.  相似文献   

Controls on regional variability in marine pore-water diagenesis below the seafloor in Upper Jurassic–Lower Cretaceous prodeltaic sandstone and shales,Scotian Basin,Eastern Canada     

Ann C. Okwese  Georgia Pe-Piper  David J.W. Piper 《Marine and Petroleum Geology》2012,29(1):175-191

Diagenesis in the uppermost Jurassic to Lower Cretaceous deltaic sandstones and shales of the Scotian Basin is an important control on reservoir quality. Ferruginous zone (sub-oxic) marine pore-water diagenesis controls the initial formation of Fe²⁺-silicates that are the precursors of grain-rimming chlorite that preserves porosity. This study assesses the regional controls on the type of marine pore-water diagenesis by studying the sedimentology, mineralogy, and geochemistry of the retrogradational units and underlying progradational units in parasequences from conventional cores in two wells in different parts of the basin. Coated grains preserve a record of whether marine pore-water diagenesis below the seafloor was dominantly in the ferruginous or sulphidic geochemical zone. Four types of coated grain were distinguished, each with a different mineral paragenesis. Mineralogical and chemical evidence of ferruginous zone diagenesis includes the presence of diagenetic chlorite and siderite, and the correlation of P with Fe or Ti. Pyrite and Fe-calcite are found where the sulphidic zone is more significant than the ferruginous zone. Ferruginous zone diagenesis was common in low-sedimentation rate retrogradational sediments with low organic carbon, and in delta-front turbidites and river-mouth sandstones. Estuarine, tidal flat and prodeltaic facies that are directly supplied by riverine sediments have a lower Fe:Ti ratio than do fully marine shoreface and open shelf facies as a result of input of detrital ilmenite and its alteration products. The relative contribution of colloidal iron (hydr)-oxides appears greater in distal low-sedimentation rate environments. Where large changes in sedimentation rate occurred at ravinement surfaces, the underlying progradational rocks have evidence of ferruginous zone diagenesis, whatever their facies. Rapid upward migration of the pore-water profile resulting from the change in sedimentation rate reduced the time available for mineral products to form in the deeper pore-water zones. This study has shown that the availability of Fe and organic carbon varying in a complex manner in marine deltaic sediments, but that the resulting diagenesis by marine pore-water can be predicted from facies and paleogeographic setting.  相似文献   

Chitin complex for the remediation of mine impacted water: Geochemistry of metal removal and comparison with other common substrates     

Mary Ann Robinson-Lora  Rachel A. Brennan 《Applied Geochemistry》2010

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Climatic change: communication changes over this journal’s first ‘century’     

Ann Henderson-Sellers 《Climatic change》2010,100(1):215-227

Over the century of ‘Climatic Change’ volumes and the 33 years that they span the climate has changed. Here I consider the challenge of interdisciplinary communication to which the first 99 volumes of this journal are dedicated. Have we succeeded and have climatic change researchers shared findings with a broader audience? If this journal has been successful, should the editorial board and publishers now consider new modes of communicating research to a still wider public, say by hiring a communication cartoonist or with an interactive blog?  相似文献   

Monitored Natural Attenuation of Contaminants in the Subsurface: Applications   总被引：3，自引：0，他引：3  

Ann Azadpour-Keeley  Jack W. Keeley  Hugh H. Russell  Guy W. Sewell 《Ground Water Monitoring & Remediation》2001,21(3):136-143

In recent years there has been increasing interest in the application of passive technologies to reduce or remove contaminants from the subsurface environment including soil and ground water. In most cases, the impetus for this interest lies in a perceived savings compared with more traditional remedial alternatives. In a few cases, the infrastructure at contaminated sites, such as buildings, paved areas, and utilities, makes the use of conventional remedial measures difficult and expensive.
To demonstrate that natural processes are effective in reaching established goals, it is necessary to determine that transformation processes are taking place at a rate that is protective of human health and the environment and that these processes will continue for an acceptable period of time. The basic conditions that must be present to confirm natural attenuation processes arc taking place are discussed along with the behavior of contaminated plumes, monitoring requirements, data analysis, rates of degradation, and mathematical modeling.  相似文献   

Acid-base status of soils in groundwater discharge zones — relation to surface water acidification     

Ann Catrine Norrstr  m 《Journal of Hydrology》1995,170(1-4):87-100

Critical load calculations have suggested that groundwater at depth of 2 m in Sweden is very sensitive to acid load. As environmental isotope studies have shown that most of the runoff in streams has passed through the soil, there is a risk in the near future of accelerated acidification of surface waters.

To assess the importance of the last soil horizon of contact before discharge, the upper 0–0.2m of soils in seven discharge zones were analysed for pools of base cations, acidity and base saturation. The sites were about 3–4 m² in size and selected from two catchments exposed to different levels of acid deposition.

The soils in the seven sites had high concentrations of exchangeable base cations and consequently high base saturation. The high correlation (r² = 0.74) between base saturation in the soils of the discharge zones and mean pH of the runoff waters suggested that the discharge zone is important for surface water acidification. The high pool of exchangeable base cations will buffer initially against the acid load. As the cation exchange capacity (meq dm⁻³) and base saturation were lower in the sites from the catchment receiving lower deposition, these streams may be more vulnerable to acidification in the near future. The high concentration of base cations in non-exchangeable fractions may also buffer against acidification as it is likely that some of these pools will become exchangeable with time.  相似文献   

The diurnal and semidiurnal barometric oscillations global distribution and annual variation     

B. Haurwitz  Ann D. Cowley 《Pure and Applied Geophysics》1973,102(1):193-222

Summary The global distributions of the annual and seasonal means of the diurnal (S ₁) and semidiurnal (S ₂) surface pressure oscillations are investigated by spherical harmonic analysis. The main waves are,S ₁ ¹ (with wave number 1) forS ₁ andS ₂ ² forS ₂.S ₁ ¹ is much less predominant among the waves ofS ₁ thanS ₂ ² among those ofS ₂. As in the case of the lunar semidiurnal barometric tideL ₂ the pressure maxima occur earlier in the Southern than in the Northern Hemisphere. In the case ofS ₂ the standing waveS ₂ ⁰ and the waveS ₂ ³ are also of interest besidesS ₂ ². Although the present analysis extends only from 60°N to 60°S, whileS ₂ ⁰ is largest at polar latitudes, its results show thatS ₂ ⁰ should be smaller at high southerly than at high northerly latitudes, as has been observed. Thus this observed asymmetrical distribution ofS ₂ ⁰ may be due to causes outside the polar regions rather than to their geographical differences. The best approximation to the observed distribution ofS ₂ ⁰ is obtained by including a mode representing an oscillation independent of longitude and latitude indicating a small semidiurnal variation of the mean global surface presure, which is an unlikely result on physical grounds.The seasonal variation ofS ₁ ¹ expressed in percent of the annual mean is smaller than that ofS ₂ ², and both are less than the unexplained seasonal variation ofL ₂ ².The main wavesS ₁ ¹ andS ₂ ² are expressed not only by associated Legendre functions, but also by Hough functions.National Center for Atmospheric Research, Boulder, Colorado, U.S.A., sponsored by the National Science Foundation.  相似文献   

Studying Regions by Studying Firms*   总被引：1，自引：0，他引：1  

Ann Markusen 《The Professional geographer》1994,46(4):477-490

This paper presents a method for inferring regional economic structure and prospects from key informant interviews. It describes assumptions which must be made and steps to be taken in moving from individuals to establishment, firm, and industry aggregations. A technique is offered for mapping core relationships among firms and other regional and external actors, and for aggregating firm-centered maps into industrial and regional maps. The mapping technique can be expanded to incorporate historicity and dynamic change.  相似文献