On the potential impact of harbour seal predation on the cod population in the eastern North Sea     

B. Johan L. Hansen  Karin C. Harding 《Journal of Sea Research》2006,56(4):329-337

Increasing Scandinavian harbour seal populations during the last decades coincide in time with the collapse of the cod fishery. Assumptions of a causal relationship have led to claims favouring re-introduction of seal hunting. Proposals for ‘adaptive management’ often assume that decimating seal populations will automatically favour the fishery. This argument presupposes seal predation to be sufficiently large to have a measurable impact on the fish population. The potential magnitude of the cod-seal interaction was analysed using data on harbour seal abundance, feeding habits and compiled information on cod life history and cod landing statistics. A size-structured life history matrix for the cod population was applied and the size-specific prey preferences of harbour seals were taken into account. Estimated seal predation was small compared to both the landings by the fishery, and to minimum estimates of the total cod population. Furthermore, since the size classes of cod targeted by seals have low reproductive values, the impact of seal predation on cod production will be further reduced. Our analyses suggest harbour seals have a negligible impact on the cod fishery.  相似文献   

Groundwater—from development to management   总被引：1，自引：0，他引：1  

Karin E. Kemper 《Hydrogeology Journal》2004,12(1):3-5

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On the Exchange of NO3 Radicals with Aqueous Solutions: Solubility and Sticking Coefficient     

Karin Thomas  Andreas Volz-Thomas  Djuro Mihelcic  Herman G. J. Smit  Dieter Kley 《Journal of Atmospheric Chemistry》1998,29(1):17-43

The exchange of NO₃ radicals with the aqueous-phase was investigated at room temperature (293 K) in a series of wetted denuders. From these experiments, the uptake coefficient of NO₃ was determined on 0.1 M NaCl solutions and was found to be (NO₃) 2 × 10^-3 in good agreement with recent studies. The Henry coefficient of NO₃ was estimated to be K_H(NO₃) = 1.8 M · atm^-1, with a (2) uncertainty of ±3 M · atm^-1. From the upper limit for the Henry coefficient (K_H = 5 M · atm^-1) and available thermodynamic data, the redox potential of dissolved NO₃/NO ₃ ^– is estimated to be in the range of 2.3 to 2.5 V. This range is at the lower boundary of earlier estimates. The results are discussed in the light of a recent publication. Based on our data and a model of the transport and chemistry in the liquid film, an upper limit is derived for the product of the Henry coefficient K_H and the rate coefficient k ₁₀ of the potential reaction NO₃ + H₂O HNO₃ + OH. For K_H = 0.6 M · atm^-1, we find k ₁₀ < 0.05 s^-1 · atm^-1, i.e., about 100 times smaller than what was suggested by Rudich and co-workers. Because of its small solubility, heterogeneous removal of NO₃ is only important under conditions where the dissolved NO₃ is removed quickly from equilibrium, for example by reactions with Cl^– or HSO ₃ ^– ions in the liquid-phase. Otherwise, heterogenous removal should mainly proceed via N₂O₅.  相似文献   

Produktionsbiologische Studien über die Moosvegetation eines klaren Gebirgssees     

Karin Bodin  A. Nauwerck 《Aquatic Sciences - Research Across Boundaries》1968,30(2):318-352

Ohne Zusammenfassung Mitteilung IV des Latnjajaureprojekts.  相似文献   

Limits on the effect of pressure on isotopic fractionation     

Robert N. Clayton  Julian R. Goldsmith  Karin J. Karel  Toshiko K. Mayeda 《Geochimica et cosmochimica acta》1975,39(8):1197-1201

The equilibrium distribution of oxygen isotopes between calcium carbonate and water was determined at 500°C at pressures from 1 to 20 kbar and at 700°C at pressures of 0.5 and 1 kbar. At both temperatures, the pressure-dependence of the fractionation factor was below the limit of detection. The experimental results are consistent with theoretical estimates of the volume change due to isotope substitution. Application of the theory to silicate systems leads to the conclusion that pressure effects on oxygen isotopic fractionation between silicates are < 0.2% at pressures of tens of kilobars. Thus the observed large variations of O¹⁸/O¹⁶ ratio in kimberlitic eclogites cannot be attributed to the effect of pressure  相似文献   

Size,shape and spatial arrangement of mega‐scale glacial lineations from a large and diverse dataset          下载免费PDF全文

Matteo Spagnolo  Chris D. Clark  Jeremy C. Ely  Chris R. Stokes  John B. Anderson  Karin Andreassen  Alastair G. C. Graham  Edward C. King 《地球表面变化过程与地形》2014,39(11):1432-1448

Mega‐scale glacial lineations (MSGLs) are a characteristic landform on ice stream beds. Solving the puzzle of their formation is key to understanding how ice interacts with its bed and how this, in turn, influences the dynamics of ice streams. However, a comprehensive and detailed characterization of this landform's size, shape and spatial arrangement, which might serve to test and refine formational theories, is largely lacking. This paper presents a detailed morphometric analysis and comparison of 4043 MSGLs from eight palaeo‐ice stream settings: three offshore (Norway and Antarctica), four onshore (Canada), and one from under a modern ice stream in West Antarctica. The length of MSGLs is lower than previously suggested (mode 1000–2000 m; median 2892 m), and they initiate and terminate at various locations on an ice stream bed. Their spatial arrangement reveals a pattern that is characterized by an exceptional parallel conformity (80% of all mapped MSGLs have an azimuth within 5° from the mean values), and a fairly constant lateral spacing (mode 200–300 m; median 330 m), which we interpret as an indication that MSGLs are a spatially self‐organized phenomenon. Results show that size, shape and spatial arrangement of MSGLs are consistent both within and also generally between different ice stream beds. We suggest this results from a common mechanism of formation, which is largely insensitive to local factors. Although the elongation of MSGLs (mode 6–8; median 12.2) is typically higher than features described as drumlins, these values and those of their width (mode 100–200 m; median 268 m) overlap, which suggests the two landforms are part of a morphological continuum and may share a similar origin. We compare their morphometry with explicit predictions made by the groove‐ploughing and rilling instability theories of MSGL formation. Although the latter was most compatible, neither is fully supported by observations. © 2014 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.  相似文献   

Rapid physicochemical changes in the high Arctic Lake Kongressvatn caused by recent climate change     

Trine Marianne Holm  Karin A. Koinig  Tom Andersen  Espen Donali  Anne Hormes  Dag Klaveness  Roland Psenner 《Aquatic Sciences - Research Across Boundaries》2012,74(3):385-395

High Arctic lakes are among the most sensitive ecosystems and climate change strongly affects their physical properties, especially water temperature, and mixing processes. To study the effect of recent climate change on such a lake in the Arctic environment, we measured water chemistry and temperature from 2005 to 2010 in Kongressvatn, a crenogenic meromictic lake in Spitsbergen (Svalbard). In addition, we monitored water column temperatures during two consecutive years and compared them to regional air temperature data and physicochemical lake data from 1962 and 1968, two relatively cold years. Summer surface water temperature was highly correlated to air temperature, and both have increased by approximately 2°C since 1962. Temperature monitoring during 2?years showed that the warm summer of 2007 resulted in increased water temperatures even in the stratified, denser hypolimnion. Our water chemistry measurements showed that the chemocline position in 2005?C2010 was ca 12?m deeper than in 1962?C1968, and a second, weaker, chemocline appeared at metalimnetic depths of 7?C15?m. During the study period, the water level decreased by 4?m, and this change accelerated between 2008 and 2010. Our data support the hypothesis that water temperatures and stratification patterns are changing rapidly with air temperature, but changes in the catchment, such as glacial retreat and permafrost melting, may have an even stronger impact on lake properties.  相似文献   

Sediment dynamics in the Gulf of Lions: The impact of extreme events     

Xavier Durrieu de Madron  Patricia L. Wiberg  Pere Puig 《Continental Shelf Research》2008

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The impacts of a Laki-like eruption on the present Swedish society     

Karin Mossberg Sonnek  Tomas Mårtensson  Ester Veibäck  Peter Tunved  Håkan Grahn  Pontus von Schoenberg  Niklas Brännström  Anders Bucht 《Natural Hazards》2017,88(3):1565-1590

In this study, we analyse and discuss the possible impacts on the Swedish society of a volcanic eruption on Iceland, emitting ash particles and large quantities of sulphur dioxide. A scenario was developed, based on the historical Laki eruption of 1783–1784, to describe the content of a potential sulphur fog over time in Sweden. Due to its high complexity and the many uncertainties in the underpinning scientific data, the scenario was developed using a cross-disciplinary approach incorporating experts from different scientific fields. An analysis of the impacts of the hazard on human health, environment and technical equipment was then performed and, finally, representatives from national authorities assessed the overall societal challenges in responding to the consequences of a massive volcanic eruption. The analysis shows that it is the peak concentrations of sulphur dioxide and sulphuric acid rather than the longer periods of moderate concentrations that contribute most to the negative consequences for human health and environment. Altogether, three societal challenges were identified: the ability to compile and disseminate relevant information fast enough, to perform continuous measurements of concentrations of different substances in affected areas and to meet the large demand for medical care.  相似文献   

A commentary on coastal research in New Zealand universities     

Paul S. Kench  Karin R. Bryan  Deirdre E. Hart  David M. Kennedy  Michael J. Hilton 《New Zealand geographer》2008,64(2):93-104

Abstract:    University research in coastal geomorphology, processes and management has made a major contribution to the fundamental understanding of coastal systems in New Zealand over the past 43 years. This article examines the growth in university-based coastal research since 1964 and discusses the geographical pattern and themes of this research. Data indicate a significant geographical concentration of research effort and focus on a narrow range of research themes. Underlying reasons for these characteristics of New Zealand coastal research are explored and challenges facing university based research are discussed. Such challenges can be overcome through a more coordinated research effort to realize the huge potential to undertake coastal science of national relevance and international significance.  相似文献