Is there a significant diffusive “salt-pump mechanism” for the transport of organic contaminants from the marine environment into fresh water aquifers? A discussion contribution     

M. E. Bridge  D. R. Lloyd 《Environmental Geology》2005,49(2):207-213

We analyse recent claims of an additional risk of diffusive intrusion by marine organic contamination (OC) into coastal aquifers, and discuss the activity-driven “salt-pump mechanism” which is claimed to accelerate this diffusion. The reported accelerations of transport of OC out of saltwater are far too large to be due to activity effects on simple diffusion. There probably is a small acceleration of diffusion out of saltwater, but there is no direct experimental evidence for this. Possible experimental artefacts are suggested. Larger effects on diffusion in the literature are shown to be not relevant to this problem. Diffusion of suspended OC, present in the experiments, is too slow to be significant; however, this suspended material is shown to have serious implications for the proposed interpretation of the results. Until these results are better understood, no conclusions about any possible environmental implications can be drawn from them.

D. R. LloydEmail: Phone: +353-1-6081726Fax: +353-1-6712826

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Twisted accretion curtains in the intermediate polar FO Aquarii     

P. A. Evans  Coel Hellier  Gavin Ramsay  Mark Cropper 《Monthly notices of the Royal Astronomical Society》2004,349(2):715-721

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The 2dF Galaxy Redshift Survey: the power spectrum and the matter content of the Universe     

Will J. Percival  Carlton M. Baugh  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Shaun Cole  Matthew Colless  Chris Collins  Warrick Couch  Gavin Dalton  Roberto De Propris  Simon P. Driver  George Efstathiou  Richard S. Ellis  Carlos S. Frenk  Karl Glazebrook  Carole Jackson  Ofer Lahav  Ian Lewis  Stuart Lumsden  Steve Maddox  Stephen Moody  Peder Norberg  John A. Peacock  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2001,327(4):1297-1306

The 2dF Galaxy Redshift Survey has now measured in excess of 160 000 galaxy redshifts. This paper presents the power spectrum of the galaxy distribution, calculated using a direct Fourier transform based technique. We argue that, within the k -space region     , the shape of this spectrum should be close to that of the linear density perturbations convolved with the window function of the survey. This window function and its convolving effect on the power spectrum estimate are analysed in detail. By convolving model spectra, we are able to fit the power-spectrum data and provide a measure of the matter content of the Universe. Our results show that models containing baryon oscillations are mildly preferred over featureless power spectra. Analysis of the data yields 68 per cent confidence limits on the total matter density times the Hubble parameter     , and the baryon fraction     , assuming scale-invariant primordial fluctuations.  相似文献   

SYNCONVERGENT, DUCTILE N-DIRECTED SHEARING ON THE WESTERN MARGIN OF THE NANGA PARBAT SYNTAXIS, N. PAKISTAN     

Tom Argles  Mike Edwards  Gavin Foster 《地学前缘》2000,(Z1)

SYNCONVERGENT, DUCTILE N-DIRECTED SHEARING ON THE WESTERN MARGIN OF THE NANGA PARBAT SYNTAXIS, N. PAKISTAN1　BurgJ P ,ChaudryMN ,GhazanfarM ,etal.StructuralevidenceforbackslidingoftheKohistanarcinthecollisionalsystemofnorthwestPakistan[J] .Geology 1996 ,2 4 ( 8) ,739～ 74 2 . 2　ChamberlainCP ,ZeitlerPK ,EricksonE .ConstraintsonthetectonicevolutionofthenorthwesternHimalayafromgeochronologicandpetrologicstudiesofBabusarPass,Pakistan[J] .Journa…  相似文献   

Benthic Disturbance and Impact Experiments in the Central Indian Ocean Basin     

Rahul Sharma  B. Nagendernath  A. B. Valsangkar  G. Parthiban  K. M. Sivakolundu  Gavin Walker 《Marine Georesources & Geotechnology》2000,18(3):209-221

As a part of the Environmental Impact Assessment studies for nodule mining, a long-term program has been initiated in the Central Indian Basin. Multidisciplinary studies on geological, biological, physical, and chemical parameters were carried out in an area selected on the basis of baseline data collected in the first phase of the program. A benthic disturbance was simulated with a hydraulic device also used in the previous experiments in the Pacific Ocean. A site of 3,000 ×200 m was repeatedly disturbed by a combination of fluidizing pump and suction pump to dislodge and discharge sediment from the seafloor into the water column 5 m above the seafloor. During 9 days of operation, 26 tows were carried out for 47 h of disturbance, resuspending about 6,000 m 3 of sediment along an 88-km line. Data for postdisturbance impact assessment were collected with sediment traps, deep-towed cameras, seafloor samples, and conductivity-temperature depth sensor (CTD)-rosette observations. Seafloor data, sediment samples, and water column studies were aimed at evaluating the impact of benthic disturbance, on the basis of pre- and postdisturbance data collected during the experiment. Observations show that vertical mixing of sediment as well as its lateral movement and resedimentation because of plume migration alters various parameters and leads to changes in the environment around the area.  相似文献   

Detection of the optical counterpart of the proposed double degenerate polar RX J1914+24     

Gavin Ramsay  Mark Cropper  Kinwah Wu  K. O. Mason  Pasi Hakala 《Monthly notices of the Royal Astronomical Society》2000,311(1):75-84

We have detected the optical counterpart of the proposed double degenerate polar RX J1914+24. The I -band light curve is modulated on the 9.5-min period seen in X-rays. There is no evidence for any other periods. No significant modulation is seen in J . The infrared colours of RX J1914+24 are not consistent with a main-sequence dwarf secondary star. Our ASCA spectrum of RX J1914+24 is typical of a heavily absorbed polar and our ASCA light curve also shows only the 9.5-min period. We find that the folded I band and X-ray light curves are out of phase. We attribute the I -band flux to the irradiated face of the donor star. The long-term X-ray light curve shows a variation in the observed flux of up to an order of magnitude. These observations strengthen the view that RX J1914+24 is indeed the first double degenerate polar to be detected. In this light, we discuss the synchronizing mechanisms in such a close binary and other system parameters.  相似文献   

Adaptation in agriculture: lessons for resilience from eastern regions of New Zealand     

Gavin Kenny 《Climatic change》2011,106(3):441-462

Assessments of adaptation in agriculture have evolved considerably from early, top-down, impact assessments. These early assessments, internationally and in New Zealand, provided a limited view of ‘smart farmer’ adaptation. While impact assessment provides some useful insights, experience with vulnerability and adaptation assessment provides a more appropriate foundation for understanding and characterising practical smart farmer adaptation. Findings are presented from 8 years of engagement with farmers in eastern regions of New Zealand. A comprehensive farm resilience picture has emerged from this work. This picture reflects a strong belief from real-world smart farmers that there is sufficient knowledge and experience to adapt to climate change. Proactive farmers are already reading multiple signals, including changes in climate, and are responding. The farm resilience picture provides a foundation for exploring alternative adaptation options and pathways for agriculture. These are presented and discussed in response to two proposed climate change scenarios, a high carbon world scenario and a rapidly decarbonising world scenario. Knowledge intensive, low input systems are consistent with the resilience picture drawn from farmers. Such systems are also consistent with a rapidly decarbonising world scenario and, it is argued, are likely to become increasingly attractive under a high carbon world scenario. A smart farming approach, focused on resilience, provides the basis for development of a response capacity, with potentially significant co-benefits in terms of adaptation and mitigation to climate change. Wider issues and needs to support the further development of farm resilience, and more widely landscape or regional resilience, are identified and discussed. It is apparent from this work that ongoing engagement with smart farmers, focused on resilience, can contribute significantly to development of a coordinated ‘bottom up’ and ‘top down’ response capacity. Addressing the psychology of change is a fundamental need to ensure wider engagement.  相似文献   

Mediated climate change in Britain: Scepticism on the web and on television around Copenhagen     

Neil T. Gavin  Tom Marshall 《Global Environmental Change》2011,21(3):1035-1044

Copenhagen 2009 was a major moment in the development of climate change as an issue. But climate sceptics before and during this event, sought to influence the nature of debate, and for this reason, the way Copenhagen was covered in the mass media was particularly important. This paper outlines the contours of contrarian arguments and claims, and assesses their reflection in the coverage at Copenhagen. The focus is on television, and extends to the assessment of internet - both modes of mass communication underrepresented in the existing literature. The results suggest a higher profile for contrarians and scepticism than is perhaps healthy, and speak to the role of these mass media, now and in the future, particularly with regard to the issue of public comprehension of the issues involved.  相似文献   

88小时:美国地质调查局国家地震信息中心对2011年3月11日Mw9.0日本地震的响应     

Gavin P Hayes  Paul S Earle  Harley MBenz  David J Wald  Richard W Briggs  左玉玲 《国际地震动态》2011,(8):1-15

引言 2011年3月11日日本本州岛东海岸附近海域发生的M9．0地震（Tohoku earthquake,以下称“东日本大地震”——译者注）及其引发的海啸造成数以万计的人员死亡,造成的财产损失可能超过1万亿美元,这是有历史记录以来最严重的自然灾害之一。  相似文献   

A palaeolimnological meta-database for assessing the ecological status of lakes   总被引：1，自引：0，他引：1  

Richard W. Battarbee  David Morley  Helen Bennion  Gavin L. Simpson  Michael Hughes  Viktorija Bauere 《Journal of Paleolimnology》2011,45(4):405-414

We describe a palaeolimnological meta-database (“LakeCores”) that includes information for lakes in Europe that have been cored for studies of recent environmental change. Only cores with intact mud-water interfaces and good chronologies for the last ~100–200 years are currently included. The information provided in the database includes the general characteristics of the lakes cored, the methods used for dating and analysis and the bibliographic source of the information selected. At present the database contains information on 1847 studies from 975 sites. Here we use the database to identify cores for which diatom-based pH and total phosphorus (TP) reconstructions have been derived and, from an inspection of the relevant papers, we compile summary data for the timing and extent of acidification and eutrophication of lakes across Europe. We show that there were few cases of acidification and eutrophication in Europe prior to about 1850, and therefore that conditions prior to 1850 can be used for reference with respect to current attempts to restore surface waters to “good ecological status”. We also show the extent to which pH and TP levels have changed across the continent both for all lakes, and, in the case of TP, for lakes of different types covering a range of alkalinities, altitudes, water depths and surface areas.  相似文献