Origin and Extent of Fresh Paleowaters on the Atlantic Continental Shelf, USA   总被引：3，自引：0，他引：3  

by Denis Cohen  Mark Person  Peng Wang  Carl W. Gable  Deborah Hutchinson  ee Marksamer  Brandon Dugan  Henk Kooi  Koos Groen  Daniel Lizarralde  Robert L. Evans  Frederick D. Day-Lewis  John W. Lane Jr. 《Ground water》2010,48(1):143-158

While the existence of relatively fresh groundwater sequestered within permeable, porous sediments beneath the Atlantic continental shelf of North and South America has been known for some time, these waters have never been assessed as a potential resource. This fresh water was likely emplaced during Pleistocene sea-level low stands when the shelf was exposed to meteoric recharge and by elevated recharge in areas overrun by the Laurentide ice sheet at high latitudes. To test this hypothesis, we present results from a high-resolution paleohydrologic model of groundwater flow, heat and solute transport, ice sheet loading, and sea level fluctuations for the continental shelf from New Jersey to Maine over the last 2 million years. Our analysis suggests that the presence of fresh to brackish water within shallow Miocene sands more than 100 km offshore of New Jersey was facilitated by discharge of submarine springs along Baltimore and Hudson Canyons where these shallow aquifers crop out. Recharge rates four times modern levels were computed for portions of New England's continental shelf that were overrun by the Laurentide ice sheet during the last glacial maximum. We estimate the volume of emplaced Pleistocene continental shelf fresh water (less than 1 ppt) to be 1300 km³ in New England. We also present estimates of continental shelf fresh water resources for the U.S. Atlantic eastern seaboard (10⁴ km³) and passive margins globally (3 × 10⁵ km³). The simulation results support the hypothesis that offshore fresh water is a potentially valuable, albeit nonrenewable resource for coastal megacities faced with growing water shortages.  相似文献   

X-ray timing behaviour of Cygnus X-2 at low intensities     

Erik Kuulkers  Rudy Wijnands  Michiel van der Klis 《Monthly notices of the Royal Astronomical Society》1999,308(2):485-492

It is known that the overall (mean) intensity of the low-mass X-ray binary Cyg X-2 varies on time-scales from a day to months, independently of the variations on time-scales of hours to a day by which the source moves between the horizontal, normal and flaring branches.
We present RXTE PCA observations of Cyg X-2, taken when its overall intensity was near its lowest values, in 1996 October and 1997 September. For the first time we perform a study of the fast timing behaviour at such low intensities. During the 1996 October observations, the source was in the left part of the horizontal branch, and during the 1997 September observations was most likely in the lower parts of the normal branch and flaring branch.
We find that the properties of the very low-frequency noise during the 1997 September observations are consistent with a monotonic decrease in its strength and power-law index as a function of overall intensity. In contrast, the strength of the ∼6 Hz normal branch quasi-periodic oscillations does not vary monotonically with overall intensity. They are strongest at medium overall intensity and weaker both when the overall intensity is low and when the overall intensity is high.  相似文献   

An improved methodology to measure flag performance for the shipping industry     

Mihail Perepelkin  Sabine Knapp  German Perepelkin  Michiel de Pooter 《Marine Policy》2010

The subject of measuring the performance of registries has been a topic of policy discussions in recent years at the regional level due to the recasting of the European Union (EU) port state control (PSC) directive which introduces incentives for flags which perform better. Since the current method used in the EU region entails some shortcomings, it has therefore been the subject of substantial scrutiny. Furthermore, the International Maritime Organization (IMO) developed a set of performance indicators which however lacks the ability to measure compliance as set out in one of its strategic directions towards fostering global compliance. This article develops a methodology to measure flag state performance which can be applied on the regional or global level and to other areas of legislative interest (e.g. recognized organizations, Document of Compliance Companies). The proposed methodology overcomes some of the shortcomings of the present method and presents a more refined, less biased approach of measuring performance. To demonstrate its usefulness, it is applied to a sample of 207,821 observations for a 3-year time frame and compared to the current method.  相似文献   

Differentiating Future Commitments on the Basis of Countries’ Relative Historical Responsibility for Climate Change: Uncertainties in the ‘Brazilian Proposal’ in the Context of a Policy Implementation   总被引：1，自引：0，他引：1  

Michel?G.?J.?Den?ElzenEmail author  Michiel?Schaeffer  Paul?L.?Lucas 《Climatic change》2005,71(3):277-301

During the negotiations on the Kyoto Protocol, Brazil proposed allocating the greenhouse gas emission reductions of Annex I Parties according to the relative effect of a country’s historical emissions on global temperature increase. This paper analyses the impact of scientific uncertainties and of different options in policy implementation (policy choices) on the contribution of countries’ historical emissions to indicators of historical responsibility for climate change. The influence of policy choices was found to be at least as large as the impact of the scientific uncertainties analysed here. Building on this, the paper then proceeds to explore the implications of applying the Brazilian Proposal as a climate regime for differentiation of future commitments on the global scale combined with an income threshold for participation of the non-Annex I regions. Under stringent climate targets, such a regime leads to high emission reductions for Annex I regions by 2050, in particular for Europe and Japan. The income threshold assumptions strongly affect the Annex I reductions, even more than the impact of another burden-sharing key. A variant of the Brazilian Proposal, allocating emission reductions on the basis of cumulative emissions since 1990, would lead to a more balanced distribution of emission reductions.  相似文献   

The shore environment: Volume 1—Methods; Volume 2—Ecosystems : Edited by J. H. Price, D. E. G. Irvine and W. F. Farnham Academic Press, London, 1980, Vol. 1: xx + 364pp, £24.80; Vol. 2: xx + 1044pp, £48.20     

Edited by J. H. Price  D. E. G. Irvine  W. F. Farnham 《Estuarine, Coastal and Shelf Science》1984,18(6):727-728

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Advances in marine biology, volume 20 : Edited by J. H. S. Blaxter, Sir F. S. Russell and Sir C. M. Yonge Academic Press, London, 1982, 398pp. £35     

Edited by J. H. S. Blaxter  Sir F. S. Russell  Sir C. M. Yonge 《Estuarine, Coastal and Shelf Science》1984,18(6):731-733

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Choptank Odyssey     

Reviewed by Catherine W. Cooper 《The Journal of geography》2017,116(3):136-137

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Interpreting Our World: 100 Discoveries that Revolutionized Geography     

Reviewed by Forrest J. Bowlick 《The Journal of geography》2017,116(6):263-264

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地质构造与矿床之关系     

纽豪士  秦鼐 《地质论评》1947,12(Z2):302-304

本书共二百八十面,十面为索引。包括文章七十九篇,分由六十五人执笔。文章按其内容分属于六章,章名如次: 一、构造现象与矿床之数种关系二、大区域内与某种矿床有关之构造现象  相似文献   

Christaller and “big data”: recalibrating central place theory via the geoweb   总被引：1，自引：1，他引：0  

Michiel van Meeteren  Ate Poorthuis 《Urban geography》2018,39(1):122-148

This article utilizes central place theory (CPT) to navigate the “deluge” brought about by big data. While originating in the 1930s, CPT is a theoretical monument of 1960s spatial science. CPT aims to understand settlement geographies based on consumption behavior and is often presented as a singular, outdated, and rationalist theory. After critically reviewing the history of CPT, we assess the microfoundations of Christaller’s CPT – the threshold and range of goods – for various central functions in Louisville, Kentucky. The microfoundations are estimated through data from social media platforms Foursquare and Twitter. These sources alleviate many of the operationalization issues that traditionally hamper empirical use of CPT. The empirical application of CPT reveals that: (i) central functions have typical ranges and thresholds relating central places to population spread; (ii) central functions cluster based on an approximate hierarchical structure. The findings indicate the ongoing importance of CPT in shaping urban-economic geographies.  相似文献