A reconnaissance study of oxygen, hydrogen and strontium isotopes in geochemically diverse lakes, Western Nebraska, USA   总被引：1，自引：1，他引：0  

David C. Gosselin  Peter E. Nabelek  Zell E. Peterman  Steve Sibray 《Journal of Paleolimnology》1997,17(1):51-65

Reconnaissance ¹⁸O,, D, and ⁸⁷Sr data for fifteen lakes in the Western Lakes Region of the Sand Hills of Nebraska indicate dynamic hydrologic systems. The rather narrow range of ⁸⁷Sr from lake water (1.1 to 2.1) and groundwater (0.9 to 1.7) indicates that the groundwater is generally unradiogenic. Groundwater residence times and relatively unradiogenic volcanic ash within the dune sediments control the ⁸⁷Sr values. Based on the mutual variations of ¹⁸O and D, the lakes can be divided into three groups. In Group 1, both ¹⁸O and D values increase from spring to fall. The ¹⁸O and D values in Group 2 decreased from spring to fall. Group 3 are ephemeral lakes that went dry some time during 1992. The data and isotopic modeling show that variations in the ratio of evaporation relative to groundwater inflow, local humidity conditions, and the _a has substantial influence on the isotopic composition. In addition, isotopic behavior in ephemeral lakes can be rather unusual because of the changing activities of water and mineral precipitation and redissolution. The annual and interannual isotopic variability of these lakes which is reflected in the paleonvironmental indicators may be the rule rather than the exception in these types of systems.  相似文献   

Buchbesprechungen     

F. Steinhauser  Peter Steinhauser 《Meteorology and Atmospheric Physics》1971,20(4):409-412

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On empirical models of the upper atmosphere in the polar regions     

Peter W. Blum  Isadore Harris 《Planetary and Space Science》1973,21(3):377-381

The expression for the exospheric temperature in Jacchia's static diffusion models of the upper atmosphere has a discontinuous gradient at the poles. Therefore it cannot describe the true state of the upper atmosphere in the polar regions. Furthermore, it cannot be used to calculate quantities that depend on the derivative of the exospheric temperature, or the density, like pressure gradients, horizontal forces or horizontal heat fluxes. A modified expression for the exospheric temperature is suggested. This modification yields variables of state of the upper atmosphere that deviate little from Jacchia's values, but it has continuous gradient at the poles and is therefore more suitable for treating dynamical problems like the global wind pattern.  相似文献   

Zur Einführung in einige Probleme der Ostalpinen Zentralzone     

Hans Peter Cornelius 《International Journal of Earth Sciences》1952,40(2):257-261

Ohne Zusammenfassung  相似文献   

Agents of landscape change in southern New Zealand, 1896–1920          下载免费PDF全文

Peter Holland  Sherry Olson  Chris Garden 《New Zealand geographer》2018,74(1):15-26

The records of two large stock and station agents, Loan & Mercantile Agency in Dunedin and Wright Stephenson in Invercargill, allowed us to track the timing, nature, magnitude and rate of landscape change in southern New Zealand between 1896 and 1920. This period extends from the final years of subdivision of large estates, and includes closer settlement, the shift from pastoral farming to intensive agriculture, growth of dairying, and increasing mechanisation of agriculture. These changes are reflected in clients’ annual expenditures on capital items such as fencing and building materials, tools and implements, materials for drains.  相似文献   

Liberalism,Illiberalism, and the Environment     

David A. Sonnenfeld  Peter Leigh Taylor 《社会与自然资源》2018,31(5):515-524

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Understanding land system dynamics and its consequences     

Wenbin Wu  Peter H. Verburg  Huajun Tang 《地理学报(英文版)》2018,28(11):1563-1566

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Drivers of long-term precipitation and runoff variability in the southeastern USA     

Johanna?Engstr?mEmail authorView author&#;s OrcID profile  Peter?Waylen 《Theoretical and Applied Climatology》2018,131(3-4):1133-1146

The hydroclimatology of the southeastern USA (AL, GA, NC, SC, and TN) is analyzed from a holistic perspective, including multiple climate drivers. Monthly precipitation modeled by the PRISM group and runoff data (1952–2011) from 18 basins are analyzed using a single-field based principal component’s analysis. Results indicate that the Atlantic Multidecadal Oscillation and El Niño-Southern Oscillation are the main atmospheric drivers of hydroclimate variability in the region, sometimes operating at several months’ lag. Their influence is the strongest in the fall through spring, which corresponds with the dry season in the southern parts of the study area thereby increasing pressure on already limited water resources. The Arctic Oscillation, North Atlantic Oscillation, and Pacific-North American patterns vary on shorter-term bases, and also show a significant, but temporally more sporadic influence. Insight is also brought to the ongoing discussion, confirming the disassociation of the Arctic and North Atlantic Oscillation. Findings can be used in water resources forecasting, giving an indication of expected water volumes several months ahead.  相似文献   

Would constraining US fossil fuel production affect global CO<Subscript>2</Subscript> emissions? A case study of US leasing policy     

Peter Erickson  Michael Lazarus 《Climatic change》2018,150(1-2):29-42

Avoiding dangerous climate change will require a rapid transition away from fossil fuels. By some estimates, global consumption and production of fossil fuels—particularly coal and oil—will need to end almost entirely within 50 years. Given the scale of such a transition, nations may need to consider policies that constrain growth in fossil fuel supplies in addition to those that reduce demand. Here, we examine the emissions implications of a supply-constraining measure that was rapidly gaining momentum in the United States (US) under the Obama administration: ceasing the issuance of new leases for fossil fuel extraction on federal lands and waters. Such a measure could reduce global carbon dioxide emissions by an estimated 280 million tons annually by 2030, comparable to that of other major climate policies adopted or considered by the Obama administration. Our findings suggest that measures to constrain fossil fuel supply—though not currently viable in a US Trump administration—deserve further consideration at subnational levels in the US or by other countries now, and by future US administrations.  相似文献   

A distinction between summer rainy season and summer monsoon season over the Central Highlands of Vietnam     

Ngo-Thanh  Huong  Ngo-Duc  Thanh  Nguyen-Hong  Hanh  Baker  Peter  Phan-Van  Tan 《Theoretical and Applied Climatology》2018,132(3-4):1237-1246

Theoretical and Applied Climatology - The daily rainfall data at 13 stations over the Central Highlands (CH) Vietnam were collected for the period 1981–2014. Two different sets of criteria...  相似文献