Seismic Travel-Time Residuals and Plates   总被引：1，自引：0，他引：1  

D. Davies  D. P. McKenzie 《Geophysical Journal International》1969,18(1):51-63

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Earth Strain Tides Observed in Yorkshire, England with a Simple Wire Strainmeter     

Roger Bilham  Russ Evans  Geoffrey King  Alette Lawson  Dan McKenzie 《Geophysical Journal International》1972,29(4):473-485

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A GEOGRAPHIC CRITERION FOR IDENTIFYING PROPERTY-TAX ASSESSMENT INEQUITY     

Grant lan Thrall 《The Professional geographer》1979,31(3):278-283

Equitable tax assessment requires that houses having the same market value must also have identical assessed values. With a map of dwellings' assessed-value-to-market-value ratios, it is possible to identify neighborhoods that are significantly overassessed or underassessed; this can lead to an understanding of the causes of misassessment. When houses or neighborhoods are demonstrated to be inequitably assessed, corrective action can be taken to eliminate the inequity. This essay is an example of the application of geographic techniques to spatial public-policy formulation.  相似文献   

Effects of observed and experimental climate change on terrestrial ecosystems in northern Canada: results from the Canadian IPY program   总被引：1，自引：0，他引：1  

Gregory H. R. Henry  Karen A. Harper  Wenjun Chen  Julie R. Deslippe  Robert F. Grant  Peter M. Lafleur  Esther Lévesque  Steven D. Siciliano  Suzanne W. Simard 《Climatic change》2012,115(1):207-234

Tundra and taiga ecosystems comprise nearly 40?% of the terrestrial landscapes of Canada. These permafrost ecosystems have supported humans for more than 4500?years, and are currently home to ca. 115,000 people, the majority of whom are First Nations, Inuit and Métis. The responses of these ecosystems to the regional warming over the past 30?C50?years were the focus of four Canadian IPY projects. Northern residents and researchers reported changes in climate and weather patterns and noted shifts in vegetation and other environmental variables. In forest-tundra areas tree growth and reproductive effort correlated with temperature, but seedling establishment was often hindered by other factors resulting in site-specific responses. Increased shrub cover has occurred in sites across the Arctic at the plot and landscape scale, and this was supported by results from experimental warming. Experimental warming increased vegetation cover and nutrient availability in most tundra soils; however, resistance to warming was also found. Soil microbial diversity in tundra was no different than in other biomes, although there were shifts in mycorrhizal diversity in warming experiments. All sites measured were sinks for carbon during the growing season, with expected seasonal and latitudinal patterns. Modeled responses of a mesic tundra system to climate change showed that the sink status will likely continue for the next 50?C100?years, after which these tundra systems will likely become a net source of carbon dioxide to the atmosphere. These IPY studies were the first comprehensive assessment of the state and change in Canadian northern terrestrial ecosystems and showed that the inherent variability in these systems is reflected in their site-specific responses to changes in climate. They also showed the importance of using local traditional knowledge and science, and provided extensive data sets, sites and researchers needed to study and manage the inevitable changes in the Canadian North.  相似文献   

Preparing for climate change in Washington State     

Lara C. Whitely Binder  Jennifer Krencicki Barcelos  Derek B. Booth  Meriel Darzen  Marketa McGuire Elsner  Richard Fenske  Thomas F. Graham  Alan F. Hamlet  John Hodges-Howell  J. Elizabeth Jackson  Catherine Karr  Patrick W. Keys  Jeremy S. Littell  Nathan Mantua  Jennifer Marlow  Don McKenzie  Michael Robinson-Dorn  Eric A. Rosenberg  Claudio O. Stöckle  Julie A. Vano 《Climatic change》2010,102(1-2):351-376

Climate change is expected to bring potentially significant changes to Washington State’s natural, institutional, cultural, and economic landscape. Addressing climate change impacts will require a sustained commitment to integrating climate information into the day-to-day governance and management of infrastructure, programs, and services that may be affected by climate change. This paper discusses fundamental concepts for planning for climate change and identifies options for adapting to the climate impacts evaluated in the Washington Climate Change Impacts Assessment. Additionally, the paper highlights potential avenues for increasing flexibility in the policies and regulations used to govern human and natural systems in Washington.  相似文献   

Potential impact of climate change on carbon in agricultural soils in Canada 2000–2099     

W. N. Smith  B. B. Grant  R. L. Desjardins  B. Qian  J. Hutchinson  S. Gameda 《Climatic change》2009,93(3-4):319-333

Under the threat of global warming it is important to determine the impact that future changes in climate may have on the environment and to what extent any adverse effects can be mitigated. In this study we assessed the impact that climate change scenarios may have on soil carbon stocks in Canada and examined the potential for agricultural management practices to improve or maintain soil quality. Historical weather data from 1951 to 2001 indicated that semi-arid soils in western Canada have become warmer and dryer and air temperatures have increased during the spring and winter months. Results from the Canadian Center for Climate Modelling and Analysis (CCCma) Coupled Global Climate Model (CGCM1,2) under two climate change forcing scenarios also indicated that future temperatures would increase more in the spring and winter. Precipitation increased significantly under the IPCC IS92a scenario and agreed with historical trends in eastern Canada whereas the IPCC SRES B2 scenario indicated very little change in precipitation and better matched historical trends in western Canada. The Century model was used to examine the influence of climate change on agricultural soil carbon (C) stocks in Canada. Relative to simulations using historical weather data, model results under the SRES B2 climate scenario indicated that agricultural soils would lose 160 Tg of carbon by 2099 and under the IS92a scenario would lose 53 Tg C. Carbon was still lost from soils in humid climatic regions even though C inputs from crops increased by 10–13%. Carbon factors associated with changes in management practices were also estimated under both climate change scenarios. There was little difference in factors associated with conversion from conventional to no-till agriculture, while carbon factors associated with the conversion of annual crops to perennial grass were lower than for historical data in semi-arid soils because water stress hampered crop production but were higher in humid soils.  相似文献   

A chemical and thermodynamic model of oil generation in hydrocarbon source rocks     

Harold C. Helgeson  Laurent Richard  William F. McKenzie  Alexandra Schmitt 《Geochimica et cosmochimica acta》2009,73(3):594-7350

Thermodynamic calculations and Gibbs free energy minimization computer experiments strongly support the hypothesis that kerogen maturation and oil generation are inevitable consequences of oxidation/reduction disproportionation reactions caused by prograde metamorphism of hydrocarbon source rocks with increasing depth of burial.These experiments indicate that oxygen and hydrogen are conserved in the process.Accordingly, if water is stable and present in the source rock at temperatures ?25 but ?100 °C along a typical US Gulf Coast geotherm, immature (reduced) kerogen with a given atomic hydrogen to carbon ratio (H/C) melts incongruently with increasing temperature and depth of burial to produce a metastable equilibrium phase assemblage consisting of naphthenic/biomarker-rich crude oil, a type-II/III kerogen with an atomic hydrogen/carbon ratio (H/C) of ∼1, and water. Hence, this incongruent melting process promotes diagenetic reaction of detritus in the source rock to form authigenic mineral assemblages.However, in the water-absent region of the system CHO (which is extensive), any water initially present or subsequently entering the source rock is consumed by reaction with the most mature kerogen with the lowest H/C it encounters to form CO₂ gas and a new kerogen with higher H/C and O/C, both of which are in metastable equilibrium with one another.This hydrolytic disproportionation process progressively increases both the concentration of the solute in the aqueous phase, and the oil generation potential of the source rock; i.e., the new kerogen can then produce more crude oil.Petroleum is generated with increasing temperature and depth of burial of hydrocarbon source rocks in which water is not stable in the system CHO by a series of irreversible disproportionation reactions in which kerogens with higher (H/C)s melt incongruently to produce metastable equilibrium assemblages consisting of crude oil, CO₂ gas, and a more mature (oxidized) kerogen with a lower H/C which in turn melts incongruently with further burial to produce more crude oil, CO₂ gas, and a kerogen with a lower H/C and so forth.The petroleum generated in the process progresses from heavy naphthenic crude oils at low temperatures to mature petroleum at ∼150 °C. For example, the results of Computer Experiment 27 (see below) indicate that the overall incongruent melting reaction in the water-absent region of the system C-H-O at 150 °C and a depth of ∼4.3 km of an immature type-II/III kerogen with a bulk composition represented by C₂₉₂H₂₈₈O_12(c) to produce a mature (oxidized) kerogen represented by C₁₂₈H₆₈O_7(c), together with a typical crude oil with an average metastable equilibrium composition corresponding to C_8.8H_16.9 (C_8.8H_16.9(l)) and CO₂ gas (CO_2(g)) can be described by writing