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91.
Since 1999, Ohio EPA hydrogeologists have used two analytic element models (AEMs), the proprietary software GFLOW and U.S. EPA's WhAEM, to delineate protection areas for 535 public water systems. Both models now use the GFLOW2001 solution engine, integrate well with Geographic Information System (GIS) technology, have a user-friendly graphical interface, are capable of simulating a variety of complex hydrogeologic settings, and do not rely upon a model grid. These features simplify the modeling process and enable AEMs to bridge the gap between existing simplistic delineation methods and more complex numerical models. Ohio EPA hydrogeologists demonstrated that WhAEM2000 and GFLOW2000 were capable of producing capture zones similar to more widely accepted models by applying the AEMs to eight sites that had been previously delineated using other methods. After the Ohio EPA delineated protection areas using AEMs, more simplistic delineation methods used by other states (volumetric equation and arbitrary fixed radii) were applied to the same water systems to compare the differences between various methods. GIS software and two-tailed paired t-tests were used to quantify the differences in protection areas and analyze the data. The results of this analysis demonstrate that AEMs typically produce significantly different protection areas than the most simplistic delineation methods, in terms of total area and shape. If the volumetric equation had been used instead of AEMs, Ohio would not have protected 265 km2 of critical upgradient area and would have overprotected 269 km2 of primarily downgradient land. Since an increasing number of land-use restrictions are being tied to drinking water protection areas, this analysis has broad policy implications. 相似文献
92.
Aggregates composed of olivine and magnesiowüstite have been deformed to large strains at high pressure and temperature to investigate stress and strain partitioning, phase segregation and possible localization of deformation in a polyphase material. Samples with 20 vol.% of natural olivine and 80 vol.% of (Mg0.7Fe0.3)O were synthesized and deformed in a gas-medium torsion apparatus at temperatures of 1127 °C and 1250 °C, a confining pressure of 300 MPa and constant angular displacement rates equivalent to constant shear strain rates of 1–3.3 × 10− 4 s− 1. The samples deformed homogeneously to total shear strains of up to γ 15. During constant strain rate measurements the flow stress remained approximately stable at 1250 °C while it progressively decreased after the initial yield stress at the lower temperature. Mechanical data, microstructures and textures indicate that both phases were deforming in the dislocation creep regime. The weaker component, magnesiowüstite, controlled the rheological behavior of the bulk material and accommodated most of the strain. Deformation and dynamic recrystallization lead to grain refinement and to textures that were not previously observed in pure magnesiowüstite and may have developed due to the presence of the second phase. At 1127 °C, olivine grains behaved as semi-rigid inclusions rotating in a viscous matrix. At 1250 °C, some olivine grains remained largely undeformed while deformation and recrystallization of other grains oriented for a-slip on (010) resulted in a weak foliation and a texture typical for pure dry olivine aggregates. Both a-slip and c-slip on (010) were activated in olivine even though the nominal stresses were up to 2 orders of magnitude lower than those needed to activate these slip systems in pure olivine at the same conditions. 相似文献
93.
Bo Li Steve Sain Linda O. Mearns Henry A. Anderson Sari Kovats Kristie L. Ebi Marni Y. V. Bekkedal Marty S. Kanarek Jonathan A. Patz 《Climatic change》2012,110(3-4):959-976
Given predictions of increased intensity and frequency of heat waves, it is important to study the effect of high temperatures on human mortality and morbidity. Many studies focus on heat wave-related mortality; however, heat-related morbidity is often overlooked. The goals of this study are to examine the historical observed relationship between temperature and morbidity (illness), and explore the extent to which observed historical relationships could be used to generate future projections of morbidity under climate change. We collected meteorological, air pollution, and hospital admissions data in Milwaukee, Wisconsin, for the years 1989–2005, and employed a generalized additive model (GAM) to quantify the relationship between morbidity (as measured by hospital admissions) and high temperatures with adjustment for the effects of potential confounders. We also estimated temperature threshold values for different causes of hospital admissions and then quantified the associated percent increase of admissions per degree above the threshold. Finally, the future impact of higher temperatures on admissions for the years 2059–2075 was examined. Our results show that five causes of admission (endocrine, genitourinary, renal, accidental, and self-harm) and three age groups (15–64, 75–84, >85 years) were affected by high temperatures. Future projections indicate a larger number of days above the current temperature threshold leading to an increase in admissions. Our results indicate that climate change may increase heat-related hospital admissions in the US urban mid-West and that health systems should include heat wave planning. 相似文献
94.
David G. Barber Matthew G. Asplin Tim N. Papakyriakou Lisa Miller Brent G. T. Else John Iacozza C. J. Mundy M. Gosslin Natalie C. Asselin Steve Ferguson Jennifer V. Lukovich Gary A. Stern Ashley Gaden Monika Pu?ko N.-X. Geilfus Fei Wang 《Climatic change》2012,115(1):135-159
Change and variability in the timing and magnitude of sea ice geophysical and thermodynamic state have consequences on many aspects of the arctic marine system. The changes in both the geophysical and thermodynamic state, and in particular the timing of the development of these states, have consequences throughout the marine system. In this paper we review the ??consequences?? of change in sea ice state on primary productivity, marine mammal habitats, and sea ice as a medium for storage and transport of contaminants and carbon exchange across the ocean-sea-ice-atmosphere interface based upon results from the International Polar Year. Pertinent results include: 1) conditions along ice edges can bring deep nutrient-rich ??pacific?? waters into nutrient-poor surface waters along the arctic coast, affecting local food webs; 2) both sea ice thermodynamic and dynamic processes ultimately affect ringed seal/polar bear habitats by controlling the timing, location and amount of surface deformation required for ringed seal and polar bear preferred habitat 3) the ice edges bordering open waters of flaw leads are areas of high biological production and are observed to be important beluga habitat. 4) exchange of climate-active gases, including CO2, is extremely active in sea ice environments, and the overall question of whether the Arctic Ocean is (or will be) a source or sink for CO2 will be dependent on the balance of competing climate-change feedbacks. 相似文献
95.
Gérald Darnis Dominique Robert Corinne Pomerleau Heike Link Philippe Archambault R. John Nelson Maxime Geoffroy Jean-éric Tremblay Connie Lovejoy Steve H. Ferguson Brian P. V. Hunt Louis Fortier 《Climatic change》2012,115(1):179-205
As part of the Canadian contribution to the International Polar Year (IPY), several major international research programs have focused on offshore arctic marine ecosystems. The general goal of these projects was to improve our understanding of how the response of arctic marine ecosystems to climate warming will alter food web structure and ecosystem services provided to Northerners. At least four key findings from these projects relating to arctic heterotrophic food web, pelagic-benthic coupling and biodiversity have emerged: (1) Contrary to a long-standing paradigm of dormant ecosystems during the long arctic winter, major food web components showed relatively high level of winter activity, well before the spring release of ice algae and subsequent phytoplankton bloom. Such phenological plasticity among key secondary producers like zooplankton may thus narrow the risks of extreme mismatch between primary production and secondary production in an increasingly variable arctic environment. (2) Tight pelagic-benthic coupling and consequent recycling of nutrients at the seafloor characterize specific regions of the Canadian Arctic, such as the North Water polynya and Lancaster Sound. The latter constitute hot spots of benthic ecosystem functioning compared to regions where zooplankton-mediated processes weaken the pelagic-benthic coupling. (3) In contrast with another widely shared assumption of lower biodiversity, arctic marine biodiversity is comparable to that reported off Atlantic and Pacific coasts of Canada, albeit threatened by the potential colonization of subarctic species. (4) The rapid decrease of summer sea-ice cover allows increasing numbers of killer whales to use the Canadian High Arctic as a hunting ground. The stronger presence of this species, bound to become a new apex predator of arctic seas, will likely affect populations of endemic arctic marine mammals such as the narwhal, bowhead, and beluga whales. 相似文献
96.
97.
Predicted changes in fire weather suggest increases in lightning fire initiation and future area burned in the mixedwood boreal forest 总被引:1,自引:0,他引:1
Forecasting future fire activity as a function of climate change is a step towards understanding the future state of the western mixedwood boreal ecosystem. We developed five annual weather indices based on the Daily Severity Rating (DSR) of the Canadian Forest Fire Weather Index System and estimated their relationship with annual, empirical counts of lightning fire initiation for 588 landscapes in the mixedwood boreal forest in central-eastern Alberta, Canada from data collected between 1983 and 2001 using zero-inflated negative binomial regression models. Two indices contributed to a parsimonious model of initiation; these were Seasonal Severity Rating (SSR), and DSR-sequence count. We used parameter estimates from this model to predict lightning fire initiation under weather conditions predicted in 1 × CO2 (1975–1985), 2 × CO2 (2040–2049) and 3 × CO2 (2080–2089) conditions simulated by the Canadian Regional Climate Model (CRCM). We combined predicted initiation rates for these conditions with existing empirical estimates of the number of fire initiations that grow to be large fires (fire escapes) and the fire size distribution for the region, to predict the annual area burned by lightning-caused fires in each of the three climate conditions. We illustrated a 1.5-fold and 1.8-fold increase of lightning fire initiation by 2040–2049 and 2080–2089 relative to 1975–1985 conditions due to changes in fire weather predicted by the CRCM; these increases were calculated independent of changes in lightning activity. Our simulations suggested that weather-mediated increases in initiation frequency could correspond to a substantial increase in future area burned with 1.9-fold and 2.6-fold increases in area burned in 2040–2049 and 2080–2089 relative to 1975–1985 conditions, respectively. We did not include any biotic effects in these estimates, though future patterns of initiation and fire growth will be regulated not only by weather, but also by vegetation and fire management. 相似文献
98.
Simon Portegies Zwart Steve McMillan Stefan Harfst Derek Groen Michiko Fujii Breanndán Ó Nualláin Evert Glebbeek Douglas Heggie James Lombardi Piet Hut Vangelis Angelou Sambaran Banerjee Houria Belkus Tassos Fragos John Fregeau Evghenii Gaburov Rob Izzard Mario Jurić Stephen Justham Andrea Sottoriva Marcel Zemp 《New Astronomy》2009,14(4):369-378
We present MUSE, a software framework for combining existing computational tools for different astrophysical domains into a single multiphysics, multiscale application. MUSE facilitates the coupling of existing codes written in different languages by providing inter-language tools and by specifying an interface between each module and the framework that represents a balance between generality and computational efficiency. This approach allows scientists to use combinations of codes to solve highly coupled problems without the need to write new codes for other domains or significantly alter their existing codes. MUSE currently incorporates the domains of stellar dynamics, stellar evolution and stellar hydrodynamics for studying generalized stellar systems. We have now reached a “Noah’s Ark” milestone, with (at least) two available numerical solvers for each domain. MUSE can treat multiscale and multiphysics systems in which the time- and size-scales are well separated, like simulating the evolution of planetary systems, small stellar associations, dense stellar clusters, galaxies and galactic nuclei. In this paper we describe three examples calculated using MUSE: the merger of two galaxies, the merger of two evolving stars, and a hybrid N-body simulation. In addition, we demonstrate an implementation of MUSE on a distributed computer which may also include special-purpose hardware, such as GRAPEs or GPUs, to accelerate computations. The current MUSE code base is publicly available as open source at http://muse.li. 相似文献
99.
A rank series of lignites and coals of low to moderate maturation levels (vitrinite reflectance (R0): 0.27–0.8%) from the New Zealand Coal Band were investigated using alkaline ester cleavage experiments to reveal compositional changes of ester bound components (fatty acids and alcohols) during increasing maturation. Ester bound alcohols are found to be present in highest amounts in the very immature lignite samples (R0: 0.27–0.29%), but show a rapid decrease during early diagenesis. Ester bound fatty acids also show an initial exponential decrease during diagenesis, but reveal an intermittent increase during early catagenesis before decreasing again during main catagenesis. This intermittent increase was related to the short chain fatty acids. To obtain a maturity related signal and to eliminate facies related scattering in the amounts of fatty acids in the coal samples, the carbon preference index of fatty acids (CPIFA) parameter is introduced here. For the long chain fatty acids (C20–C32) originating from terrigenous plant debris, the CPIFA decreases with increasing maturity, showing a strong maturation related signal. During diagenesis, the same trend can be observed for the short chain fatty acids, but the intermittent increase in the amounts of short chain fatty acids is also accompanied by high CPIFA values. This indicates less altered organic biomass at this advanced maturation level and is in contrast to the mature CPIFA signal of the long chain fatty acids of the same samples. One possible reason for this discrepancy could be extremely different amounts of short and long chain fatty acids in the original source organic matter of these samples. However, another intriguing explanation could be the incorporation of immature bacterial biomass from deep microbial communities containing C16 and C18 fatty acids as main cell membrane components. Deep microbial life might be stimulated at this interval by the increasing release of thermally generated potential substrates from the organic matrix during early catagenesis. In contrast to the fatty acids, the high amounts of alcohols in the immature lignite samples are also visible in the alkene distribution from the open system pyrolysis experiments of the organic matrix before and after saponification. 相似文献
100.
In recent years the widespread occurrence of microorganisms was demonstrated in deep marine and terrestrial sediments. With this discovery inevitably the question of the potential carbon and energy sources for this deep subsurface microbial life arises. In the current study a new method for the investigation of low molecular weight (LMW) organic acids linked to the kerogen matrix is presented. These LMW organic acids form a potential feedstock for deep microbial populations. Twelve coal samples of different maturity (vitrinite reflectance (R0) of 0.28–0.80%) from several coal mines on the North and South Island of New Zealand (NZ) were examined to assess the amount of bound LMW organic acids. Formate, acetate and oxalate were detected in significant amounts whereas the amounts of these compounds decrease with increasing maturity of the coal sample. This decrease of LMW organic acids mainly correlates to the phase of diagenetic alteration of the organic matter characterized by the release of oxygen containing compounds. Concomitantly, it coincides with temperature conditions assumed to be still compatible with microbial life in the deep subsurface. First assessments of the feedstock potential and generation rates of LMW organic acids indicate that the NZ coals investigated exhibit the potential to feed deep terrestrial microbial life with appropriate substrates over geological time spans. 相似文献