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661.
Identifying factors influencing flood mitigation at the local level in Texas and Florida: the role of organizational capacity 总被引:1,自引:0,他引:1
In the United States, mitigating the adverse impacts of flooding has increasingly become the responsibility of local decision
makers. Despite the importance of understanding why flood mitigation techniques are implemented at the local level, few empirical
studies have been conducted over the last decade. Our study addresses this lack of research by examining the factors influencing
local communities to adopt both structural and non-structural flood mitigation strategies. We use statistical models to predict
multiple flood mitigation techniques implemented by cities and counties based on a survey of floodplain administrators and
planning officials across Texas and Florida. Particular attention is paid to the role of organizational capacity to address
floods in addition to various local geophysical and socioeconomic characteristics. Results indicate that organizational capacity
is a significant factor contributing to the implementation of both structural and non-structural flood mitigation techniques,
even when controlling for contextual characteristics. 相似文献
662.
Alfred S. McEwen Maria E. Banks Kris Becker James W. Bergstrom Edward Bortolini Shane Byrne Frank C. Chuang Ingrid Daubar Donald G. Deardorff W. Alan Delamere Colin M. Dundas Yisrael Espinoza Kathryn E. Fishbaugh Paul E. Geissler Jennifer L. Griffes Virginia C. Gulick Kenneth E. Herkenhoff Windy L. Jaeger Bob Kanefsky Robert King Kelly J. Kolb Alexandra Lefort Kevin W. Lewis Sarah Mattson Michael T. Mellon Moses P. Milazzo Tahirih Motazedian Albert Ortiz Joseph Plassmann Patrick S. Russell Mindi L. Searls Steven W. Squyres Nicolas Thomas Livio L. Tornabene Circe Verba James J. Wray 《Icarus》2010,205(1):2-216
The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) acquired 8 terapixels of data in 9137 images of Mars between October 2006 and December 2008, covering ∼0.55% of the surface. Images are typically 5-6 km wide with 3-color coverage over the central 20% of the swath, and their scales usually range from 25 to 60 cm/pixel. Nine hundred and sixty stereo pairs were acquired and more than 50 digital terrain models (DTMs) completed; these data have led to some of the most significant science results. New methods to measure and correct distortions due to pointing jitter facilitate topographic and change-detection studies at sub-meter scales. Recent results address Noachian bedrock stratigraphy, fluvially deposited fans in craters and in or near Valles Marineris, groundwater flow in fractures and porous media, quasi-periodic layering in polar and non-polar deposits, tectonic history of west Candor Chasma, geometry of clay-rich deposits near and within Mawrth Vallis, dynamics of flood lavas in the Cerberus Palus region, evidence for pyroclastic deposits, columnar jointing in lava flows, recent collapse pits, evidence for water in well-preserved impact craters, newly discovered large rayed craters, and glacial and periglacial processes. Of particular interest are ongoing processes such as those driven by the wind, impact cratering, avalanches of dust and/or frost, relatively bright deposits on steep gullied slopes, and the dynamic seasonal processes over polar regions. HiRISE has acquired hundreds of large images of past, present and potential future landing sites and has contributed to scientific and engineering studies of those sites. Warming the focal-plane electronics prior to imaging has mitigated an instrument anomaly that produces bad data under cold operating conditions. 相似文献
663.
Jeffrey L. Collett Jr. Pierre Herckes Sarah Youngster Taehyoung Lee 《Atmospheric Research》2008,87(3-4):232
Considerable effort has been put into characterizing the ionic composition of fogs and clouds over the past twenty-five years. Recently it has become evident that clouds and fogs often contain large concentrations of organic material as well. Here we report findings from a series of studies examining the organic composition of radiation fogs in central California. Organic compounds in these fogs comprise a major fraction of total solute mass, with total organic carbon sometimes reaching levels of several tens of mg/L. This organic matter is comprised of a wide variety of compounds, ranging from low molecular weight organic acids to high molecular weight compounds with molecular masses approaching several hundred to a thousand g/mole. The most abundant individual compounds are typically formic acid, acetic acid, and formaldehyde. High concentrations are also observed of some dicarboxylic acids (e.g., oxalate) and dicarbonyls (e.g., glyoxal and methylglyoxal) and of levoglucosan, an anhydrosugar characteristically emitted by biomass combustion. Many other compounds have been identified in fog water by GC/MS, including long chain n-alkanoic acids, n-alkanes, PAH, and others, although these compounds typically comprise a total of only a few percent of fog TOC. Measurements of fog scavenging of organic and elemental carbon reveal preferential scavenging of organic carbon. Tracking of individual organic compounds utilized as source type markers suggests the fogs differentially scavenge carbonaceous particles from different source types, with more active processing of wood smoke than vehicle exhaust. Observations of high deposition velocities of fog-borne organic carbon, in excess of 1 cm/s, indicate that fogs in the region represent an important mechanism for cleansing the atmosphere of pollution. 相似文献
664.
Sarah M. Hayes Scott A. White Thomas L. Thompson Raina M. Maier Jon Chorover 《Applied Geochemistry》2009
Desert mine tailings may accumulate toxic metals in the near surface centimeters because of low water through-flux rates. Along with other constraints, metal toxicity precludes natural plant colonization even over decadal time scales. Since unconsolidated particles can be subjected to transport by wind and water erosion, potentially resulting in direct human and ecosystem exposure, there is a need to know how the lability and form of metals change in the tailings weathering environment. A combination of chemical extractions, X-ray diffraction, micro-X-ray fluorescence spectroscopy, and micro-Raman spectroscopy were employed to study Pb and Zn contamination in surficial arid mine tailings from the Arizona Klondyke State Superfund Site. Initial site characterization indicated a wide range in pH (2.5–8.0) in the surficial tailings pile. Ligand-promoted (DTPA) extractions, used to assess plant-available metal pools, showed decreasing available Zn and Mn with progressive tailings acidification. Aluminum shows the inverse trend, and Pb and Fe show more complex pH dependence. Since the tailings derive from a common source and parent mineralogy, it is presumed that variations in pH and “bio-available” metal concentrations result from associated variation in particle–scale geochemistry. Four sub-samples, ranging in pH from 2.6 to 5.4, were subjected to further characterization to elucidate micro-scale controls on metal mobility. With acidification, total Pb (ranging from 5 to 13 g kg−1) was increasingly associated with Fe and S in plumbojarosite aggregates. For Zn, both total (0.4–6 g kg−1) and labile fractions decreased with decreasing pH. Zinc was found to be primarily associated with the secondary Mn phases manjiroite and chalcophanite. The results suggest that progressive tailings acidification diminishes the overall lability of the total Pb and Zn pools. 相似文献
665.
New 40Ar/39Ar thermochronology results and thermal modeling support the hypothesis of Hollister et al. (2004), that reheating of the mid-Cretaceous Ecstall pluton by intrusion of the Coast Mountains Batholith (CMB) was responsible for spatially variable remagnetization of the Ecstall pluton. 40Ar/39Ar ages from hornblende and biotite from 12 locations along the Skeena River across the northern part of the Ecstall pluton decrease with proximity to the Quottoon plutonic complex, the nearest member of the CMB to the Ecstall pluton. The oldest 40Ar/39Ar ages are found farthest from the Quottoon plutonic complex, and are 90 ± 3 Ma for hornblende, and 77.9 ± 1.2 Ma for biotite. The youngest 40Ar/39Ar ages are found closest to the Quottoon plutonic complex, and are 51.6 ± 1.2 Ma for hornblende, and 45.3 ± 1.7 Ma for biotite. No obvious relationship between grain size and age is seen in the Ecstall pluton biotites. Spatial trends in 40Ar/39Ar ages are consistent with model results for reheating by a thermal wall at the location of the Quottoon plutonic complex. Although no unique solution is suggested, our results indicate that the most appropriate thermal history for the Ecstall pluton includes both reheating and northeast side up tilting of the Ecstall pluton associated with intrusion of the Quottoon plutonic complex. Estimates of northward translation from shallow paleomagnetic inclinations in the western part of the Ecstall pluton are reduced to ∼3000 km, consistent with the Baja-BC hypothesis, when northeast side up tilting is accounted for. 相似文献
666.
This paper introduces the special issue ‘organisational geographies of power’ by examining the theoretical and empirical context for debates. It does this, firstly, with reference to existing theoretical work on what power is and does as well as work on the construction of power relations. Building on this, the paper then, secondly, examines the way relational and production network approaches have incorporated power into work on transnational corporations before, thirdly, considering how work on neoliberalism has studied the construction of spatial power relations. In doing this the paper highlights four important questions for future research relating to the practices and spatiality of power, the exercising of power and the situated effects of power relations. 相似文献
667.
A driving force of urban development is “accumulation by dispossession” which occurs through expropriation, privatization, and commodification of land. While the macro theory is now well refined, there is still much we do not know about how the underlying processes occur and how they shape economic development and urbanization. In this study, we analyze 2009 survey data of land expropriation cases across 12 Chinese cities, and find that expropriation takes different forms leading to specific outcomes. In half the cases, local governments followed central government policies requiring them to pay standard rates of compensation, but in the other half, local governments negotiated with farmers over the terms of expropriation. In the latter scenario, farmers were more likely to receive compensation higher than the standard rate, particularly if they were embedded in local power structures, which we argue could be counteracted if all households in a rural collective negotiate one agreement rather than individual agreements. These findings move us closer to understanding why accumulation through dispossession sometimes contributes to economic growth and social development, and at other times undermines urban development leading to social instability. 相似文献
668.
Christopher W. Hamilton Sarah A. Fagents Thorvaldur Thordarson 《Bulletin of Volcanology》2010,72(4):469-485
We have applied quantitative geospatial analyses to rootless eruption sites in the Hnúta and Hrossatungur groups of the 1783–1784
Laki lava flow to establish how patterns of spatial distribution can be used to obtain information about rootless cone emplacement
processes and paleo-environments. This study utilizes sample-size-dependent nearest neighbor (NN) statistics and Voronoi tessellations
to quantify the spatial distribution of rootless eruption sites and validate the use of statistical NN analysis as a remote
sensing tool. Our results show that rootless eruption sites cluster in environments with abundant lava and water resources,
but competition for limited groundwater in these clusters can cause rootless eruption sites to develop repelled distributions.
This pattern of self-organization can be interpreted within the context of resource availability and depletion. Topography
tends to concentrate lava (fuel) and water (coolant) within topographic lows, thereby promoting explosive lava–water interactions
in these regions. Given an excess supply of lava within broad sheet lobes, rootless eruption sites withdraw groundwater from
their surroundings until there is insufficient water to maintain analogs to explosive molten fuel–coolant interactions. Rootless
eruption sites may be modeled as a network of water extraction wells that draw down the water table in their vicinity. Rootless
eruptions at locations with insufficient groundwater may either fail to initiate or terminate before explosive activity has
ceased at nearby locations with a greater supply of water, thus imparting a repelled distribution to observed rootless eruption
sites. 相似文献
669.
Hermann Albert J.; Hinckley Sarah; Megrey Bernard A.; Napp Jeffrey M. 《ICES Journal of Marine Science》2001,58(5):1030-1041
670.
Sarah E. M. Gain Yoann Grau Hadrien Henry Elena Belousova Ivars Dainis William L. Griffin Suzanne Y. O'Reilly 《Geostandards and Geoanalytical Research》2019,43(3):339-354
Zircon megacrysts from the Mud Tank carbonatite, Australia, are being used in many laboratories as a reference material for LA‐ICP‐MS U‐Pb dating and trace element measurement, and LA‐MC‐ICP‐MS determination of Hf isotopes. We summarise a database of > 10000 analyses of Mud Tank zircon (MTZ), collected from 2000 to 2018 during its use as a secondary reference material for simultaneous U‐Pb and trace element analysis, and for Hf‐isotope analysis. Trace element mass fractions are highest in dark red‐brown stones and lowest in colourless and gem‐quality ones. Individual unzoned grains can be chemically homogeneous, while significant variations in trace element mass fraction are associated with oscillatory zoning. Chondrite‐normalised trace element patterns are essentially parallel over large mass fraction ranges. A Concordia age of 731.0 ± 0.2 Ma (2s, n = 2272) is taken as the age of crystallisation. Some grains show lower concordant to mildly discordant ages, probably reflecting minor Pb loss associated with cooling and the Alice Springs Orogeny (450–300 Ma). Our weighted mean 176Hf/177Hf is 0.282523 ± 10 (2s, n = 9350); the uncertainties on this ratio reflect some heterogeneity, mainly between grains. A few analyses suggest that colourless grains have generally lower 176Hf/177Hf. MTZ is a useful secondary reference material for U‐Pb and Hf‐isotope analysis, but individual grains need to be carefully selected using CL imaging and tested for homogeneity, and ideally should be standardised by solution analysis. 相似文献