Urban tree planting programs, function or fashion? Los Angeles and urban tree planting campaigns   总被引：1，自引：0，他引：1  

Stephanie Pincetl  Thomas Gillespie  Diane E. Pataki  Sassan Saatchi  Jean-Daniel Saphores 《GeoJournal》2013,78(3):475-493

Tree planting programs are being implemented in many US cities (most notably New York, Los Angeles, and Chicago) on the basis of the multiple environmental and health benefits they may provide. However, the magnitude and even the direction of the impacts of trees on specific urban environments have seldom been directly measured. In addition, there has been little research on the historical, cultural, political or institutional origins of such programs, or on their implementation process. Pending questions include the degree to which these programs are integrated in the existing frameworks of city government and infrastructure management, how they are paid for, and the kinds of collaborations between nonprofit organizations, the public, and public agencies at all levels they may require in order to succeed. This paper reports on an interdisciplinary research project examining the Million Tree Program of the City of Los Angeles.  相似文献   

NanoSIMS: Technical Aspects and Applications in Cosmochemistry and Biological Geochemistry   总被引：2，自引：0，他引：2  

Peter Hoppe  Stephanie Cohen  Anders Meibom 《Geostandards and Geoanalytical Research》2013,37(2):111-154

The NanoSIMS ion probe is a new‐generation SIMS instrument, characterised by superior spatial resolution, high sensitivity and multi‐collection capability. Isotope studies of certain elements can be conducted with 50–100 nm resolution, making the NanoSIMS an indispensable tool in many research fields. We review technical aspects of the NanoSIMS ion probe and present examples of applications in cosmochemistry and biological geochemistry. This includes isotope studies of presolar (stardust) grains from primitive meteorites and of extraterrestrial organics, the search for extinct radioactive nuclides in meteoritic materials, the study of lunar samples, as well as applications in environmental microbiology, cell biology, plant and soil science, and biomineralisation.  相似文献   

Effects of alkaline-activated fly ash and Portland cement on soft soil stabilisation     

Nuno Cristelo  Stephanie Glendinning  Lisete Fernandes  Amândio Teixeira Pinto 《Acta Geotechnica》2013,8(4):395-405

This paper studies the effects of sodium-based alkaline activators and class F fly ash on soil stabilisation. Using the unconfined compressive strength test (UCS), the effectiveness of this binder is compared with that of a common cement-based binder. Influence of the activator/ash ratio, sodium oxide/ash ratio and sodium hydroxide concentration was also analysed. Sodium hydroxide concentrations of 10, 12.5 and 15 molal were used for the alkaline-activated specimens (AA), with activator/ash ratios between 1 and 2.5 and ash percentages of 20, 30 and 40 %, relatively to the total solids (soil + ash). UCS was determined at curing periods of 7, 28, 90 and 365 days, and the most effective mixtures were analysed for mineralogy with XRD. The results showed a clear increase in strength with decreasing activator/ash ratio (up to a maximum of 43.4 MPa), which is a positive result since the activator is the most expensive component in the mixture. Finally, UCS results of the cement and AA samples, at 28 days curing, were very similar. However, AA results proved to be just between 20 and 40 % of the maximum UCS obtained at 1 year curing, while cement results at 28 days are expected to be between 80 and 90 % of its maximum.  相似文献   

Dong W, Ren F, Huang J and Guo Y: The atlas of climate change: based on SEAP-CMIP5     

Stephanie Hänsel 《Environmental Earth Sciences》2013,69(8):2799-2800

  相似文献   

Vulnerability Studies: A Bibliometric Review     

A. T. Fuller  Stephanie Pincetl 《The Professional geographer》2013,65(3):319-329

This article presents a bibliometric analysis of the vulnerability research field. We analyze 200 articles on vulnerability published between 1973 and 2012, in the context of the United States. The intent of this article is to compare the levels of activity of several academic disciplines and bodies of work in vulnerability scholarship and to examine which topics are most studied in them. Topic code use was assessed using the qualitative research data analysis tool Atlas.ti, which permits users to locate, code, and annotate article text fragments. Article categorization was measured both by coding first author organizational affiliation and using the ISI Web of Knowledge journal citation reports categorization scheme that assigns journals to a discipline; each article was coded by its journal category.  相似文献   

Determining the impact of the Holocene highstand at the coastal‐fluvial interface,Shoalhaven River,south‐eastern Australia     

Stephanie J. Kermode  Martin R. Gibling  Brian G. Jones  Tim J. Cohen  David M. Price  James S. Daley 《地球表面变化过程与地形》2013,38(13):1481-1495

With enhanced rates of sea‐level rise predicted for the next century, the upstream extent of sea‐level influence across coastal plains is a topic of public importance. Australian coastal rivers provide a testing ground for exploring this issue because the area is tectonically stable, was not glaciated, and experienced a Holocene highstand between 7.4 and 2 ka of up to 1.5 m above Australian Height Datum (AHD). In the Shoalhaven River of New South Wales, investigation of a confined bedrock reach at Wogamia, 32 km inland, has identified a unit of dark, cohesive silt and sand with marine diatoms, shell fragments, and enhanced pyrite content, interpreted as estuarine. The unit is up to 13 m thick, thickens downstream, and is overlain by fluvial channel and floodplain deposits. The estuarine unit on‐laps a remnant Pleistocene terrace and extends to approximately +2.2 m AHD. Optically stimulated luminescence (OSL) and radiocarbon ages suggest that estuarine deposition commenced prior to 7.8 ka cal bp , predating the highstand by ~ 500 years, and that marine influence in the area continued to 5.3 ± 0.7 ka. During this period, a delta probably persisted at Wogamia, where a narrow upstream reach opens out, and subsequently advanced to fill the broad Shoalhaven coastal embayment. Although the effect of sea‐level rise depends on many factors, the results suggest that, during a highstand at or above present sea level, a strong marine influence may extend for tens of kilometres inland and penetrate confined bedrock reaches landward of coastal embayments. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Differential melt scaling for oblique impacts on terrestrial planets     

Oleg Abramov  Stephanie M. Wong  David A. Kring 《Icarus》2012,218(2):906-916

Analytical estimates of melt volumes produced by a given projectile and contained in a given impact crater are derived as a function of impact velocity, impact angle, planetary gravity, target and projectile densities, and specific internal energy of melting. Applications to impact events and impact craters on the Earth, Moon, and Mars are demonstrated and discussed. The most probable oblique impact (45°) produces ～1.6 times less melt volume than a vertical impact, and ～1.6 and 3.7 times more melt volume than impacts with 30° and 15° trajectories, respectively. The melt volume for a particular crater diameter increases with planetary gravity, so a crater on Earth should have more melt than similar-size craters on Mars and the Moon. The melt volume for a particular projectile diameter does not depend on gravity, but has a strong dependence on impact velocity, so the melt generated by a given projectile on the Moon is significantly larger than on Mars. Higher surface temperatures and geothermal gradients increase melt production, as do lower energies of melting. Collectively, the results imply thinner central melt sheets and a smaller proportion of melt particles in impact breccias on the Moon and Mars than on Earth. These effects are illustrated in a comparison of the Chicxulub crater on Earth, linked to the Cretaceous–Tertiary mass extinction, Gusev crater on Mars, where the Mars Exploration Rover Spirit landed, and Tsiolkovsky crater on the Moon. The results are comparable to those obtained from field and spacecraft observations, other analytical expressions, and hydrocode simulations.  相似文献   

Two successive phases of ultrahigh temperature metamorphism in Rogaland,S. Norway: Evidence from Y‐in‐monazite thermometry          下载免费PDF全文

Antonin T. Laurent  Stephanie Duchene  Bernard Bingen  Valerie Bosse  Anne‐Magali Seydoux‐Guillaume 《Journal of Metamorphic Geology》2018,36(8):1009-1037

In Rogaland, South Norway, a polycyclic granulite facies metamorphic domain surrounds the late‐Sveconorwegian anorthosite–mangerite–charnockite (AMC) plutonic complex. Integrated petrology, phase equilibria modelling, monazite microchemistry, Y‐in‐monazite thermometry, and monazite U–Th–Pb geochronology in eight samples, distributed across the apparent metamorphic field gradient, imply a sequence of two successive phases of ultrahigh temperature (UHT) metamorphism in the time window between 1,050 and 910 Ma. A first long‐lived metamorphic cycle (M1) between 1,045 ± 8 and 992 ± 11 Ma is recorded by monazite in all samples. This cycle is interpreted to represent prograde clockwise P–T path involving melt production in fertile protoliths and culminating in UHT conditions of ~6 kbar and 920°C. Y‐in‐monazite thermometry, in a residual garnet‐absent sapphirine–orthopyroxene granulite, provides critical evidence for average temperature of 931 and 917°C between 1,029 ± 9 and 1,006 ± 8 Ma. Metamorphism peaked after c. 20 Ma of crustal melting and melt extraction, probably supported by a protracted asthenospheric heat source following lithospheric mantle delamination. Between 990 and 940 Ma, slow conductive cooling to 750–800°C is characterized by monazite reactivity as opposed to silicate metastability. A second incursion (M2) to UHT conditions of ~3.5–5 kbar and 900–950°C, is recorded by Y‐rich monazite at 930 ± 6 Ma in an orthopyroxene–cordierite–hercynite gneiss and by an osumilite gneiss. This M2 metamorphism, typified by osumilite paragenesis, is related to the intrusion of the AMC plutonic complex at 931 ± 2 Ma. Thermal preconditioning of the crust during the first UHT metamorphism may explain the width of the aureole of contact metamorphism c. 75 Ma later, and also the rarity of osumilite‐bearing assemblages in general.  相似文献   

On the hydrological difference between catchments above and below the intermittent-persistent snow transition     

Hannah N. Harrison  John C. Hammond  Stephanie Kampf  Leonie Kiewiet 《水文研究》2021,35(11):e14411

Because of the importance of snow for river discharge in mountain regions, hydrological research often focuses on seasonally snow-covered zones. However, in many basins the majority of the land surface area is intermittently snow-covered. Discharge monitoring in these areas is less common, so their contributions to downstream rivers remain largely unknown. We evaluated hydrological differences between three intermittently snow-covered (mean annual Jan 1–Jul 3 snow persistence <60%) and two seasonally snow-covered headwater catchments in the Colorado Front Range. We compared water balance variables to evaluate how and why discharge differs between the snow zones and estimated the relative contributions from each snow zone to regional river discharge. We focused on water years 2016–2019 and used a combination of in situ sensors and regional climate datasets. Annual discharge from the intermittent snow zone was low for all three catchments (10–77 mm), despite covering a wide range in annual snow persistence (25%–64%), whereas annual discharge from the seasonal snow zone was up to 73 times higher. Soil moisture in the seasonal snow zone was above field capacity for longer periods of time than in the intermittent snow zone, and the intermittent snow zone was uniquely subject to soil freezing (up to 102 days per year). For most of the year, potential evapotranspiration exceeded rainfall and snowmelt inputs in the intermittent snow zone, but was lower than rainfall and snowmelt inputs in the seasonal snow zone. This is likely a primary driver of the differences in soil moisture and discharge for catchments with a seasonal versus intermittent snow cover. Despite the large difference in discharge between these two snow zones, the intermittent snow zone contributed about a quarter of the discharge in the regional river, highlighting the importance of studying discharge generation across all elevations.  相似文献   

Hydrogeophysical exploration of three-dimensional salinity anomalies with the time-domain electromagnetic method (TDEM)     

Peter Bauer-Gottwein  Bibi N. Gondwe  Lars Christiansen  Daan Herckenrath  Lesego Kgotlhang  Stephanie Zimmermann 《Journal of Hydrology》2010,380(3-4):318-329

  相似文献