Uncertainties in global climate change estimates     

Elisabeth Paté-Cornell 《Climatic change》1996,33(2):145-149

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Evaluation of microbiologically induced corrosion in an estuary     

Brenda Little  Pat Wagner  John Jacobus  Louis Janus 《Estuaries and Coasts》1989,12(3):138-141

A dockside experiment was designed at the mouth of the Pascagoula River in Pascagoula, Mississippi, to evaluate corrosion in welded Cu/Ni piping systems. Localized corrosion was shown to be due to the following sequence of events: (1) metal segregation during welding processes, (2) settlemnt of sulfide-producing bacteria in welds, (3) disruption of surface films by turbulence, and (4) formation of adjacent cathodic and anodic areas.  相似文献   

Time-based correlation of biogenic,lithogenic and authigenic sediment components with anthropogenic inputs in the Gulf of Mexico NECOP study area     

Terry A. Nelsen  Pat Blackwelder  Terri Hood  Brent McKee  Nidia Romer  Carlos Alvarez-Zarikian  Simone Metz 《Estuaries and Coasts》1994,17(4):873-885

Hypotheses related to variability in seasonal hypoxic conditions, coastal nutrient enhancement, and off-shelf transport of carbon on the Louisiana continental shelf were tested by characterization of biogenic, lithogenic, and authigenic components from two shelf and one Mississippi Canyon sediment cores. The authigenic-phase glauconite occurs above detection limits only in the core from the hypoxic area. A major increase in glauconite concentration was coincident with the onset (≈1940) of the increased use of commercial fertilizers in the United States. In the same hypoxic-area core, benthic foraminifera species diversity decreases upcore from approximately the turn of the century to the present in a manner concurrent with glauconite and fertilizer increases. A subset of opportunistic benthic foraminifera species, known to become more prominent in stressed environments (i.e., hypoxic), increased upcore from ～52% of the total population at core bottom to ≈90% at core top. These benthic foraminifera population and diversity changes were not apparent in a “control” core outside the area of documented hypoxia. Seaward of the shelf, in the Mississippi Canyon, coincident increases in sediment accumulation rate, percentages of coarse fraction and of organic carbon at core top indicate increased offshelf transport of carbon and other components. Quartz percentages indicate that episodic down-canyon transport has been active to core bottom (prior to the mid 1800s).  相似文献   

Message from 2014 Best Paper Award Winners     

Martí Lloret-Cabot  Gordon A. Fenton  Michael A. Hicks 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2015,9(2)

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South East Europe electricity roadmap – modelling energy transition in the electricity sectors     

László Szabó  Ágnes Kelemen  András Mezősi  Zsuzsanna Pató  Enikő Kácsor  Gustav Resch 《Climate Policy》2019,19(4):495-510

One of the most important challenges for the South East Europe region will be replacing more than 30% of its presently installed fossil fuel generation capacity by the end of 2030, and more than 95% by 2050 if its age structure is considered. This requires a strong policy framework to incentivise new investments in a region currently lacking investors, but also presents an opportunity to shape the electricity sector over the long term according to the broader energy transition strategy of the EU and the Energy Community. The aim of this paper is to assess what type of long-term pathways exist for electricity sector development in the region if they follow the energy transition process of the EU. In this model-based scenario assessment, long term electricity sector futures are explored using a set of interlinked electricity models evaluating the level of renewable energy investment required in the region to reach a deep decarbonization target, assuming emission reduction above 94% by 2050 compared to 1990 in line with the long term market integration and climate policy goals of the EU. It also explores what are the most important system wide impacts of the high deployment of renewable energy concerning generation adequacy and security of supply.

Key policy insights

• Energy policies in the South East Europe (SEE) region, both at the national and regional level, should focus on enabling renewable energy integration, as this will be a key component of the future energy mix.

• EU and Energy Community policies should be incorporated into national energy planning to ensure that SEE countries embark on the energy transition process at an early stage.

• Stranded costs should be carefully considered in decision-making on new fossil-fuel generation and gas network investment in order to avoid lock-in to carbon intensive technologies.

• If consistent decarbonization policy prevails, with a significant and persistent CO2 price signal, the role of natural gas remains transitory in the region.

• The SEE region offers relatively cheap decarbonization options: the power sector can reduce GHG emissions above 94% by 2050 in the modelled scenarios.

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Lode–gold mineralization in the Tanami region, northern Australia     

David L. Huston  Leon Vandenberg  Andrew S. Wygralak  Terrence P. Mernagh  Leon Bagas  Andrew Crispe  Alexis Lambeck  Andrew Cross  Geoff Fraser  Nick Williams  Kurt Worden  Tony Meixner  Bruce Goleby  Leonie Jones  Pat Lyons  David Maidment 《Mineralium Deposita》2007,42(1-2):175-204

The Tanami region of northern Australia has emerged over the last two decades as the largest gold-producing region in the Northern Territory. Gold is hosted by epigenetic quartz veins in sedimentary and mafic rocks, and by sulfide-rich replacement zones within iron formation. Although limited, geochronological data suggest that most mineralization occurred at about 1,805–1,790 Ma, during a period of extensive granite intrusion, although structural relationships suggest that some deposits predate this period. There are three main goldfields in the Tanami region: the Dead Bullock Soak goldfield, which hosts the world-class Callie deposit; The Granites goldfield; and the Tanami goldfield. In the Dead Bullock Soak goldfield, deposits are hosted by carbonaceous siltstone and iron formation where a late (D₅) structural corridor intersects an early F₁ anticlinorium. In The Granites goldfield, deposits are hosted by highly sheared iron formation and are interpreted to predate D₅. The Tanami goldfield consists of a large number of small, mostly basalt-hosted deposits that probably formed at a high structural level during D₅. The D₅ structures that host most deposits formed in a convergent structural regime with σ ₁ oriented between E–W and ENE–WSW. Structures active during D₅ include NE-trending oblique thrust (dextral) faults and ESE-trending (sinistral) faults that curve into N- to NNW-trending reverse faults localized in supracrustal belts between and around granite complexes. Granite intrusions also locally perturbed the stress field, possibly localizing structures and deposits. Forward modeling and preliminary interpretations of reflection seismic data indicate that all faults extend into the mid-crust. In areas characterized by the N- to NW-trending faults, orebodies also tend to be N- to NW-trending, localized in dilational jogs or in fractured, competent rock units. In areas characterized by ESE-trending faults, the orebodies and veins tend to strike broadly east at an angle consistent with tensional fractures opened during E–W- to ENE–WSW-directed transpression. Many of these deposits are hosted by reactive rock units such as carbonaceous siltstone and iron formation. Ore deposition occurred at depths ranging from 1.5 to 11 km from generally low to moderate salinity carbonic fluids with temperatures from 200 to 430°C, similar to lode–gold fluids elsewhere in the world. These fluids are interpreted as the product of metamorphic dewatering caused by enhanced heat flow, although it is also possible that the fluids were derived from coeval granites. Lead isotope data suggest that lead in the ore fluids had multiple sources. Hydrogen and oxygen isotope data are consistent with both metamorphic and magmatic origins for ore fluids. Gold deposition is interpreted to be caused by fluid unmixing and sulfidation of host rocks. Fluid unmixing is caused by three different processes: (1) CO₂ unmixing caused by interaction of ore fluids with carbonaceous siltstone; (2) depressurization caused by pressure cycling in shear zones; and (3) boiling as ore fluids move to shallow levels. Deposits in the Tanami region may illustrate the continuum model of lode–gold deposition suggested by Groves (Mineralium Deposita 28:366–374, 1993) for Archean districts.  相似文献   

Decolonizing Benjamin in the Tropics: The long history of Guayaquil's arcades     

Robert Priessman Fenton III 《Singapore journal of tropical geography》2020,41(3):367-383

This essay interrogates the long historical development of Guayaquil's arcades, or soportales, by analysing their historical development and relation to global commerce through littoral Ecuador's experience of cacao capitalism (1700–1925). I do so by employing and referencing Walter Benjamin's now paradigmatic texts concerning commodity culture and modernity in Paris' arcades. My work critically and synthetically examines archival and historical sources that catalogue Guayaquil's urban and architectural development in that tropical city-region. I explore how environmental factors, indigenous architectural techniques, globalizing commercial culture, cacao exports, and liberal ideologies form historical constellations expressing the multi-layered influences contributing to the growth and modification of Guayaquil's arcades. This transnational history of the particular attempts to recast understandings of urban space, architecture, and the tropical as dynamic edges of capitalist cultural modernity. This essay both deepens and decolonizes Benjamin's work by analysing the importance of the ‘coloniality of power’ on the formation of Guayaquil's arcades and their afterlives as aura. Whereas the arcades of Benjamin's Paris presented him with the primary form of capitalism's cultural modernity, I argue that Guayaquil's soportales serve as constellations for reading an alternative (tropical) modernity predicated on plantation agriculture, Eurocentrism, and cultural hybridization as an expression of political economy.  相似文献   

Documenting natural wear on antlers: A first step in identifying use-wear on purported antler tools     

Jennie J.H. Jin  Pat Shipman 《Quaternary International》2010,211(1-2):91-102

Natural behavior of the deer can leave various modifications on the antlers. Deer often rub their antlers against tree bark and bushes and use them intensively during male–male competition. All of these behaviors can leave marks on the antlers. Distinguishing these naturally-made marks from human-made marks is crucial in accurately identifying antler tools from archaeological sites. This study examined 347 white-tailed deer antlers to document the types and frequencies of the natural modifications. Scratches, polish, deformation, and fractures on the tip are the most frequently found modifications. Unless the modifications on the antlers from archaeological sites can be distinguished from these natural modifications, the nature of the purported antler tools remains questionable.  相似文献   

Relationships between rocky desertification and spatial pattern of land use in typical karst area,Southwest China   总被引：7，自引：4，他引：3  

Yongjun Jiang  Linli Li  Chris Groves  Daoxian Yuan  Pat Kambesis 《Environmental Earth Sciences》2009,59(4):881-890

Karst rocky desertification is a typical type of land degradation in the Southwest China. An attempt was made to study quantitatively the relationships between rocky desertification and spatial pattern of land use through applying spatial analysis of Geographical Information System in Nandong underground river system, a typical karst area, Southwest China. The spatial distribution of rocky desertification and spatial pattern of land use were obtained from interpreting Landsat Images in Nandong area in 2007 by supervised classifications, and verified and rectified through field survey. The results indicate that: (1) the total land deserted area covers 378.3 km², or 23.4% of the total area, of which intense, moderate and slight rocky desertification covers 269.46, 54.2, and 54.63 km², respectively, in Nandong area. (2) There is an obvious effect of spatial pattern of land use on rocky desertification. With the increase of elevation and slope, there is a higher occurrence ratio of rocky desertification in the cultivated land and grass land. Also, more than half of total rocky desertification was dominated within the areas of 4 km from the construction land, and 97% of total rocky desertification was dominated within the areas of 10 km from the construction land in Nandong area. And what can be known from the data is that the primary effect distance of human on rocky desertification from the construction land is 4 km, and the farthest effect distance of human on rocky desertification from the construction land is 10 km in Nandong area.  相似文献   

Neural network prediction of the reliability of heterogeneous cohesive slopes          下载免费PDF全文

Y.H. Chok  M.B. Jaksa  W.S. Kaggwa  D.V. Griffiths  G.A. Fenton 《国际地质力学数值与分析法杂志》2016,40(11):1556-1569

The reliability of heterogeneous slopes can be evaluated using a wide range of available probabilistic methods. One of these methods is the random finite element method (RFEM), which combines random field theory with the non‐linear elasto‐plastic finite element slope stability analysis method. The RFEM computes the probability of failure of a slope using the Monte Carlo simulation process. The major drawback of this approach is the intensive computational time required, mainly due to the finite element analysis and the Monte Carlo simulation process. Therefore, a simplified model or solution, which can bypass the computationally intensive and time‐consuming numerical analyses, is desirable. The present study investigates the feasibility of using artificial neural networks (ANNs) to develop such a simplified model. ANNs are well known for their strong capability in mapping the input and output relationship of complex non‐linear systems. The RFEM is used to generate possible solutions and to establish a large database that is used to develop and verify the ANN model. In this paper, multi‐layer perceptrons, which are trained with the back‐propagation algorithm, are used. The results of various performance measures indicate that the developed ANN model has a high degree of accuracy in predicting the reliability of heterogeneous slopes. The developed ANN model is then transformed into relatively simple formulae for direct application in practice. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献