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111.
112.
Erika Nathan 《The Australian geographer》1999,30(3):295-310
The groundwater recharge-discharge model, or hydro-equilibrium model, has driven Victorian dryland salinity research for the last 30 years. This paper challenges its application to the Dundas Tableland, south-western Victoria, on historical grounds. In exposing the weak historical foundation of the model for one geographical area so well represented in mainstream investigations, the critique is designed to question the validity of applying the model to other parts of Australia without corresponding historical research. More generally, it is hoped that this contribution from another discipline gives a respectful but significant nudge to the hegemony of physical science in defining and finding solutions for environmental problems. 相似文献
113.
Sharp boundary inversion of 2D magnetotelluric data 总被引:6,自引:0,他引:6
Torquil Smith Michael Hoversten Erika Gasperikova & Frank Morrison 《Geophysical Prospecting》1999,47(4):469-486
We consider 2D earth models consisting of laterally variable layers. Boundaries between layers are described by their depths at a set of nodes and interpolated laterally between nodes. Conductivity within each layer is described by values at a set of nodes fixed within each layer, and is interpolated laterally within each layer. Within the set of possible models of this sort, we iteratively invert magnetotelluric data for models minimizing the lateral roughness of the layer boundaries, and the lateral roughness of conductivities within layers, for a given level of data misfit. This stabilizes the inverse problem and avoids superfluous detail. This approach allows the determination of boundary positions between geological units with sharp discontinuities in properties across boundaries, while sharing the stability features of recent smooth conductivity distribution inversions.
We compare sharp boundary inversion results with smooth conductivity distribution inversion results on a numerical example, and on inversion of field data from the Columbia River flood basalts of Washington State. In the synthetic example, where true positions and resistivities are known, sharp boundary inversion results determine both layer boundary locations and layer resistivities accurately. In inversion of Columbia flood basalt data, sharp boundary inversion recovers a model with substantially less internal variation within units, and less ambiguity in both the depth to base of the basalts and depth to resistive basement. 相似文献
We compare sharp boundary inversion results with smooth conductivity distribution inversion results on a numerical example, and on inversion of field data from the Columbia River flood basalts of Washington State. In the synthetic example, where true positions and resistivities are known, sharp boundary inversion results determine both layer boundary locations and layer resistivities accurately. In inversion of Columbia flood basalt data, sharp boundary inversion recovers a model with substantially less internal variation within units, and less ambiguity in both the depth to base of the basalts and depth to resistive basement. 相似文献
114.
Acid sulfate-chloride thermal water samples collected together with fumarolic gases from various volcanic areas in northeastern Japan were studied chemically and isotogdically. δ34S (COT) values of sulfate and hydrogen sulfide from these volcanic hot springs range from +4.0 to +31 and from ?15.0 to ?2.0% respectively, with δ34Sys value of +2.5 to +31. The δ34S of the sulfate in the more saline waters tends to become smaller with increasing ratio of SO4 to Cl, although the chemical and isotopic composition of acid thermal water within some areas may be altered by secondary processes during the discharge of the thermal waters. This trend can be explained by the reaction of the volcanic gases, having S/Cl of 4 ~ 7 and total sulfur of ~0% in δ34S, with ground water at 200°C, and/or the removal of sulfide phase depleted in 34S from the acid thermal water formed by the disproportionation of volcanic sulfur. The sulfur species in acid sulfate-chloride thermal water are shown to be volcanic exhalations. 相似文献
115.
The isotopic compositions of S (δ34S) and C (δ13C) were determined for the coal utilized by a power plant and for the fly ash produced as a by-product of the coal combustion in a 220-MW utility boiler. The coal samples analyzed represent different lithologies within a single mine, the coal supplied to the power plant, the pulverized feed coal, and the coal rejected by the pulverizer. The ash was collected at various stages of the ash-collection system in the plant. There is a notable enrichment in 34S from the base to the top of the coal seam in the mine, with much of the variation due to an upwards enrichment in the δ34S values of the pyrite. Variations in δ34S and in the amount of pyritic S in the coal delivered to the plant show that there was a change of source of coal supplied to the plant, between week one and week two of monitoring, supporting a previous study based on metal and sulfide geochemistry for the same plant. The fly ash has a more enriched δ34S than the pulverized coal and, in general, the δ34S is more enriched in fly ashes collected at cooler points in the ash-collection system. This pattern of δ34S suggests an increased isotopic fractionation due to temperature, with the fly ash becoming progressively depleted in 34S and the flue gas S-containing components becoming progressively enriched in 34S with increasing temperatures. Substantially less variation is seen in the C isotopes compared to S isotopes. There is little vertical variation in δ13C in the coal bed, with δ13C becoming slightly heavier towards the top of the coal seam. An 83–93% loss of solid phase C occurs during coal combustion in the transition from coal to ash owing to loss of CO2. Despite the significant difference in total C content only a small enrichment of 0.44–0.67‰ in 13C in the ash relative to the coal is observed, demonstrating that redistribution of C isotopes in the boiler and convective passes prior to the arrival of the fly ash in the ash-collections system is minor. 相似文献
116.
Under communism local authorities tended to be largely passive bystanders in a regional development process which emerged
through the central planning process through the spatial allocations of investment by government ministries. Attention was
given to physical planning, but comparatively little material entered the public domain on location policy and spatial priorities
generally, apart from the objective of greater equality between regions and a commitment to backward areas generally. Now
that much investment is down to private enterprise and government has become more decentralised and accountable, there is
a need for concepts and strategies to coordinate public sector investment and provide guidelines for the evaluation of private
development proposals. At the same time, there is an open competition for investment which requires communities to promote
themselves in terms of their identity and development potential. This paper offers an overview by taking two countries - Hungary
and Romania - where progress can be compared and where the focus can be placed on a common frontier which is diverting attention
from conventional regional planning to cross-border cooperation. In both contexts however, attention is given to the ways
in which planning can divert investment away from the main centres to the peripheral areas, including action to strengthen
the role of small towns and also to improve cohesion among functionally-related groups of settlements and communes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
117.
Geohazards Monitoring in Roma from InSAR and In Situ Data: Outcomes of the PanGeo Project 总被引:1,自引:0,他引:1
118.
Erika P.Blanco-Donado Ismael L.Schneider Paulo Artaxo Jesus Lozano-Osorio Luana Portz Marcos L.S.Oliveira 《地学前缘(英文版)》2022,(1):404-416
Black carbon(BC)is one of the short-lived air pollutants that contributes significantly to aerosol radiative forcing and global climate change.It is emitted by the incomplete combustion of fossil fuels,biofuels,and biomass.Urban environments are quite complex and thus,the use of mobile jointly with fixed monitoring provides a better understanding of the dynamics of BC distribution in such areas.The present study addresses the measurement of BC concentration using real-time mobile and ambient monitoring in Barranquilla,an industrialized urban area of the Colombian Caribbean.A microaethalometer(MA200)and an aethalometer(AE33)were used for measuring the BC concentration.The absorption ?ngstr?m exponent(AAE)values were determined for the study area,for identifying the BC emission sources.The results of the ambient sampling show that vehicle traffic emissions prevail;however,the influence of biomass burning was also observed.The mean ambient BC concentration was found to be 1.04±1.03μg/m3 and varied between 0.5 and 4.0μg/m3.From the mobile measurements obtained in real traffic conditions on the road,a much higher average value of 16.1±16.5μg/m3 was measured.Many parts of the city showed BC concentrations higher than 20μg/m3.The spatial distribution of BC concentration shows that vehicle emissions and traffic jams,a consequence of road and transport infrastructure,are the factors that most affect the BC concentration.A comparison of results obtained from two aethalometers indicates that the concentrations measured by MA200 are 9%lower than those measured by AE33.The AAE obtained was found to vary between 1.1 and 1.6,indicating vehicular emissions as the most crucial source.In addition,it was observed that the BC concentration on working days was 2.5 times higher than on the weekends in the case of mobile monitoring and 1.5 times higher in the case of ambient monitoring. 相似文献
119.
Although coral reefs worldwide are subject to increasing global threats, humans also impact coral reefs directly through localized activities such as snorkeling, kayaking and fishing. We investigated five sites on the northern shore of Moorea, French Polynesia, and quantified the number of visitors on the beach and in shallow water. In field surveys, we measured total coral cover and colony sizes of two common genera, Porites and Acropora, a massive and branching morphology, respectively. One site, which hosted over an order of magnitude more people than the other four, had significantly less total coral cover and supported very little branching Acropora. In addition, size frequency distributions of both the branching and massive genera were skewed toward smaller colony sizes at the high use site. Our results demonstrated that the use of tropical beaches may result in less coral cover, with branching colonies rare and small. 相似文献
120.
Erika B. Guttmann Ian A. Simpson Donald A. Davidson Stephen J. Dockrill 《Geoarchaeology》2006,21(1):61-92
The arable soils from two multiperiod settlements were analyzed to identify changes in agricultural methods over time. The settlement middens were also analyzed to determine whether potential fertilizers were discarded unused. Results suggest that in the Neolithic period (˜4000–2000 B.C. in the UK) the arable soils at Tofts Ness, Orkney, and Old Scatness, Shetland, were created by flattening and cultivating the settlements' midden heaps in situ. The arable area at Tofts Ness was expanded in the Bronze Age (˜2000–700 B.C. in the UK), and the new land was improved by the addition of ash, nightsoil, and domestic waste. Cultivation continued briefly after the fields were buried in windblown sand in the Late Bronze Age or Early Iron Age, but by the Early Iron Age cultivation ceased and organic‐rich material was allowed to accumulate within the settlement. By contrast, at Old Scatness, arable production was increased in the Iron Age (˜700 B.C.–A.D. 550 in Scotland) by the intensive use of animal manures. The results indicate that during the lifespan of the two settlements the arable soils were fertilized to increase production, which was intensified over time. © 2006 Wiley Periodicals, Inc. 相似文献