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81.
Andrew Swales R. Bruce Williamson Laurence F. Van Dam Morag J. Stroud Matt S. McGlone 《Estuaries and Coasts》2002,25(1):43-56
Cores were collected from the length of Pakuranga estuary, a small urban estuary in Auckland, New Zealand, to determine sedimentation
and contaminant history, and in particular the impact of urbanization. Catchment sediment loads for the most recent history
(1953–1995), including urbanization since 1960, were reconstructed using the landcover history and soil erosion modeling.
Pollen and14C dating and pre-urban landcover history were used to reconstruct early estuary sedimentation (i.e., post-3000 yr BP to 1960).
Heavy metal concentrations, particle size,137Cs, pollen, and catchment sediment loads were all needed to disentangle the complex estuarine response to urbanization.137Cs profiles did not reflect the historical fallout pattern, but deposition of137Cs-labelled eroded catchment soil, coinciding with peaks in urban construction. Temporal variations in stormwater137Cs concentrations are likely due to varying contributions from137Cs-rich topsoil and137Cs-poor subsoils. A similar pattern was observed in heavy-metal concentrations and attributed to street runoff rather than
topsoil being diluted by metal-poor subsoils. Dating of the sediment profiles showed that during urbanization sedimentation
rates in the tidal creek and estuary were higher than sedimentation rates associated with past agricultural landuse and the
original forest landcover. Urbanization has brought about substantial environmental changes in the upper estuary through continued
infilling of shallow, intertidal areas, contamination by heavy metals to levels of ecological concern, sediment textural changes,
and rapid mangrove colonization of formerly bare intertidal sediments. 相似文献
82.
Olivier Rozenbaum Luc Barbanson Fabrice Muller Ary Bruand 《Comptes Rendus Geoscience》2008,340(6):345-355
Stone substitution is a conventional operation during heritage buildings’ restoration, but becomes problematic for architects and restorers when the quarry is mined out. The compatibility of the substitution stones with the original ones has been for long mainly based on the aesthetical aspect, this resulting too often in a patchwork of original and substitution stones with different patina after several years because of differences of properties. In this study, the objective is to show how substitution stones can be selected by combining aesthetic criteria and stones properties that are relevant for analyzing their compatibility. A couple of French limestones with their potential substitution stones were selected for the study. Our results showed that potential substitution stones selected on their aesthetic criteria require to be rejected because of their differences of physical properties. On the other hand, our results showed also the possibility to select substitution stones with satisfactory aesthetic aspect and properties that enable to expect a satisfactory compatibility with the original stone. 相似文献
83.
Luc Bernier 《Geochimica et cosmochimica acta》2007,71(23):5684-5697
Coupled S speciation and acid generation resulting from S processing associated with five different microbial treatments, all primarily Acidithiobacillus spp. (i.e. autotrophic S-oxidizers) were evaluated in batch laboratory experiments. Microbial treatments included two culture-adapted strains, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, their consortia and two environmental enrichments from a mine tailings lake that were determined to be >95% Acidithiobacillus spp., by whole-cell fluorescent hybridization. Using batch experiments simulating acidic mine waters with no carbon amendments, acid generation, and S speciation associated with the oxidation of three S substrates (thiosulfate, tetrathionate, and elemental S) were evaluated. Aseptic controls showed no observable pH decrease over the experimental time course (1 month) for all three S compounds examined. In contrast, pH decreased in all microbial treatments from starting pH values of 4 to 2 or less for all three S substrates. Results show a non-linear relationship between the pH dynamics of the batch cultures and their corresponding sulfate concentrations, and indicate how known microbial S processing pathways have opposite impacts, ultimately on pH dynamics. Associated geochemical modeling indicated negligible abiogenic processes contributing to the observed results, indicating strong microbial control of acid generation extending over pH ranges from 4 to less than 2. However, the observed acid generation rates and associated S speciation were both microbial treatment and substrate-specific. Results reveal a number of novel insights regarding microbial catalysis of S oxidation: (1) metabolic diversity in S processing, as evidenced by the observed geochemical signatures in S chemical speciation and rates of acid generation amongst phylogenetically similar organisms (to the genus level); (2) consortial impacts differ from those of individual strain members; (3) environmental enrichments of Acidithiobacillus spp. catalyze different S reaction arrays than pure strain Acidithiobacillus spp.; and (4) microbial catalysis of S reactions involves significant disproportionation tied to substantial H+ consumption, with the formation of as yet, poorly characterized intermediate S species, most likely polythionates and polysulfane monosulfonic acids that are thought to be involved in microbial S storage mechanisms. 相似文献
84.
We present a comparison between several methods used to reconstruct fluxes and vertical profiles of wind, temperature and
humidity from measurements at two levels in the atmospheric surface layer for different practical applications. An analytical
method and an iterative method are tested by evaluating the quality of estimations of surface fluxes from detailed field measurements
obtained during a campaign on the site of Lannemezan in the south-west of France. The iterative method yields better results,
but the analytical one can give results of the same level of accuracy provided that specific constants in its formulation
are modified. Then these techniques are applied to wind and temperature reconstruction for an experiment dedicated to wind
power estimates over flat terrain. If turbulent fluxes are not needed, a simple power law appears to be sufficient, as the
method based on Monin–Obukhov theory does not improve the accuracy of the vertical profile reconstruction. 相似文献
85.
Seamless integration of spatial statistics and GIS: The S-PLUS for ArcView and the S+Grassland Links
Shuming Bao Luc Anselin Doug Martin Diana Stralberg 《Journal of Geographical Systems》2000,2(3):287-306
The extension of the functional capacity of geographic information systems (GIS) with tools for statistical analysis in general
and exploratory spatial data analysis (ESDA) in particular has been an increasingly active area of research in recent years.
In this paper, two operational implementations that combine the functionality of spatial data analysis software with a GIS
are considered more closely. They consist of linkages between the S-PLUS software for data analysis and two different GIS implementations, the ArcView desktop system, which is mostly vector-oriented, and the primarily raster-based Grassland open GIS environment. We emphasize conceptual and technical issues related to the software implementation of these approaches
and suggest future directions for linking spatial statistics and GIS.
Received: 14 January 1999 / Accepted: 11 May 1999 相似文献
86.
Results of mercury and organochlorine analyses in pooled muscle and blubber samples representing in all 417 long-finned pilot whales (Globicephala melas) sampled in 1997 in the Faroe Islands are presented. The 28 pooled muscle samples from (in all) 9 pods were analysed for total mercury and the same number of pooled blubber samples were analysed for PCB (IUPAC CBs no. 28, 52, 99, 101, 105, 118, 128, 138, 153, 170, 180, 183 and 187), p,p′-DDT and metabolites and o,p′-DDT and metabolites, cis () and trans (γ)-chlordane, cis- and trans-nonachlor, oxychlordane, mirex, hexachlorobenzene, β-HCH and toxaphene (Parlars no. 26 (T2), 32, 50 (T12), 62 (T20) and 69. 相似文献
87.
88.
Luc Dam 《Journal of Astrophysics and Astronomy》2000,21(3-4):135-140
The PICARD microsatellite mission will provide 2 to 6 years simultaneous measurements of the solar diameter, differential
rotation and solar constant to investigate the nature of their relations and variabilities. The 100 kg satellite has a 40
kg payload consisting of 3 instruments which will provide an absolute measure (better than 10 milliarcsec) of the diameter
and the solar shape, a measure of total solar irradiance, and UV and visible flux in selected wavelength bands. Now in Phase
B, PICARD is expected to be launched before mid-2003. The engineering model of the diameter telescope will be used on ground
simultaneously with the satellite to investigate the atmospheric bias and state on the possible accuracy of the ground measurements
carried up to now. We review the scientific goals linked to the diameter measurement, present the payload, and give a brief
overview of the program aspects. 相似文献
89.
Summary This paper discusses the causes of the current wave of renewal and relocation of football stadiums in the Netherlands and tries to shed some light on the changing form and location of Dutch football stadiums. Comparison with developments in the United Kingdom shows not only remarkable resemblances and mutual influences, but also some significant differences. In an inextricable upward spiral of causes and consequences such as recent successes of clubs and the national team, rising attendances, increasingly positive media attention, rising interests of commercial investors, new international and national requirements on stadium construction and an increasingly positive attitude of municipalities, a new wave of stadium redevelopment and relocation has emerged in the Netherlands. In this paper it will become clear that every stadium tells its own story; some of these stories are highlighted. 相似文献
90.
This study aims at determining the macroscopic strength of porous materials having a Drucker–Prager solid phase at microscale and two populations of saturated pores with different pressures at both micro and meso scales. To this end, and taking account of the available results by Maghous et al. (2009), we first derive a closed‐form expression of approximate criterion for a dry porous medium whose matrix obeys to a general elliptic criterion. The methodology to formulate this criterion is based on limit analysis of a hollow sphere subjected to a uniform strain rate boundary conditions. The obtained results are then implemented in a two‐step homogenization procedure, which interestingly delivers analytical expression of the macroscopic criterion for dry double porous media whose solid phase at microscale obeys to a Drucker–Prager criterion. After a brief discussion of the results, we propose an extension to double porous saturated media, allowing therefore to quantify the simultaneous effects of the different pore pressures applied on each voids population. The results are discussed in terms of the existence or not of effective stresses. Finally, they are assessed by comparing them to recently available results. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献