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Contributions of boron isotopes to understanding the hydrogeochemistry of the coastal detritic aquifer of Castellón Plain,Spain 总被引：1，自引：0，他引：1
The Castellón Plain alluvial aquifer, Spain, is intensively exploited to meet the demand for agricultural irrigation and industrial water supply. The geochemistry of its groundwater shows complex salinization in the northern and southern parts of the aquifer, with significant pollution from human origin in the central portion. Boron content and B isotope geochemistry are useful for distinguishing between various sources of pollution and their relative importance in different parts of this aquifer. Boron concentrations in the groundwater vary between 0.01 and 0.85 mg/L. In the more saline groundwaters, found at the northern and southern ends of the study area, the presence of B is linked to inputs from seawater and water with a calcium-magnesium sulphate facies, which feed the aquifer and clearly influence the chemistry of its waters. Evidence of B adsorption processes in some samples is shown by the low B/Cl ratios and the high values of δ11B. In the central portion of the aquifer, the high B/Cl ratios and the strongly negative δ11B are related to pollution of human origin. 相似文献
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I .C. Baillie N. B. Inciong P. M. Evangelista 《Singapore journal of tropical geography》2001,22(1):1-14
The soils on the southeastern coastal plain of Palawan, Philippines are developed on alluvium derived from various lithologies of the Palawan Ophiolitic Complex. There is little lateral mixing of the alluvium. The soil pattern is interpreted as the result of increasing weathering and leaching with age on deposits of different lithological origins. In the ultramafic catchment the younger soils are infertile due to several unfavourable characteristics, including high contents of heavy metals and Mg, deficiencies of P and micro‐nutrients, and impermeability. These soils improve with increased weathering and leaching, and the older soils have better physical and Mg characteristics. In felsic alluvia the reverse is found, and the soils on younger deposits are the most fertile, while the older soils have unfavourable combinations of subsoil compaction, acidity and dominance by aluminium. These patterns are reflected in the current land use, with areas of sparse settlement and cultivation on the less fertile soils on younger ultramafic and older felsic alluvia. These areas have been avoided or abandoned, rather than overlooked, by farmers and cannot be considered as “empty lands”. Their sustainable development will require careful management. Most of the more fertile land is already cultivated. 相似文献
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Nicola Nocilla Aldo Evangelista Anna Scotto di Santolo 《Rock Mechanics and Rock Engineering》2009,42(5):815-833
In recent years, rock fall phenomena in Italy have received considerable attention for risk mitigation through in situ observations
and experimental data. This paper reports the study conducted at Camaldoli Hill, in the urban area of Naples, and at Monte
Pellegrino, Palermo, Italy. The rocks involved are volcanic Neapolitan yellow tuff (NYT) in the former area and dolomitic
limestone in the latter. Both rocks, even though with different strength characteristics, have shown a significant tendency
towards rock fragmentation during run out. This behavior was first investigated by comparing the volumes of removable blocks
on the cliff faces (V
0) and fallen blocks on the slopes (V
f). It was assumed that the ratio V
f/V
0 decreases with the distance (x
f) from the detachment area by an empirical law, which depends on a coefficient α, correlated with the geotechnical properties of the materials involved in the rock fall. Finally, this law was validated
by observation of well-documented natural rock falls (Palermo) and by in situ full-scale tests (Naples). From the engineering
perspective, consideration of fragmentation processes in rock fall modeling provides a means for designing low-cost mitigation
measures. 相似文献
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Pedro N. Carvalho Pedro Nuno R. RodriguesRafael Evangelista M. Clara P. BastoM. Teresa S.D. Vasconcelos 《Estuarine, Coastal and Shelf Science》2011
Sediments are depositories of toxic substances such as organochlorine pesticides and there is a global need for their removal in contaminated environments. Studies that combine contaminated sediments and phytoremediation are relatively recent and their number has been increasing. This work aimed to investigate whether salt marsh plants (sea club-rush Scirpus maritimus, sea rush Juncus maritimus and sea purslane Halimione portulacoides) can favor DDT and metabolites remediation in estuarine environment. For this purpose the levels of DDT, DDE and DDD were compared in vegetated and non-vegetated sediments from an estuary in the North of Portugal (in-situ study) and from another in the South of Portugal (ex-situ study). Results obtained both in the in-situ study, involving S. maritimus and J. maritimus, and in the ex-situ study, involving H. portulacoides, indicated that these plants did not have a significant role in DDTs removal and/or degradation. Therefore, it seems that the tested plants cannot influence levels and distribution of DDTs in estuarine areas. 相似文献
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A joint analysis of down-hole (DH) and multichannel analysis of surface waves (MASW) measurements offers a complete evaluation of shear wave velocity profiles, especially for sites where a strong lateral variability is expected, such as archeological sites. In this complex stratigraphic setting, the high “subsoil anisotropy” (i.e., sharp lithological changes due to the presence of anthropogenic backfill deposits and/or buried man-made structures) implies a different role for DH and MASW tests. This paper discusses some results of a broad experimental program conducted on the Palatine Hill, one of the most ancient areas of the city of Rome (Italy). The experiments were part of a project on seismic microzoning and consisted of 20 MASW and 11 DH tests. The main objective of this study was to examine the difficulties related to the interpretation of the DH and MASW tests and the reliability limits inherent in the application of the noninvasive method in complex stratigraphic settings. As is well known, DH tests provide good determinations of shear wave velocities (Vs) for different lithologies and man-made materials, whereas MASW tests provide average values for the subsoil volume investigated. The data obtained from each method with blind tests were compared and were correlated to site-specific subsurface conditions, including lateral variability. Differences between punctual (DH) and global (MASW) Vs measurements are discussed, quantifying the errors by synthetic comparison and by site response analyses. This study demonstrates that, for archeological sites, VS profiles obtained from the DH and MASW methods differ by more than 15 %. However, the local site effect showed comparable results in terms of natural frequencies, whereas the resolution of the inverted shear wave velocity was influenced by the fundamental mode of propagation. 相似文献
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Gopal Adhikari Lorenza Petrini Gian Michele Calvi 《Bulletin of Earthquake Engineering》2010,8(4):897-919
The paper investigates the applicability of current direct displacement based seismic design (DDBD) procedure, developed by
Priestley and his coworkers, for straight long span bridges under transverse seismic excitation synchronous to all supports.
This category of bridges often possess some additional features such as massive tall piers, highly irregular distribution
of mass and stiffness due to unequal superstructure spans and pier heights, large deformation capacity etc. that are absent
in short-to-moderate span bridges for which DDBD has extensively been verified. It is shown that DDBD in its current form
is unable to capture both displacement and base shear demand when compared with nonlinear dynamic analysis results. Accordingly,
a simple mechanics based extension of the current procedure that takes into account the effect of pier mass while computing
base shear demand as well as a modal combination rule for estimating displacement demand is proposed and validated using a
series of parametric studies. The new procedure also allows engineer to allocate strength at the potential plastic hinge location
in more general terms. 相似文献
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Some observations on the prediction of the dynamic parameters of debris flows in pyroclastic deposits in the Campania region of Italy 总被引：1，自引：0，他引：1
Over the last 20 years, many tools have been developed for the prediction of the post-failure behaviour of rapid landslides.
However, as pointed out by several researchers, knowledge may be improved by the performance of back-analyses using different
models and the evaluation of their reliability. This paper reports the back-analysis, conducted using numerical models, of
57 rapid landslides that have occurred in the Campania region. The back-analysis has been performed using the 2-D DAN_W code
(version 2003) with two different rheological models: the Voellmy and the frictional models. The latter has been immediately
discarded because it did not match the observed data. Instead, using the Voellmy model, the best-fit values of the parameters
(friction μ and turbulence ξ) for different types of flow (channelled, un-channelled and mixed flows) have been researched.
With these values a parametric study has been carried out on four representative slope profiles of the Campania region, enabling
the prediction of runout, velocity and depth of flow (dynamic parameters) of potential debris flows.
相似文献
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