Physico-chemical characteristics and pollutants of the benthic environment in the Montevideo coastal zone,Uruguay     

Muniz P  Venturini N  Martínez A 《Marine pollution bulletin》2002,44(9):962-968

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Products and Mechanism of the NO<Subscript>3</Subscript> Reaction with Thiophene     

B.?Caba?asEmail author  M.?T.?Baeza  P.?Martín  S.?Salgado  F.?Villanueva  E.?Monedero  K.?Wirtz 《Journal of Atmospheric Chemistry》2005,51(3):317-335

Products of the gas-phase reaction of the NO₃ radical with thiophene have been investigated using different experimental systems. On the one hand, experiments have been conducted in our laboratory using two different methods, a Teflon static reactor coupled to a gas chromatograph combined with mass-spectrometry (GC-MS) and a discharge flow tube with direct MS spectroscopic detection. A qualitative analysis in these cases indicates that possible products for the reaction of thiophene+NO₃ at room temperature include: sulphur dioxide, acetic and formic acids, a short-chain aldehyde, 2-nitrothiophene and 3-nitrothiophene. On the other hand, quantitative experiments have been performed in the European Photoreactor (EUPHORE) in Valencia, Spain. In this case, the major products were: HNO₃ (≈80%), nitrothiophenes (≈30%), SO₂ (≈20%), propanal (3%) and a fraction of particles (≈10%). The results obtained indicate that at least 70% of the reaction of NO₃ with thiophene proceeds by an H-abstraction process at room temperature. The mechanism of the reaction studied is proposed on the basis of experimental results.  相似文献   

The Use of Ambient Seismic Noise Measurements for the Estimation of Surface Soil Effects: The Motril City Case (Southern Spain)     

Z. Al Yuncha  F. Luzón  A. Posadas  J. Martín  G. Alguacil  J. Almendros  S. Sánchez 《Pure and Applied Geophysics》2004,161(7):1549-1559

This paper presents a study of the ambient seismic noise features in Motril City. The predominant resonant period at each site was determined using the Horizontal to Vertical Noise Ratio (HVNR) of the microtremors records; it was applied to 91 points which cover the city and we present the distribution of the periods over a map which shows important characteristics requiring consideration in a study focussing on the mitigation of the seismic risk. Using these results, two zones can be distinguished: north of the GG profile with predominant periods smaller than 0.25 sec which corresponds with a hard soil, and south of GG with periods ranging from 0.25 to 0.6 indicating a medium-soft soil. Microtremors are a preliminary useful tool that compensates for the lack of seismic recorded data, and that can complement other valuable information (borehole logs, geology, etc.) to evaluate the seismic risk on places as Motril City where some of this information is unavailable. Through the predominant period the HVNR indicates the kind of soil we are dealing with.  相似文献   

Neotectonics and morphotectonics of the southern Almería region (Betic Cordillera-Spain) kinematic implications     

José?J.?Martínez-DíazEmail author  J.?L.?Hernández-Enrile 《International Journal of Earth Sciences》2004,93(2):189-206

Most previous studies related to the recent tectonic development of southeastern Betic Cordillera, and in particular the south of Almería, agree with the kinematic variety that can be observed in the post-Miocene structures at different scales. This variety is difficult to explain if we consider only the regional stress field related to the convergence of the Eurasian and African plates that remained relatively steady over the last 9 Ma. This work proposes a block tectonics with horizontal and vertical relative movements driven by strike-slip movements of major faults to explain the variety of kinematics observed in the area from Middle Miocene to present. The combined activity of the Alpujarras fault zone (dextral strike-slip) and the Carboneras fault zone (sinistral strike-slip) induces, within the major block bounded by them, the squeezing of minor pre-existing fault bounded crustal blocks. This process generates traction areas inside the escaping block, which are linked with the existence of gradients of westward movement rate. This tectonics can explain some of the structures related with the extensional tectonics predominant in the south of Almería province and the development of the minor and major morphostructures driven by faults with different kinematics. The tectonics of blocks proposed is useful to give a coherent interpretation of apparently incoherent local structural data into a regional and homogeneous compressional stress field.Sadly, Professor José L. Hernández Enrile died in April 2003, and thus this paper represents his last thoughts on the topic. Reviews were addressed by the first author; however, some of the suggested changes were discussed to preserve Professor Hernández Enriless thoughts.  相似文献   

Horizontal sighting range and Secchi depth as estimators of underwater PAR attenuation in a coastal lagoon     

Martín?A.?Montes-Hugo  Saúl?Alvarez-BorregoEmail author  Alma?D.?Giles-Guzmán 《Estuaries and Coasts》2003,26(5):1302-1309

Attenuation of photosynthetically available radiation (PAR) measured using a light meter, was related to Secchi disk, horizontal black disk and horizontal sighting ranges observed in a coastal lagoon of the Southern California Current System. Vertical attenuation coefficient (K_PAR) was calculated from radiometric PAR profiles. Vertical (Z_D) and horizontal (HS) sighting ranges were measured with white (Secchi depth or Z_SD, HS _W ) and black (Z _BD, HS _B ) targets. Empirical power models for the K_PAR-Z_SD (K_PAR=1.47 Z_SD ^−1.13), K_PAR-Z _BD (K_PAR=0.98 Z _BD ^−1.26), K_PAR-HS _W (K_PAR=1.22 HS _W ^−1.14) and K_PAR-HS _B (K_PAR=0.73 HS _B ^−1.07) relationships were developed. The parameters of these models may not apply to other water bodies because their values depend on the range of water reflectance in each case, as reported in the literature. This is the first contribution reporting K_PAR-HS empirical relations in an estuarine environment but their application may be limited to this coastal lagoon. While this approach may be universal, more data are needed to explore the variability of the parameters between different water bodies.  相似文献   

The nonadiabatic general-relativistic stellar oscillations     

José Ma. Martí  Juan A. Miralles  José Ma. Ibánez  Luis Herrera 《Astrophysics and Space Science》1990,168(2):305-316

We have derived the equations which govern the linear nonadiabatic general-relativistic radial oscillations. The perturbation produces a heat flux that is coupled with the geometry, through the Einstein field equations of a stellar configuration. The classical limit is recovered. The stability conditions are examined by means of a simplified one-zone model.  相似文献   

Geology and rural landscapes in central Spain (Guadalajara, Castilla—La Mancha)     

A. García-Quintana  J. F. Martín-Duque  J. A. González-Martín  J. F. García-Hidalgo  J. Pedraza  P. Herranz  R. Rincón  H. Estévez 《Environmental Geology》2005,47(6):782-794

Methods commonly used in regional geological analysis were employed to study the visual landscapes of the Sigüenza–Molina de Aragón area (Spain). Landscape data were compiled to produce a landscape map and a photograph catalogue. Lithological composition, tectonic structure and recent erosive processes are the main factors controlling the visual landscapes. Territorial properties, such as colours and agricultural capacities, are controlled by these geological characteristics. The landscape map and the photographic catalogue is the main contribution of this paper. The first level of landscape classification distinguishes zones with dominance of either flat, concave or convex areas. Other parts of the territory are, however, composed of concave and convex combinations that originate hybrid orographic structures. In a second level of classification, several subdivisions for each of these types are established.  相似文献   

Subcompositional Patterns in Cenozoic Volcanic Rocks of Hungary     

J. A. Martín-Fernández  C. Barceló-Vidal  V. Pawlowsky-Glahn  L. ó. Kovács  G. P. Kovács 《Mathematical Geology》2005,37(7):729-752

Data selected from an extensive major element database of Cenozoic volcanic rocks (including calc-alkaline andesites, dacites, rhyolites, and alkali basalts) of Hungary are used to illustrate the detection and modeling of subcompositional patterns using a statistical analysis based on the assumption that relative differences between the observed values are more meaningful than absolute ones. In particular, two roughly linear compositional patterns (associated one to the alkaline basalts, the other to the calc-alkaline series) are revealed and evaluated, and it is shown how principal component analysis can be used to obtain the estimated subcomposition of their incidental intersection point.  相似文献   

Review of the tectonics of the Levant Rift system: the structural significance of oblique continental breakup   总被引：3，自引：0，他引：3  

Yossi Mart  William B.F. Ryan  Oxana V. Lunina 《Tectonophysics》2005,395(3-4):209-232

The Levant Rift system is an elongated series of structural basins that extends for more than 1000 km from the northern Red Sea to southern Anatolia. The system consists of three major segments, the Jordan Rift in the south, El Gharb–Kara-Su Rift in the north, and the Lebanese Fault splay in between. The rifted parts of this structural system are accompanied by intensively uplifted margins that mirror-image the basinal pattern, namely, the deeper the basin—the higher its margins, and vice versa. Uplifts also occur along the fault splay section. The Jordan Rift comprises axial basins that diminish in size from the south northwards, and are separated from each other by shallow threshold zones along the axis of the rift, where the margins are also subdued. The Lebanese Fault splay consists of five faults that emerge from the northern edge of the Jordan Rift and trend like a fan between the north and the northeast. One of these faults connects the Jordan and El Gharb–Kara-Su rifts. The Levant Rift and its uplifted margins started to develop in the middle-late Miocene, and most of the structural development occurred in the Plio-Pleistocene.The Levant Rift system is characterized by its oblique displacement, and evidence for both dip-slip and strike-slip displacement was measured on its faults. Earthquakes also indicate that same mixed pattern, some of them show strike-slip offset, and others normal. It is generally conceded that the amount of normal offset along the boundary faults of the Rift system reaches 8–10 km, but the lateral displacement is disputed, and offsets ranging from 11 to 107 km were suggested. Assessment of the available data led us to suggest that the sinistral offset along the Levant Rift system is approximately 10–20 km. The similarity between the vertical and the lateral displacements, the basin and threshold structural pattern of the Rift, model experiments in oblique rifting, as well as the significant tectonic resemblance to the Red Sea and the East African rifts, indicate that the Levant Rift is the product of continental breakup, and it is probably an emerging oceanic spreading center.  相似文献   

Analysis of the mobilization of solid loads and heavy metals in runoff waters from granite quarries     

Enrique Peña González  Joaquín Suárez López  Jordi Delgado Martín  Alfredo Jácome Burgos  Jerónimo Puertas Agudo 《Environmental Geology》2006,50(6):823-834

The cutting operations of dimension stone at quarries produce a large amount of fines that, in turn, cause a negative environmental impact over local surface waters. This article presents a detailed analysis of the mobilized contamination associated with runoff waters in a large granite quarry (～200 ha) which is located in Porriño (Galicia, NW Spain), the most important production centre of dimension stone in Spain. There, an intensive monitoring survey was developed in order to characterize the hydrology of the system as well as the release and transport of pollutants. This was accomplished by means of different control sections for the flow and by the collection of 52 random water samples. Automatic samplers were also used to collect 192 water samples associated with runoff generated by significant rain events. For each of the samples collected, a wide battery of analytic determinations was performed, including solid loads, turbidity, organic pollution, nutrient and selected metals. Upon careful examination it has been possible to obtain different parameters related to the contamination control, like the “event mean concentration” (EMC), maximum concentrations and specific sediment loads. Moreover, a comprehensive statistical study including parameter correlation and cumulative probability analyses helped to understand the pollutant mobilization behaviour within the quarry system. It can be concluded that mobilized contamination shows the anomalous presence of some metals, whose concentrations are in excess when compared to the natural rock. This excess metal amount must be attributed to an anthropogenic source associated to mining and cutting operations.  相似文献