Organochlorine pesticide levels in loggerhead turtles (Caretta caretta) stranded in the Canary Islands, Spain     

Monagas P  Orós J  Araña J  González-Díaz OM 《Marine pollution bulletin》2008,56(11):1949-1952

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Multivariate discriminant analysis distinguishes metal- from non metal-related biomarker responses in the clam Chamaelea gallina     

Rodríguez-Ortega MJ  Rodríguez-Ariza A  Gómez-Ariza JL  Muñoz-Serrano A  López-Barea J 《Marine pollution bulletin》2009,58(1):64-327

Molecular biomarkers are among the most sensitive and earliest responses to pollutants. However, lack of detailed knowledge on variability of responses and their possible seasonal variation limit their use. In addition, the seasonality of biological processes modulates the response of organisms to pollutant stressors. Using multivariate statistics, we have studied the influence of environmental and biological factors on the response of a battery of molecular biomarkers in the clam Chamaelea gallina collected along the South-Spanish littoral. Multivariate discriminant analysis clearly distinguished biomarker response between clean and polluted areas, using heavy metals as indicator of pollution. Such differences disappeared when the dataset was normalised for metal content, thus indicating that pollution was the main significant cause of the changes observed between clean and polluted sites. In conclusion, this work shows that, when applying a complete biomarker panel, multivariate statistical tools can be used to discern pollutant- from non pollutant-related responses.  相似文献   

Bloom of Scrippsiella trochoidea (Gonyaulacaceae) in a shrimp pond in the southwestern Gulf of California, Mexico     

Gárate-Lizárraga I  Band-Schmidt CJ  López-Cortés DJ  Muñetón-Gómez Mdel S 《Marine pollution bulletin》2009,58(1):145-149

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Coseismic Three-Dimensional Displacements Determined Using SAR Data: Theory and an Application Test   总被引：1，自引：0，他引：1  

Pablo J. González  José Fernández  Antonio G. Camacho 《Pure and Applied Geophysics》2009,166(8-9):1403-1424

We present a methodology to construct three-dimensional deformation maps using different parameters that can be extracted using SAR data. We apply the methodology using ENVISAT SAR data before and after the December 26^th, 2003 M_w 6.6 Bam earthquake in Iran to determine spatial quasi-continuous three-dimensional coseismic deformation maps. Two near vertical deformation offset components are computed using Envisat ASAR differential interferometry (DInSAR), while two horizontal deformation offset components are measured using sub-pixel correlation techniques applied to ASAR amplitude images. Using the presented methodology, we combine four unevenly precise independent projections of surface coseismic deformation to obtain the full three-dimensional coseismic deformation field caused by an earthquake. The full 3-D coseismic displacement vector is modeled using elastic deformation models constraining details of the fault geometry and slip distribution at depth. Results from the inversion are interpreted in the framework of the Iranian present-day tectonism. Full exploitation of dense 3-D coseismic surface deformation using SAR data, even for moderate earthquakes, should facilitate distinguishing between different interpretations of the mechanical properties of seismically active areas and within the inherent ambiguity of the geophysical inversion solutions.  相似文献   

Controls on event runoff coefficients in the eastern Italian Alps   总被引：3，自引：0，他引：3  

Daniele Norbiato  Marco Borga  Ralf Merz  Günther Blschl  Alberto Carton 《Journal of Hydrology》2009,375(3-4):312-325

Analyses of event runoff coefficients provide essential insight on catchment response, particularly if a range of catchments and a range of events are compared by a single indicator. In this study we examine the effect of climate, geology, land use, flood types and initial soil moisture conditions on the distribution functions of the event runoff coefficients for a set of 14 mountainous catchments located in the eastern Italian Alps, ranging in size from 7.3 to 608.4 km². Runoff coefficients were computed from hourly precipitation, runoff data and estimates of snowmelt. A total of 535 events were analysed over the period 1989–2004. We classified each basin using a “permeability index” which was inferred from a geologic map and ranged from “low” to “high permeability”. A continuous soil moisture accounting model was applied to each catchment to classify ‘wet’ and ‘dry’ initial soil moisture conditions. The results indicate that the spatial distribution of runoff coefficients is highly correlated with mean annual precipitation, with the mean runoff coefficient increasing with mean annual precipitation. Geology, through the ‘permeability index’, is another important control on runoff coefficients for catchments with mean annual precipitation less than 1200 mm. Land use, as indexed by the SCS curve number, influences runoff coefficient distribution to a lesser degree. An analysis of the runoff coefficients by flood type indicates that runoff coefficients increase with event snowmelt. Results show that there exists an intermediate region of subsurface water storage capacity, as indexed by a flow–duration curve-based index, which maximises the impact of initial wetness conditions on the runoff coefficient. This means that the difference between runoff coefficients characterised by wet and dry initial conditions is negligible both for basins with very large storage capacity and for basins with small storage capacity. For basins with intermediate storage capacities, the impact of the initial wetness conditions may be relatively large.  相似文献   

Earthquake swarms at Upptyppingar,north-east Iceland: A sign of magma intrusion?     

S. S. Jakobsdóttir  M. J. Roberts  G. B. Guđmundsson  H. Geirsson  R. Slunga 《Studia Geophysica et Geodaetica》2008,52(4):513-528

In 2007, intense swarms of deep, tectonic earthquakes, amounting to at least 5 300 epicentres, were detected near to Mount Upptyppingar, which forms part of the Kverkfjöll volcano system in Iceland’s Northern Volcanic Zone. Although micro-seismicity is common within such volcanic regions, the Upptyppingar swarms have been more intensive and persistent than any other deep-seated seismicity observed in Iceland. Here we outline the spatial and temporal changes in ongoing seismicity that began in February 2007; in addition, we document enhanced levels of GPS-derived crustal deformation, recorded within 25 km of the area of swarming. Besides displaying spatial clustering, the Upptyppingar micro-earthquakes are noteworthy because: (i) they concentrate at focal depths of 14–22 km; (ii) the swarms comprise brittle-type earthquakes < 2 in magnitude, yielding a b-value of 2.1; and (iii) several of the swarms originate at focal depths exceeding 18 km. Additionally, different parts of the affected region have exhibited seismicity at different times, with swarm sites alternating between distinct areas. The activity moved with time towards east-north-east and to shallower depths. Linear regression approximates the seismicity on a southward-dipping, ～41° plane. Alongside sustained earthquake activity, significant horizontal displacement was registered at two permanent GPS stations in the region. High strain rates are required to explain brittle fracturing under visco-elastic conditions within the Earth’s crust; similarly, intense, localised deformation at considerable depth is necessary to reconcile the measured surface deformation. Such remarkable seismicity and localised deformation suggests that magma is ascending into the base of the crust.  相似文献   

Terrestrial photogrammetric techniques applied to the control of a parabolic dune in the Liencres dune system,Cantabria (Spain)     

Carlos Arteaga  José Juan de Sanjosé  Enrique Serrano 《地球表面变化过程与地形》2008,33(14):2201-2210

The spatial–temporal variations of a dune system can be determined by using diverse ‘geomatic’ methodologies: geodesy, global positioning system (GPS) and photogrammetry. In the case of the Liencres dune system, a study will be carried out using the ‘close‐range’ photogrammetry technique and the topography technique (total station and GPS). In order to determine the dynamic of the dune system it is necessary to repeat the process of study after a specific interval of time. For this reason, three dimensional data should be available in two different time periods, between which the displacement of the object of analysis (the front portion of the dune) will be significant enough to evaluate its magnitude. This work analyses the viability of photogrammetry for the determination of the spatial–temporal changes of a coastal parabolic dune. Two factors have been analysed: first, the comparison of the photogrammetric results with the results obtained from topographic methods (total station and GPS), and second, the quantification of the displacement of the dune system. The analysis of the correspondence between the movement of different parts of the dune and the influence of the intensity and direction of the prevailing wind in the area is also desired. The dune advanced 12·15 ± 0·06 m (an average of 8·5 m/yr), and the partial implications for the dynamic of human modified processes on the natural park have been established. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Improvements to Remote Sensing Using Fuzzy Classification, Graphs and Accuracy Statistics     

Daniel Gómez  Javier Montero  Gregory Biging 《Pure and Applied Geophysics》2008,165(8):1555-1575

This paper puts together some techniques that have been previously developed by the authors, but separately, relative to fuzzy classification within a remote sensing setting. Considering that each image can be represented as a graph that defines proximity between pixels, certain distances between the characteristic of contiguous pixels are defined on such a graph, so a segmentation of the image into homogeneous regions can be produced by means of a particular algorithm. Such a segmentation can be then introduced as information, previously to any classification procedure, with an expected significative improvement. In particular, we consider specific measures in order to quantify such an improvement. This approach is being illustrated with its application into a particular land surface problem.  相似文献   

Patos Lagoon outflow within the Río de la Plata plume using an airborne salinity mapper: Observing an embedded plume     

Derek Burrage  Joel Wesson  Carlos Martinez  Tabare Pérez  Osmar Möller Jr.  Alberto Piola 《Continental Shelf Research》2008

Major river systems discharging into continental shelf waters frequently form buoyant coastal currents that propagate along the continental shelf in the direction of coastal trapped wave propagation (with the coast on the right/left, in the northern/southern hemisphere). The combined flow of the Uruguay and Paraná Rivers, which discharges freshwater into the Río de la Plata estuary (Lat. ∼36°S), often gives rise to a buoyant coastal current (the ‘Plata plume’) that extends northward along the continental shelf off Uruguay and Southern Brazil. Depending upon the prevailing rainfall, wind and tidal conditions, the Patos/Mirim Lagoon complex (Lat. ∼32°S) may also produce a freshwater outflow plume that expands across the inner continental shelf. Under these circumstances the Patos outflow plume can be embedded in temperature, salinity and current fields that are strongly influenced by the larger Plata plume. The purpose of this paper is to present observations of such an embedded plume structure and to determine the dynamical characteristics of the ambient and embedded plumes.  相似文献   

Flood‐based analysis of high‐magnitude sediment transport using a non‐parametric method     

T. Francke  J. A. López‐Tarazón  D. Vericat  A. Bronstert  R. J. Batalla 《地球表面变化过程与地形》2008,33(13):2064-2077

Upland erosion and the resulting reservoir siltation is a serious issue in the Isábena catchment (445 km² Central Spanish Pyrenees). During a three‐month period, water and sediment fluxes have been monitored at the catchment outlet (Capella), two adjacent subcatchments (Villacarli, 41 km²; Cabecera, 145 km²) and the elementary badland catchment Torrelaribera (8 ha). This paper presents the results of the monitoring, a method for the calculation of a sedigraph from intermittent measurements and the derived sediment yields at the monitored locations. The observed suspended sediment concentrations (SSCs) demonstrate the role of badlands as sediment sources: SSCs of up to 280 g l^?1 were encountered for Villacarli, which includes large badland areas. SSCs at the Cabecera catchment, with great areas of woodland, barely exceeded 30 g l^?1. SSCs directly at the sediment source (Torrelaribera) were comparable to those at Villacarli, suggesting a close connection within this subcatchment. At Capella, SSCs of up to 99 g l^?1 were observed. For all sites, SSC displayed only a loose correlation with discharge, inhibiting the application of a simple sediment rating curve. Instead, ancillary variables acting as driving forces or proxies for the processes (rainfall energy, cumulative discharge, rising/falling limb data) were included in a quantile regression forest model to explain the variability in SSC. The variables with most predictive power vary between the sites, suggesting the predominance of different processes. The subsequent flood‐based calculation of sediment yields attests high specific sediment yields for Torrelaribera and Villacarli (6277 and 1971 t km^?2) and medium to high yields for Cabecera and Capella (139 and 410 t km^?2) during the observation period. In all catchments, most of the sediment was exported during intense storms of late summer. Later flood events yield successively less sediment. Relating upland sediment production to yield at the outlet suggests considerable effects of sediment storage within the river channel. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献