A Spatio‐Temporal Graph Model for Marine Dune Dynamics Analysis and Representation     

Rémy Thibaud  Géraldine Del Mondo  Thierry Garlan  Ariane Mascret  Christophe Carpentier 《Transactions in GIS》2013,17(5):742-762

Defining a model for the representation and the analysis of spatio‐temporal dynamics remains an open domain in geographical information sciences. In this article we investigate a spatio‐temporal graph‐based model dedicated to managing and extracting sets of geographical entities related in space and time. The approach is based on spatial and temporal local relations between neighboring entities during consecutive times. The model allows us to extract sets of connected entities distant in time and space over long periods and large spaces. From GIS concepts and qualitative reasoning on space and time, we combine the graph model with a dedicated spatial database. It includes information on geometry and geomorphometric parameters, and on spatial and temporal relations. This allows us to extend classical measurements of spatial parameters, with comparisons of entities linked by complex relations in space and time. As a case study, we show how the model suggests an efficient representation of dunes dynamics on a nautical chart for safe navigation.  相似文献   

Use of LIDAR in landslide investigations: a review   总被引：13，自引：0，他引：13  

Michel Jaboyedoff  Thierry Oppikofer  Antonio Abellán  Marc-Henri Derron  Alex Loye  Richard Metzger  Andrea Pedrazzini 《Natural Hazards》2012,61(1):5-28

This paper presents a short history of the appraisal of laser scanner technologies in geosciences used for imaging relief by high-resolution digital elevation models (HRDEMs) or 3D models. A general overview of light detection and ranging (LIDAR) techniques applied to landslides is given, followed by a review of different applications of LIDAR for landslide, rockfall and debris-flow. These applications are classified as: (1) Detection and characterization of mass movements; (2) Hazard assessment and susceptibility mapping; (3) Modelling; (4) Monitoring. This review emphasizes how LIDAR-derived HRDEMs can be used to investigate any type of landslides. It is clear that such HRDEMs are not yet a common tool for landslides investigations, but this technique has opened new domains of applications that still have to be developed.  相似文献   

Coastal habitat degradation and green sea turtle diets in Southeastern Brazil     

Santos RG  Martins AS  Farias Jda N  Horta PA  Pinheiro HT  Torezani E  Baptistotte C  Seminoff JA  Balazs GH  Work TM 《Marine pollution bulletin》2011,62(6):1297-1302

To show the influence of coastal habitat degradation on the availability of food for green turtles (Chelonia mydas), we assessed the dietary preferences and macroalgae community at a feeding area in a highly urbanized region. The area showed low species richness and was classified as degraded. We examined stomach contents of 15 dead stranded turtles (CCL = 44.0 cm (SD 6.7 cm)). The diet was composed primarily of green algae Ulva spp. (83.6%). In contrast, the macroalgae community was dominated by the green alga Caulerpa mexicana. We found a selection for red algae, seagrass and Ulva spp., and avoidance for C. mexicana and brown alga Dictyopteris delicatula. The low diversity of available food items, possibly a result of environmental degradation, likely contributed to the low dietary diversity. The nutritional implications of this restricted diet are unclear.  相似文献   

The ECORS-Truc Vert’08 nearshore field experiment: presentation of a three-dimensional morphologic system in a macro-tidal environment during consecutive extreme storm conditions     

Nadia Senechal  Stéphane Abadie  Edith Gallagher  Jamie MacMahan  Gerd Masselink  Hervé Michallet  Ad Reniers  Gerben Ruessink  Paul Russell  Damien Sous  Ian Turner  Fabrice Ardhuin  Philippe Bonneton  Stéphane Bujan  Sylvain Capo  Raphael Certain  Rodrigo Pedreros  Thierry Garlan 《Ocean Dynamics》2011,61(12):2073-2098

A large multi-institutional nearshore field experiment was conducted at Truc Vert, on the Atlantic coast of France in early 2008. Truc Vert’08 was designed to measure beach change on a long, sandy stretch of coast without engineering works with emphasis on large winter waves (offshore significant wave height up to 8 m), a three-dimensional morphology, and macro-tidal conditions. Nearshore wave transformation, circulation and bathymetric changes involve coupled processes at many spatial and temporal scales thus implying the need to improve our knowledge for the full spectrum of scales to achieve a comprehensive view of the natural system. This experiment is unique when compared with existing experiments because of the simultaneous investigation of processes at different scales, both spatially (from ripples to sand banks) and temporally (from single swash events to several spring-neap tidal cycles, including a major storm event). The purpose of this paper is to provide background information on the experiment by providing detailed presentation of the instrument layout and snapshots of preliminary results.  相似文献   

Petrochemistry of subvolcanic dike swarms associated with the Golden Revenue Au–Cu and the Stoddart Mo–Cu ± W mineralizations (Dawson Range, Yukon Territory, Canada) and implications for ore genesis     

Thierry Bineli Betsi  David Lentz 《Ore Geology Reviews》2011,39(3):134-163

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Stratigraphy of the Cenomanian–Turonian Oceanic Anoxic Event OAE2 in shallow shelf sequences of NE Egypt     

Ahmed El-Sabbagh  Abdel Aziz Tantawy  Gerta Keller  Hassan Khozyem  Jorge Spangenberg  Thierry Adatte  Brian Gertsch 《Cretaceous Research》2011,32(6):705-722

Two shallow water late Cenomanian to early Turonian sequences of NE Egypt have been investigated to evaluate the response to OAE2. Age control based on calcareous nannoplankton, planktic foraminifera and ammonite biostratigraphies integrated with δ¹³C stratigraphy is relatively good despite low diversity and sporadic occurrences. Planktic and benthic foraminiferal faunas are characterized by dysoxic, brackish and mesotrophic conditions, as indicated by low species diversity, low oxygen and low salinity tolerant planktic and benthic species, along with oyster-rich limestone layers. In these subtidal to inner neritic environments the OAE2 δ¹³C excursion appears comparable and coeval to that of open marine environments. However, in contrast to open marine environments where anoxic conditions begin after the first δ¹³C peak and end at or near the Cenomanian–Turonian boundary, in shallow coastal environments anoxic conditions do not appear until the early Turonian. This delay in anoxia appears to be related to the sea-level transgression that reached its maximum in the early Turonian, as observed in shallow water sections from Egypt to Morocco.  相似文献   

In situ U/Pb dating of impact‐produced zircons from the Vargeão Dome (Southern Brazil)     

Anne Nédélec  Jean‐Louis Paquette  Elder Yokoyama  Ricardo I. F. Trindade  Thierry Aigouy  David Baratoux 《Meteoritics & planetary science》2013,48(3):420-431

The Vargeão impact structure was formed in the Serra Geral basaltic and rhyodacitic to rhyolitic lava flows of southern Brazil, that belong to the Paraná‐Etendeka large igneous province. The Chapecó‐type rhyodacites contain small baddeleyite crystals recently dated at 134.3 (±0.8) Ma, which is regarded as the age of this acid volcanism coeval to the flood basalt eruption. Inside the impact structure, a brecciated rhyodacitic sample displays fine veinlets containing numerous lithic fragments in a former melt. This impact breccia contains newly formed zircons, either in the veins or at the contact between a vein and the volcanic matrix. The zircons are 10–50 μm in length, clear and nearly unzoned. In situ laser‐ablation dating of the zircons provides a concordant Early Aptian age of 123.0 ± 1.4 Ma that is regarded as the age of the impact event. As in situ age determination ensures the best possible selection of the analyzed mineral grains, the methodology employed in this study also represents a promising method for dating other impact structures.  相似文献   

Application of trichloroacetic acid (TCA) to extraction of soft body for the determination of tissue Cd, Cu, Pb and Zn in the prosobranch Hydrobia ulvae (Pennant)     

Sokolowski A  Richard P  Fichet D  Radenac G  Guyot T 《Marine pollution bulletin》2003,46(10):1326-1333

The application of trichloroacetic acid (TCA) as a shell extractant for preparation of soft body parts with reference to tissue metal concentrations (Cd, Cu, Pb, Zn) in shellfish has been evaluated on the example of the mud snail Hydrobia ulvae, a small marine prosobranch densely present in rocky and soft-bottom habitats of the eastern Atlantic. A solution of 0.1 M TCA was tested on individuals treated according to two different protocols: (1) thawed after freezing ("non-dried") and (2) thawed and air-dried to a constant weight ("dried"). Two points were investigated in detail to improve the method: individual soft tissue dry weight and tissue metal concentration following a standard digestion method. In both instances, the results were compared with those from manually dissected snails. Conditions for total shell decalcification of 60 individuals (3-4 mm long) were 5.5 h in 20 ml of 0.1 M TCA.No differences in individual soft tissue weight were observed between the treatments, indicating good efficiency of the TCA extraction with respect to weight of soft body parts. In contrast, tissue metal concentrations varied among treatments. The TCA extraction of the dried animals had a good recovery for Cd, most likely due to the lower solubility of Cd vital cellular components (proteins and mineral concretions) from the dried tissue. Satisfactory recoveries of the tissue concentrations of Cu and Pb were obtained for the non-dried individuals. This might be related to the specific distribution of metals in the organism (namely in the digestive glands and gonads) and their different chemical reactivity with TCA after the tissue was dried. Limited susceptibility of Zn-bearing protein bindings to complexing with TCA also accounts for significantly lower concentrations of Zn in the mud snail's soft tissue that was extracted. The 0.1 M TCA solution is therefore recommended for extraction of the shells of Hydrobia ulvae for tissue determination of Cd, Cu and Pb; however the treatment protocol does affect metal recovery and thus a consistent procedure should be followed.The extracted metals from the soft tissues and shells of the mud snails (on the basis of both metal concentrations and contents) were ranked in order of increasing contribution of soft body parts to the total (shell+tissue): Pb相似文献   

Uptake and tissue distribution of C4-C7 alkylphenols in Atlantic cod (Gadus morhua): relevance for biomonitoring of produced water discharges from oil production     

Sundt RC  Baussant T  Beyer J 《Marine pollution bulletin》2009,58(1):72-79

The sensitivity of different tissues for assessment of chronic low-dose environmental exposure of fish to alkylphenols (APs) was investigated. We exposed Atlantic cod (Gadus morhua) in the laboratory to tritium labelled 4-tert-butylphenol, 4n-pentylphenol, 4n-hexylphenol, and 4n-heptylphenol via seawater (8 ng/l) and via contaminated feed (5 μg/kg fish per day). Measurements of different fish tissues during eight days of exposure and eight subsequent days of recovery revealed that APs administered via spiked seawater were readily taken up whereas the uptake was far less efficient when APs were administered in spiked feed. AP residues were mainly located in the bile fluid whereas the concentrations in liver were very low, indicating a rapid excretion and the liver-bile axis to be the major route of elimination. The biological half-life of APs in the exposed cod was short, between 10 and 20 h. Our study shows that in connection with biomonitoring of AP exposure in fish, assessment of AP metabolites in bile fluid is a more sensitive tool than detection of parent AP levels in liver or other internal tissues.  相似文献   

Regional patterns of observed sea level change: insights from a 1/4° global ocean/sea-ice hindcast     

Alix Lombard  Gilles Garric  Thierry Penduff 《Ocean Dynamics》2009,59(3):433-449

A global eddy-admitting ocean/sea-ice simulation driven over 1958–2004 by daily atmospheric forcing is used to evaluate spatial patterns of sea level change between 1993 and 2001. In the present study, no data assimilation is performed. The model is based on the Nucleus for European Models of the Ocean code at the 1/4° resolution, and the simulation was performed without data assimilation by the DRAKKAR project. We show that this simulation correctly reproduces the observed regional sea level trend patterns computed using satellite altimetry data over 1993–2001. Generally, we find that regional sea level change is best simulated in the tropical band and northern oceans, whereas the Southern Ocean is poorly simulated. We examine the respective contributions of steric and bottom pressure changes to the total regional sea level changes. For the steric component, we analyze separately the contributions of temperature and salinity changes as well as upper and lower ocean contributions. Generally, the model results show that most regional sea level changes arise from temperature changes in the upper 750 m of the ocean. However, contributions of salinity changes and deep steric changes can be locally important. We also propose a map of ocean bottom pressure changes. Finally, we assess the robustness of such a model by comparing this simulation with a second simulation performed by MERCATOR-Ocean based on the same core model, but differing by its short length of integration (1992–2001) and its surface forcing data set. The long simulation presents better performance over 1993–2001 than the short simulation, especially in the Southern Ocean where a long adjustment time seems to be needed. In memory of my little brother Jean-Eudes, whose thirst for science filled out the rich discussions we had about my investigations and his job as user-service provider for MERCATOR-Ocean.  相似文献