A structural and geophysical approach to the study of fractured aquifers in the Scansano-Magliano in Toscana Ridge, southern Tuscany, Italy   总被引：1，自引：0，他引：1  

Roberto Francese  Francesco Mazzarini  Andrea Bistacchi  Gianfranco Morelli  Giorgio Pasquarè  Nicola Praticelli  Henry Robain  Nigel Wardell  Annalisa Zaja 《Hydrogeology Journal》2009,17(5):1233-1246

Fresh water availability has recently become a serious concern in the Italian Apennines, as various activities rely on a predictable supply. Along the ridge between Scansano and Magliano in Toscana, in southern Tuscany, the situation is further complicated by contamination of the nearby alluvial aquifers. Aquifers locally consist of thin fractured reservoirs, generally within low-permeability formations, and it can be difficult to plan the exploitation of resources based on conventional techniques. An integrated study based on geological data investigated the link between tectonics and groundwater circulation, to better define the hydrological model. After the regional identification of fault and fracture patterns, a major structure was investigated in detail to accurately map its spatial position and to understand the geometry and properties of the associated aquifer and assess its exploitation potential. The subsurface around the fault zone was clearly imaged using ground probing radar, two-dimensional and three-dimensional resistivity tomography, and three-dimensional shallow seismic surveys. The vertical and horizontal contacts between the different geological units of the Ligurian and Tuscan series were resolved with a high degree of spatial accuracy. Three-dimensional high-resolution geophysical imaging proved to be a very effective means of characterising small-scale fractured reservoirs.  相似文献   

Factors influencing the distribution of coastal lichens Hydropunctaria maura and Wahlenbergiella mucosa          下载免费PDF全文

Niall F. Higgins  Solène Connan  Dagmar B. Stengel 《Marine Ecology》2015,36(4):1400-1414

Responses to abiotic and biotic stresses that potentially drive the vertical zonation of the intertidal lichens Hydropunctaria maura, an upper littoral lichen, and Wahlenbergiella mucosa, a lower littoral lichen, were investigated in field and laboratory experiments. When transplanted, both lichens exhibited an inability to survive outside their normal vertical distribution range. W. mucosa appeared to be unable to tolerate prolonged periods of desiccation following translocation from lower to upper littoral regions, whereas H. maura was unable to survive in lower littoral zones possibly owing to increased grazing pressure. The effect of desiccation in both lichens was compared using pulse amplitude modulated chlorophyll fluorescence and infra‐red gas analysis; results indicated a more hydration‐dependent nature of W. mucosa. Photosynthetic (algal) pigments and phenolic compounds were determined in both lichen thalli, and a range of additional coastal lichens occupying a natural gradient from upper to lower shore levels. Pigment composition and concentration in both lichen thalli were similar whereas levels of phenolic compounds were up to three times higher in W. mucosa than H. maura. Pigment and phenolic concentration and composition exhibited some seasonality across 13 different lichens originating from different shore levels. Phenolic concentration increased towards the lower shore, suggesting a potential anti‐herbivory function. This marks the first study of pigments and phenolics in coastal lichen communities, and prompts further investigations on the particular physiological features of marine and maritime lichens that enable them to thrive in this extreme environment.  相似文献   

An Early Sunspot Catalog by Miguel Aguilar for the Period 1914 – 1920     

L. Lefèvre  A. J. P. Aparicio  M. C. Gallego  J. M. Vaquero 《Solar physics》2016,291(9-10):2609-2628

  相似文献   

Early Mars volcanic sulfur storage in the upper cryosphere and formation of transient SO2‐rich atmospheres during the Hesperian          下载免费PDF全文

F. Schmidt  E. Chassefière  F. Tian  E. Dartois  J.‐M. Herri  O. Mousis 《Meteoritics & planetary science》2016,51(11):2226-2233

In a previous paper (Chassefière et al. 2013 ), we have shown that most volcanic sulfur released to the early Mars atmosphere could have been trapped in the upper cryosphere under the form of CO₂‐SO₂ clathrates. Huge amounts of sulfur, up to the equivalent of an ~1 bar atmosphere of SO₂, would have been stored in the Noachian upper cryosphere, then massively released to the atmosphere during the Hesperian due to rapidly decreasing CO₂ pressure. It could have resulted in the formation of the large sulfate deposits observed mainly in Hesperian terrains, whereas no or little sulfates are found at the Noachian. In the present paper, we first clarify some aspects of our previous work. We discuss the possibility of a smaller cooling effect of sulfur particles, or even of a net warming effect. We point out the fact that CO₂‐SO₂ clathrates formed through a progressive enrichment of a pre‐existing reservoir of CO₂ clathrates and discuss processes potentially involved in the slow formation of a SO₂‐rich upper cryosphere. We show that episodes of sudden destabilization at the Hesperian may generate 1000 ppmv of SO₂ in the atmosphere and contribute to maintaining the surface temperature above the water freezing point.  相似文献   

Geophysical and magneto‐structural study of the Maâdna structure (Talemzane,Algeria): Insights on its age and origin          下载免费PDF全文

A. Lamali  P. Rochette  N. Merabet  A. Abtout  S. Maouche  J. Gattacceca  L. Ferrière  M. Hamoudi  E.H. Meziane  M. Ayache 《Meteoritics & planetary science》2016,51(12):2249-2273

The Maâdna structure is located approximately 400 km south of Algiers (33°19′ N, 4°19′ E) and emplaced in Upper‐Cretaceous to Eocene limestones. Although accepted as an impact crater on the basis of alleged observations of shock‐diagnostic features such as planar deformation features (PDFs) in quartz grains, previous works were limited and further studies are desirable to ascertain the structure formation process and its age. For this purpose, the crater was investigated using a multidisciplinary approach including field observations, detailed cartography of the different geological and structural units, geophysical surveys, anisotropy of magnetic susceptibility, paleomagnetism, and petrography of the collected samples. We found that the magnetic and gravimetric profiles highlight a succession of positive and negative anomalies, ones that might indicate the occurrence of a causative material which is at least in part identical. Geophysical analysis and modeling suggest the presence of this material within the crater at a depth of about 100 m below the surface. Using soil magnetic susceptibility measurements, the shallowest magnetized zone in the central part of the crater is identified as a recently deposited material. Paleomagnetic and rock magnetic experiments combined with petrographic observations show that detrital hematite is the main magnetic carrier although often associated with magnetite. A primary magnetization is inferred from a stable remanence with both normal and reverse directions, carried by these two minerals. Although this is supposed to be a chemical remagnetization, its normal polarity nature is considered to be a Pliocene component, subsequent to the crater formation. The pole falls onto the Miocene‐Pliocene part of the African Apparent Polar Wander Path (APWP). Consequently, we estimate the formation of the Maâdna crater to have occurred during the time period extending from the Late Miocene to the Early Pliocene. Unfortunately, our field and laboratory investigations do not allow us to confirm an impact origin for the crater as neither shatter cones, nor shocked minerals, were found. A dissolved diapir with inverted relief is suggested as an alternative to the impact hypothesis, which can still be considered as plausible. Only a drilling may provide a definite answer.  相似文献   

A Revised Collection of Sunspot Group Numbers     

J. M. Vaquero  L. Svalgaard  V. M. S. Carrasco  F. Clette  L. Lefèvre  M. C. Gallego  R. Arlt  A. J. P. Aparicio  J.-G. Richard  R. Howe 《Solar physics》2016,291(9-10):3061-3074

  相似文献   

Preface to Topical Issue: Recalibration of the Sunspot Number     

F. Clette  E. W. Cliver  L. Lefèvre  L. Svalgaard  J. M. Vaquero  J. W. Leibacher 《Solar physics》2016,291(9-10):2479-2486

  相似文献   

Carbonyl Sulphide (OCS) Variability with Latitude in the Atmosphere     

Gisèle Krysztofiak  Yao Veng Té  Gwenaël Berthet  Geoffrey C. Toon  Fabrice Jégou 《大气与海洋》2015,53(1):89-101

Abstract

Carbonyl sulphide (OCS) is an important precursor of sulphate aerosols and consequently a key species in stratospheric ozone depletion. The SPectromètre InfraRouge d'Absorption à Lasers Embarqués (SPIRALE) and shortwave infrared (SWIR) balloon-borne instruments have flown in the tropics and in the polar Arctic, and ground-based measurements have been performed by the Qualité de l'Air (QualAir) Fourier Transform Spectrometer in Paris. Partial and total columns and vertical profiles have been obtained to study OCS variability with altitude, latitude, and season. The annual total column variation in Paris reveals a seasonal variation with a maximum in April–June and a minimum in November–January. Total column measurements above Paris and from SWIR balloon-borne instrument are compared with several MkIV measurements, several Network for the Detection of Atmospheric Composition Change (NDACC) stations, aircraft, ship, and balloon measurements to highlight the OCS total column decrease from tropical to polar latitudes. OCS high-resolution in situ vertical profiles have been measured for the first time in the altitude range between 14 and 30?km at tropical and polar latitudes. OCS profiles are compared with Atmospheric Chemistry Experiment (ACE) satellite measurements and show good agreement. Using the correlation between OCS and N₂O from SPIRALE, the OCS stratospheric lifetime has been accurately determined. We find a stratospheric lifetime of 68?±?20 years at polar latitudes and 58?±?14 years at tropical latitudes leading to a global stratospheric sink of 49?±?14?Gg?S?y^?1.  相似文献   

HydroCube: an entity-relationship hydrogeological data model   总被引：1，自引：1，他引：0  

Piotr Wojda  Serge Brouyère  Johan Derouane  Alain Dassargues 《Hydrogeology Journal》2010,18(8):1953-1962

Managing, handling and accessing hydrogeological information depends heavily on the applied hydrogeological data models, which differ between institutions and countries. The effective dissemination of hydrogeological information requires the convergence of such models to make hydrogeological information accessible to multiple users such as universities, water suppliers, and administration and research organisations. Furthermore, because hydrogeological studies are complex, they require a wide variety of high-quality hydrogeological data with appropriate metadata in clearly designed and coherent structures. A need exists, therefore, to develop and implement hydrogeological data models that cover, as much as possible, the full hydrogeological domain. A new data model, called HydroCube, was developed for the Walloon Region in Belgium in 2005. The HydroCube model presents an innovative holistic project-based approach which covers a full set of hydrogeological concepts and features, allowing for effective hydrogeological project management. The model stores data relating to the project locality, hydrogeological equipment, and related observations and measurements. In particular, it focuses on specialized hydrogeological field experiments such as pumping and tracer tests. This logical data model uses entity-relationship diagrams and it has been implemented in the Microsoft Access environment. It has been enriched with a fully functional user interface.  相似文献   

The Decline and Restoration of a Coastal Lagoon (Lake Veere) in the Dutch Delta     

Sander Wijnhoven  Vincent Escaravage  Eugène Daemen  Herman Hummel 《Estuaries and Coasts》2010,33(6):1261-1278

The former tidal inlet Lake Veere was turned into a stagnant brackish lake in 1961. Ever since, the system has shown a continuous degradation. The current study shows the monitoring results for the macrozoobenthic communities and the abiotic conditions for the period 1990–2008. This includes the first step to remediation, the restoration of the exchange between the tidal marine Eastern Scheldt and Lake Veere in 2004. A continuous decline in water clearance co-occurring with decreasing macrofauna densities and richness was observed till 2004. Water quality (e.g., secchi depth, nutrient levels, and oxygen conditions) improved significantly after the measure at a higher salinity level with less variation. But the macrofauna densities, biomass, and diversity did not improve yet. First indications of changes in the benthic communities by arrival of new and returning species are however observed and show that restoration at macrofauna level follows the improved abiotic conditions with a delay of several years.  相似文献