Origin of talc in the Ionian Sea waters     

Renzo Sartori  Luciano Tomadin 《Marine Geology》1977,25(4):M13-M18

Talc and/or pyrophyllite have been detected as suspended particulates in the waters of the Ionian Sea (eastern Mediterranean). Differing from similar findings reported in some recent works by many authors, the presence of these silicates is completely attributable to unavoidable contamination during collection and analytical processing of the water samples.  相似文献   

Rock pool tufa stromatolites on a modern South African wave‐cut platform: partial analogues for Archaean stromatolites?     

Alan M. Smith  Julian E. Andrews  Ronald Uken  Zane Thackeray  Renzo Perissinotto  Rio Leuci  Alina Marca‐Bell 《地学学报》2011,23(6):375-381

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Detecting the flow relationships between deep and shallow aquifers in an exploited groundwater system,using long‐term monitoring data and quantitative hydrogeology: the Acque Albule basin case (Rome,Italy)     

Francesco La Vigna  Roberto Mazza  Giuseppe Capelli 《水文研究》2013,27(22):3159-3173

Five years of hydrogeological monitoring and field activities performed in the complex hydrogeological system of the Acque Albule basin (AAB) were conducted to define the hydrogeological setting, the relationship between deep and shallow aquifers and a conceptual groundwater flow model of this exploited area using conventional quantitative techniques. The basin, which is located close to Rome (Italy) on the west side of the Apennine chain and just north of the Colli Albani volcano, subsided after development of a north–south fault system (about 115 000 y bp). The AAB experiences intense hydrothermal activity, which has produced a large travertine deposit (80‐m thick). The travertine deposit constitutes a fractured aquifer that is the final destination of more than 5 m³ s^‐1 of water and is strongly dewatered by quarry activities. The complex hydrogeology of this basin was investigated, revealing two main hydraulically connected aquifers, one thermalised and partly confined into the limestone bedrock and one unconfined in the travertine. The two aquifers are separated by a non‐continuous clayey aquiclude. The hydrogeological survey and geological characterisation contributed to the development of the groundwater flow conceptual model. Analysis and comparison of the monitored levels highlighted the pattern of flow between the deep and shallow parts of the flow system. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

GIS-based hydrostratigraphic modeling of the city of Rome (Italy): analysis of the geometric relationships between a buried aquifer in the Tiber Valley and the confining hydrostratigraphic complexes   总被引：1，自引：0，他引：1  

C. Di Salvo  E. Di Luzio  M. Mancini  M. Moscatelli  G. Capelli  G. P. Cavinato  R. Mazza 《Hydrogeology Journal》2012,20(8):1549-1567

A preliminary hydrostratigraphic model of the city of Rome (Italy) was completed through the analysis of geological and hydrogeological data, and by using geographic information system (GIS)-based operations. The complex lithostratigraphic setting of a local Quaternary volcano-sedimentary multilayer was simplified into hydrostratigraphic complexes considering textural properties of terrains and hydraulic conductivity values. The Tiber River Valley, in the middle of the urban area, was analyzed separately from the surrounding areas. GIS tools were used in a multiple-step procedure to reconstruct the geometry of bounding surfaces of the main hydrostratigraphic complexes. Particular care was given to the characterization of a confined gravelly aquifer lying at the base of the upper Pleistocene?CHolocene alluvium that fills the Tiber Valley. Updated isobaths and thickness maps of this layer were produced. Three-dimensional reconstruction identifies areas of potential recharge between the alluvium aquifer and the surrounding hydrostratigraphic complexes. In the central sector of the city, the gravel deposits are laterally confined by a thick aquitard corresponding to the Pliocene clayey bedrock of the city; in contrast, a potential recharge area can be hypothesized in the northern areas, where the upper Pleistocene?CHolocene valley cross cuts the Paleotiber Graben, filled with older and highly permeable gravels and clays.  相似文献   

Wind-induced salt-wedge intrusion in the Tiber river mouth (Rome–Central Italy)     

Fabio Manca  Giuseppe Capelli  Francesco La Vigna  Roberto Mazza  Annalisa Pascarella 《Environmental Earth Sciences》2014,72(4):1083-1095

The wind effect on river water quality was illustrated by means of thermohaline measurements carried out in the Tiber River in May 2012. The survey was carried out using a boat, in stations located in the two Tiber branches: Fiumara Grande and Traiano Canal. Thermohaline variables (salinity and temperature) were used to describe the water-type patterns and to define the salt-wedge position. Although the river flow rate was rather high, saltwater intrusion happened. Wind data suggested that the more probable cause of salt-wedge intrusion was the wind action. Especially wind speeds higher than 4 m/s are able to dominate the sea current at surface layers, determining an increase in the sea level. Therefore, westerly winds determined a seawater inflow in the river mouths.  相似文献   

Cold gas accretion in galaxies     

Renzo Sancisi  Filippo Fraternali  Tom Oosterloo  Thijs van der Hulst 《Astronomy and Astrophysics Review》2008,15(3):189-223

Evidence for the accretion of cold gas in galaxies has been rapidly accumulating in the past years. HI observations of galaxies and their environment have brought to light new facts and phenomena which are evidence of ongoing or recent accretion: (1) A large number of galaxies are accompanied by gas-rich dwarfs or are surrounded by HI cloud complexes, tails and filaments. This suggests ongoing minor mergers and recent arrival of external gas. It may be regarded, therefore, as direct evidence of cold gas accretion in the local universe. It is probably the same kind of phenomenon of material infall as the stellar streams observed in the halos of our galaxy and M 31. (2) Considerable amounts of extra-planar HI have been found in nearby spiral galaxies. While a large fraction of this gas is undoubtedly produced by galactic fountains, it is likely that a part of it is of extragalactic origin. Also the Milky Way has extra-planar gas complexes: the Intermediate- and High-Velocity Clouds (IVCs and HVCs). (3) Spirals are known to have extended and warped outer layers of HI. It is not clear how these have formed, and how and for how long the warps can be sustained. Gas infall has been proposed as the origin. (4) The majority of galactic disks are lopsided in their morphology as well as in their kinematics. Also here recent accretion has been advocated as a possible cause. In our view, accretion takes place both through the arrival and merging of gas-rich satellites and through gas infall from the intergalactic medium (IGM). The new gas could be added to the halo or be deposited in the outer parts of galaxies and form reservoirs for replenishing the inner parts and feeding star formation. The infall may have observable effects on the disk such as bursts of star formation and lopsidedness. We infer a mean “visible” accretion rate of cold gas in galaxies of at least . In order to reach the accretion rates needed to sustain the observed star formation (), additional infall of large amounts of gas from the IGM seems to be required.  相似文献   

Hydrologic response of upland catchments to wildfires     

Maria Cristina Rulli  Renzo Rosso 《Advances in water resources》2007

To which extent do wildfires affect runoff production, soil erosion and sediment transport in upland catchments? This transient effect is investigated here by combining data of long term precipitation, sediment yield and wildfire records with a fine resolution spatially distributed modeling approach to flow generation and surface erosion. The model accounts for changes in the structure and properties of soil and vegetation cover by combining the tube-flux approach to topographic watershed partition with a parsimonious parametrization of hydrologic processes. This model is used to predict hydrologic and sediment fluxes for nine small catchments in Saint Gabriel mountains of southern California under control (pre-fire) and altered (post-fire) conditions. Simulation runs using a 45 years record of hourly precipitation show the passage of fire to significantly modify catchment response to storms with a major effect on erosion and flood flows. The probability of occurrence of major floods in the post-fire season is shown to increase up to an order of magnitude under same precipitation conditions. Also, the expected anomaly of sediment yield can increase dramatically the desertification hazard in upland wildfire prone areas. One should further consider the role of firefloods produced by the combined occurrence of wildfires and storms as a fundamental source of non-stationarity in the assessment of hydrologic hazard.  相似文献   

Sunspot Observations and Counting at Specola Solare Ticinese in Locarno Since 1957     

Sergio Cortesi  Marco Cagnotti  Michele Bianda  Renzo Ramelli  Andrea Manna 《Solar physics》2016,291(9-10):3075-3080

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A cross-analysis framework for multi-source volunteered,crowdsourced, and authoritative geographic information: The case study of volunteered personal traces analysis against transport network data     

Gloria Bordogna  Steven Capelli  Daniele E. Ciriello 《地球空间信息科学学报》2018,21(3):257-271

Abstract

The paper discusses the need of a high-level query language to allow analysts, geographers and, in general, non-programmers to easily cross-analyze multi-source VGI created by means of apps, crowd-sourced data from social networks and authoritative geo-referenced data, usually represented as JSON data sets (nowadays, the de facto standard for data exported by social networks). Since an easy to use high-level language for querying and manipulating collections of possibly geo-tagged JSON objects is still unavailable, we propose a truly declarative language, named J-CO-QL, that is based on a well-defined execution model. A plug-in for a GIS permits to visualize geo-tagged data sets stored in a NoSQL database such as MongoDB; furthermore, the same plug-in can be used to write and execute J-CO-QL queries on those databases. The paper introduces the language by exemplifying its operators within a real study case, the aim of which is to understand the mobility of people in the neighborhood of Bergamo city. Cross-analysis of data about transportation networks and VGI from travelers is performed, by means of J-CO-QL language, capable to manipulate and transform, combine and join possibly geo-tagged JSON objects, in order to produce new possibly geo-tagged JSON objects satisfying users’ needs.  相似文献   

The recovery of microalgal production and biomass in a South African temporarily open/closed estuary, following mouth breaching     

Akash Anandraj  Renzo Perissinotto  Christian Nozais  Derek Stretch 《Estuarine, Coastal and Shelf Science》2008,79(4):599-606

Mouth breaching is a recurrent event in temporarily open/closed estuaries (TOCEs). Such disturbances result in flushing and sediment scouring, reducing the microalgal biomass stock. The depletion of these microalgae may have negative repercussions in the form of depleted stocks of commercial fish, game fish, crustaceans and mollusks. The aim of this investigation was therefore: (1) to monitor the recovery of microalgal biomass and production following a breaching event; and (2) to determine the key environmental parameters influencing primary production during the open and recovery phases. Phytoplankton and benthic microalgal production was measured (¹⁴C-uptake method) successively during the closed, open and recovery phases of the Mdloti TOCE (South Africa). Upon breaching, 94–99% of microalgal biomass was washed out to sea through flushing and sediment scouring. A temporary recovery of phytoplankton and benthic microalgal biomass was observed during the open phase, but this was not sustained because of continual flushing and scouring of the sediment. During the re-closure (recovery phase), microalgal biomass immediately increased, reaching pre-breaching levels 35–40 days following the breaching event. In contrast to biomass, autochthonous pelagic primary production reached a maximum level (341 mg C m⁻² h⁻¹) during the open phase. Pelagic primary production normalized to biomass (P^B) significantly increased during the open phase. This is attributed to a favorable combination of optimum light conditions, high influx of macronutrients and high water temperatures (33 °C). Similarly, benthic primary production normalized to biomass (P^B) peaked during the open phase (35 mg C mg chl-a⁻¹ h⁻¹). Multivariate analysis showed that major variations in primary production were mainly controlled by temperature, dissolved inorganic nitrogen (DIN) to phosphorus (DIP) molar ratios (water-column and pore-water) and light extinction (K_d), all of which were regulated by the state of the mouth.  相似文献