Chlorinated compounds and polybrominated diphenyl ethers (PBDEs) in mussels (Mytilus galloprovincialis) collected from Apulia Region coasts     

Santina Giandomenico  Lucia Spada  Cristina Annicchiarico  Giorgio Assennato  Nicola Cardellicchio  Nicola Ungaro  Antonella Di Leo 《Marine pollution bulletin》2013

This project was carried out to assess the levels and spatial distribution of organochlorine compounds in the coastal marine environment, using mussels as bioindicators to evaluate the coastal water quality. Levels of polychlorobiphenils (PCB), chlorinated pesticides (DDT isomers, HCH isomers, Aldrin, Dieldrin, alfa-Endosulfan, Hexachlorobenzene, Pentachlorobenzene) and polybrominated diphenyl ethers (PBDEs) were determined in tissues from mussels (Mytilus galloprovincialis) collected along the Apulia Region coasts (Mediterranean Sea). Results indicate that contamination by organochlorine compounds is higher in mussels sampled in the Ionian Sea than in those from the Adriatic Sea, with PCB levels up to seven times higher in mussels from Ionian than from the Adriatic Sea. Although PCB levels were above the maximum values indicated by both European Community (EC) and National regulation in several sample sites, the PCB concentrations were particularly high in some stations, suggesting that these locations require a much specific attention. Conversely, results on the mussel contamination by PBDEs highlight their ubiquitous environmental distribution, and underline the need to establish the maximum level for these compounds in foodstuff, according to European Regulations.  相似文献   

Landslide HotSpot Mapping by means of Persistent Scatterer Interferometry   总被引：1，自引：0，他引：1  

Silvia Bianchini  Francesca Cigna  Gaia Righini  Chiara Proietti  Nicola Casagli 《Environmental Earth Sciences》2012,67(4):1155-1172

Landslide detection and mapping represent fundamental requirements for every hazard and risk evaluation and consequent improvement of the management strategies for such natural hazards. Optical and radar remote sensing can be used to observe landslide-induced ground deformation, ranging from regional to local scales. This work presents a methodology called Landslide HotSpot Mapping; this approach integrates cartographic, thematic and optical data with Persistent Scatterer Interferometry for the identification of extremely slow to very slow moving landslides, and for the evaluation of their state of activity and intensity. This methodology scans wide areas to detect hotspots, which are narrow unstable zones characterized by higher landslide hazard. To these hotspots, priority has to be given when planning field surveys and in situ validation campaigns, so that field work time and effort can be optimized and significantly reduced. The approach is tested in Central Calabria, over a 4,470?km² area located in southern Italy. ENVISAT ascending images acquired between 2003 and 2009 and processed with the Persistent Scatterer Pairs (PSP) technique are used to analyse deformation patterns. Combining conventional photo-interpretation with the analysis of PSP data, 64 new landslides are identified and the spatial (boundaries) and temporal (activity) information of 980 pre-mapped phenomena (23.6% of updated inventory) are updated. 1,012 active (continuous or reactivated) landslides are identified and 4 hotspot areas selected: San Fili, Rende, Lago, Catanzaro. Urgent field checks have to be organized for these hotspots to validate the satellite-based observations and to design appropriate mitigation measures to reduce impacts on the elements at risk.  相似文献   

Middle and late Pleistocene glaciations in the Campo Felice Basin (central Apennines, Italy)   总被引：1，自引：0，他引：1  

Carlo Giraudi  Giulia Bodrato  Nicola Cipriani  Biagio Giaccio 《Quaternary Research》2011,75(1):219-230

The present paper refers to research conducted in the tectonic-karst depression of Campo Felice in the central Apennines (Italy), in which glacial, alluvial and lacustrine sediments have been preserved. Stratigraphic interpretations of sediments underlying the Campo Felice Plain are based on evidence obtained from nine continuous-core boreholes. The boreholes reach a depth of 120 m and provide evidence of five sedimentation cycles separated by erosion surfaces. Each cycle is interpreted as an initial response to a mainly warm stage, characterized by low-energy alluvial and colluvial deposition, pedogenesis, and limited episodes of marsh formation. In turn, a mainly cold stage follows during which a lake formed, and glaciers developed and expanded, leading to deposition of glacial and fluvioglacial deposits. The chronological framework is established by eleven accelerator mass spectrometer ¹⁴C ages and three ³⁹Ar-⁴⁰Ar ages on leucites from interbedded tephra layers. These age determinations indicate five glacial advances that respectively occurred during marine oxygen isotope stages 2, 3-4, 6, 10 and 14.  相似文献   

Quantifying Multipath Using MNR Ratios     

Ricardo Ernesto Schaal  Nicola Paciléo Netto 《GPS Solutions》2000,3(3):44-48

The global positioning system (GPS) is used increasingly to control horizontal and vertical displacement of large civil constructions. The displacements can occur over varius time scales. For example, in case of the loading test of a bridge, the time span between measurements is on the order of 30 min. The achievable precision in the vertical component and its relation to residual multiplath effects become critically important in such aaplications. A multipath-to-noise ratio (MNR) on individual satellites is introduced to quantify the multipath effects. ? 2000 John Wiley & Sons, Inc.  相似文献   

Examining the difficulties in letting social housing within England     

Nicola Morrison 《GeoJournal》2000,51(4):339-349

This paper provides an overview of the current literature on why difficulties are being experienced in letting social housing within England. The first part of the paper focuses on whether the management of the social housing stock, and in particular the current allocation system, has contributed to the growing number of difficult to let (DTL) properties in the social sector. Drawing on findings from in-depth interviews with twenty local authorities, the paper provides evidence to support this argument and also highlights a number of initiatives which authorities have adopted to fill DTL properties. However, the paper argues that these initiatives are likely to have limited value in the long run in stemming the fall in demand for social housing, particularly in the North of England. The second part of the paper focuses on the changing aspirations of tenants and the way that social housing is in competition with alternative forms to housing provision, such as private rented housing. It concludes by advocating that an appropriate response to difficulties in letting social housing has to go beyond internal housing management initiatives. Instead a more strategic approach needs to be adopted which builds up an understanding of the operation of the local housing market and the complex interaction of neighbourhoods.  相似文献   

Regularized tomographic inversion with geological constraints          下载免费PDF全文

Vincenzo Lipari  Domenico Urbano  Emmanuel Spadavecchia  Jacopo Panizzardi  Nicola Bienati 《Geophysical Prospecting》2017,65(1):305-315

Reflection tomography is the industry standard tool for velocity model building, but it is also an ill‐posed inverse problem as its solution is not unique. The usual way to obtain an acceptable result is to regularize tomography by feeding the inversion with some a priori information. The simplest regularization forces the solution to be smooth, implicitly assuming that seismic velocity exhibits some degree of spatial correlation. However, velocity is a rock property; thus, the geometry and structure of rock formations should drive correlation in velocity depth models. This observation calls for constraints driven by geological models. In this work, we present a set of structural constraints that feed reflection tomography with geometrical information. These constraints impose the desired characteristics (flatness, shape, position, etc.) on imaged reflectors but act on the velocity update. Failure to respect the constraints indicates either velocity inaccuracies or wrong assumptions concerning the constraints. Reflection tomography with structural constraints is a flexible framework that can be specialized in order to achieve different goals: among others, to flatten the base of salt bodies or detachment surfaces, to recover the horizontalness of oil–water contacts, or to impose the co‐location of the same imaged horizon between PP and PS images. The straightforward application of structural constraints is that of regularizing tomography through geological information, particularly at the latest stages of the depth imaging workflow, when the depth migration structural setting reached a consistent geological interpretation. Structural constraints are also useful in minimizing the well‐to‐seismic mis‐ties. Moreover, they can be used as a tool to check the consistency of interpreters' hypothesis with seismic data. Indeed, inversion with structural constraints will preserve image focusing only if the interpreters' insights are consistent with the data. Results from synthetic and real data demonstrate the effectiveness of reflection tomography with structural constraints.  相似文献   

Mechanisms linking active rock glaciers and impounded surface water formation in high‐mountain areas          下载免费PDF全文

Nicola Colombo  Luigi Sambuelli  Cesare Comina  Chiara Colombero  Marco Giardino  Stephan Gruber  Gaetano Viviano  Livia Vittori Antisari  Franco Salerno 《地球表面变化过程与地形》2018,43(2):417-431

Rock glaciers are slowly flowing mixtures of debris and ice occurring in mountains. They can represent a reservoir of water, and melting ice inside them can affect surface water hydrochemistry. Investigating the interactions between rock glaciers and water bodies is therefore necessary to better understand these mechanisms. With this goal, we elucidate the hydrology and structural setting of a rock glacier–marginal pond system, providing new insights into the mechanisms linking active rock glaciers and impounded surface waters. This was achieved through the integration of waterborne geophysical techniques (ground penetrating radar, electrical resistivity tomography and self‐potentials) and heat tracing. Results of these surveys showed that rock glacier advance has progressively filled the valley depression where the pond is located, creating a dam that could have modified the level of impounded water. A sub‐surface hydrological window connecting the rock glacier to the pond was also detected, where an inflow of cold and mineralised underground waters from the rock glacier was observed. Here, greater water contribution from the rock glacier occurred following intense precipitation events during the ice‐free season, with concomitant increasing electrical conductivity values. The outflowing dynamic of the pond is dominated by a sub‐surface seepage where a minor fault zone in bedrock was found, characterised by altered and highly‐fractured rocks. The applied approach is evaluated here as a suitable technique for investigating logistically‐complex hydrological settings which could be possibly transferred to wider scales of investigation. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Transport of moderately sorted gravel at low bed shear stresses: The role of fine sediment infiltration          下载免费PDF全文

Emeline Perret  Céline Berni  Benoît Camenen  Albert Herrero  Kamal El Kadi Abderrezzak 《地球表面变化过程与地形》2018,43(7):1416-1430

A reliable estimation of sediment transport in gravel‐bed streams is important for various practical engineering and biological studies (e.g., channel stability design, bed degradation/aggradation, restoration of spawning habitat). In the present work, we report original laboratory experiments investigating the transport of gravel particles at low bed shear stresses. The laboratory tests were conducted under unsteady flow conditions inducing low bed shear stresses, with detailed monitoring of the bed topography using a laser scanner. Effects of bed surface arrangements were documented by testing loose and packed bed configurations. Effects of fine sediments were examined by testing beds with sand, artificial fine sand or cohesive silt infiltrated in the gravel matrix. Analysis of the experimental data revealed that the transport of gravel particles depends upon the bed arrangement, the bed material properties (e.g., size and shape, consolidation index, permeability) and the concentration of fine sediments within the surface layer of moving grains. This concentration is directly related to the distribution of fine particles within the gravel matrix (i.e., bottom‐up infiltration or bridging) and their transport mode (i.e., bedload or suspended load). Compared to loose beds, the mobility of gravel is reduced for packed beds and for beds clogged from the bottom up with cohesive fine sediments; in both cases, the bed shear stress for gravel entrainment increases by about 12%. On the other hand, the mobility of gravel increases significantly (bed shear stress for particle motion decreasing up to 40%) for beds clogged at the surface by non‐cohesive sand particles. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Assessment of a monumental masonry bell-tower after 2016 Central Italy seismic sequence by long-term SHM     

Filippo Ubertini  Nicola Cavalagli  Alban Kita  Gabriele Comanducci 《Bulletin of Earthquake Engineering》2018,16(2):775-801

The response of the San Pietro monumental bell-tower located in Perugia, Italy, to the 2016 Central Italy seismic sequence is investigated, taking advantage of the availability of field data recorded by a vibration-based SHM system installed in December 2014 to detect earthquake-induced damages. The tower is located about 85 km in the NW direction from the epicenter of the first major shock of the sequence, the Accumoli Mw6.0 earthquake of August 24th, resulting in a small local PGA of about 30 cm/s², whereby near-field PGA was measured as 915.97 cm/s² (E–W component) and 445.59 cm/s² (N–S component). Similar PGA values also characterized the two other major shocks of the sequence (Ussita Mw5.9 and Norcia Mw6.5 earthquakes of October 26th and 30th, respectively). Despite the relatively low intensity of such earthquakes in Perugia, the analysis of long-term monitoring data clearly highlights that small permanent changes in the structural behavior of the bell-tower have occurred after the earthquakes, with decreases in all identified natural frequencies. Such natural frequency decays are fully consistent with what predicted by non-linear finite element simulations and, in particular, with the development of microcracks at the base of the columns of the belfry. Microcracks in these regions, and in the rest of tower, are however hardly distinguishable from pre-existing ones and from the physiological cracking of a masonry structure, what validates the effectiveness of the SHM system in detecting earthquake-induced damage at a stage where this is not yet detectable by visual inspections.  相似文献   

Characterization of carbon monoxide,methane and nonmethane hydrocarbons in emerging cities of Saudi Arabia and Pakistan and in Singapore     

Barbara?BarlettaEmail authorView author&#;s OrcID profile  Isobel?J.?Simpson  Nicola?J.?Blake  Simone?Meinardi  Louisa?K.?Emmons  Omar?S.?Aburizaiza  Azhar?Siddique  Jahan?Zeb  Liya?E.?Yu  Haider?A.?Khwaja  Muhammad?A.?Farrukh  Donald?R.?Blake 《Journal of Atmospheric Chemistry》2017,74(1):87-113

We investigate the composition of 63 C₂-C₁₀ nonmethane hydrocarbons (NMHCs), methane (CH₄) and carbon monoxide (CO), in Jeddah, Mecca, and Madina (Saudi Arabia), in Lahore, (Pakistan), and in Singapore. We established a database with which to compare and contrast NMHCs in regions where ambient levels and emissions are poorly characterized, but where conditions are favorable to the formation of tropospheric ozone, and where measurements are essential for improving emission inventories and modeling. This dataset will also serve as a base for further analysis of air pollution in Western Saudi Arabia including, but not limited to, the estimation of urban emissions and long range pollution transport from these regions. The measured species showed enhanced levels in all Saudi Arabian cities compared to the local background but were generally much lower than in Lahore. In Madina, vehicle exhaust was the dominant NMHC source, as indicated by enhanced levels of combustion products and by the good correlation between NMHCs and CO, while in Jeddah and Mecca a combination of sources needs to be considered. Very high NMHC levels were measured in Lahore, and elevated levels of CH₄ in Lahore were attributed to natural gas. When we compared our results with 2010 emissions from the MACCity global inventory, we found discrepancies in the relative contribution of NMHCs between the measurements and the inventory. In all cities, alkenes (especially ethene and propene) dominated the hydroxyl radical (OH) reactivity (k _OH) because of their great abundance and their relatively fast reaction rates with OH.  相似文献