Relative sea-level (RSL) evolution during Marine Isotopic Stage (MIS) 5 in the Mediterranean basin is still not fully understood despite a plethora of morphological, stratigraphic and geochronological studies carried out on highstand deposits of this area. In this review we assembled a database of 323 U/Th-dated samples (e.g. corals, molluscs, speleothems) which were used to chronologically constrain RSL evolution within MIS 5. The application of strict geochemical criteria to the U/Th samples indicates that only ~33% of data available for the Mediterranean Sea can be considered ‘reliable’. Most of these data (~65%) refer to the MIS 5e highstand, while only ~17% could be related to the MIS 5a. No attribution to MIS 5c can be unequivocally supported. Nevertheless, the resulting framework does not allow us to define a satisfactory RSL trend during the MIS 5e highstand and subsequent MIS 5 substages. Overall, the proposed selection of reliable/unreliable data would be useful for detecting areas where MIS 5 substage attributions are not supported by confident U/Th chronological data and thus the related reconstructions need to be revised. In this regard, the resulting framework calls for a reappraisal and re-examination of the Mediterranean records with advanced geochronological methodologies. 相似文献
Geotechnical and Geological Engineering - Distribution constant, (Kc) is employed to account for desorption of water molecules from soil particles. When water molecules have strong affinity for... 相似文献
Reducing Emissions from Deforestation and forest Degradation (REDD+) has emerged as a promising climate change mitigation mechanism in developing countries. In order to identify the enabling conditions for achieving progress in the implementation of an effective, efficient and equitable REDD+, this paper examines national policy settings in a comparative analysis across 13 countries with a focus on both institutional context and the actual setting of the policy arena. The evaluation of REDD+ revealed that countries across Africa, Asia and Latin America are showing some progress, but some face backlashes in realizing the necessary transformational change to tackle deforestation and forest degradation. A Qualitative Comparative Analysis (QCA) undertaken as part of the research project showed two enabling institutional configurations facilitating progress: (1) the presence of already initiated policy change; and (2) scarcity of forest resources combined with an absence of any effective forestry framework and policies. When these were analysed alongside policy arena conditions, the paper finds that the presence of powerful transformational coalitions combined with strong ownership and leadership, and performance-based funding, can both work as a strong incentive for achieving REDD+ goals.
Key policy insights
The positive push of already existing policy change, or the negative stress of resource scarcity together with lack of effective policies, represents institutional conditions that can support REDD+ progress.
Progress also requires the presence of powerful transformational coalitions and strong ownership and leadership. In the absence of these internal drivers, performance-based funding can work as a strong incentive.
When comparing three assessments (2012, 2014, 2016) of REDD+ enabling conditions, some progress in establishing processes of change can be observed over time; however, the overall fluctuation in progress of most countries reveals the difficulty in changing the deforestation trajectory away from business as usual.
Greek intermediate‐depth earthquakes, occurring in the subducted plate of the Hellenic Arc, are felt at greater distances than expected, reaching Italy in some cases. We study in detail macroseismic intensity data from intermediate‐depth Italian and Greek earthquakes collected from Internet users who felt the shaking in Italy. The huge amount of data allowed us to outline the felt/not‐felt limit and to find a correspondence between attenuation areas and the presence of asthenospheric material at shallow depths. We show that plate boundaries, known to produce the majority of earthquakes, are, in some specific cases, the boundaries of areas in which earthquakes are felt. The Ionian subducted lithosphere propagates seismic waves with low attenuation over large distances, whereas high‐attenuation zones in Italy, linked to asthenospheric upwelling, limit the propagation, as evidenced also by PGA values. We identify a typical pattern that can be used to recognize intermediate‐depth earthquakes, and to properly locate historical events. 相似文献
The Buenos Aires (Argentina) and Venice (Italy) coastlands have experienced significant saltwater contamination of the phreatic
aquifer, coastal erosion, hydrodynamic changes and relative sea level rise processes due to natural and man-induced factors.
These factors expose coastal areas to morpho-hydro-geological hazards, such as soil desertification, frequency and degree
of flooding, littoral erosion, and the silting of river mouths and channels. Man-made interventions and actions, such as beach
mining, construction of coastal structures and exploitation of aquifers without an adequate knowledge of the hydrology setting
and an adequate management program, worsen these natural hazards. Uncontrolled human activity induces environmental damage
to the overall coastal plains. The coastal plains play an important role in the social/economic development of the two regions
based on land use, such as agriculture, horticulture, breeding, and tourism, as well as industry. Results of investigations
on saltwater contamination, sea level rise and morphological changes recently performed in these two coastal areas are presented
here. 相似文献
In this paper we present the 18O profile of Globigerinoides ruber measured in the GT90/3 shallow water Ionian sea core, dated with high precision. The 18O profile covers the period 1200–1900 AD, with a resolution of 3.87 years. This long record of 700 years of 18O allows us to identify the imprint of the solar cycle in a climatic record. In fact, the spectral analysis of the time series performed with different methods shows a dominant periodicity of about 11 years with an amplitude of 0.07. The signal is in opposition to the sunspot number cycle. This component is identified at a high significance level by Monte Carlo Singular Spectrum Analysis (MC-SSA). 相似文献
The residual (time-average) salinity and circulation in a numerical ocean model of the Tampa Bay estuary are shown to experience
significant temporal variation under realistic forcing conditions. A version of the Estuarine Coastal Ocean Model developed
for Tampa Bay with 70 by 100 horizontal grid points and 11 sigma levels is examined for the years 2001–2003. Model output
variables are averaged over the entire time of the simulation to generate long-term residual fields. The residual axial current
is found to be dominated by the buoyancy-driven baroclinic circulation with an outflow (southwestward) at the surface and
to the sides of the shipping channel, and an inflow (northeastward) usually occurring subsurface within or above the shipping
channel. Averages over 30 d are used to examine variations in the residual fields. During the simulation the average surface
salinity near the head of Tampa Bay varies with the freshwater inflow, from 12‰ to 33%. At the bay mouth salinity varies from
30%. to 36%.. A localized measure of the baroclinic circulation in the shipping channel indicates the residual circulation
can vary strongly, attaining a magnitude triple the long-term mean value. The baroclinic circulation can be disrupted, going
to near zero or even reversing, when the buoyancy-driven flow is weak and the surface winds are to the northeast. Three time
periods, representing different environmental conditions, are chosen to examine these results in detail. A scaling argument
indicates the relative strength of buoyancy versus wind as ΔρgH2(LCDω2)−1, where δρ is head-to-mouth density difference across the bay,g is gravitational acceleration,H is depth,L is bay length,CD is the surface wind drag coefficient, andw is wind speed. Tampa Bay is usually in the buoyancy dominated regime. The importance of winds in the weak-buoyancy case is
demonstrated in an additional simulation without wind stress. 相似文献
Tidal conditions differently influence inter‐tidal organisms in terms of general physiological and metabolic responses. In this study we investigated the morphological response in shells of Mytilus galloprovincialis native to different micro‐tidal coastal environments in the Northern Adriatic Sea. Our purpose was to highlight the ecophenotypic variability across tidal levels and to elucidate how tidal currents and waves produced by anthropogenic activities may play a part in modulating shell morphology. Three sampling sites were selected: an open‐sea area 15 km off‐shore and two sites within the lagoon of Venice, the first near one of its three inlets, and the other one in the proximity of Venice city centre. At each sampling site, organisms were seasonally collected at different depths within their vertical zonation, either in the inter‐tidal zone – i.e. at both the highest and lowest tide zonation limits, and subtidally. The mussel shells were analysed by investigation of their morphometric relationships (height/length and width/length ratios) and by elliptic Fourier analysis of the shell contours. Shell thickness and condition index were also evaluated for a better comprehension of energy allocation/partitioning. Estimates based on long‐term measurements, visual observation, wind statistics and wave growth laws allowed an evaluation of the forces acting on shells. At the open‐sea site, the observed phenotypic variability of both shell shape and thickness was clearly related to the tidal vertical zonation. At the two lagoon sites, the currents generated by tidal flow through the inlet and the waves caused by the frequent passage of boats influenced both shell shape and thickness. A trade‐off between protection and growth was apparent along the tide gradient, as emphasized by the differences in the partitioning and allocation of energy between shell and flesh production. 相似文献