214 research outputs found

    The Holocene marine depositional event in the historical centre of Palermo

    Get PDF
    Studi recenti hanno indicato come al di sopra della classica sequenza del Quaternario marino della Piana di Palermo ricorra, in alcunisiti del Centro Storico, un limitato spessore di depositi marini di età post-tirreniana. Con lo scopo di precisare l’età di tali depositi sonostate studiate le associazioni di microfossili di campioni provenienti da sondaggi geognostici. Utilizzando lo schema ecobiozonale anannofossili calcarei recentemente proposto per l’ultima deglaciazione nel Mediterraneo centrale (Canale di Sicilia) detti depositi contengononannoflore attribuibili all’Olocene. Un'analisi al radiocarbonio ha confermato tale attribuzione, limitando alla parte bassadell'Olocene la pertinenza stratigrafica di tali depositi.Recent data have pointed out that, above the classical depositional sequence of the Quaternary marine sediments of the PalermoCoastal plain, post-Tyrrhenian sediments occur. In order to determine the age of these sediments and to confirm the deposition of arecent sedimentary cycle, microfossil assemblage of several samples, coming from geognostic drillings, have been analysed. Usingthe calcareous nannofossil ecobiozone scheme recently proposed for the last deglaciation of the central Mediterranean (SicilyChannel), examined sediments can be ascribed to the Holocene. Radiocarbon analysis confirmed such an attribution providing a moreaccurate stratigraphic determination

    Uniqueness of Planktonic Ecosystems in the Mediterranean Sea: The Response to Orbital- and Suborbital-Climatic Forcing over the Last 130,000 Years

    Get PDF
    The Mediterranean Sea is an ideal location to test the response of organisms to hydrological transformations driven by climate change. Here we review studies carried out on planktonic foraminifera and coccolithophores during the late Quaternary and attempt the comparison of data scattered in time and space. We highlight the prompt response of surface water ecosystems to both orbital- and suborbital-climatic variations. A markedly different spatial response was observed in calcareous plankton assemblages, possibly due to the influence of the North Atlantic climatic system in the western, central and northern areas and of the monsoon system in the easternmost and southern sites. Orbital-induced climatic dynamics led to productive surface waters in the northern, western and central Mediterranean Sea during the last glacial and to distinct deep chlorophyll maximum layers in the eastern Mediterranean Sea coinciding with bottom anoxia episodes. High-frequency planktonic modifications are well documented in the Sicily Channel and Alboran Sea and highlight the occurrence of different steps within a single stadial (cold phase)/interstadial (warm phase) oscillation. The review of planktonic organisms in the marine sedimentary archive casts light on the uniqueness of the Mediterranean Sea, especially in terms of climatic/oceanographic/biological interaction and influence of different climatic systems on distinct areas. Further research is needed in the eastern Mediterranean Sea where results are obscured by low-resolution sedimentary records and by a strong focus on sapropel deposition dynamics

    Junior Students’ with Hearing Impairment Psychological Correction of Learning Motivation Development

    Get PDF
    У статті розглянуто основні методологічні принципи, методи, етапи корекційного процесу. Обґрунтовано використання гуманістичного підходу до корекції мотиваційної сфери учіння та підібрано комплекс корекційних завдань для розвитку цієї сфери в молодших школярів із порушеннями слуху. The article presents basic methodological principles, methods, main stages of correctional process. A humanitarian approach to learning motivation development correction has been grounded and a complex of correctional tasks for junior students with hearing impairment has been selected

    Hydroclimate variability in the central Mediterranean during MIS 17 interglacial (Middle Pleistocene) highlights timing offset with monsoon activity

    Get PDF
    Mediterranean climates are characterized by warm, dry summers and mild, rainy winters. Previous studies suggest that over the last 1.36 Myr, Mediterranean winter rainfalls were in phase with the African monsoon. Here we present a high-resolution terrestrial and marine dataset for the Marine Isotope Stage 17 interglacial (Middle Pleistocene) from Southern Italy, showing that precipitation rates and regimes in the central Mediterranean varied independently of the monsoon system. Specifically, events of extreme summer precipitation were promoted by increased regional insolation rates and/or extratropical cyclones, and their magnitude was further enhanced by the advection of cool and humid North Atlantic air during stadials. Our findings provide new information on the short- to mid-term natural hydroclimatic variability of the Mediterranean basin, and offer new critical insights on land–ocean interactions at the regional scale by complementing previous analyses on the displacement of storm tracks toward southern Europe

    Holocene climate variability of the Western Mediterranean: surface water dynamics inferred from calcareous plankton assemblages

    Get PDF
    A high-resolution study (centennial scale) has been performed on the calcareous plankton assemblage of the Holocene portion of the Ocean Drilling Program Site 976 (Alboran Sea) with the aim to identify the main changes in the surface water dynamic. The dataset also provided a seasonal foraminiferal sea surface water temperatures (SSTs), estimated using the modern analog technique SIMMAX 28, and it was compared with available geochemical and pollen data at the site. Three main climate shifts were identified as (1) the increase in abundance of Syracosphaera spp. and Turborotalita quinqueloba marks the early Holocene humid phase, during maximum summer insolation and enhanced river runoff. It is concomitant with the expansion of Quercus, supporting high humidity on land. It ends at 8.2 ka, registering a sudden temperature and humidity reduction; (2) the rise in the abundances of Florisphaera profunda and Globorotalia inflata, at ca. 8 ka, indicates the development of the modern geostrophic front, gyre circulation, and of a deep nutricline following the sea-level rise; and (3) the increase of small Gephyrocapsa and Globigerina bulloides at 5.3 ka suggests enhanced nutrient availability in surface waters, related to more persistent wind-induced upwelling conditions. Relatively higher winter SST in the last 3.5 ka favored the increase of Trilobatus sacculifer, likely connected to more stable surface water conditions. Over the main trends, a short-term cyclicity is registered in coccolithophore productivity during the last 8 ka. Short periods of increased productivity are in phase with Atlantic waters inflow, and more arid intervals on land. This cyclicity has been related with periods of positive North Atlantic Oscillation (NAO) circulations. Spectral analysis on coccolithophore productivity confirms the occurrence of millennial-scale cyclicity, suggesting an external (i.e. solar) and an internal (i.e. atmospheric/oceanic) forcing.Geoscience PhD scholarship, Universita degli Studi di BariPotenziamento Strutturale dell'Universita degli Studi di Bari, Laboratorio per lo Sviluppo Integrato delle Scienze e delle Tecnologie dei Materiali Avanzati e per dispositivi innovativi (SISTEMA) [PONa3_00369]Fundacao para a Ciencia e a Tecnologia (FCT)Portuguese Foundation for Science and TechnologyEuropean Commission [SFRH/BPD/111433/2015]info:eu-repo/semantics/submittedVersio

    Northern Hemisphere atmospheric pattern enhancing Eastern Mediterranean Transient-type events during the past 1000 years

    Get PDF
    High-resolution climate model simulations for the last millennium were used to elucidate the main winter Northern Hemisphere atmospheric pattern during enhanced Eastern Mediterranean Transient (EMT-type) events, a situation in which an additional overturning cell is detected in the Mediterranean at the Aegean Sea. The differential upward heat flux between the Aegean Basin and the Gulf of Lion was taken as a proxy of EMT-type events and correlated with winter mean geopotential height at 500 mbar in the Northern Hemisphere (20-90 degrees N and 100 degrees W-80 degrees E). Correlations revealed a pattern similar to the East Atlantic/Western Russian (EA/WR) mode as the main driver of EMT-type events, with the past 1000 years of EA/WR-like mode simulations being enhanced during insolation minima. Our model results are consistent with alkenone sea surface temperature (SST) reconstructions that documented an increase in the west-east basin gradients during EMT-type events

    Planktic foraminiferal changes in the western Mediterranean Anthropocene

    Get PDF
    Unidad de excelencia María de Maeztu CEX2019-000940-MAltres ajuts: Acord transformatiu CRUE-CSICThe increase in anthropogenic induced warming over the last two centuries is impacting marine environment. Planktic foraminifera are a globally distributed calcifying marine zooplankton responding sensitively to changes in sea surface temperatures and interacting with the food web structure. Here, we study two high resolution multicore records from two western Mediterranean Sea regions (Alboran and Balearic basins), areas highly affected by both natural climate change and anthropogenic warming. Cores cover the time interval from the Medieval Climate Anomaly to present. Reconstructed sea surface temperatures are in good agreement with other results, tracing temperature changes through the Common Era (CE) and show a clear warming emergence at about 1850 CE. Both cores show opposite abundance fluctuations of planktic foraminiferal species (Globigerina bulloides, Globorotalia inflata and Globorotalia truncatulinoides), a common group of marine calcifying zooplankton. The relative abundance changes of Globorotalia truncatulinoides plus Globorotalia inflata describe the intensity of deep winter mixing in the Balearic basin. In the Alboran Sea, Globigerina bulloides and Globorotalia inflata instead respond to local upwelling dynamics. In the pre-industrial era, changes in planktic foraminiferal productivity and species composition can be explained mainly by the natural variability of the North Atlantic Oscillation, and, to a lesser extent, by the Atlantic Multidecadal Oscillation. In the industrial era, starting from about 1800 CE, this variability is affected by anthropogenic surface warming, leading to enhanced vertical stratification of the upper water column, and resulting in a decrease of surface productivity at both sites. We found that natural planktic foraminiferal population dynamics in the western Mediterranean is already altered by enhanced anthropogenic impact in the industrial era, suggesting that in this region natural cycles are being overprinted by human influences
    corecore