palaeoproductivity in the ross sea antarctica during the last 15 kyr bp and its link with ice core temperature proxies

AbstractA detailed study of organic carbon content obtained from two sediment cores collected in the Joides basin, western Ross Sea, Antarctica, was carried out. The variations observed during the last deglaciation and the Holocene were compared to the high-resolution climatic records (EPICA DC and Taylor Dome) preserved in the ice. The importance of the carbon content as a proxy for palaeoclimatic and palaeoenvironmental changes was investigated. A dramatic decrease in the Ross Sea palaeoproductivity was observed during the Antarctic Cold Reversal (12.5–14 kyr BP). Another decrease in total organic carbon in the second half of the Holocene (after 5–6 kyr BP) confirms the climate worsening observed in previous studies

EVENTI NELL'EVOLUZIONE TARDO-QUATERNARIA DI UN SETTORE DEL MARE DI ROSS (ANTARTIDE) E DELLO STRETTO DI MAGELLANO (RAMO PACIFICO)

1994/1995VIII Ciclo1964Versione digitalizzata della tesi di dottorato cartacea

Ostracod and Foraminifer Responses to Late Pleistocene–Holocene Volcanic Activity in Northern Victoria Land as Recorded in Ross Sea (Antarctica) Marine Sediments

The impacts on ostracods and foraminifers caused by three Late Quaternary ashfalls of different intensities and recovered in the ANTA02-NW2 core sediments (Drygalski Basin, western Ross Sea) were analysed for the first time. Albeit with different timing, both associations demonstrated similar response patterns associated with the deposition of material from volcanic eruptions. In particular, based on the palaeontological evidence, it was possible to divide the cores into four intervals/phases recording the evolution of the ecosystem before and after the deposition events: (1) Pre-extinction phase (high abundance and high diversity values). (2) Extinction phase, characterised by the complete disappearance of ostracod fauna; the foraminiferal assemblage, although not entirely absent, records extremely low values of abundance and diversity (survivor assemblage). (3) Recovery phase (increasing abundance and diversity values), characterised by the recolonisation of some opportunistic taxa; species such as Australicythere devexa and Australicythere polylyca dominate the ostracod assemblage. (4) Post-extinction phase (high abundance and high diversity values), with the return to an environmental equilibrium characterised by the colonisation of specialised taxa such as Argilloecia sp., Cytheropteron sp., Echinocythereis sp., and Hemicytherura spp. Our results may aid in the understanding of how communities (i.e., ostracods and foraminifers) recovered after the impact of direct deposits of volcanic ash into ocean waters. The mechanisms by which disappearance and/or mortality was induced are still not clear. The release of toxic metals during the reaction of the volcanic ash with seawater, the resulting chemical alteration in the seawater, and the change in pH, together with the possible suppression of planktonic organisms, may have caused the two main extinction phases recorded by the ANTA02-NW2 core sediments

Accumulation of As, Cd, Pb, and Zn in sediment, chironomids and fish from a high-mountain lake: First insights from the Carnic Alps

Though mountain lakes are generally much less influenced by human activities than other habitats, anthropogenic threats can still alter their natural condition. Amajor source of global environmental pollution inmountain ecosystems is trace element contamination. For this studywe investigated for the first time the accumulation of As, Cd, Pb, and Zn in sediment, Diptera Chironomidae (prey), and bullhead Cottus gobio (predator) in a typical high-mountain lake (Dimon Lake) in the Carnic Alps. Significant differences in trace element levels were observed between sediment, Diptera Chironomidae, and C. gobio liver and muscle samples (Kruskal-Wallis test; p b .03 for all elements). As and Pb levels were highest in sediment, Cd and Zn levels were highest in Diptera Chironomidae, and the lowest values for all elementswere measured in C. gobio muscle and liver. Bioaccumulation factor values weremuch higher in Diptera Chironomidae than fish muscle and liver, with the highest values recorded for Cd (5.16) and Zn (4.37). Trophic transfer factor valueswere very lowfor all elements in fish muscle and liver, suggesting a biodilution effect along the food chain. Further studies are needed to expand on these first findings that provide useful insights to inform environmental monitoring and policy in remote high-mountain lakes

Infralittoral ostracode fauna of Porto Puddu Rias (northern Sardinia)

The knowledge of the infralittoral ostracodes presents an increasing interest since it is an essential tool for several fields of research such as human impact of the coastal environments, including environmental monitoring, geoarchaeology and reconstruction of ancient shorelines. The study of the infralittoral ostracode fauna of a small bay of northern Sardinia may represent an useful piece of this knowledge. This bay near Porto Puddu is characterized by shallow seafloors presenting wide vegetated areas, progression of the shoreline and seasonal strem (southern sector). Moreover, its water column is conditioned by winds along the year (Astraldi et al., 1980)

Foraminifer and ostracod occurrence in a cool-water carbonate factory of the cape adare (Ross sea, Antarctica): A key lecture for the climatic and oceanographic variations in the last 30,000

Foraminifers and ostracods were studied in a gravity-core recovered near Cape Adare (Ross Sea, Antarctica) with the aim of identifying the climatic and oceanographic variations during the last 30 ka. The sedimentary sequence represents conditions of a cool-water carbonate factory, which evidences that during the Marine Isotope Stage 2 (MIS2) the area was ice-free and very productive. The overall preservation of delicate skeletal remains such as bryozoans and molluscs indicated moderate bottom currents. This carbonate factory was interrupted by some terrigenous levels, representing conditions of instability/retreat of the ice shelves southward. The younger levels were referred to the meltwater pulse (MWP)-1A and 1B events. The Holocene sequence comprised more terrigenous sediments, reflecting high bottom-currents similar to the present-day conditions. Very abundant and well preserved foraminifers and ostracods, representative of shelf-upper slope paleoenvironments, were recovered. Epistominella exigua, among the foraminifers, suggested the influence of the Circumpolar Deep Water during some periods of the late Quaternary. Heavy-test taxa, such as Cibicides refulgens, indicated strengthening bottom hydrodynamics. As for the ostracods, peaks in the presence of Australicythere devexa, Bairdoppilata simplex and Pseudocythere aff. caudata together with significant values of Polycope spp. allowed us to identify environments rich in nutrients with the influence of cold and deep water upwelling phenomena

OSTRACOD FAUNA FROM THE SEDIMENTS OF LAGO DI BORDAGLIA (FRIULI VENEZIA GIULIA - NE ITALY)

Research on recent freshwater ostracods of Friuli Venezia Giulia region has not been carried out on a regular basis and available data mostly rely on occasional investigations (COLIZZA et al., 1987; 1990). However, detailed accounts on taxonomy, ecology and geographic distribution of ostracods in Friuli Venezia Giulia have recently been published (PIERI et al., 2009; STOCH, 2003; 2004). In this study, we analyzed 55 bottom sediments collected in Lago di Bordaglia, a small glacial lake located in the northernmost sector of the Carnic Alps at altitudes of 1750 m a.s.l., during three different summer surveys (1991,1992 and 2012). Bathymetry, physical and hydrochemical variables were measured (pH, Oxygen, Carbonates), sedimentological (textural) analysis was also carried out

Divulgazione scientifica nella sezione di Trieste del Museo Nazionale dell'Antartide

Defining the cultural mission of the nation museum of Antarctica and in general of the science museum is a complex issue

Scienza e cultura nel Museo Nazionale dell\u2019Antartide Felice Ippolito (Sezione di Trieste)

Essiste nel nostro pianeta un immenso laboratorio naturale per lo studio dei grandi problemi del futuro. Questo laboratorio \ue8 l'Antartide, il continente pi\uf9 affascinante ed inesplorato della terra. Per rendere noto e visibile ad un ampio pubblico lo sforzo scientifico ed economico del nostro paese, viene proposta la creazione di un Museo per l'Antartide che ha l'obiettivo di rendere disponibili le attivit\ue0 di ricerca effettuate dall'Italia nel Continente Bianco, nonch\ue9 di valorizzare e riscoprire la coscienza storica polare italiana. Al Museo \ue8 altres\uec affidato il compito di promuovere la diffusione e la divulgazione dei risultati dell'attivit\ue0 scientifica svolta in Antartide, nonch\ue9 la formzione tecnica e scientifica delle scienze polari a vari livelli