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Last Decades Warming Evidences in the NW Barent Sea (Arctic)
No full textThe Arctic area is responding more rapidly to global warming than most other areas on our planet. The Kveithola Trough located in the NW Barents Sea has an interesting sedimentary record due to its geographical conditions and its dynamic glacial history formation. Its location allows the input and interaction of two of the main water masses, the cold, fresh Arctic Water coming from the north and the warm, salty Atlantic Water flowing from the south. Four sediment cores collected in the Kveithola Trough area during the oceanographic cruise EUROFLEETS2-BURSTER were analysed with regard to benthic foraminiferal assemblages and sedimentological parameters in order to elucidate past variability of the water masses, the organic matter flux and oxygen concentration to the sea floor during the last decades. The foraminiferal assemblages composition and and taxonomic abundance allow inferring significant environmental differences between the evolution of the inner and outer shelf areas. The dominant foraminiferal species recurrent in the study area may indicate that during the last 45 years a higher influence of warm water and an increase in the anoxic conditions has been established along of the Kveithola Trough area. These evidences need to be confirm by further multidisciplinary analysis including biological, sedimentological and chemical data
Environmental changes in Krossfjorden, Svalbard, since 1950 : Benthic foraminiferal and stable isotope evidence
Get PDFEnvironmental changes for the past ca. 50 years were studied in a short sediment core from inner Krossfjorden, Svalbard, investigating benthic foraminifera and stable isotopes (delta O-18, delta C-13). A depth-age model based on anthropogenic Cs-137 time markers indicates that record covers the period from 1955 to 2007 and has sediment accumulation rates of ca. 0.3 to 1 cm/year. The benthic foraminifera are arctic and/or common in glaciomarine environments. Six fauna assemblages were identified using stratigraphically constrained cluster analysis. Benthic foraminiferal fauna assemblages are mainly dominated by Cassidulina reniforme. Elphidium clavatum is dominant from 1973 to 1986 and 2002 to 2007, likely due to greater turbidity in the water column. We interpret the increased percentages of Spiroplectammina biformis over the same intervals to reflect a slightly lower salinity probably caused by meltwater. During a short time period, 1970 to 1973, Stainforthia concava dominates the benthic foraminiferal fauna interpreted to reflect increased productivity within a marginal ice zone. Other species as Islandiella norcrossi, Nonionellina labradorica, Islandiella helenae, and Melonis barleanus also indicate more nutrient-rich waters are present but not very abundant throughout the record probably due to the glacier proximal position of the study site. The stable isotope record (delta O-18) shows lighter values from 2001 to 2007, which seem to correlate well with oceanographic monitoring data showing increasing core temperatures of West Spitsbergen Current.Peer reviewe
Deciphering Paleoceanographic Shifts Inferred from the Foraminiferal Record of the Western Svalbard Slope (Bellsund Drift) over the Past Century
Get PDFThe objective of this study was to reconstruct the last century’s climatic oscillations in the
Arctic region around the Fram Strait using high-resolution analysis of foraminiferal assemblages as
proxies for surface and deep-water mass properties. In this area, warm Atlantic water masses are
advected to the Arctic Ocean through theWest Spitsbergen Current, representing the northernmost
tip of the Global Thermohaline Circulation. The interaction between the cold Arctic and the warm
Atlantic water masses significantly influences the entire foraminiferal community. Planktic species
such as Neogloboquadrina pachyderma and Turborotalita quinqueloba are respectively used as indicators
of cold Arctic water and warm Atlantic water masses. Among the main benthic species, Cibicidoides
wuellerstorfi, Epistominella exigua, and Oridorsalis tener stand out, serving as proxies for the bottom
water mass current velocity and paleoproductivity. The paleoenvironmental reconstruction obtained
with the foraminiferal assemblages, together with data from satellite monitoring of the sea ice extent
and the long-term record of the annual temperature of the West Spitsbergen Current measured over
the last 50 years, support the evidence of a progressively rising heat influx into the Arctic Ocean due
to an increasing Atlantic water inflow, forcing the consequent decay of the sea ice extent
Paleoceanographic changes suggested by planktic and benthic foraminifera in the Western Svalbard Slope (Bellsund Drift) during the last century.
No full textThe objective of this study is to reconstruct the last century’s climatic oscillations in the Western Svalbard Slope (Arctic region) using high-resolution analysis of planktic and benthic foraminiferal assemblages as proxies for surface and deep-water mass properties. In the studied area, warm Atlantic water masses are
advected to the Arctic Ocean through the West Spitsbergen Current, representing the northernmost tip of the Global Thermohaline Circulation. The interaction between the cold Arctic and the warm Atlantic water masses significantly influences the entire foraminiferal community. The paleoenvironmental reconstruction obtained with the microfossil assemblages, together with data from satellite monitoring of the sea ice extent and the long-term record of the annual temperature of the West Spitsbergen Current measured over the last 50 years,
support the evidence of a progressively rising heat influx into the Arctic Ocean due to an increasing Atlantic water inflow, forcing the consequent decay of the sea ice extent
Paleoenviromental changes during the last 2 ka BP in the Eastern Side of Fram Strait.
No full textPolar regions regulate the climate through the heat exchange between ocean and atmosphere, the sea ice
formation or melting, and bottom water formation. Lately, the scientific community has been focusing on the
study of the last 2000 years. This interval gives information about climate natural variability versus change
induced by human activity. Moreover, the studies of environmental changes recorded in this period offer the
possibility to understand how our climate may evolve in the near future. This study is focused on the last 2 ka
BP and has the aim to understand the paleoenvironmental variations in the eastern side of Fram Strait, through
multidisciplinary micropaleontological and sedimentological analyses, focussing on the diatom assemblages.
Two long Calypso cores GS191-01 PC (19.68 m) and GS191-02 PC (17.37 m) were collected on the Bellsund
and Isfjorden Drift, during the expedition of RV G.O. Sars (5th–15th June 2014), in the framework of the
project Eurofleets-2 PREPARED. Here we present the study of the first 80 cm for core GS191-01PC and
the first 18 cm for core GS191-02 PC corresponding to the last 2 ka years BP. The investigated sedimentary
sequence is dominated by muddy, bioturbated sediments with very rare/sparse IRD (Ice Rafted Debris). The
Diatom assemblage was analysed every 2-cm, corresponding to a resolution of 30 years for GS191-01PC and
at every 1-cm in core GS191-02PC, corresponding to a resolution of 126 year. On the basis of the age model
proposed by Caricchi et al. (2019), the multi-proxy analyses on the diatoms and foraminifera assemblages, and
sedimentological data, allowed us to distinguish in the record four different climatic periods indicated as Units.
Unit A (2000 - 1500 cal yr BP) is the older, and indicates relatively warm conditions, suggesting the influence
of warm water with a cooling period between between 1800 to 1700 cal yr BP, characterized by increased sea
ice coverage and the presence of cold water masses.
In unit B (1500 - 1300 cal yr BP) is period of cooler conditions compared with the previous one, and it is
characterized by the presence of extended sea ice and a minor inflow of the warm water.
Unit C (1300- 700 cal yr BP) records a warming surface water with presence of freshwater of continentally
origin. Unit C ends with the worsening of climatic conditions characterized by a progressive cooling.
Unit D (700 cal yr BP to recent) represents a cooling period characterized by extended sea ice coverage and
an increased distribution of cold-water taxa
Paleontological and sedimentological evidences in the Holocenic sedimentary record of the Bellsund Drift (Svalbard – Arctic)
No full textThe Arctic region represents a sensitive area to climatic variations. The Bellsund Drift is located in the Fram
Strait area, between Greenland and Svalbard, and represents the only deep connection to the Arctic Ocean. In
this strait occurs the interaction of two water masses, the warm Atlantic Water (AW) and the cold Arctic water
(ArW). This interaction produces an important heat and mass exchange with the Arctic Ocean, influencing the
climate in the entire Arctic region.
During the EUROFLEETS-2 Cruise PREPARED on board the R/V G.O. Sars, June 2014, a Calypso piston
core GS191-01PC (1647 m water depth), was collected in the Bellsund Drift area. The core contains a highresolution
depositional sedimentary record of the last 20 kyr (Lucchi et al., 2014). For this work, we focused on
the expanded Holocene sequence (more than 5 m-thick), defined using the age model constructed by Caricchi
et al. (2019). Our study is based on the benthic and planktic foraminifera and grain size analysis.
The millennial record of the Bellsund Drift indicates a progressive increase of the water temperature, due
to the incoming of the warm Atlantic water and the decreasing extension of sea-ice, which retreat by melting,
producing cold superficial water masses facilitating the incoming of the AW into the entire water column.
The IRD input during the end of the Upper Pleistocene indicates diffuse sea-ice and cold conditions. Higher
productivity and warmer conditions characterised the Early Holocene. A shift from warm to colder conditions
occurred during the Mid Holocene, affecting the ocean productivity. The Late Holocene showed the prevalence
of surface cold-water conditions related to the sea ice melting, determined by increased AW heat inflow to the
Arctic
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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