24 research outputs found
Glacial, \ufb02uvioglacial and \ufb02uvial sedimentary discharge in the northwestern coastal sectorof the Ross Sea continental margin since upper Miocene to LGM
The Borchgrevink Coast stretches from the Coulman Island northward to the Cape Adare for at least 200 km, bordering the western side of the northern Drygalski Trough. The early phase of the acquisition objectives of the PNRAProjectGlevors(GlacialEvolutioninthenorthwesternRossSea,offshoreNorthVictoriaLand,Antarctica) was accomplished in the north western coastal sector of the Ross Sea continental margin along the Borchgrevink Coast, from Coulman Island to Cape Hallett. Single channel seismic and sub bottom pro\ufb01les, swath bathymetry and gravity cores were collected during the Austral summer of 2016/2017, by the scienti\ufb01c research vessel OGS/Explora. The studied area along this segment of the Borchgrevink Coast documents, by the analysis and the interpretation of available geophysical, geological and oceanographic data, the paleo ice discharge and ice \ufb02owing patterns of the inferred Mariner-Borchgrevink and Tucker coastal glaciers, since at least the Upper Miocene until the Holocene Time. The repeated and possibly asynchronous oscillations of these valley glaciers from the North Victoria Land coast, at least about tens km offshore, and their interaction with fast \ufb02owing ice streams from the south are recorded. In particular, the analysis of the architecture and of the geometrical relationship of the interpreted seismic facies and units allows to infer past glacial and interglacial environments. Modelling of paleo environments and related climate condition is achieved despite the age constrain uncertainty of local seismic stratigraphy and of biostrathigraphic correlations to coeval sediment section in southern Ross Sea inner-shelf sector (McMurdo Sound), and besides the acoustic facies ambiguity due to not enough data resolution. The interpreted shallower and Holocene-Present glacial related features are simple or composite ice-marginal landforms, with overstepping smaller recessional deposits on top or behind. They testify the coastal glaciers grounded events and the ice retreat modality during the pre-LGM and the LGM. We infer that northern coastal glaciers, from the Tucker glacier northward, about 72\u25e6 latitude, did not advance or reach the northwestern Ross Sea shelf edge at the LGM, but possibly before. The grounding line of NVL coastal glaciers would correlate with the pre-LGM grounding lineament reconstructed for the major ice-streams \ufb02owing from the south. More ancient and buried wedge, underlying the main composite Grounding Zone Wedge (GZW) system raises the issue if it was possible the formation and the preservation as a pinning point, of a previously developed GZW or of the upper part of a \ufb02uvioglacial delta in late Miocene or Pliocene time. Moreover, further offshore from the coast, the evidence, of an ancient buried glacial/\ufb02uvioglacial or \ufb02uvial delta, embedded within the glaciomarine clinoforms of the Trough Mouth Fans (TMFs) deposits \ufb01lling the Northern Drygalski Trough, suggest climate change and an inferred preceding coastal open-sea condition
The discovery of the southernmost ultra-high-resolution Holocene paleoclimate sedimentary record in Antarctica
The response of the Antarctic ice sheet to climate warming is the main source of uncertainty regarding future global sea level rise, since little is known about its present and past dynamics. The last deglaciation is the most recent interval of large-scale climate warming, during which the Northern and Southern Hemisphere ice sheets retreated, and sea level rose globally, although at a non-uniform rate. Geologic records from the polar regions are
fundamental in determining the factors that caused the major changes in ice sheets during the last deglacial under different boundary conditions. Here, we combine morpho-bathymetric and seismic data with sediment cores and oceanographic measurements to reconstruct the processes that influenced the deposition of the southernmost, most extensive, ultrahigh-resolution record of the Holocene in Edisto Inlet fjord (Ross Sea,
Antarctica). We find that post-glacial sedimentation resulted in a layered diatom mud up to 110 m thick that was locally redistributed by bottom currents over confined drifts-moats in the central part of the fjord. After the Holocene climatic optimum, the fjord was not carved by ground ice, and there continued to be internal fjord water circulation associated with Ross Sea circulation. These results support a retreat of coastal glaciers by about
11 kiloyears ago (ka) from the continental shelf of North Victoria Land
The newly discovered Odyssea Drift (Ross Sea): preliminary results
The Hillary Canyon is one of the main conduits for dense shelf water forming in the Ross Sea, over-flowing the
shelf edge and transforming into the Antarctic Bottom Water (AABW). The main changes in past ocean circulation
are recorded in the adjacent sediment drift. A wealth of data was acquired on the drift west of the Hillary
Canyon during the 2017 OGS Explora expedition, which included the PNRA ODYSSEA and EUROFLEETS
ANTSSS projects. The multi-disciplinary dataset acquired includes: single channel seismics, sub-bottom profiling,
multibeam bathymetry, gravity and box cores, XBT launching, water sampling, CTD, L-ADCP, ADCP-VM,
turbidity and florescence profiling. The sediment drift, which we named Odyssea Drift, is elongated in the NNE
direction with dimensions of several tens of km. Prominent landslide scars and a giant landslide deposit, over
70 ms thick and spanning 200 km2, are visible on the drift. The sediment cores evidence well-developed cross
beddings suggesting the effect of vigorous bottom currents. The oceanographic data show a ⇠200 m thick layer,
near the bottom, with AABW characteristics (potential temperature < 0 C). The deeper layer displays also a
strong velocity, mainly flowing along the isobaths. The energetic mixing between the along slope currents, mainly
CDW, and the RSBW coming from the basin interior increase the turbidity of the bottom boundary layer.
Our results will be merged with those obtained from the 2018 IODP drilling expedition 374 to develop a
conceptual model of sediment deposition relating to marine-based ice sheet and oceanic processes along the Ross
Sea continental margin occurring through the Neogene and Quaternary
Biogeochemical properties of Adriatic dense waters
Distribution and characteristics of dense waters in the Adriatic Sea were monitored during their formation in winter 2008, and later, in autumn at the end of the seasonal stratification period in the Adriatic Sea. Different types of dense waters were identified on the basis of their physical features. In order to characterised their biogeochemical properties dissolved oxygen, nutrient, and particulate organic matter (chlorophyll a, particulate organic carbon, particulate nitrogen and phosphorus) were analysed
L.: Direct estimate of water, heat, and salt transport through the Strait of Otranto
Abstract Water, heat and salt transport across the Strait of Otranto are estimated. Historical data sets (from December 94 through November 95) are used in this study Keywords: Adriatic Sea, Strait Of Otranto, Water Transport, Heat Budget The water, heat and salt transports through the Strait of Otranto are estimated applying direct method to historical current and hydrographical data (from December 94 through November 95). A variational inverse method based on a variational principle and a finite element solver is used to reconstruct the current, temperature and salinity fields across the Strait section from sparse measurements. Characteristics of the current field obtained by this new application are comparable to the historical studies The heat and salt transports due to advection process are calculated for the first time. These estimations are carried out for five monthly periods, namely December 1994, February, May, August and November 1995. Considering these five periods representative of the seasonal cycle during the year (Autumn 1994 and four seasons of 1995), their average values show that there is a net heat advection into the Adriatic Sea on a yearly basis. The estimated value of advected heat and the corresponding error are 2.408±0.490 TW, which is equivalent to a heat gain of 17.37±3.53 W m for the whole basin. The heat exchange through the air-sea interface is estimated by applying the bulk formulas to the meteorological data, namely the ERA-40 reanalysis data set extracted from European Centre for Medium-Range Weather Forecasts (ECMWF). The average surface heat flux for the study period is estimated as a heat loss of -36±152 (std) W m through the air-sea interface over the Adriatic Sea. The final estimates of the advected heat through the Strait of Otranto are compared and discussed with the relationship to air-sea heat exchange over the Adriatic Sea. The two values are expected to balance each other in order to close the heat budget of the basin. The possible reasons for a difference to occur are discussed. On an annual time scale the advected heat should be compensated with the air-sea heat loss. However, on a seasonal time scale a significant disagreement might be expected. This is due to seasonal variation of the heat content of the Adriatic Sea, seasonal cooling or warming. Moreover, it can be related to the fact that the heat advection and surface heat exchange are basically two different mechanisms in time and space. Therefore, the spatial and temporal scales of these processes are different. Consequently, they can not balance each other on a short time scale as monthly or even a seasonal one. The potential temperature distribution indicates that the upper layer (first 200 m from the surface, including thermocline layer) is associated with higher temperature and elevated variability, while the lower layers are associated with lower temperature and smaller variability. This fact may set up the different role that each of the two layers plays in transporting heat. To examine this, the heat transport rates are then calculated for the two layers separately: the upper layer from sea surface down to 200 m depth and the lower layer from 200 m depth to bottom. The results show that the upper layer has larger contribution to the heat transport into the Adriatic Sea (hea
Proposal for Guidelines for the Treatment of Vitiligo in Croatia
Vitiligo, an acquired depigmentation disorder, because of its impressive clinical presentation has a large impact on psychosocial life of patients. Although the exact etiopathogenesis still remains uncertain, several therapeutic options are available for treatment of this condition. Unfortunately, patients are often confronted with difficulties regarding to receiving suitable therapy. Because of the fact that vitiligo is not contagious and not life-threatening disease, physicians usually do not recognize patients’ problems and consider vitiligo as only a cosmetic problem, which should be treated only by camouflage and sun protection products. On the other hand, because of the lack of the accurate information for patients, a widely open market for different kind of alternative questionable therapies occurs so patients are often experimenting with different types of unproven medications. The need for widely accepted consensus concerning vitiligo treatment and establishment of the therapeutic guidelines exists worldwide. Our aim was to introduce for the first time vitiligo therapy guidelines in Republic of Croatia, based on the evidence-based accepted vitiligo therapy world recommendations and our experience. We present a review of therapy for vitiligo regarding to various vitiligo types and severity of lesions as well adequate therapeutic options. Also, our intention is to improve social component of patient’s life through rising awareness of this condition which affects over 35 million people worldwide
Proposal for Guidelines for the Treatment of Vitiligo in Croatia
Abstract: Vitiligo, an acquired depigmentation disorder, because of its impressive clinical presentation has a large
impact on psychosocial life of patients. Although the exact etiopathogenesis still remains uncertain, several therapeutic
options are available for treatment of this condition. Unfortunately, patients are often confronted with difficulties regarding
to receiving suitable therapy. Because of the fact that vitiligo is not contagious and not life-threatening disease,
physicians usually do not recognize patients’ problems and consider vitiligo as only a cosmetic problem, which should be
treated only by camouflage and sun protection products. On the other hand, because of the lack of the accurate
information for patients, a widely open market for different kind of alternative questionable therapies occurs so patients
are often experimenting with different types of unproven medications. The need for widely accepted consensus
concerning vitiligo treatment and establishment of the therapeutic guidelines exists worldwide. Our aim was to introduce
for the first time vitiligo therapy guidelines in Republic of Croatia, based on the evidence-based accepted vitiligo therapy
world recommendations and our experience. We present a review of therapy for vitiligo regarding to various vitiligo types
and severity of lesions as well adequate therapeutic options. Also, our intention is to improve social component of
patient’s life through rising awareness of this condition which affects over 35 million people worldwide
Preliminary results of the oceanographic features of the bottom density-driven currents on the Storfjorden continental slope (Svalbard)
Nutrients and Particulate Matter dynamics and exchanges in the Otranto Strait
A series of seasonal cruises and Eulerian current measurements in the Otranto Strait were carried out to study the biogeochemical characteristics of the strait and to estimate the exchange of water, dissolved and particulate matter between the Adriatic and the Ionian Sea. From the biogeochemical distributions obtained, the role for the Adriatic Sea in supporting the N:P ratio anomaly of the Mediterranean is hypothesized. Examining the bottom oxygen distribution, the deep ventilation of the Eastern Mediterranean seems to follow a more complex pathway than previously hypothesized. Fluxes computation shows a net outflow through the strait for nitrate, phosphate and silicate, while a slight net inflow was obtained for POC and PN