10 research outputs found
Paleoclimatic and Paleoceanographic reconstruction of the Pleistocene-Holocene through the study of planktonic foraminifera of two sedimentary cores collected in North Atlantic Ocean, southwest of the Azores Islands.
Geophysical Constraints to Reconstructing the Geometry of a Shallow Groundwater Body in Caronia (Sicily)
The characterization of a groundwater body involves the construction of a conceptual model that constitutes the base knowledge for monitoring programs, hydrogeological risk assessment, and correct management of water resources. In particular, a detailed geological and geophysical approach was applied to define the alluvial Caronia Groundwater Body (CGWB) and to reconstruct a hydrogeological flow model. The analysis of the CGWB, located in north-eastern Sicily, was initially approached through a reanalysis of previous stratigraphic (boreholes) and geophysical (vertical electrical soundings and seismic refraction profiles) data, subsequently integrated by new seismic acquisitions, such as Multichannel Analysis of Surface Waves (MASW) and horizontal-to-vertical seismic ratio (HVSR). The analysis and reinterpretation of geoelectrical data allowed the construction of a preliminary 3D resistivity model. This initial modeling was subsequently integrated by a geophysical data campaign in order to define the depth of the bottom of the shallow CGWB and the thickness of alluvial deposits. Finally, a preliminary mathematical model flow was generated in order to reconstruct the dynamics of underground water. The results show that integration of multidisciplinary data represent an indispensable tool for the characterization of complex physical systems
Planktonic foraminifera as proxies of the Holocene climatic variability (Tyrrhenian, Mediterranean Sea)
Introduction. The focus of this study is the paleoclimatic reconstruction of the southern Tyrrhenian
between ~9.2 and 2.9 ka, through the study of planktonic foraminiferal assemblages and stable
isotopes, and comparing data with other coeval intervals. Several authors have studied the climatic
sensitivity of Holocene planktonic foraminifera in different parts of the Mediterranean. Planktonic
foraminifera produce good records of Holocene climatic variability, especially as regards the suborbital
events such as Bond events (Bond et al., 1997) and other cooling/warming oscillations.
Therefore, the obtained eco-biostratigraphy has allowed us to analyze how climatic forcing influenced
sea surface temperature (SST) and water column structure during the Holocene in this sector
of the southern Tyrrhenian Sea.
Methodology. A sedimentary core (196 cm long) was collected in the Gulf of Palermo at the base
of the upper continental slope (990 m bsl) and sub-sampled every 2 cm. Micropaleontological and
geochemical analyses were performed on 98 samples, and three AMS 14C dates were determined.
Micropaleontological analyses consisted of qualitative and quantitative characterization of the
planktonic foraminiferal assemblages, in the size fraction greater than 125 ÎĽm. Geochemical analyses
were performed on 8–10 specimens of Globigerina bulloides.
Results. The calibrated AMS 14C ages, together with planktonic foraminiferal fluctuations and G.
bulloides oxygen isotope records, were used to develop an age model of the studied interval. In order
to obtain additional age control points, the studied records were also tuned to the NGRIP δ18O
(GICC05) (Svensson et al., 2008) and GISP2 ice core temperature (Alley, 2000) records.
Twenty species and eco-morphotypes were recognized in the planktonic foraminiferal assemblage
and grouped depending upon their climatic and feeding affinity. The warm-water species, minus
the typical cold-water species, were used to obtain the paleoclimatic curve, whilst the herbivorous/
carnivorous ratio has permitted us to reconstruct the trophism of the southern Tyrrhenian. In
particular, between ~8 and 6.4 ka, an important warming phase was recognized, clearly indicated
by the increase of Globigerinoides gr. ruber and G. gr. quadrilobatus. This interval corresponds to
the deposition of Sapropel S1b-equivalent stage (Sprovieri et al., 2003; Lirer et al., 2013; Siani et
al., 2013), when high SSTs and oligotrophy characterized the entire Mediterranean region, especially
during the summer seasons. Between ~5.9 and 4.2 ka, another warming phase occurred in the
Gulf of Palermo, differing from the previous one due to the enhanced winter mixing of the water
column, testified by the high abundance of deep dweller species, such as Globorotalia truncatulinoides
and Globorotalia inflata left coilings. The last important warming phase corresponds to the
Minoan Warm Period, briefly interrupted by a rapid cooling event (at ~3.5 ka).
Among these warm climatic phases, several rapid cold-cool events were recognized. In particular,
Neogloboquadrina pachyderma and Turborotalita quinqueloba represent the best cold-water indicators,
increasing in abundance during the Bond events (B2, B3, B4, B5, B6) and other rapid cooling
events that characterized the western (M3, M4, M5, M6, M7) (Frigola et al., 2007) and central
Mediterranean (TC2, TC3, TC4) (Cacho et al., 2001) during the 9.2–2.9 ka interval.
Conclusions. Planktonic foraminifera and oxygen isotope variations highlight the climatic oscillations
of the relatively stable Holocene stage. These oscillations are linked to the North Atlantic millennial
scale climatic variability that forced cool/high productivity periods and warm/oligotrophic
conditions. In particular, during the ~8–6.4 (S1b-equivalent), ~5.9–4.2, and ~3.7–3.2 (Minoan
Warm Period) ka intervals, warm surface waters characterized the Gulf of Palermo. On the contrary,
during rapid climatic phases, centered at 9.1, 8.2, 7.2, 6.2–5.9, 5.4, 4.7, 3.9, 3.5, and 3 ka,
cool/high productivity conditions occurred in this sector of the southern Tyrrhenian.
References
Alley, R.B., 2000. The Younger Dryas cold interval as viewed from central Greenland. Quaternary
Science Reviews 19(1–5): 213–226.
Bond G., Showers, W., Cheseby, M., Lotti, R., Almasi, P., de Menocal, P., Priore, P., Cullen, H.,
Hajdas, I. and Bonani, G., 1997. A pervasive millennial-scale cycle in North Atlantic
Holocene and glacial climates. Science 278: 1257–1266.
Cacho, I., Grimalt, J.O., Canals, M., Sbaffi, L., Shackleton, N.J., Schönfeld, J., and Zahn, R., 2001.
Variability of the Western Mediterranean Sea surface temperature during the last 30,000
years and its connection with the northern hemisphere climatic changes. Paleoceanography
16(1): 40–52.
Frigola, J., Moreno, A., Cacho, I., Canals, M., Sierro, F.J., Flores, J.A., Grimalt, J.O., Hodell, D.A.,
and Curtis, J.H., 2007. Holocene climate variability in the western Mediterranean region
from a deepwater sediment record. Paleoceanography 22(2): PA2209.
Lirer, F., Sprovieri, M., Ferraro, L., Vallefuoco, M., Capotondi, L., Cascella, A., Petrosino, P.,
Insinga, D.D., Pelosi, N., Tamburrino, S., and Lubritto, C., 2013. Integrated stratigraphy
for the late Quaternary in the eastern Tyrrhenian Sea. Quaternary International 292, 71–
85.
Siani, G., Magny, M., Paterne, M., Debret, M., and Fontugne, M., 2013. Paleohydrology
reconstruction and Holocene climate variability in the South Adriatic Sea. Climate of the
Past 9: 499–515.
Sprovieri, R., Di Stefano, E., Incarbona, A., and Gargano, M.E., 2003. A high-resolution record of
the last deglaciation in the Sicily Channel based on foraminiferal and calcareous
nannofossil quantitative distribution. Palaeogeography, Palaeoclimatology, Palaeoecology
202(1–2): 119–142.
Svensson, A., Andersen, K.K., Bigler, M., Clausen, H.B., Dahl-Jensen, D., Davies, S.M., Johnsen,
S.J., Muscheler, R., Parrenin, F., Rasmussen, S.O., Röthlisberger, R., Seierstad, I.,
Steffensen, J.P., and Vinther, B.M., 2008.
Geophysical Contribution to the Reconstruction of the Hydrological Model of “Barcellona-Milazzo Plain” Groundwater Body, Northen Sicily
The “Barcellona-Milazzo plain” groundwater body in the northen Sicily, was analysed in detail, through numerous
geophysical measurements that were integrated with stratigraphic data in order to reconstruct the hydrological
model.
The “Barcellona-Milazzo plain” (BMP) groundwater body has been identified within the coastal sector between the
village of Oliveri, to the west, and Capo Rasocolmo, to the east. It also includes several rivers that rise further south
in correspondence with the Peloritani ridge and flow into the wide Barcellona-Milazzo alluvial plain.
On the basis of several geophysical and geological data analysis and interpretation have been used to reconstruct the composition and thickness of the marine and alluvial deposits to construct the conceptual model of groundwater circulation in the Barcellon-Milazzo plain.
For the reconstruction of the subsurface model of the water body, 466 vertical electric surveys and 72 refraction seismic sections acquired in the 70s and 80s (CASMEZ surveys reports) have been reprocessed and reinterpreted. These data have been integrated with 50 HVSR surveys and 85 geognostic boreholes. These data have been integrated with 85 stratigraphic boreholes to obtain the floods in contact with the clayey substrate has been reconstructed, which delimits in depth the groundwater body to calculate the hydrological model
Georadar investigations in the Church of San Paolo (San Giacomo dei Militari, Palermo)
As part of a research project aimed at drawing up a restoration project for the church of San Paolo, the monument was investigated with georadar surveys. The investigations were followed in a targeted manner by archaeological excavations, under the supervision of the Superintendence of Cultural and Environmental Heritage of Palermo. The San Paolo church is located in the oldest part of the city. The geophysical investigations will be useful to identify any pre-existing structures on which the church could be founded. The georadar investigations focused on the central nave and one of the side aisles to identify buried structures and crypts. The data showed several anomalies. One of these, located in the middle of the central nave, has been verified with an excavation. The entrance to a crypt, not yet explored, and several bone fragments were then found. Finally, some high-frequency profiles were acquired in the walls and columns of the church, which highlighted numerous anomalies that will be verified with exploratory tests
MODELLO IDROGEOLOGICO DEL CORPO IDRICO “FIUMARA DI CARONIA” (SICILIA SETTENTRIONALE)
L’Osservatorio delle acque del Dipartimento dell’Acqua e dei Rifiuti (DAR) della Regione Siciliana e l’Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo hanno attivato un accordo di collaborazione che prevede l’effettuazione di attività finalizzate alla redazione del “Piano di gestione delle Acque” della Regione Siciliana per numerosi bacini idrogeologici del territorio siciliano attraverso la definizione di modelli concettuali
da sviluppare, previo approfondimento del quadro conoscitivo esistente, con l’effettuazione di indagini geologiche, idrogeologiche, geofisiche, idrogeochimiche ed isotopiche. In questo contesto, è stato analizzato il corpo idrico sotterraneo della fiumara di Caronia attraverso
numerose indagini geofisiche integrate con dati stratigrafic
LIPOPROTEIN (A) AND FIBRINOLYTIC SYSTEM IN LIVER-CIRRHOSIS
Several observations have suggested that lipoprotein (a) (Lp(a)) is a risk factor for coronary artery disease because of potential interference with fibrinolysis secondary to its activation of plasminogen. However, there are few data on the possible role of Lp(a) in liver cirrhosis. The present study was carried out, to better elucidate its relationship to the fibrinolytic system in liver cirrhosis We studied the plasma levels of Lp(a) and the fibrinolytic parameters of 95 patients with liver cirrhosis (57 men, 38 women, aged 26-81). Patients in Child-Pugh class C (rt = 32) had significantly lower levels of Lp(a) than those in class B (n = 45), and the class B had lower Lp(a) values than class A (n = 18) (1.4 (0.0 - 3.7) vs 2.9 (0.0 - 6.1) vs 3.4 (1.8 - 5.5); the data are log-transformed). Alpha-2-antiplasmin and plasminogen, had patterns similar to those of Lp(a), tissue plasminogen activator (t-PA) was significantly increased only in class C (class A: 7.5 +/- 5.8 ng/ml; class B: 10.8 +/- 7.7 ng/ml; class C: 19.1 +/- 11.3 ng/ml). Patients with systemic hyperfibrinolysis (cross-linked fibrin degradation products, XDP > 200 ng/ml) also had lower levels of Lp(a) than those without 1.6 (0.0 - 4.4) vs (0.0 - 6.1); p = 0.0002. There was a significant correlation between Lp(a) and plasminogen (r = 0.43; p = 0.001). Lipoprotein (a) progressively decreases as liver cirrhosis worsens but it appears unlikely to be involved in causing the hyperfibrinolytic state often observed in advanced liver cirrhosis, in which there are marked abnormalities of several other fibrinolytic parameters, also including increased t-PA and decreased inhibitors