Reconstructing Antarctic Holocene climate/environmental changes from ice and marine cores

Paleotemperature reconstructions from Antarctic ice cores rely mainly on δD and δ18O records, with the main key factors controlling their observed distribution in Antarctic surface snow being related to the condensation temperature of the precipitation and the origin of the moisture. Reconstructions of past sea-surface temperatures (SST) and sea ice cover (SIC) from marine cores at high southern latitudes mainly rely on diatom-based transfer functions. However, quantitative records of SST and SIC are concentrated in the mid-latitudes of the Southern Ocean and only few records exist in the Antarctic coastal areas. Here we present an overview of the Holocene climate records that have been compiled in the framework of the ESF-HOLOCLIP project, as well as a new isotopic record from the TALDICE ice core, recently drilled in a peripheral dome facing the Ross Sea. One of the main goals of HOLOCLIP is to reconstruct Holocene climate/environmental changes from ice and marine cores and integrate these data in model simulations. The main common features recognized in Holocene climate records obtained from ice cores are a warm early Holocene (from about 10 to 11.5 ka BP), a cool period centred at ~8 ka BP and a secondary optimum peaking at ~4 ka BP. The Holocene climate reconstructions obtained from sediment cores demonstrate a warmer early-mid Holocene hypsithermal followed by a cooler neoglacial with an amplitude and timing of the transitions variable regionally around Antarctica. Though there exist some problems in both ice and marine core records (chronologies, temporal resolution, global vs. regional, annual vs. seasonal), such approach is unique to fuel paleoclimate models and to better understand the ocean-ice-atmosphere interactions at high southern latitudes beyond the instrumental period

Risultati preliminari delle indagini isotopiche svolte sulle acque delle falde profonde della Bassa Pianura Friulana.

The following paper reports the preliminary results of isotopic analyses that have been carried out on the basis of 55 water-wells of the alluvial Friuli Plain. Most wells are located in the Low Plain between the spring and the coast lines, where a multistrata aquifer system characterizes the underground environment. One well is located in the High Plain, bounded by the Tagliamento moraines to the N and the spring line to the S; it reaches the unconfined aquifer system continuously developing in the highly pervious alluvial sediments of the sector. Hydrogen and oxygen isotopic composition of the waters (sampled in April 2003 \u2013 April 2006 \u2013 July 2006 \u2013 October 2006 \u2013 March 2007) are shown and compared to the ones coming from 17 sampling points of surfacing spring waters and to the weighted mean composition of the precipitations registered in some stations of the area (Trieste, Basovizza, Udine and Rivo). The outcoming distribution of the above-mentioned isotopes related with the Northern Italy Meteoric Water Line (MWL_S) and the Global Meteoric Water Line (GMWL) supports the meteoric origin of the studied groundwaters. The involvement of precipitations occurring at higher altitude and/or at lower temperature in past ages is pointed out. Radiocarbon data, related to three water samples of the deepest Aquifer H (more than -300 m b.s.l.), are also reported and discussed

Aragonite-Calcite Relationships in Speleothems (Grotte De Clamouse, France): Environment, Fabrics, and Carbonate Geochemistry

In Grotte de Clamouse (France), aragonite forms in a variety of crystal habits whose properties reflect the conditions of formation. Prolonged degassing and evaporation yield needle aragonite, which is more enriched in 18O and 13C than aragonite ray crystals, which form near isotopic equilibrium. At present, aragonite ray crystals form at the tops of stalagmites at very low discharge (0.00035 ml/ min), and when fluid Mg/Ca ratio is \u3e 1.1. Temperature and evaporation do not seem to have a significant role in their formation. The presence of aragonite in stalagmites should be indicative of a decrease in drip rate related to either dry climate conditions or local hydrology. Fossil aragonite was in part replaced by calcite in a time frame \u3c 1.0 ka, possibly through the combined effects of dissolution of aragonite, and precipitation of calcite, which preferentially nucleated on calcite cements that had previously formed between aragonite rays. Commonly, the replacement phase inherited the textural and chemical characteristics of the precursor aragonite prisms and needles (and in particular the δ13C signal and U content), and preserved aragonite relicts (up to 16 weight %). The isotope signal of different aragonite habits may reflect conditions of formation rather than climate parameters. The real extent of aragonite-to-calcite transformation may be underestimated when replacement calcite inherits both textural and chemical properties of the precursor

Studio dei materiali da costruzione come contributo alla storia della fabbrica

La Chiesa Parrocchiale ed il Monastero Abbaziale di San Pietro a Modena, nella sua originaria configurazione comprendente anche l’ex caserma Garibaldi, rappresentano esempi emblematici della complessa evoluzione dell’edilizia storica modenese, sia in termini di approvvigionamento delle materie prime che di evoluzione delle fasi costruttive. Tale complessità emerge dal confronto, non solo con gli illustri esempi del sito UNESCO modenese, il Duomo e la torre Ghirlandina [Lugli et al. 2009 e 2010], ma anche con il panorama edilizio dell’intera provincia modenese: il Palazzo Ducale di Sassuolo [Lugli, 1996; 2000], la Rocca di Formigine [Lugli 1997, Marchetti Dori 2005], il palazzo Comunale di Modena [Lugli, 2010] e la Rocca di Vignola [Lugli e Marchetti Dori 2006; Lugli et al. 2013]. Tra i fattori più significativi e peculiari annoveriamo il reimpiego di materiale lapideo romano mai segnalato fino ad oggi, come il marmo tasio dalla Grecia [Lugli et al. 2010] e l’utilizzo di materie prime non appartenenti alla tradizione modenese, come la pozzolana

An Oceanic Cold Reversal During the Last Deglaciation

International audienc

Mechanisms regulating CO2 and CH4 dynamics in the Azorean volcanic lakes (Sao Miguel Island, Portugal)

Chemical and isotopic vertical profiles from the volcanic lakes of Sete Cidades, Santiago, Fogo, Congro and Furnas (Island of Sao Miguel, Azores Archipelago, Portugal) were studied to investigate the biogeochemical processes acting at different depths, with a focus on the CO2 and CH4 dynamics. These lakes are fed by meteoric water affected by seawater spray and interacting with volcanic rocks at a relatively low extent. In addition to volcanogenic gas inputs, the biogeochemical processes are influenced by microbial activities since the lakes offer specialized ecological niches for oxic and anoxic metabolism. The lakes were sampled in two extreme conditions of (partial) mixing (winter) and stratification (summer), respectively. The seasonal thermal stratification favored the development of anaerobic hypolimnia, showing relatively high concentrations of NH4+, NO3-, P and other minor species (Fe, Mn, Zn, As) controlled by microbial activity and minerogenetic processes occurring within the lake sediments. The strongly negative ?13C-TDIC values measured in almost all the studied lakes suggest dominant contribution of organic carbon. Dissolved gases were mostly consisting of atmospheric compounds with significant concentrations of CO2 and CH4. The ?13C-CO2 values were intermediate between those measured in the hydrothermal fluids and those typical of biogenic CO2. Dissolved CH4, which was the most abundant extra-atmospheric gas in the anoxic waters, was measured at significant concentrations even in the aerobic layers, especially in the winter season. This unexpected feature may tentatively be explained by admitting i) convective mixing of shallow and deep waters, and/or ii) aerobic CH4 production. Further investigations, focusing on the recognition of microbial populations able to produce CH4 at different redox conditions, may be useful to corroborate these intriguing hypotheses

Groundwater characterization from an ecological and human perspective: an interdisciplinary approach in the Functional Urban Area of Parma, Italy

In the Parma Functional Urban Area, hydro-geo-ecology was investigated through an interdisciplinary approach, with emphasis on the shallow aquifer system. The study pointed out that domestic wells and fontanili are both fed by shallow groundwater affected by PCE and nitrate contamination, upgradient of the rural area located north of Parma City. Moreover, Folsomia candida tests suggested the possibility that other types of contaminants (not analysed in this study) can affect the shallow groundwater. Nowadays, PCE concentrations in the city centre are slightly higher than the limit set by law. Moreover, PCE aerobic biodegradation can be due to the local microbial community and then an effective natural attenuation can be expected along the groundwater flow pathway. These results suggest a very low risk for human health, linked to the groundwater consumption in the rural area north of Parma City. Conversely, no forecasts can be made at present about the possible impact of low PCE concentrations on the aquatic ecosystem observed at the fontanili. Concerning nitrate contamination, the higher concentrations detected in some wells and fontanili suggest a high risk for both human health and aquatic ecosystems. In a wider context, thanks to the interdisciplinary approach that combines successfully well-established investigation methods, the present study allows a better knowledge of the hydro-geo-ecological behaviour of groundwater-dependent ecosystems. At the same time, through purpose-designed experimental investigations and simulation models, this approach could be used as a sort of guideline useful in studying such complex environmental systems