Patterns of Posidonia oceanica (L.) Delile Beds around the Island of Ischia (Gulf of Naples) and in Adjacent Waters

Abstract. Posidonia oceanica prairies have been studied and mapped around the Island of Ischia and in adjacent waters. Prairies were found to cover an area of 15.7 km² and to be distributed between 0.5 and 39 m depth. The observed distribution is comparable to those reported by previous authors indicating that prairies have not undergone remarkable regressions in the last 50 years. Patterns recorded within the beds and at their lower limits, as indicated also by their sediments characteristics, are correlated to hydrodynamic energy. Two main types of water motion are responsible for the different types of erosive features: a) steady currents flowing parallel to the coast; b) rip-, wave induced currents flowing normal to the coast.     

Induction of cytochrome P4501A and biliary PAH metabolites in European eel Anguilla anguilla: Seasonal, dose- and time-response variability in field and laboratory conditions

Induction of cytochrome P4501A in fish is a well-known indicator of exposure to polycyclic aromatic hydrocarbons (PAHs) and determination of PAH metabolites in bile by fixed wavelength fluorescence (FF) or synchronous fluorescence spectroscopy (SFS), has become an useful method in monitoring programs. In this work the relationship between cytochrome P4501A (EROD activity) and levels of biliary PAH metabolites was measured in the European eel Anguilla anguilla, in both field and laboratory conditions: organisms were sampled on a seasonal basis from the Orbetello lagoon (Tuscany) to characterize the natural variability of these biological parameters, while in laboratory eels were intraperitoneally injected with benzo[a]pyrene to investigate temporal and dose-dependent induction patterns. Results showed that induction of cytochrome P450 and accumulation of PAHs metabolites in bile are not necessarily correlated either in field, or in laboratory investigations; different seasonal changes were measured in natural conditions and slight variations in dose and time response patterns were also obtained in laboratory exposures.     

Sul regime termico degli strati superiori della crosta terrestre

Riassunto Si esamina il regime termico negli strati superiori della crosta terrestre in alcuni casi elementari di discontinuità del materiale, nonchè nell'ipotesi di una superficie esterna sagomata a gradino, traendone deduzioni atte a facilitare l'interpretazione ed a valorizzare i dati geotermici.

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Summary In the present paper the thermal conditions in the heigher layer of the earth's crust are examined, in some elementary cases with discontinuity of the material as well as when the external surface presents a step. The results may facilitate the interpretation and application of the geothermic data.

     

The Messinian salinity crisis in Cyprus: a further step towards a new stratigraphic framework for Eastern Mediterranean

A revised stratigraphic framework for the Messinian succession of Cyprus is proposed demonstrating that the three‐stage model for the Messinian salinity crisis recently established for the Western Mediterranean also applies to the Eastern Mediterranean, at least for its marginal basins. This analysis is based on a multidisciplinary study of the Messinian evaporites and associated deposits exposed in the Polemi, Pissouri, Maroni/Psematismenos and Mesaoria basins. Here, we document for the first time that the base of the unit usually referred to the ‘Lower Evaporites’ in Cyprus does not actually correspond to the onset of the Messinian salinity crisis. The basal surface of this unit rather corresponds to a regional‐scale unconformity, locally associated with an angular discordance, and is related to the erosion and resedimentation of primary evaporites deposited during the first stage of the Messinian salinity crisis. This evidence suggests that the ‘Lower Evaporites’ of the southern basins of Cyprus actually belong to the second stage of the Messinian salinity crisis; they can be thus ascribed to the Resedimented Lower Gypsum unit that was deposited between 5.6 and 5.5 Ma and is possibly coeval to the halite deposited in the northern Mesaoria basin. Primary, in situ evaporites of the first stage of the Messinian salinity crisis were not preserved in Cyprus basins. Conversely, shallow‐water primary evaporites deposited during the third stage of the Messinian salinity crisis are well preserved; these deposits can be regarded as the equivalent of the Upper Gypsum of Sicily. Our study documents that the Messinian stratigraphy shows many similarities between the Western and Eastern Mediterranean marginal basins, implying a common and likely coeval development of the Messinian salinity crisis. This could be reflected also in intermediate and deep‐water basins; we infer that the Lower Evaporites seismic unit in the deep Eastern Mediterranean basins could well be mainly composed of clastic evaporites and that its base could correspond to the Messinian erosional surface.     

Geochemistry of regional aquifer systems hosted by carbonate-evaporite formations in Umbria and southern Tuscany (central Italy)

In central Italy Mesozoic carbonates represent the principal reservoir of freshwater of the region. The hydrogeological setting is linked to the geological evolution of the Apennine chain and is generally characterised by a lower aquifer and one or more shallower aquifers separated by thin aquicludes. In these systems, groundwater composition is the result of a complex array of regional and local geochemical processes. The main geochemical processes are the dissolution of calcite, the influx of deeply derived CO₂ related to a regional process of mantle degassing, dedolomitization and mixing with deep saline fluids. The occurrence of saline fluids, characterised by a Na–Cl(HCO₃) composition, is related to the presence of a deep regional aquifer at the base of Mesozoic carbonates. The extremely high pCO₂ values computed for the saline waters suggest that the deep aquifer is also a structural trap for the mantle derived CO₂ during its ascent towards the surface. In central Italy, geological and geophysical data highlight the presence of two different crustal sectors: the eastern sector, where the geometry of the Apennine thrust belt is still preserved, and the western sector, where the compressive structures are dislocated by important extensional deformations. In the western sector, the normal faults disrupting the compressive structures allow the mixing of the deep Na–Cl(HCO₃) fluids with the shallow groundwater causing a salinity increase and the natural deterioration of groundwater quality.     

Fluorine speciation in topsoils of three active volcanoes of Sicily (Italy)

Fluorine is one of the many environmental harmful elements released by volcanic activity. The content of total oxalate-extractable and water-extractable fluorine was determined in 96 topsoils of three active volcanic systems of southern Italy (Mt Etna, Stromboli and Vulcano). Total fluorine (F) content (F _TOT) ranges from 112 to 7,430 mg kg⁻¹, F extracted with oxalate (F _OX) ranges from 16 to 2,320 mg kg⁻¹ (2–93% of F _TOT) and F extracted with distilled water ( ) ranges from 1.7 to 159 mg kg⁻¹ (0.2–40 % of F _TOT). Fluorine in the sampled topsoils derives both from the weathering of volcanic rocks and ashes and from the enhanced deposition due to volcanic gas emissions either from open-conduit passive degassing (Mt Etna and Stromboli) or from a fumarolic field (Vulcano). Fluorine accumulation in the studied soils does not generally present particular environmental issues except for a few anomalous sites at Vulcano, where measured contents could be dangerous both for vegetation and for grazing animals.     

Parameterization,sensitivity analysis,and inversion: an investigation using groundwater modeling of the surface-mined Tivoli-Guidonia basin (Metropolitan City of Rome,Italy)

With respect to model parameterization and sensitivity analysis, this work uses a practical example to suggest that methods that start with simple models and use computationally frugal model analysis methods remain valuable in any toolbox of model development methods. In this work, groundwater model calibration starts with a simple parameterization that evolves into a moderately complex model. The model is developed for a water management study of the Tivoli-Guidonia basin (Rome, Italy) where surface mining has been conducted in conjunction with substantial dewatering. The approach to model development used in this work employs repeated analysis using sensitivity and inverse methods, including use of a new observation-stacked parameter importance graph. The methods are highly parallelizable and require few model runs, which make the repeated analyses and attendant insights possible. The success of a model development design can be measured by insights attained and demonstrated model accuracy relevant to predictions. Example insights were obtained: (1) A long-held belief that, except for a few distinct fractures, the travertine is homogeneous was found to be inadequate, and (2) The dewatering pumping rate is more critical to model accuracy than expected. The latter insight motivated additional data collection and improved pumpage estimates. Validation tests using three other recharge and pumpage conditions suggest good accuracy for the predictions considered. The model was used to evaluate management scenarios and showed that similar dewatering results could be achieved using 20 % less pumped water, but would require installing newly positioned wells and cooperation between mine owners.     

Timing of the first drainage of the Baltic Ice Lake synchronous with the onset of Greenland Stadial 1

Glacial varves can give significant insights into recession and melting rates of decaying ice sheets. Moreover, varve chronologies can provide an independent means of comparison to other annually resolved climatic archives, which ultimately help to assess the timing and response of an ice sheet to changes across rapid climate transitions. Here we report a composite 1257‐year‐long varve chronology from southeastern Sweden spanning the regional late Allerød–late Younger Dryas pollen zone. The chronology was correlated to the Greenland Ice‐Core Chronology 2005 using the time‐synchronous Vedde Ash volcanic marker, which can be found in both successions. For the first time, this enables secure placement of the Lateglacial Swedish varve chronology in absolute time. Geochemical analysis from new varve successions indicate a marked change in sedimentation regime accompanied by an interruption of ice‐rafted debris deposition synchronous with the onset of Greenland Stadial 1 (GS‐1; 12 846 years before AD 1950). With the support of a simple ice‐flow/calving model, we suggest that slowdown of sediment transfer can be explained by ice‐sheet margin stabilization/advance in response to a significant drop of the Baltic Ice Lake level. A reassessment of chronological evidence from central‐western and southern Sweden further supports the hypothesis of synchronicity between the first (penultimate) catastrophic drainage of the Baltic Ice Lake and the start of GS‐1 in Greenland ice‐cores. Our results may therefore provide the first chronologically robust evidence linking continental meltwater forcing to rapid atmosphere–ocean circulation changes in the North Atlantic.