Parameters of flow in porous alluvial aquifers evaluated by tracers

Dye tracer tests, DNA biotracer, alluvial aquifer Marche, multiwell tests

Hydraulic contacts identification in the aquifers of limestone ridges: tracer tests in the Montelago pilot area (Central Apennines)

The investigated area, located in the inner part of the Marche region (central Italy) and belonging to the carbonate Umbria- Marche ridges in the central Apennines, is characterised by very complex geo-structural setting and widespread karst phenomena that make difficult the definition of the relation among the aquifers basing only on the hydrogeological survey. Hence, the presence of different flowpaths among aquifers of the Umbria-Marche hydrostratigraphic sequence and of tectonic contacts among the different structures is verified using tracer tests. In particular, the tests showed that the Calcare Massiccio and the Maiolica aquifers are connected under certain tectonic conditions. A new tracer given by a single stranded DNA molecule and traditional fluorescent dyes have been injected into the Montelago sinkhole in different periods (during the recharge and during the discharge) and recovered in several points along the expected hydrogeological basin, using either manual and automatic sampling. Fluorescent traps were positioned in creeks, rivers and springs. The DNA molecule is useful to trace surface water and groundwater, is detectable even at very low concentrations, no significant change in water density and viscosity can be observed and its use is not dangerous for the environment. The results stress the suitability of DNA as hydrogeological tracer, capable to identify connections among aquifers and study different flowpaths even in high flow conditions when traditional tracers are more and more diluted. Moreover, fluorescein tracer allowed for the transport parameter determination, giving mean velocities ranging from 100 to 3000 m/day and mean residence time from some tens to hundreds of hours, and determining the aquifer volumes

H2AX promotes replication fork degradation and chemosensitivity in BRCA-deficient tumours

Histone H2AX plays a key role in DNA damage signalling in the surrounding regions of DNA double-strand breaks (DSBs). In response to DNA damage, H2AX becomes phosphorylated on serine residue 139 (known as γH2AX), resulting in the recruitment of the DNA repair effectors 53BP1 and BRCA1. Here, by studying resistance to poly(ADP-ribose) polymerase (PARP) inhibitors in BRCA1/2-deficient mammary tumours, we identify a function for γH2AX in orchestrating drug-induced replication fork degradation. Mechanistically, γH2AX-driven replication fork degradation is elicited by suppressing CtIP-mediated fork protection. As a result, H2AX loss restores replication fork stability and increases chemoresistance in BRCA1/2-deficient tumour cells without restoring homology-directed DNA repair, as highlighted by the lack of DNA damage-induced RAD51 foci. Furthermore, in the attempt to discover acquired genetic vulnerabilities, we find that ATM but not ATR inhibition overcomes PARP inhibitor (PARPi) resistance in H2AX-deficient tumours by interfering with CtIP-mediated fork protection. In summary, our results demonstrate a role for H2AX in replication fork biology in BRCA-deficient tumours and establish a function of H2AX separable from its classical role in DNA damage signalling and DSB repair

Problems in the application of environmental isotopes to the hydrogeology of high mountain aquifers

In the present work some issues have been analysed, concerning the application of environmental isotopes to hydrogeology problems. Furthermore, a local meteoric water line for central Apennines has been proposed, and an isotope altitude gradient, valid for central Apennines, has been calculated by monthly rain samples. The studied areas are located in central Apennines, and belong to the Meso-cenozoic limestone ridge The main problems were related to the effect of orography and climate on isotopic contents, and to the hydrogeological complexity. In fact, in such zones the orography led to meteoric precipitations having a peculiar isotope content. Moreover, the occurrence of snowpack (especially in the Mt. Sibillini area, at south), persistent even until late spring, caused the aquifers to be recharged mainly by snowmelt; this fact brought to actual variations in the isotopic contents of springs. For these reasons, the sampling procedure and the location of rain and snow samplers took on particular importance. Finally, an application of isotopic data to some springs in Umbria and Marche regions has been made and presented at the end of the paper, to assess the suitability of the calculated gradient to define the recharge elevation of aquifers. The obtained results underlined the suitability of isotopes techniques for hydrogeologic purposes, especially where the relationships among aquifers, the karstification and the structural setting were quite complex but defined. In other cases, with an even more complex hydrogeological setting a good interpretation of the isotopic data is very hard. Further investigations will be necessary to define the effectiveness of isotope techniques in such complicated conditions

Il contributo della cartografia antica negli studi sul rischio idrogeologico: l'esempio del Bacino delle Acque Albule (Lazio)

L'originalità dello studio sta nell'aver ricavato dalla lettura di carte e documenti cartografici anche molto antichi, dettagli, particolarità, descrizioni ed elementi che hanno contribuito ad una migliore definizione del rischio idrogeologico nel bacino delle Acque Albule presso Tivoli, fortemente antropizzato. I risultati ottenuti da tale indagine hanno permesso la creazione di una banca dati alfanumerica e la produzione di uno schema cartografico in ambiente GIS, in cui sono stati riportati tutti quei i dati storici che, raffrontati con i risultati di indagini geologiche e geomorfologiche recentemente condotte nella piana, hanno contribuito ad una migliore delimitazione delle zone a maggiore pericolosità geologica e potenzialmente sottoposte a rischio idrogeologico

The Mt Conero Limestone Ridge: the contribution of stable isotopes in the identification of the recharge area of aquifers

The recharge settings of aquifers (as those of the carbonate ridges in central Apennines) is strongly dependent on hydrogeological and geo-structural complexity; in fact, geochemical data, hydrographs interpretation, hydrogeological and geo-structural surveys, tracer and isotope data are usually not so developed and quite difficult to put into relation each other. In this paper, the importance of relating isotope techniques to hydrogeological survey on the recharge area evaluation is demonstrated by studying the system of the Mt Conero limestone ridge, located in central Italy close to the Adriatic sea. A closed system, at a pilot scale, with sufficiently well defined outcropping areas of aquifer, which is offering a contribution to the aquifer recharge area evaluation. In this study a hydrogeological investigation was performed to identify the infiltration areas in the aquifer, analysing the entire geological formation divided into several members, each of them showing different hydrogeological behaviour. In addition, periodic sampling of groundwater and of precipitation at different elevations were carried out to study the isotopic composition over a period of about 4 years. Weighted mean and arithmetic mean of isotopes were used in the gradient calculation and compared giving actually different results. The mean recharge altitude of the aquifer, as evaluated by weighted mean of isotopes, is about 100 m higher than the average elevation of the aquifer outcrop; moreover, it was proven that the vast majority of the recharge is due to the more permeable members of the aquifer (about 20% of the outcropping rocks, located at higher elevation). The recharge mechanism of the aquifer is therefore depending both on the isotope values of the local precipitation and on the distinct infiltration conditions existing in the lithotypes

Dalle mappe cinquecentesche all'attuale cartografia: un percorso storico nell'analisi del rischio idrogeologico di aree antropizzate

L'analisi di documenti storici, scritti e cartografici, ha contribuito ad una migliore individuazione, in una piana fortemente antropizzata come quella delle Acque Albule (Lazio), delle aree maggiormente esposte a rischio idrogeologic