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Abstract: U–Th ages of phreatic overgrowths on speleothems in coastal caves of the Western Mediterranean record high sea level positions during marine isotope stage (MIS) 5e of the last interglacial. While relative sea level (RSL) on the southeastern coast of Mallorca stood ∼2.6m above present sea level (apsl) during MIS 5e, it stood ∼4.3m apsl at this time in northwestern Sardinia. The difference between the two sites during MIS 5e and the deviation from the eustatic sea level trend during the Holocene was investigated using the numerical code SELEN. The offset between the eustatic curve and those pertaining to the two sites principally reflect the vertical deformations and geoidal variations in response to meltwater loading. As Sardinia is closer to the center of the Mediterranean basin, the hydro-isostatic component of RSL is enhanced here compared to Mallorca, which results in a modeled offset of ∼60cm between the two sites. This result is qualitatively useful as it provides a partial reconciliation for the site differences. However, the need for refinement in the model is also recognized, as it does not match the observation based on U–Th dating of speleothem overgrowths in Mallorca that sea level there has remained stable for the past 2800 years. Overall, the results of the study first suggest that both sites largely track the eustatic sea level curve, and second suggest that glacial isostatic adjustment is a viable mechanism to reconcile some, if not most, of the relatively small elevation difference of MIS 5e sea level observed at Mallorca and Sardinia, although minor tectonic adjustments cannot be ruled out in explaining some low-amplitude local variations. [Copyright &y& Elsevier]

About 15 years ago, a fuelling station in Roma (Italy) was dismissed. When underground tanks were removed, a subsoil NAPL (Non-Aqueous Phase Liquid) contamination came out, showing gasoline leakage from the reservoirs. Monitoring actions took place next and only recently radon dissolved in groundwater was measured for a year and used as tracer of NAPLs in view of its high solubility in these substances. The relative deficit of radon in polluted groundwater compared to radon in background "clean" water allowed us to detect areas where residual gasoline is still located. The source of pollution was identified in correspondence of former gasoline tanks, in agreement with direct measurements of dissolved NAPLs, mainly Methyl Tertiary Butyl Ether (MTBE), a resistant and water-soluble additive introduced in gasoline in place of lead. A short and transient plume of MTBE was occasionally recognized. We hypothesize that the rise of groundwater table enhances removal of MTBE, likely adsorbed onto soil minerals such as zeolites, thus increasing its concentration in water. MTBE levels are then progressively reduced by natural attenuation processes, with half-life of about 23 days. Estimates of MTBE saturation from radon-deficit equations were not reliable because the aquifer is not homogeneous in terms of 226Ra distribution, porosity and emanation power and no equilibrium is reached for radon partitioning between NAPL and water. • In 2004 a fueling station was dismissed and a subsoil contamination appeared. • Radon-deficit in MTBE-contaminated groundwater allowed to identify residual NAPLs. • The source of pollution was documented in correspondence of former gasoline tanks. • A transient plume, mobilized by the rising water table, was occasionally recognized. • MTBE levels are reduced by natural attenuation processes, with half-life of 23 days. [ABSTRACT FROM AUTHOR]

Non-polar liquids released in environment cause a long-term soil and groundwater contamination. The costs associated with a multi-year remediation are high and the uncertainty in the allotment of legal responsibilities could defer the decontamination planning. Therefore, a reliable method to assess the residence time of spilled Non-Aqueous Phase Liquids (NAPLs) in soil is highly needed. In this paper, a method, using low environmental radioactivity and radiometric dating, is described and applied to real contaminations. After being alpha-recoiled from 232Th in soils,228Ra accumulates in light NAPLs, generating 228Th. A disequilibrium clock, based on γ-spectrometric determination of the ratio 228Th/228Ra, was conceived to measure the residence time of LNAPL pollutants in a soil. The pollutant extraction and γ-counting procedures are described. This approach inverts the role played by pollutants and contaminated matrixes, because the flux of alpha recoil from soil generates in pollutants a reliable model of "closed system", which is preserved in LNAPLs due to the peculiar properties of non-polar liquids. All case studies are sited in Italy and have been supported by preliminary lab tests. Dating tests of 15 samples (including LNAPLs, contaminated soils and oil socks) were performed, in most cases, blindly. Then, the results were compared to historical data about contaminations. A good correlation between test results and site history was generally obtained. But an increasing error has to be considered in old contaminations due to the nonlinear nature of disequilibrium time equation. Other reasons of discrepancies, due to system opening, include the use of surfactants, the presence of significant amount of MnO 2 in soil and the interactions of different spillages. The outcomes of this research evidence the possibility to precisely date the contamination both in soil and in non-polar liquids, offering a potential tool to settle legal disputes. Further studies could broad and improve the applicability of the method. [Display omitted] • Apolar pollutants in soil and groundwater can be dated using environmental radioactivity. • In non-polar fluids, alpha-recoiled nuclides can be accumulated from soil grains. • The 228Th/228Ra method is tested in the laboratory and on real cases. • 228Th/228Ra method has versatility and low environmental impact. • Dating tests could reduce litigation times and losses of natural and economic resources. [ABSTRACT FROM AUTHOR]

Abstract An integration of laboratory radon and thoron exhalation data with gamma radiation mapping is applied to assess the geogenic radon and the exposure of people to natural radiation in a highly-urbanized city (Roma, Italy). The study area is a protected territory where ignimbrites from Colli Albani volcano and alluvial sediments largely crop out. A map of total gamma radiation, a gamma transect across Caffarella valley and 9 vertical gamma profiles have been carried out, showing that the main control of gamma levels is, of course, the lithological nature, without neglecting the simultaneous effect of other parameters such as slope morphology, erosion/weathering processes, occurrence of sinkholes or underground tunnels. The surveys allowed to distinguish the medians of ignimbrites (from 816 ± 16 cps to 936 ± 19 cps) from that of alluvial materials (611 ± 14) cps), but showed also that alluvial sediments with anomalously high radioactivity (769 ± 14 cps) can be locally recognized, providing valuable information on the interaction between sedimentation and erosion in fluvial valleys. Total gamma activity was converted into absorbed gamma dose rate ranging from 0.33 to 0.38 μSv/hr. Outdoor Annual Effective Dose Equivalents were also estimated between 0.58 and 0.67 mSv y−1. Laboratory radon and thoron exhalation rates of collected material are positively correlated with gamma radiation. Volcanic and alluvial sediments are well-discriminated. The correlation between the two variables is evident, but not robust because of the variable concentration of 40 K, which is not contributing to radon and thoron exhalation rates. Anomalous data of soil samples located at the foot of a slope can be interpreted as due to reworking and accumulation processes. Similar gamma radiation data documents analogous concentration of radon and thoron parent-nuclides, but coexisting different radon and thoron exhalation rates provides an additional information on different grain size distributions which can be considered as a proxy for soil gas permeability. The integration of gamma mapping and radon and thoron exhalation measurements is a very useful tool to assess people exposure to natural radiation, in terms of dose rates and potential indoor radon. Gamma mapping, which provides data on the radiation source (the bedrock) is fast and not expensive. It allows to obtain very detailed pictures of a study area, but it needs to be combined with laboratory determination of radon and thoron release in order to definitely and correctly interpret variations of gamma signal. Furthermore, laboratory determination of soil radon exhalation gives information on the release of radon and is a good proxy for soil gas permeability. It has the great advantage over in-situ measurements of gas flow not to be influenced by seasonal pedoclimatic parameters and is affected by lower analytical uncertainties. These data are thus reproducible and precise and can be used to estimate potential radon hazard, which is the main source of exposure and thus the most important parameter for human protection from environmental radioactivity. Highlights • Gamma surveys and radon flux data allowed to distinguish ignimbrites from alluvial sediments. • Soil morphology, shallow caves and weathering affect gamma and radon flux data. • Gamma dose rates ranging from 0.41 to 0.59 μSv/hr allowed to assess people exposition. • Laboratory radon flux data are reproducible and a good proxy for soil permeability. • Integrated approaches to study radioactivity improve strength of single methods. [ABSTRACT FROM AUTHOR]

A soil radon-deficit survey was carried out in a site polluted with kerosene (Rome, Italy) in winter 2016 to assess the contamination due to the NAPL residual component in the vadose zone and to investigate the role of the vapor plume. Radon is indeed more soluble in the residual NAPL than in air or water, but laboratory experiments demonstrated that it is also preferentially partitioned in the NAPL vapors that transport it and may influence soil radon distribution patterns. Specific experimental configurations were designed and applied to a 31-station grid to test this hypothesis; two RAD7 radon monitors were placed in-series and connected to the top of a hollow probe driven up to 80-cm depth; the first instrument was directly attached to the probe and received humid soil gas, which was counted and then conveyed to the second monitor through a desiccant (drierite) cylinder capturing moisture and eventually the NAPL volatile component plus the radon dissolved in vapors. The values from the two instruments were cross-calibrated through specifically designed laboratory experiments and compared. The results are in agreement within the error range, so the presence of significant NAPL vapors, eventually absorbed by drierite, was ruled out. This is in agreement with low concentrations of soil VOCs. Accordingly, the radon-deficit is ascribed to the residual NAPL in the soil pores, as shown very well also by the obtained maps. Preferential areas of radon-deficit were recognised, as in previous surveys. An average estimate of 21 L (17 Kg) of residual NAPL per cubic meter of terrain is provided on the basis of original calculations, developed from published equations. A comparison with direct determination of total hydrocarbon concentration (23 kg per cubic meter of terrain) is provided. [ABSTRACT FROM AUTHOR]

Soil radon is employed to trace residual NAPL (Non-Aqueous Phase Liquid) contamination because it is very soluble in these substances and is strongly depleted over polluted volumes of the subsoil. The solubility of radon into NAPL vapors, generally poorly considered, is investigated here, either as growth of radon exhalation from a material contaminated with increasing volumes of kerosene, or as radon partition between liquid kerosene, water and total air, considered ad the sum of kerosene vapors plus air. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) and polylactic acid (PLA) bottles were tested to evaluate radon loss from water during 15 days of storage. PET bottles (lower surface/volume-ratio vials) lost 0.4–7.1% of initial radon, whereas PLA bottles lost 3.7% of it. PET bottles with volume of 0.5 L, lower surface/weight ratio, and hence higher thickness display proportionally reduced radon loss. Corrections for dissolved radium are needed during analyses. Formulas for calculating degassing efficiency and water interference on electrostatic collections are developed. [ABSTRACT FROM AUTHOR]

Glass bottles are generally employed for water sampling because glass is impervious to radon and is not lost during sample storage. On the other hand, glass is fragile and may break, so 1 L High Density PolyEthylene (HDPE) bottles (Thermo Scientific Nalgene) are tested in place of glass vessels employing Big Bottle RAD H 2 O device (Durridge Company) coupled with RAD7 monitor. The purpose of this calibration is to quantify radon loss during storage in HDPE bottles, evaluate possible radon uptake by known volume of desiccant (Drierite, granular CaSO 4 ) and quantify radon interaction with the rubber and plastic parts of the experimental circuit. These processes have been separately investigated, performing proper experiments for the assessment of their influence on resulting radon data using seven series of solutions at known activity concentrations in the range from 27 to 194 Bq/L. Percent radon loss during storage in 1 L HDPE bottles has been estimated at 0.0045 min −1 . Radon absorption by desiccant, expressed as ‘equivalent’ volume of Drierite is 0.673 ± 0.092 L and is somehow independent, within errors, from i ) the amount of water already absorbed in Drierite, ii ) a recirculation time greater than 30 min and iii ) radon concentrations. Radon absorption/desorption from rubber and plastic parts of the experimental device has been assessed as a function of concentration gradient between the inner volume of the circuit and the pores of polymer's. A final algorithm accounting for the above described physical processes has been developed for long runs (2–3 h). A simplified calculation method for short measurements (30 min) is also provided. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate that the age of 43ka obtained for the topmost calcrete layer in the Guadix-Baza remains the only reliable numerical dating of the flat geomorphic surface that marks the end of the sedimentation in the basin. Consequently, the late Pleistocene to Holocene erosion rates derived from the incision of the present-day drainage network into the flat geomorphic surface remain valid. The calcrete radiometric ages reported by Díaz-Hernández and Julià (2012) in their comment are untenable due to the contamination with detrital 230Th (not corrected with the applied U/Th technique) and the possible mix of textural elements with different ages (older inherited grains and newly formed grains). Díaz-Hernández and Julià also quote U/Th ages for travertine terraces formed later than the calcrete layer. These ages lack internal consistency probably due to systematic contamination and/or weathering of the samples. The archaeological ages reported by Díaz-Hernández and Julià are subjected to great uncertainties, but independently of the age assumed as most realistic, they are completely compatible with the age of 43ka that we obtained for the topmost calcrete layer in the Guadix-Baza basin. [Copyright &y& Elsevier]

Abstract: The landscape evolution in Neogene intramontane basins is a result of the interaction of climatic, lithologic, and tectonic factors. When sedimentation ceases and a basin enters an erosional stage, estimating erosion rates across the entire basin can offer a good view of landscape evolution. In this work, the erosion rates in the Guadix–Baza basin have been calculated based on a volumetric estimate of sediment loss by river erosion since the Late Pleistocene. To do so, the distribution of a glacis surface at ca. 43 kyr, characterised by a calcrete layer that caps the basin infilling, has been reconstructed. To support this age, new radiometric data of the glacis are presented. The volume of sediment loss by water erosion has been calculated for the entire basin by comparing the reconstructed geomorphic surface and the present-day topography. The resulting erosion rates vary between 4.28 and 6.57 m3 ha−1 yr−1, and are the consequence of the interaction of climatic, lithologic, topographic, and tectonic factors. Individual erosion rates for the Guadix and Baza sub-basins (11.80 m3 ha−1 yr−1 and 1.77 m3 ha−1 yr−1 respectively) suggest different stages of drainage pattern evolution in the two sub-basins. We attribute the lower values obtained in the Baza sub-basin to the down-throw of this sub-basin caused by very recent activity along the Baza fault. [Copyright &y& Elsevier]

Abstract: This paper deals with the chronology and the possible correlations among levels of different excavated areas in the Pleistocene vertebrate-bearing deposits at the large San Teodoro Cave (North-Eastern Sicily). Two trenches have been excavated along the eastern side of the cave, located at a distance from the entrance, respectively, of 8m (α trench) and 28m (β trench) and at different depths. Lithological features, biometrical data from small mammals and ecological data from molluscs point to similar environmental conditions for the α trench deposits and those located along the eastern wall of the cave in the eastern part of the β trench. The same evidence, and the taphonomic features of large mammals, points to different environmental conditions and perhaps to different ages for the deposits located in the western part of the β trench. The survival of elephants in Sicily up to 32,000 years ago is a new significant result of the 230Th/234U dating carried out from a concretionary stratum from the β trench and represents the youngest elephant survival in the western Mediterranean islands. [Copyright &y& Elsevier]

The origin of the 226Ra-excess during the last cycle of Vesuvius activity was investigated by high-resolution γ-spectrometry, TIMS and EDXRF. Lavas display high initial 226Ra-excess (500–1000%), similar (230Th/232Th) activity ratios (0.87–0.91) and most samples show significant 238U-excess. During the period 1631–1944 the initial absolute 226Ra-excess reached the highest values (19–44 dpm g−1) recorded for earth volcanoes. Crystal fractionation and particularly leucite floating did not cause the 226Ra-excess in spite of the high 226Ra activity (21–85 dpm g−1) in leucite. The presence of phlogopite in the mantle source, documented by field and petrological evidences on local mantle-derived xenoliths, rules out that equilibrium partial melting can be responsible for the 226Ra-excess. This primary feature may be explained by a multistage process involving metasomatic mantle fluids (MMFs) flowing through a mantle wedge where U is concentrated as U-accessory minerals deposited along microfractures. Fluids, passing through the mantle wedge, are supplied of 226Ra, 230Th and 234U by α-decay recoil of parent nuclides from U-enriched microfractures. This model calculates that the ascent time of fluids through the mantle wedge was ≤ 12 ka. Successively MMFs mixed with mantle-derived melts, giving rise to 226Ra-enriched magmas, which entered the Vesuvius plumbing system less than 7 ka. Crystal fractionation did not affect extensively the initial 226Ra/Ba ratio, which varied in the 1631–1944 period according to a pattern reflecting periodic inputs of 226Ra-enriched magma, variable reservoir volumes and residence times in magmatic chamber(s). The temporal trend of the reservoir volumes, extrapolated to the present time, indicates a volume of magma of ∼ 0.021 km3, stored most probably in a shallow chamber. [Copyright &y& Elsevier]

• Severe land degradation affected the Sila Massif (south Italy) until the late 1950s. • Reforestation promoted biomass increase and slope stabilization even on steep slopes. • Shallow A horizons formed by humus accumulation under reforested stands. • Topsoils are enriched in 210Pb ex and 137Cs, favored by tree canopies interception. • Gamma-emitting radionuclides in the soil profiles show overall low hazard potential. We investigated the genesis and local response of soils in mountain sites of the Sila Massif (Calabria, southern Italy), reforested ca. 60 years ago, and their relationships with geomorphic dynamics and forest stand structure. A multidisciplinary approach is proposed, focused on an often neglected soil profile scale and horizon-wise sampling strategy, and including pedological field observations, physical, chemical, mineralogical analyses, isotope geochemistry including fallout radionuclides (137Cs and 210Pb ex), geomorphology, historical documentation of anthropogenic land cover changes, forestry and dendrometric measurements. Reforestation was carried out following extreme land degradation, which took place after forest clearance and field cultivation. Different tree species and soil preparation techniques were used according to site conditions. We focused on the main properties of selected soil profiles and the distribution of some radionuclides, in order to understand the effects of forest stands on hampering soil erosion and promoting novel soil formation, and to evaluate the potential hazard of natural gamma radiation. A comparison with soil profiles developed under naturally regenerated forest and field crops was achieved. The soil profiles in reforested sites showed a poor degree of development and a complex history of reworking processes alternated with soil-formation processes, in line with modern to historical radiocarbon dates increasing downprofile, the presence of buried horizons and 137Cs in the topsoils. Inventory changes obtained for 210Pb ex and 137Cs highlight a process of soil stabilization occurred after reforestation, with more efficient effects under Calabrian pine than oak forest, whereas major geomorphic dynamics (erosion and accumulation) were triggered by forest coppicing, thinning and agricultural practices. Our data remark a positive response of the soil ecosystem to reforestation against erosion, trapping mobile material, stabilizing buried soils, promoting humus accumulation leading to new shallow topsoils, and the protective role of forests against anthropogenic and climatic-induced threats. Average values of the annual outdoor effective dose equivalents of gamma-emitting radionuclides calculated for all the soil horizons showed lower values than the population-weighted world's average, with the exception of the soil profiles under forest stands developed on granite, exceeding this threshold. A deeper comprehension of soil genesis, geomorphic processes, land use and vegetation dynamics in vulnerable ecosystems such as mountain environments represents a fundamental basis for sustainable land management policies. [ABSTRACT FROM AUTHOR]

• Transfer zones play as permeable volumes channeling geothermal fluids. • Travertine deposition is coeval with faulting. • Travertine deposits are useful tools to reconstruct the activity of faults. • The Bagno Vignoni geothermal area is located along active fault segments. • Earthquakes with M < 4 are concentrated along fault segments defining the transfer zone Studying travertine deposits and the network of banded calcite veins that form their roots in the substratum can place important constraints on neotectonic activity and the seismotectonic settings of geothermal areas. In this paper, we present the results of integrated studies of a geothermal area located in the inner Northern Apennines (Bagno Vignoni area, Italy), where low magnitude (M < 4) seismicity suggests the occurrence of active faults, but information on their location, time-span of activity and seismotectonic setting is lacking. The study area is characterised by thermal springs (T<50 °C) and travertine deposits well exposed in saw-cut walls of abandoned quarries. We investigate the relationships between faults and the travertine deposits, in order to reconstruct the syn-sedimentary tectonic activity and the age of faulting, by combining analyses of: i) geological setting and structural/kinematic analyses of faults; ii) travertine morpho-structural and architectural setting; iii) travertine facies; iv) U-Th radiometric, stable- and clumped isotopes of travertine and banded calcite veins. The results highlight the occurrence of a wide brittle shear zone (>3 km) formed by two orthogonal faults systems, NE- and NW-striking, characterised by oblique-slip to normal kinematics, respectively; these faults belong to a tract of the so-named "Grosseto-Pienza" transfer zone, crossing the southern Tuscany from the sea-cost to the outer Apennines belt. The Grosseto-Pienza transfer zone formed with extensional tectonics that have been affecting the inner Northern Apennines since the middle Miocene. U-Th dating of travertine and banded calcite veins indicates that faulting enhanced the hydrothermal fluid circulation since the middle Pleistocene, in an unvaried tectonic setting, as indicated by the δ18O signature and temperature of the hydrothermal fluids, which remained stable through time. The activity of the faults continued until the Holocene and still produces seismicity. Finally, our findings permit to define the seismo-tectonic setting of this sector of the inner Northern Apennines, demonstrating more broadly the utility of travertine deposits in reconstructing the neotectonics in geothermal areas. [ABSTRACT FROM AUTHOR]