Aims This study investigates, in a montane forest in Kenya, the changes in amount and stability of soil organic carbon (SOC) as a consequence of: a) forest degradation, by comparing primary and ...degraded forests; b) the replacement of degraded forests with cypress and tea plantations, by considering sites installed at different time in the past. Methods The SOC concentrations and stocks were determined in different layers to 1 m depth, and the SOC turnover time (TT) derived by measuring the 14C concentration in the layers within the 0–30 cm depth. Results A significant SOC decline was evident in the 0–5 and 5–15 cm layers of degraded forest while, on the long term, both plantations induced a significant SOC increase in the 0–30 cm depth. The longer TT's and lower SOC concentrations in the upper layers of degraded rather than primary forests imply an impact of forest degradation on the decomposition of the fast cycling SOC. Similarly, the shorter TT with increasing plantations age implies differences in SOC stabilization mechanisms between plantations and forests. Conclusions Cypress and tea plantations established on degraded forests stimulate a long term SOC accrual but at the same time decrease the stability of the SOC pool.
The reaction Be(p7,γ)8B plays an important role in the Sun, where it determines the high energy component of the solar neutrino spectrum. The importance of this reaction triggered several experiments ...over the last decades. A combined analysis of their results produces an overall consistent picture for the energy dependence of the cross section, while an inflation of the quoted uncertainties is needed to accommodate the observed discrepancy in the absolute scale of the different data sets. The origin of this discrepancy needs to be understood for a reliable estimate of the astrophysical rate of Be(p7,γ)8B and its uncertainty. In addition, there is a question about possible common systematic effects, considering that all measurements performed so far share the same experimental approach, i.e. an intense proton beam impinging on a Be7 radioactive target. A direct measurement using a radioactive Be7 ion beam on a pure hydrogen gas target has been since long envisioned as a way to improve the situation. First attempts showed the feasibility of an experiment based on the use of a recoil mass separator to collect reaction products with high efficiency, but failed to reach a useful statistical significance because of the low beam intensity. Here we present the results obtained using the intense Be7 beam available at the Tandem Accelerator Laboratory at CIRCE, University of Campania, Italy coupled to the recoil mass separator ERNA in the energy range Ecm=367 to 812 keV. Our results are compatible only with a part of previous measurements, in particular those indicating a low value of the astrophysical S-factor at zero energy S17, thus exacerbating the discrepancy between existing measurements. The analysis of our data together with the results of previous data provides an estimate S17(0)=20.0±0.8 eV⋅b, where systematic uncertainties are inflated to obtain a statistically compatible data set.
•Vernacular sculptures are rarely investigated.•XRF analysis showed Lead White, Zn, Fe, Ti and As.•Radiocarbon dated the sculpture.•Diagnostic is necessary before restoration.•Re-painting was ...assessed by stratigraphic analysis.
The sculpture of Sant'Antonio Abate represents an interesting example of vernacular art, it is a devotional object celebrated and carried in procession in many villages of Tuscia. The poor documentation and the observations of technical and stylistic characteristics do not allow the placement of the artifact at a well-defined period. It is also necessary to know the materials used for its realization before the start of restoration operations. Preliminary diagnostic investigations have allowed to date by radiocarbon, the sculpture, which was carved on lime wood, in the second half of the fifteenth century. XRF analysis has identified White Lead, Titanium and Zinc, this last in the habit of the sculpture. XRF data’s interpretation is not so obvious because all the investigated repainted areas did not show strong compositional differences from the original ones. Re-depicting were assessed after stratigraphic sections. The obtained data support exploitation of the cultural heritage in the museum and are the basic information for restoration
Past climate has always influenced human adaptation to the environment. In order to reconstruct palaeoclimate fluctuations and their role in the evolution of Near Eastern societies during the ...mid-Holocene, high-resolution Δ
C records from fossil wood remains at the archaeological site of Arslantepe (eastern Turkey) have been developed.
After chemical treatment, δ
C values were measured by sample combustion flow using a FLASH EA-CHNS instrument interfaced with a Delta V isotope ratio mass spectrometer via a CONFLO III. Two replicates per sample were analysed. The measurement precision was evaluated by propagating variations of the δ
C values of samples and V-PDB standards, whereas the accuracy was checked by a quality control sample. To account for changes in atmospheric CO
, Δ
C values were calculated. In addition,
C/
C ratios were measured by means of ann AMS system (3 MV tandem accelerator).
Mean Δ
C curves of deciduous Quercus and Juniperus from archaeological levels between 4700 and 2000 BC (Arslantepe periods VIII-VI D) were produced, where the isotope values were ordered by the available RC ages. Interspecific variations of evergreen vs deciduous plants were postulated for the juniper Δ
C values being higher than 3‰. The seasonal rainfall amount was recorded by the juniper remains, while the water table levels were obtained from the oak samples.
The local climate experienced times of enhanced/reduced precipitation in concert with regional trends. Anomalies in the air mass circulation from the Mediterranean basin also produced oscillations of rainfall amount. In such a frame the Rapid Climate Change dry events had a consistent signature in the Arslantepe Δ
C record, thus potentially contributing to social or organisational changes at the site.
In this study, we quantified the contribution of forest-derived carbon (FDC) to the soil organic C (SOC) pool along a natural succession from savanna (S) to mixed Marantaceae forest (MMF) in the Lopè ...National Park, Gabon. Four 1-ha plots, corresponding to different stages along the natural succession, were used to determine the SOC stock and soil C isotope composition (δ
13
C) to derive the FDC contribution in different soil layers down to 1 m depth. Besides, to investigate changes in SOC stability, we determined the
14
C concentration of SOC to 30 cm depth and derived turnover time (TT). Results indicated that SOC increased only at the end of the succession in the MMF stage, which stored 46% more SOC (41 Mg C ha
−1
) in the 0–30 cm depth than the S stage (28.8 Mg C ha
−1
). The FDC contribution increased along forest succession affecting mainly the top layers of the initial successional stages to 15 cm depth and reaching 70 cm depth in the MMF stage. The TT suggests a small increase in stability in the 0–5 cm layer from S (146 years) to MMF (157 years) stages. Below 5 cm, the increase in stability was high, suggesting that FDC can remain in soils for a much longer time than savanna-derived C. In conclusion, the natural succession toward Marantaceae forests can positively impact climate change resulting in large SOC stocks, which can be removed from the atmosphere and stored for a much longer time in forest soils compared to savanna soils.
We compared a calcareous soil developed from a lignite vein (natural outcrop) and a control adjacent soil without lignite in order to assess the impact of lignite on pedogenetic processes and ...microbial functions in Mediterranean soils. Lignite was evidenced by the 14C analysis, δ13C signature and SS 13C CPMAS NMR spectroscopy in the various soil horizons. Physico-chemical (particle size analysis, pH, total organic carbon, carbonate content, nitrogen, sulfur, cation exchange capacity, crystalline and amorphous Fe and Al, mineralogy, bulk density) and biological (enzyme activities: β-glucosidase, arylsulfatase, acid phosphatase, arylamidase, fluorescein dilaurate hydrolase and fluorescein diacetate hydrolase; basal respiration and Biolog ® catabolic profile) properties were also analyzed in all horizons. We showed that the naturally-occurring lignite modified soil organic matter quality and mineralogy and improved some soil properties such as clay content, Corg, CEC and porosity. On the contrary, lignite had a higher C/N and higher recalcitrant C content compared to recent soil organic matter, which resulted in a decrease in the expression of microbial soil functions involved in the turn-over of the main bio-elements C, N, P and S due to lignite acting as a diluting factor (i.e. inert regarding microbial activities). The information derived from this study offers insight on the long term fate of lignite in soil, especially relevant if lignite is aimed at being used as amendment.
•Impact of naturally-occurring lignite on Mediterranean soil characteristics•Evidence of lignite in the soil is assessed by combined approaches.•Lignite influences positively the physico-chemical characteristics on the long-term.•Lignite appears inert regarding microbial activity on the long-term.
The assessment of the radiological impact of decommissioning activities at a Nuclear Power Plant requires a detailed mapping of the distribution of radionuclides both in the environment surrounding ...the NPP and in its structural material. The detection of long-lived actinide isotopes and possibly the identification of their origin is particularly interesting and valuable if ultrasensitive measurement of the relative abundance of U isotopes is performed via Accelerator Mass Spectrometry (AMS). In this paper we present an investigation carried out on the structural materials of the Garigliano NPP aiming to determine the abundance of 235,236,238U in the various compartments of the plant buildings under decommissioning. Since the expected values both for isotopic ratios and total U concentrations range over different orders of magnitude, we have developed a novel methodology for the measurement of 234,235U/238U isotopic ratios in low U concentration samples. This allowed a systematic investigation of the distribution of all U isotopes in concrete and metal matrices of the NPP. The behavior of 235,236U/238U isotopic ratios in the different compartments of the NPP is discussed. The correlation of these ratios with 60Co and 137Cs specific activities is also studied to show a different behavior for concrete and metal samples. These data represent a very valuable information to direct the decommissioning procedures under course.
Nuclear Physics Mid Term Plan at LNGS Buompane, R.; Cavanna, F.; Curceanu, C. ...
European physical journal plus,
03/2024, Letnik:
139, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The Istituto Nazionale di Fisica Nucleare—Laboratori Nazionali del Gran Sasso (LNGS) is one of the largest underground physics laboratory, a very peculiar environment suited for experiments in ...Astroparticle Physics, Nuclear Physics and Fundamental Symmetries. The newly established Bellotti Ion Beam facility represents a major advance in the possibilities of studying nuclear processes in an underground environment. A workshop was organized at LNGS in the framework of the Nuclear Physics Mid Term Plan in Italy, an initiative of the Nuclear Physics Division of the Instituto Nazionale di Fisica Nucleare to discuss the opportunities that will be possible to study in the near future by employing state-of-the-art detection systems. In this report, a detailed discussion of the outcome of the workshop is presented.
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