The aim of this research was the understanding of a peculiarly expanded soil sequence in Bologna (i.e., Roman Bononia, Etruscan Felsina), one of the most important archaeological poles for Etruscan ...colonisation and settlement in northern Italy. The uppermost part of the chronological sequence dating from the Bronze Age up to medieval and modern times was analysed for the first time from geochemical and pedological viewpoints. The integration of archaeological, stratigraphical and pedological data supported by soil chemical analysis, a fundamental key for reconstructing a correct evolutionary sequence, made it possible to recognise seventeen buried Soil Units (ancient Technosols, Anthrosols and Cambisols) characterised by different kinds and degrees of intensity of anthropogenic influence. In some cases, the results show a relatively severe element concentration (Cu, Sn) mainly characterising the Iron Age (Etruscan and Villanovan) stratigraphic units, representing an ancient industrial pollution linked to local dispersal of melting activity dump products generated in near-site surrounding areas. Therefore, a comparison was possible between natural blank and anthropogenically polluted geochemical values for some local soils.
•An archaeological sequence ranging from Bronze to Middle Ages was analysed.•Field descriptions and lab multi-elemental analysis were performed on different soil units.•The WRB classification was used to recognise ancient Technosols, Anthrosols, and Cambisols.•A case of paleo-environmental pollution was recognised due to the metal melting activity.•Garbic Technosols and Technic Anthrosol were found in Villanovan-Etruscan Age characterised by intensive human activity.
The aim of the study was to examine soil microbial activity and functional diversity in different parts of coastal landscapes influenced by recurring saltwater intrusion in the Ravenna area (Italy). ...For this reason, seven profiles were selected in the San Vitale Pinewood, in low-lying interdune spot and next to dune crests and swales. Soils were classified as Typic Psammaquent, Typic Ustipsamment, Aquic Ustipsamment and Sodic Psammaquent. Chemical, physical and biochemical properties of soil horizons, such as microbial biomass metabolic quotient and enzyme activity, were determined to examine the effects of soil salinity and sodicity levels on microbial activity and functional diversity. The various soils and horizons could be split into distinct groups based on Differential Function Analysis of their properties. Cellulase, xylosidase and arylsulfatase showed a peak of their activity in surface horizons of sodic soils. α-glucosidase activity also was high in deeper horizons of those soils. Moreover, functional diversity, evaluated through calculation of Shannon's diversity index, was higher in the surface and deeper horizons of saline soils than non-saline soils. Conversely, soil with shallow water-table showed similar enzyme activity to soil located in the highest spots of the dune system. However, the highest values of specific activity (per unit of organic carbon) recorded in the deep horizons of the Typic Ustipsamment soil suggested more efficient hydrolytic activity of organic substrates due to oxygenation of soil. In conclusion, hydromorphic conditions in these soils influence the efficiency of organic substrate hydrolysis while soil salinity and sodicity increase both biochemical activity and functional diversity of microbial communities.
► We assessed changes of microbial activity in soil subjected to saltwater intrusion. ► Seven soil profiles were examined in San Vitale Pinewood (Ravenna, Italy). ► Three of the seven soils were classified as Sodic Psammaquent. ► Four soils were classified as Typic Psammaquent or Ustipsamment, Aquic Ustipsamment. ► Soil salinity and sodicity promote microbial activity and functional diversity.
Soil organic matter (SOM) pools and soil available calcium (Ca
exch
) were monitored during a 4-year period in an experimental chestnut stand treated for the restoration of timber production. In 2004 ...the stand was cut and stumps were grafted. Before the forestry operations, the biocycling process seemed to contrast soil nutrient loss, returning Ca to mineral soil through plant activity. Therefore, we hypothesized that the regrowing vegetation after forestry operations would supply Ca to the soil surface and maintain a certain soil fertility level. In fact, from 2005, a progressive recovery of 460 mg Ca
exch
kg
−1
year
−1
at the soil surface was found, corresponding to about 5 % of the Ca of the leaf litter (8,605 mg Ca kg
−1
, chestnut leaves sampled in 2007). However, the Ca
exch
seemed to depend on the humified C (
r
2
= 0.858;
p
< 0.01). At the soil surface, the humified C decreased. Therefore, other processes involving SOM dynamics may be taken into account. After the first year, the scarce presence of litter layer at the soil surface could have exacerbated soil erosion and reduction of SOM content, as shown by the change in horizon thickness and C amount. In later years a litterfall layer was present due to the regrowing vegetation and soil erosion was reduced, but SOM turnover did not change. In parallel the amount of microbial biomass C and soil respiration increased. Because the addition of new C source from regrowing vegetation can stimulate soil microbial activity, we hypothesized that the occurrence of a priming effect in our soil could further affect soil C and nutrient availability in later years management change.
We report the detection of a faint optical flash by the 2-m Faulkes Telescope North simultaneously with the second of two prompt γ-ray pulses in INTEGRAL gamma-ray burst (GRB) 080603A, beginning at t
...rest= 37 s after the onset of the GRB. This optical flash appears to be distinct from the subsequent emerging afterglow emission, for which we present comprehensive broad-band radio to X-ray light curves to 13 d post-burst and rigorously test the standard fireball model. The intrinsic extinction towards GRB 080603A is high (A
V, z
= 0.8 mag), and the well-sampled X-ray-to-near-infrared spectral energy distribution is interesting in requiring an LMC2 extinction profile, in contrast to the majority of GRBs. Comparison of the γ-ray and extinction-corrected optical flux densities of the flash rules out an inverse-Compton origin for the prompt γ-rays; instead, we suggest that the optical flash could originate from the inhomogeneity of the relativistic flow. In this scenario, a large velocity irregularity in the flow produces the prompt γ-rays, followed by a milder internal shock at a larger radius that would cause the optical flash. Flat γ-ray spectra, roughly F∝ν−0.1, are observed in many GRBs. If the flat spectrum extends down to the optical band in GRB 080603A, the optical flare could be explained as the low-energy tail of the γ-ray emission. If this is indeed the case, it provides an important clue to understanding the nature of the emission process in the prompt phase of GRBs and highlights the importance of deep (R > 20 mag), rapid follow-up observations capable of detecting faint, prompt optical emission.
The Fermi GBM and LAT follow-up of GW150914 Bissaldi, E.; Connaughton, V.; Omodei, N. ...
EPJ Web of Conferences,
01/2017, Letnik:
136
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
As the first detection of Gravitation Wave (GW) event arising from the coalescence of two stellar-mass Black Holes (BH) was announced by LIGO, a new era for astronomy began. Searches for ...electromagnetic (EM) counterparts of GW events is of fundamental importance, as they increase the confidence in the GW detection and help characterize the parameters of the merger. The Fermi gamma-ray space telescope has the best sensitivity to simultaneously observe a large fraction of the sky from 10 keV to more than 300 GeV, providing the unique capability of rapidly covering the entire probability region from a LIGO candidate. Here we present observations by the Fermi Gamma-Ray BurstMonitor (GBM) 1 and by the Large Area Telescope (LAT) 2 of the LIGO Gravitational Wave event GW150914, which has been associated to the merger of two stellar-mass BHs. We report the presence of a weak transient event in GBM data, close in time to the LIGO one. We discuss the characteristics of this GBM transient, which are consistent with a weak short GRB arriving at a large angle to the direction in which Fermi was pointing. Furthermore, we report LAT upper limits (ULs) for GW150914, and we present the strategy for follow-up observations of GW events with the LAT.
This study aimed to evaluate the role of different plant covers on brown soil profile development changing SOM stability in the epipedons. In particular, two brown soils (Eutric Cambisols), located ...in Monghidoro at the Italian Apennines, were analysed in order to test the hypothesis that plant cover affects the brown soil profile development under eutric qualifier changing SOM stability and soil pH. Also we verified if soil biochemical activities and microbial biomass size could be promoted by factors supporting Eutric Cambisols development. The two soil profiles were formed under coniferous (M
con) and beech cover (M
beech), respectively; both of them had similar lithology, morphology, exposition, slope and elevation. The development of soil profiles was evaluated by the determination of their physical, chemical and biochemical properties, while SOM stability of the epipedons was assessed through the determination of some properties of humic substances by thermal (TG-DSC) and spectroscopic (FTIR) analysis, humification indexes and eco-physiological indicators such as microbial quotient (C
mic:C
org) and metabolic quotient (qCO
2).
The C
org content decreased along both soil profiles. The epipedon of M
beech soil was richer in SOM that in turn showed a higher level of humification than M
con. The pH value, CEC and the concentrations of all earth-alkaline cations were also higher in M
beech than in M
con soil profile. Differences in soil reaction and SOM quality seemed to affect weathering process, since the content of all Al forms (amorphous—Alo, crystalline—Ald and linked to SOM—Alp) increased as the soil pH decreased, and the Fe forms increased as the humification level of SOM increased. Nevertheless, the active iron ratio (Feo/Fed) calculated in the two soil profiles did not highlight significant differences between them in terms of podzolitation intensity. The activity of hydrolytic enzymes (β-glucosidase, cellulase and chitinase) was higher in M
beech soil than in M
con soil profile. The activity of all enzymes, on mass basis, decreased along both soil profiles, while the specific activity (per unit of organic carbon), increased only in the endopedons of M
beech. Although biochemical properties were not correlated with physical and chemical properties of soil profile, significant correlations were observed between enzyme activity and the soil organic carbon or nitrogen content. As far as the epipedons SOM quality is concerned, the content of humified C, the microbial biomass carbon (C
mic), as well as the C
mic:C
org were higher in M
beech than in M
con, whereas the qCO
2 was lower in M
beech than in M
con. Also the FTIR and TG-DSC analysis showed differences on HAs and FAs hydrophilic character and thermal stability between epipedons of M
beech and M
con. The SOM quality of epipendon under coniferous resulted in a more recalcitrant and hydrophobic composition than that of epipedon under beech.
In conclusion the type of plant cover (coniferous
vs. beech-tree) affected the weathering of the pedogenetic substrate changing the SOM properties and soil pH. Even if the beech-tree cover promoted SOM accumulation in soil profile, which represented the organic substrates for microbial biochemical activities, the weathering of soil under coniferous appeared more marked than beech-trees covered soil. Consequently, soil biochemical activity of microbial biomass along soil profile was not promoted by factors supporting weathering processes.
Display omitted
► We studied the effect of plant cover on soil development and biochemical properties. ► Two Eutric Cambisols were examined, under coniferous and beech-tree, respectively. ► Soil weathering appears more marked under coniferous than under beech-trees. ► Some chemical properties are affected, but no correlation is found with soil biochemical activity. ► Soil biochemical activity doesn't seem to be promoted by weathering processes.
Context. The multi-purpose INTEGRAL mission is continuously contributing to Gamma Ray Burst (GRB) science, thanks to the performances of its two main instruments, IBIS and SPI, operating in the hard ...X-ray / soft γ-ray domain. Aims. We investigate the possibilities offered to the study of GRBs by PICsIT, the high-energy detector of the IBIS instrument. Methods. We searched for transient episodes in the PICsIT light curves archive from May 2006 to August 2009, using stringent criteria optimized for the detection of long events. In the time interval under examination PICsIT provides an energy coverage from 208 to 2600 keV, resolved in eight energy channels, combined with a fine time resolution of 16 ms. Results. PICsIT successfully observes GRBs in the 260–2600 keV energy range with an incoming direction spread over half the sky for the brightest events. We compiled a list of 39 bursts, most of which are confirmed GRBs or simultaneous to triggers from other satellites/instruments. We produced light curves with a time sampling down to 0.25 s in three energy intervals for all events. Because an adequate response matrix is not yet available for the PICsIT burst sample, we obtained a calibration coefficient in three selected energy bands by comparing instrumental counts with physical fluences inferred from observations with different satellites. The good time resolution provided by the PICsIT data allows a spectral variability study of our sample through the hardness ratio.
Context
. Simultaneous
γ
-ray measurements of
γ
-ray burst spectra and polarization offer a unique way to determine the underlying emission mechanism(s) in these objects, as well as probing the ...particle acceleration mechanism(s) that lead to the observed
γ
-ray emission.
Aims
. We examine the jointly observed data from POLAR and
Fermi
-GBM of GRB 170114A to determine its spectral and polarization properties, and seek to understand the emission processes that generate these observations. We aim to develop an extensible and statistically sound framework for these types of measurements applicable to other instruments.
Methods
. We leveraged the existing
3ML
analysis framework to develop a new analysis pipeline for simultaneously modeling the spectral and polarization data. We derived the proper Poisson likelihood for
γ
-ray polarization measurements in the presence of background. The developed framework is publicly available for similar measurements with other
γ
-ray polarimeters. The data are analyzed within a Bayesian probabilistic context and the spectral data from both instruments are simultaneously modeled with a physical, numerical synchrotron code.
Results
. The spectral modeling of the data is consistent with a synchrotron photon model as has been found in a majority of similarly analyzed single-pulse gamma-ray bursts. The polarization results reveal a slight trend of growing polarization in time reaching values of ∼30% at the temporal peak of the emission. We also observed that the polarization angle evolves with time throughout the emission. These results suggest a synchrotron origin of the emission but further observations of many GRBs are required to verify these evolutionary trends. Furthermore, we encourage the development of time-resolved polarization models for the prompt emission of gamma-ray bursts as the current models are not predictive enough to enable a full modeling of our current data.
The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years ...of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass ≲100 GeV annihilating via quark and τ-lepton channels.
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