Fe xxv and Fe xxvi lines from low-velocity, photoionized gas in the X-ray spectra of active galactic nuclei

We have calculated the equivalent widths of the absorption lines produced by Fe  xxv and Fe  xxvi in a Compton-thin, low-velocity photoionized material illuminated by the nuclear continuum in active galactic nuclei. The results, plotted against the ionization parameter and the column density of the gas, are a complement to those presented by Bianchi & Matt for the emission lines from the same ionic species. As an extension to the work by Bianchi & Matt, we also present a qualitative discussion on the different contributions to the He-like iron emission line complex in the regimes where recombination or resonant scattering dominates, providing a useful diagnostic tool to measure the column density of the gas. Future high-resolution missions (e.g. Astro-E2 ) will allow us to fully take advantage of these plasma diagnostics. In the meantime, we compare our results with an up-to-date list of Compton-thick and unobscured (at least at the iron line energy) Seyfert galaxies with emission and/or absorption lines from H- and He-like iron observed with Chandra and XMM–Newton .     

Numerical modelling of the effect of horizontal drains in centrifuge tests on soil-structure interaction in liquefiable soils

Bulletin of Earthquake Engineering - The research presented herein was carried out in the framework of the H2020 LIQUEFACT project ( http://www.LIQUEFACT.eu/ ). This paper presents the results of a...     

Typology of detrital zircon as a key to unravelling provenance in rift siliciclastic sequences (Permo-Carboniferous of Spiti,N India)

Abstract

Detrital zircon populations from Carboniferous to Permian sandstones from the Lozar Section of Spiti, northern India, were analyzed with the typology method in order to obtain complementary information on the source areas of the sediments. Zircon grains were subdivided into several groups and subgroups, according to degree of abrasion and morphological features.

First appearance of detrital zircons with distinct typologic signature within successive stratigraphic intervals provided useful data about the tectono-magmatic evolution of the northern Indian margin during Late Paleozoic rifting of Gondwana and initial opening of Neotethys. The base of the studied sequence (Lower Carboniferous Thabo Fm.) is characterized by a largely cratonic provenance, seemingly from the Indian Shield to the South. In the Upper Carboniferous Chichong Fm., first occurrence of typical zircons from anatectic granites and increasing abundance of granitoid detritus suggest rapid uplift and unroofing of anatectic rocks of probable Cambro-Ordovician age. In the lowermost Permian (Asselian) glaciomarine Ganmachidam Diamictite, euhedral detrital zircons with peculiar features, associated with Cr-rich chromian spinels and mafic to felsic volcanic rock fragments, hint at emplacement of bimodal alkaline magmatic suites. The same sources, possibly including subvolcanic bodies, continued to be eroded until final break-up, documented by the Permian Kuling Group.     

The interplay between basement fabric,rifting, syn-rift folding,and inversion in the Rio do Peixe Basin,NE Brazil

The Rio do Peixe Basin is part of a series of aborted Cretaceous rifts formed within the Proterozoic Borborema Province, onshore NE Brazil in response to rifting between Africa and South America. The basin is remarkably well-imaged and comprises fault-bounded depocentres, the main ones being the NE-oriented Brejo das Freiras and the E–W-oriented Sousa half-grabens. These grabens and their bounding faults are influenced by Neoproterozoic basement shear zones and present a complex framework of secondary normal faults and folds. Recent workers also interpret large reverse faults and regional post-rift shortening driven by far-field stresses from the Andes. For those reasons, the basin represents an ideal setting to investigate the multiphase history of rift basins. We thus combine borehole-calibrated 2D and 3D seismic and magnetic data with section restoration and numerical modelling to investigate the architecture and evolution of this basin. We aim to understand: (i) the controls of the basement fabric in 3D fault architecture and kinematics and (ii) how syn-rift faults controlled the geometry and development of fault-related folds. By doing this, we also investigate the timing, kinematics, and magnitude of inversion in the basin to explore its multiphase history. We demonstrate that (i) the basement fabric controlled not only the strike of faults but also their geometry and polarity at depth, (ii) folds in the syn-rift sequence are attributed simply to syn-rift extension along stepped and/or curved faults, and (iii) inverted and/or reverse faults occur within the basin, but these are minor and appear to have formed during rifting. We explain this minor inversion by a change in plate kinematics related to the onset of the nearby transform margin to the north. These results have implications for understanding the 3D evolution of oblique grabens, the role of structural inheritance, and the recognition of inversion- versus extension-related folds in rift basins worldwide.     

Effects of Compost Addition on Pyrene Removal from Soil Cultivated with Three Selected Plant Species

A greenhouse pot experiment was conducted to investigate the effect of compost addition on the phytoremediation ability of Medicago sativa, Brassica napus, and Lolium perenne in soils contaminated with pyrene. Pyrene concentrations were evaluated after 90 days in contaminated uncultivated amended‐soil, cultivated amended‐soils, and shoots and roots of the three plant species. The addition of compost enhances significantly pyrene dissipation from 16 to 26% in uncultivated soil, whereas in cultivated soils it appears not to have any significant effect on pyrene dissipation, neither pyrene was detectable in shoots and roots of the three species examined. The high partition coefficient of pyrene to compost dissolved organic matter (DOM) and the molar absorptivity values at 280 nm (ε₂₈₀) indicate a high affinity of pyrene to compost DOM molecules, likely due to their aromatic character. These results suggest that compost improves pyrene removal from soil, possibly by promoting its adsorption onto compost DOM. This property is very important in indicating that compost can be used, besides for its amendment capacity, also as a potential tool for remediation of contaminated soils.     

Perfluorinated compounds in blood of Caretta caretta from the Mediterranean Sea

Perfluorinated compounds (PFCs), widely used for their hydro-oil repellent properties, are almost non-degradable in the environment; there is scientific evidence that indicate bioaccumulation. They represent a threat to many organisms, because they are toxic and are endocrine disruptors. Scientific studies have demonstrated the presence of PFCs in blood and liver samples of fish, turtles, birds and mammals of marine ecosystems in different geographical areas. The aim of this study was to determine the distribution of PFOS and PFOA in blood samples of the marine turtle Caretta caretta, using a minimally invasive sampling procedure. 49 blood samples of marine turtle, taken from several Italian marine turtle rescue centers, were analyzed. While PFOA was never detected, measurable concentrations of PFOS were found in 15 blood samples; the values show a range from 1.14 ng/g to 28.51 ng/g (wet wt.). No differences between groups of samples taken from different areas were found.     

Tracer hydrology of the data-scarce and heterogeneous Central American Isthmus

Numerous socio-economic activities depend on the seasonal rainfall and groundwater recharge cycle across the Central American Isthmus. Population growth and unregulated land use changes resulted in extensive surface water pollution and a large dependency on groundwater resources. This work combines stable isotope variations in rainfall, surface water, and groundwater of Costa Rica, Nicaragua, El Salvador, and Honduras to develop a regionalized rainfall isoscape, isotopic lapse rates, spatial–temporal isotopic variations, and air mass back trajectories determining potential mean recharge elevations, moisture circulation patterns, and surface water–groundwater interactions. Intra-seasonal rainfall modes resulted in two isotopically depleted incursions (W-shaped isotopic pattern) during the wet season and two enriched pulses during the mid-summer drought and the months of the strongest trade winds. Notable isotopic sub-cloud fractionation and near-surface secondary evaporation were identified as common denominators within the Central American Dry Corridor. Groundwater and surface water isotope ratios depicted the strong orographic separation into the Caribbean and Pacific domains, mainly induced by the governing moisture transport from the Caribbean Sea, complex rainfall producing systems across the N-S mountain range, and the subsequent mixing with local evapotranspiration, and, to a lesser degree, the eastern Pacific Ocean fluxes. Groundwater recharge was characterized by (a) depleted recharge in highland areas (72.3%), (b) rapid recharge via preferential flow paths (13.1%), and enriched recharge due to near-surface secondary fractionation (14.6%). Median recharge elevation ranged from 1,104 to 1,979 m a.s.l. These results are intended to enhance forest conservation practices, inform water protection regulations, and facilitate water security and sustainability planning in the Central American Isthmus.