Microbial oxidation of environmental antimonite (Sb(III)) to antimonate (Sb(V)) is an antimony (Sb) detoxification mechanism. Ensifer adhaerens ST2, a bacterial isolate from a Sb-contaminated paddy ...soil, oxidizes Sb(III) to Sb(V) under oxic conditions by an unknown mechanism. Genomic analysis of ST2 reveals a gene of unknown function in an arsenic resistance (ars) operon that we term arsO. The transcription level of arsO was significantly upregulated by the addition of Sb(III). ArsO is predicted to be a flavoprotein monooxygenase but shows low sequence similarity to other flavoprotein monooxygenases. Expression of arsO in the arsenic-hypersensitive Escherichia coli strain AW3110Δars conferred increased resistance to Sb(III) but not arsenite (As(III)) or methylarsenite (MAs(III)). Purified ArsO catalyzes Sb(III) oxidation to Sb(V) with NADPH or NADH as the electron donor but does not oxidize As(III) or MAs(III). The purified enzyme contains flavin adenine dinucleotide (FAD) at a ratio of 0.62 mol of FAD/mol protein, and enzymatic activity was increased by addition of FAD. Bioinformatic analyses show that arsO genes are widely distributed in metagenomes from different environments and are particularly abundant in environments affected by human activities. This study demonstrates that ArsO is an environmental Sb(III) oxidase that plays a significant role in the detoxification of Sb(III).
•Novel stochastic optimization to enable fast rolling-horizon procedures.•Classification of methodologies as Aggregating-Rule-based Stochastic Optimization.•Decoupling a N-scenario problem into N ...deterministic sub-problems.•Cost-based aggregator to select the final dispatching strategy.•Numerical case study comparing the new approach with standard stochastic procedures.
Stochastic management strategies have proven to achieve cheaper resource scheduling both in large power systems and microgrids, but suffer from high computational requirements with respect to traditional deterministic approaches; therefore, using stochastic formulations in advanced infra-daily operating strategies is quite challenging, especially in isolated hybrid energy systems with limited computational assets. This paper proposes a methodology for the microgrid operation based on a novel two-stage formulation that decomposes the stochastic problem into several deterministic subproblems, whose solutions are afterwards aggregated by the aggregator using simulations and a cost-based rule. In the first stage, every subproblem is solved, then each optimal dispatching is simulated in the second stage to evaluate the corresponding expected operating cost, which is used by the aggregator to select the final optimal scheduling. When compared to traditional methods for a rural microgrid in Uganda, the proposed approach not only achieves interesting savings in operational costs, up to 5%, but also sharply reduces the computational requirements, even more than 5–100 times with respect to traditional stochastic approaches. The paper also proposes a review and first classification of this kind of methodologies, to highlight the novelties of the approach.
Geochemical and isotopic (87Sr/86Sr and 18O/16O) data have been acquired on whole rock and separated mineral samples from volcanic products of the 1302AD Arso eruption, Ischia volcanic island (Gulf ...of Naples, Southern Italy), to investigate magmatic processes. Our results highlight petrographic and isotopic disequilibria between phenocrysts and their host rocks. Similar disequilibria are observed also for more mafic volcanic rocks from Ischia and in the Phlegraean Volcanic District in general. Moreover, 87Sr/86Sr and 18O/16O values suggest mixing between chemically and isotopically distinct batches of magma, and crystals cargo from an earlier magmatic phase. The radiogenic Sr isotope composition suggests that the mantle source was enriched by subduction-derived sediments. Furthermore, magmas extruded during the Arso eruption were affected by crustal contamination as suggested by high oxygen isotope ratios. Assimilation and fractional crystallization modelling of the Sr-O isotope compositions indicates that not more than ~7% of granodioritic rocks from the continental crust have been assimilated by a mantle-derived mafic magma. Hence the recent volcanic activity of Ischia has been fed by distinct batches of magma, variably contaminated by continental crust, that mixed during their ascent towards the surface and remobilized phenocrysts left from earlier magmatic phases.
•Arso rocks show strong petrographic and isotopic disequilibria.•Mixing between distinct batches of magma is recognized.•Possible entrapment of crystals grown during an earlier magmatic phase•Sr-O isotopes indicate a mantle source enriched by 1% of subducted sediments.
The island of Ischia, located at the northwestern end of the Gulf of Napoli (Italy), is a volcanic area that is historically active (the Arso eruption, in 1302 and the Casamicciola earthquake, in ...1883) and has diffuse hydrothermal phenomena. We present in this work a study of the surface deformation occurring in the island, which is based on applying the Differential Synthetic Aperture Radar Interferometry (DInSAR) algorithm referred to as Small BAseline Subset (SBAS) technique. This study is focused on the 1992–2003 time interval and SAR data acquired by the European Remote Sensing (ERS) satellites from ascending and descending orbits have been used, thus allowing us to discriminate the vertical and east–west components of the displacements. A validation of the DInSAR results has been carried out first by comparing the vertical deformations estimated from the SAR data with those measured from the spirit leveling network that is present in the area. In particular, we computed the difference between the mean vertical deformation velocities estimated from the SAR and the corresponding geodetic measurements along three main leveling lines; the maximum value of the root mean square difference is of about 1 mm/yr. The final discussion is dedicated to the interpretation of the detected displacements, benefiting from the overall information extracted from the ascending and descending DInSAR measurements. In particular, DInSAR data relative to the vertical deformation component show that the present-day subsidence of Ischia mainly develops in areas characterized by active landsliding and along faults; moreover, the deflation of the island, which is recorded by the horizontal displacement component, is probably related to the de-pressurization of the hydrothermal system.
Stochastic operation of power systems has risen attention of researchers as fluctuating energy sources like renewables are being increasingly integrated into existing grids. Uncertainties can be ...higher in small power systems like isolated microgrids, where both renewables and load can be extremely unpredictable, thus causing increasing operating costs and business risks. In the last years, many approaches have been proposed to account for uncertainties in off-grid microgrids, usually simulating several size, load and renewables scenarios. Among them, a simplified stochastic approach, namely Aggregating-Rule-based Stochastic Optimization (ARSO), which decomposes the N-scenario problem into N deterministic subproblems whose solutions are finally processed and aggregated, has been recently proposed with interesting results in terms of optimality of results and computational requirements. In this paper, two ARSO approaches are compared with standard stochastic and deterministic methodologies used to operate isolated microgrids, to assess advantages and drawbacks of all these techniques and their ability in handling uncertainties. The two ARSO methodologies differ in the aggregating rule: to take into account the load and RES forecasting errors, the Improved-ARSO employs a Monte Carlo procedure, whereas the Mixed ARSO technique makes use of statistical rules. A numerical case study for a typical isolated microgrid in Africa is proposed and discussed.
The intricate pathways of fluid–mineral reactions occurring underneath active hydrothermal systems are explored in this study by applying reaction path modelling to the Ischia case study. Ischia ...Island, in Southern Italy, hosts a well-developed and structurally complex hydrothermal system which, because of its heterogeneity in chemical and physical properties, is an ideal test sites for evaluating potentialities/limitations of quantitative geochemical models of hydrothermal reactions. We used the EQ3/6 software package, version 7.2b, to model reaction of infiltrating waters (mixtures of meteoric water and seawater in variable proportions) with Ischia’s reservoir rocks (the Mount Epomeo Green Tuff units; MEGT). The mineral assemblage and composition of such MEGT units were initially characterised by ad hoc designed optical microscopy and electron microprobe analysis, showing that phenocrysts (dominantly alkali–feldspars and plagioclase) are set in a pervasively altered (with abundant clay minerals and zeolites) groundmass. Reaction of infiltrating waters with MEGT minerals was simulated over a range of realistic (for Ischia) temperatures (95–260°C) and CO2 fugacities (10−0.2 to 100.5) bar. During the model runs, a set of secondary minerals (selected based on independent information from alteration minerals’ studies) was allowed to precipitate from model solutions, when saturation was achieved. The compositional evolution of model solutions obtained in the 95–260°C runs were finally compared with compositions of Ischia’s thermal groundwaters, demonstrating an overall agreement. Our simulations, in particular, well reproduce the Mg-depleting maturation path of hydrothermal solutions, and have end-of-run model solutions whose Na–K–Mg compositions well reflect attainment of full-equilibrium conditions at run temperature. High-temperature (180–260°C) model runs are those best matching the Na–K–Mg compositions of Ischia’s most chemically mature water samples, supporting quenching of deep-reservoir conditions for these surface manifestations; whilst Fe, SiO2 and, to a lesser extent, SO4 contents of natural samples are better reproduced in low-temperature (95°C) runs, suggesting that these species reflect conditions of water–rock interaction in the shallow hydrothermal environment. The ability of model runs to reproduce the compositional features of Ischia’s thermal manifestations, demonstrated here, adds supplementary confidence on reaction path modelling as a realistic and insightful representation of mineral–fluid hydrothermal reactions. Our results, in particular, demonstrate the significant impact of host rock minerals’ assemblage in governing the paths and trends of hydrothermal fluids’ maturation.
Mean directions of magnetization from Mounts Arso (Ischia Island, Gulf of Naples), Etna and Vesuvius lava flows have been determined based on very stringent linearity criteria. These indicate that, ...regardless of the source volcano, the lava flow mean directions of magnetization form a common path, the SISVC (Southern Italy Secular Variation Curve). This curve enables a reassessment of the age of eruption of several lavas. A date of AD 1169 is demonstrated to be the only possible time of emplacement for one Etna lava flow previously assigned an age of AD 812/1169. It is also demonstrated that two Etna lava flows, which, according to the literature, were emplaced in AD 1536 and 1595 respectively, were actually both emplaced around AD 1037. Three other Etna lava flows, one ascribed to AD 1566 and two to AD 1595, were actually emplaced between AD 1169 and 1284/85. The same time window also holds for a Vesuvius lava flow for which only an upper time threshold was previously available. Only one of the studied flows needs further sampling and analysis to verify whether this flow has been affected by a complete remagnetization or has an erroneous historical dating. The applied procedure seems to be the most appropriate one in carrying out palaeomagnetic surveys of lava flows, as also suggested by the broad agreement with some 17th and 19th century measurements of the geomagnetic field in Rome, relocated to Etna, and is likely to improve knowledge of past history of a volcano significantly
Achieving universal electrification is a challenging goal for governments in developing countries; the traditional approach of extending the national grid to rural areas has been usually pursued but ...since many communities are located far from the national grid, this approach may be sub-optimal. Hybrid microgrids, composed by renewables, batteries and a backup fuel-fired genset, are very promising solutions, but socio-political and geographical concerns undermine the optimal design of the system and the economic viability of projects. Recent advanced approaches use Monte Carlo techniques to size the system accounting for uncertainties regarding the load and renewable production; however, few papers have investigated the optimal number of Monte Carlo scenarios to evaluate for a proper sizing. In this study, we investigate the benefits and drawbacks of using Monte Carlo techniques to cope with uncertainties involved in the optimal design and operation of hybrid microgrids, proposing new sizing criteria and highlighting best practices. A case study using real data from a minigrid in Kenya is proposed.
Two surveys of soil-gas and diffuse flux of CO2 and CH4 were carried out at Ustica Island (southern Tyrrhenian back-arc basin) in 1997 and 1999 to examine the degassing role of fault and fracture ...systems, as local evidence of wider structures of regional importance. Both surveys show that the Arso fault, crossing the island, is the main degassing structure. Fault-linked positive CH4 fluxes confirm that methanotrophic consumption in soil is higher in warmer periods but seems to be insufficient for consuming all leaking geologic CH4.Chemical and isotopic analyses of soil gases at higher degassing sites show that despite the extensive atmospheric contamination, He concentrations are always above the atmospheric level. 3He/4He isotopic ratios also suggest that a contribution of a deep-originated component is still detectable on the island.
"Clear legal action must be taken against violators of the law indiscriminately. As a metter of principle, if a shooting is committed by a soldier in violation of standard procedure, he cannot escape ...legal prosecution," Harry Maturbongs, coordinator of Kontras' Papua chapter, said. Isak was shot on his way from Kofiau to Arso Timur, Keerom District, Papua Province. The shooting incident happened near the Indonesian-PNG border at Bewain Patrol Post which was manned by eight members of the Indonesian Defense Forces (TNI). According to Anton Psakor, the victim's father, his three children, namely Isak, Wens and John Psakor, were walking from Skowt Jauh kampong to Air Asin kampong in East Arso which borders on PNG territory on Monday (June 22).
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