Leaking And Non-leaking Systems: Study Of Natural CO2 Accumulations For Geological Sequestration

The potential risks of geological CO2 storage must be understood and geologists are required to predict how CO2 may behave once stored underground. As natural geological accumulations of carbon dioxide occur in many basins in Italy and volcanic and seismically active areas allow CO2 rich fluids to migrate to the near surface, many of these areas have been investigated in order to study long-term geochemical processes that may occur following geological storage of anthropogenic CO2. A study representing an example of "leaking" system is the Solfatara crater (Campi Flegrei, Southern Italy) characterised by the presence of both CO2 rich-waters and fumarole. Soil gas flux measurements show that the entire area discharges between 1200 and 1500 tons of CO2 a day. Most part of analysed waters is the effect of a mixing between a shallow meteoric water and a deep thermal Na-Cl end-member and/or seawater, resulting in sodiumchloride waters. A high dissolved CO2 content (max value 566.28 cc/l) is also present. Furthermore, the Campi Flegrei frequently undergo bradyseism related to the elastic response of the shallow crust to increasing pressure within a shallow magma chamber. The study of this phenomenon could be useful to detect ground deformation linked to geomechanical changes in a geological CO2 reservoir. In contrast, an example of "non-leaking" system is the Pisticci oil and gas Field (Southern Italy) where a great variety of hydrocarbons traps are formed by horst and tilted blocks in the Mesozoic carbonate substratum covered by an almost continuous sequence of Lower Pliocene marls and Middle Pliocene-Pleistocene marly blue clays. Soil gas surveys were performed after a MD 4.5 earthquake and two years later to test the permanence of the gas distribution pattern. CO2 distribution in soil gas seems not to be affected by changes in stress, as suggested by the average values of both surveys. The principal aim of our research has been to evaluate and mitigate risks for local populations as the studied areas are densely populated. To date, the obtained results suggest that gas uprising is generally well localised around restricted areas, often controlled by local tectonics (faults and/or fractures). This implies that, in the frame of geological CO2 sequestration, it is necessary to carefully assess the presence of pathways (fault and/or fractures) that might allow the migration of CO2 out of the reservoir

SOFC Micro-CHP integration in residential buildings

SOFC technology has reached many of the performance goals that where indicated by scientific society and is providing several application that permits market penetration. One of the main targets is related to Micro Cogeneration Heat and Power (μ-CHP) for residential application. The integration of this system with a residential house has to be deeply investigated to individuate market targets in terms of costs and efficiency. This study evaluates the Italian market condition and analyzes the integration possibility with both thermal and electrical systems. Different solutions are investigated evaluating thermal and electrical driven logic for μ-CHP SOFC based unit and the opportunity of integration with local electrical grid. Evaluation on heat and electricity storage was also considered as integration strategy. The study is based on electrical and thermal loads in typical residential users and the evaluation is based on Italian technical standards and guidelines. Several operating conditions were evaluated and compared to obtain an optimized size and integration of μHP SOFC based solution

One-dimensional Ising ferromagnet frustrated by long-range interactions at finite temperatures

We consider a one-dimensional lattice of Ising-type variables where the ferromagnetic exchange interaction J between neighboring sites is frustrated by a long-ranged anti-ferromagnetic interaction of strength g between the sites i and j, decaying as |i-j|^-alpha, with alpha>1. For alpha smaller than a certain threshold alpha_0, which is larger than 2 and depends on the ratio J/g, the ground state consists of an ordered sequence of segments with equal length and alternating magnetization. The width of the segments depends on both alpha and the ratio J/g. Our Monte Carlo study shows that the on-site magnetization vanishes at finite temperatures and finds no indication of any phase transition. Yet, the modulation present in the ground state is recovered at finite temperatures in the two-point correlation function, which oscillates in space with a characteristic spatial period: The latter depends on alpha and J/g and decreases smoothly from the ground-state value as the temperature is increased. Such an oscillation of the correlation function is exponentially damped over a characteristic spatial scale, the correlation length, which asymptotically diverges roughly as the inverse of the temperature as T=0 is approached. This suggests that the long-range interaction causes the Ising chain to fall into a universality class consistent with an underlying continuous symmetry. The e^(Delta/T)-temperature dependence of the correlation length and the uniform ferromagnetic ground state, characteristic of the g=0 discrete Ising symmetry, are recovered for alpha > alpha_0.Comment: 12 pages, 7 figure

Chemical and isotopic characterisation of gas and water in a scientific

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Spatial distribution of arsenic, uranium and vanadium in the volcanic-sedimentary aquifers of the Vicano–Cimino Volcanic District (Central Italy)

Arsenic concentrations were analysed for 328 water samples collected in the Vicano–Cimino Volcanic District (VCVD), an areawhere severe contamination of groundwater has become a serious problemfollowing the recent application of the EU Directive on the maximum allowable concentration level for As in drinking waters. In addition, uranium and vanadium concentrations were also analysed in light of the enhanced interest on their environmental toxicity. Waters were collected from springs and wells fed by cold and shallow volcanic–sedimentary aquifers, which locally represent the main drinking water source. Thermal springs (≤63 °C) related to an active hydrothermal reservoir and waters associated with a CO2-rich gas phase of deep provenance were also analysed. The collected data showed that the As concentrations in the shallow aquifers varied in a wide range (0.05–300 μg/L) and were primarily controlled by water–rock interaction processes. High As concentrations (up to 300 μg/L) were measured in springs and wells discharging from the volcanic products, and about 66% exceeded the limit of 10 μg/L for drinkingwaters,whereaswaters circulatingwithin the sedimentary formations displayed much lower values (0.05–13 μg/L; ~4% exceeding the threshold limit). Thermal waters showed the highest As concentrations (up to 610 μg/L) as the result of the enhanced solubility of As-rich volcanic rocks during water–rock interaction processes at high temperatures. Where the local structural setting favoured the rise of fluids from the deep hydrothermal reservoir and their interaction with the shallow volcanic aquifer, relatively higher concentrations were found. Moreover, well overexploitation likely caused the lateral inflow of As-rich waters towards not contaminated areas. Uraniumand vanadiumconcentrations ofwaters circulating in the volcanic rocks ranged from0.01 to 85 μg/L and 0.05 to 62 μg/L, respectively. Less than 2% of analysed samples exceeded theWorld Health Organization's provisional guidelines for U (30 μg/L), while none of them was above the Italian limit value of V in drinking water (120 μg/L). Lower U (0.07–22 μg/L and 0.02–13 μg/L, respectively) and V concentrations (0.05–24 μg/L and 0.18–17 μg/L, respectively) were measured in the water samples from the sedimentary aquifer and thermal waters. Local lithology appeared as the main factor affecting the U and V contents in the shallow aquifers, due to the high concentrations of these two elements in the volcanic formations when compared to the sedimentary units. In addition, high U concentrations were found in correspondence with U mineralization occurring within the VCVD, fromwhich U is released in solution mainly through supergene oxidative alteration. Redox conditions seem to play amajor role in controlling the concentrations of U and V inwaters. Oxidizing conditions characterizing the cold waters favour the formation of soluble U- and V-species, whereas thermal waters under anoxic conditions are dominated by relatively insoluble species. Geostatistical techniques were used to draw contour maps by using variogram models and kriging estimation aimed to define the areas of potential health risk characterized by As, U and V-rich waters, thus providing a useful tool for water management in a naturally contaminated area to local Authorities

Broad band X-ray spectral properties of Gamma-ray bursts with BeppoSAX

In about one year, five gamma-ray bursts were simultaneously observed with the Wide Field Cameras and Gamma Ray Burst Monitor aboard the BeppoSAX satellite. From some of them X-ray afterglow emission has been clearly detected with the same satellite. In order to understand how GRB emission is related to the X-ray afterglow, we are performing a systematic study of the spectral properties of these events. We report here preliminary results of this study.Comment: 5 pages, 3 figures. To appear in the Proceedings of the 4th Huntsville Gamma-ray Burst Symposiu

Scanning Electron Microscopy of the Small Intestine Mucosa in Children with Celiac Disease After Long-Term Dietary Treatment

Jejunal mucosal specimens from twenty children with celiac disease were studied by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) after one year of dietary treatment. An ultrastructural morphometric study was performed in five patients who had an intestinal permeability (IP) test. Seventeen patients were tested for serum antigliadin antibodies (AGA). In ten children, in whom LM showed partial villous atrophy, SEM and TEM examination confirmed the lesion. In the second group (10 children) with normal morphology at routine LM, SEM showed lesions of variable degree in 70% of cases. The morphological ultrastructural investigation showed good correlation with the immunological and functional data (IP test): ultrastructural damage of the jejunal mucosa after one year of a gluten-free diet was found in patients with positive serum AGA and an abnormal IP test. Furthermore, the morphometric study of the ultrastructural alterations allowed a quantitative, closer correlation between morphological and functional data. Our results suggest: 1) SEM and TEM investigations offer additional and more complete information on celiac patients, over LM alone. 2) The morphometric evaluation of the ultrastructural alterations highlights quantitative and reproducible correlations between morphological and clinical data, not strengthened by the subjective, qualitative study

Magnitude and Duration of Elevated Gastric pH in Patients Infected with Human Immunodeficiency Virus After Administration of Chewable, Dispersible, Buffered Didanosine Tablets

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90191/1/phco.24.16.1539.50959.pd