Nota sobre la captura d'Ocythoe tuberculata Rafinesque, 1814 (Cephalopoda: Ocytohoidae) en aigües de Menorca

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Dissolution experiments of commercial PWR (52 MWd/kgU) and BWR (53 MWd/kgU) spent nuclear fuel cladded segments in bicarbonate water under oxidizing conditions. Experimental determination of matrix and instant release fraction

The denominated instant release fraction (IRF) is considered in performance assessment (PA) exercises to govern the dose that could arise from the repository. A conservative definition of IRF comprises the total inventory of radionuclides located in the gap, fractures, and the grain boundaries and, if present, in the high burn-up structure (HBS). The values calculated from this theoretical approach correspond to an upper limit that likely does not correspond to what it will be expected to be instantaneously released in the real system. Trying to ascertain this IRF from an experimental point of view, static leaching experiments have been carried out with two commercial UO2 spent nuclear fuels (SNF): one from a pressurized water reactor (PWR), labelled PWR, with an average burn-up (BU) of 52 MWd/kgU and fission gas release (FGR) of 23.1%, and one from a boiling water reactor (BWR), labelled BWR, with an average BU of and 53 MWd/kgU and FGR of 3.9%.; One sample of each SNF, consisting of fuel and cladding, has been leached in bicarbonate water during one year under oxidizing conditions at room temperature (25 +/- 5) degrees C. The behaviour of the concentration measured in solution can be divided in two according to the release rate. All radionuclides presented an initial release rate that after some days levels down to a slower second one, which remains constant until the end of the experiment. Cumulative fraction of inventory in aqueous phase (FIAPc) values has been calculated. Results show faster release in the case of the PWR SNF. In both cases Np, Pu, Am, Cm, Y, Tc, La and Nd dissolve congruently with U, while dissolution of Zr, Ru and Rh is slower. Rb, Sr, Cs and Mo, dissolve faster than U. The IRF of Cs at 10 and 200 days has been calculated, being (3.10 +/- 0.62) and (3.66 +/- 0.73) for PWR fuel, and (035 +/- 0.07) and (0.51 +/- 0.10) for BWR fuel. (C) 2015 Elsevier B.V. All rights reserved.Peer ReviewedPostprint (author's final draft

Fiscal policy shocks in the euro area and the US: an empirical assessment

We analyse the impact of fiscal policy shocks in the euro area as a whole, using a newly available quarterly dataset of fiscal variables for the period 1981-2007. To allow for comparability with previous results on euro area countries and the US, we use a standard structural VAR framework, and study the impact of aggregated and disaggregated government spending and net taxes shocks. In addition, to frame euro area results, we apply the same methodology for the same sample period to US data. We also explore the sensitivity of the provided results to the inclusion of variables aiming at measuring “financial stress” (increases in risk) and “fiscal stress” (sustainability concerns). Analysing US and euro area data with a common methodology provides some interesting insights on the interpretation of fiscal policy shocks. JEL Classification: E62, H30euro area, Fiscal multipliers, Fiscal shocks, SVAR

UO2 surface oxidation by mixtures of water vapor and hydrogen as a function of temperature

In the present work, X-Ray Photoelectron Spectroscopy (XPS) was used to study the effect of water vapor on the UO2 surface as a function of temperature. The experiments were performed in situ inside a high pressure chamber attached to the XPS instrument. UO2 samples were put in contact with either hydrogen or argon streams, saturated with water at room temperature, and the sample surface evolution was analyzed by XPS. In the case of the water vapor/argon experiments, one experiment at 350°C was performed and, in the case of the water vapor/hydrogen experiments, the temperatures used inside the reactor were 60, 120, 200 and 350°C. On one hand, in presence of argon, the results obtained showed that the water vapor in the argon stream oxidized 93% of the U(IV) in the sample surface. On the other hand, the degree of UO2 surface oxidation showed a different dependence on the temperature in the experiments performed in the presence of hydrogen: the maximum surface oxidation occurred at 120°C, where 65.4% of U(IV) in the sample surface was oxidized, while at higher temperatures, the surface oxidation decreased. This observation is attributed to the increase of hydrogen reducing effect when temperature increases which prevents part of the oxidation of the UO2 surface by the water vapor.Peer ReviewedPostprint (author's final draft

Exploring alternative practices in urban water management through the lens of circular economy: a case study in the Barcelona metropolitan area

Urban water management has recently been questioned because of the fragmented nature of the urban water system and its linear model. The integration and management of water systems are currently recognized as a socio-technical challenge that must be addressed for a more sustainable urban water management. In the short term, a key factor for its transition will be integration of alternative practices that allow for experimentation, learning, and scaling up. This study aims to identify potential shifts supported by two alternative practices for water reuse: nature-based solutions and water reuse technologies, using circular economy principles as analytical categories. The research uses a case study, the Besòs river of the Barcelona metropolitan area, to show that: i) improving biodiversity and water quality helps to regenerate natural capital; ii) water reuse for streamflow augmentation keeps resources in use and promotes synergies, which benefits social livability; and iii) risk management and a potential fit-to-purpose strategy can marginally help to avoid waste externalities. This research has shown that the CE principles are applicable as a framework for identifying the interconnected shifts promoted by water systems. A reflexive understanding of the alternative practices provides deeper insight into the experiences, barriers, and shifts that allow innovative interactions in specific urban contexts and can deliver additional benefits for society. This knowledge can be useful for integrated urban management; however, further integration of cross-sectoral collaboration and flexibility are required.Peer ReviewedPostprint (published version

Monopoles in arbitrary dimension

"Vegeu el resum a l'inici del document del fitxer adjunt"

Unraveling the active microbial populations involved in nitrogen utilization in a vertical subsurface flow constructed wetland treating urban wastewater

The dynamics of the active microbial populations involved in nitrogen transformation in a vertical subsurface flow constructed wetland (VF) treating urban wastewater was assessed. The wetland (1.5 m2) operated under average loads of 130 g COD m- 2 d- 1 and 17 g TN m- 2 d- 1 in Period I, and 80 g COD m- 2 d- 1 and 19 g TN m- 2 d- 1 in Period II. The hydraulic loading rate (HLR) was 375 mm d- 1 and C/N ratio was 2 in both periods. Samples for microbial characterization were collected from the filter medium (top and bottom layers) of the wetland, water influent and effluent at the end of Periods I (Jun–Oct) and II (Nov–Jan). The combination of qPCR and high-throughput sequencing (NGS, MiSeq) assessment at DNA and RNA level of 16S rRNA genes and nitrogen-based functional genes (amoA and nosZ-clade I) revealed that nitrification was associated both with ammonia-oxidizing bacteria (AOB) (Nitrosospira) and ammonia-oxidizing archaea (AOA) (Nitrososphaeraceae), and nitrite-oxidizing bacteria (NOB) such as Nitrobacter. Considering the active abundance (based in amoA transcripts), the AOA population revealed to be more stable than AOB in both periods and depths of the wetland, being less affected by the organic loading rate (OLR). Although denitrifying bacteria (nosZ copies and transcripts) were actively detected in all depths, the denitrification process was low (removal of 2 g TN m- 2 d- 1 for both periods) concomitant with NOx-N accumulation in the effluent. Overall, AOA, AOB and denitrifying bacteria (nosZ) were observed to be more active in bottom than in top layer at lower OLR (Period II). A proper design of OLR and HLR seems to be crucial to control the activity of microbial biofilms in VF wetlands on the basis of oxygen, organic-carbon and NOx-N forms, to improve their capacity for total nitrogen removal.Peer ReviewedPostprint (author's final draft

Immobilization of selenite onto natural siderite (FeCO3)

The sorption processes of metals and semimetals on siderite are being studied because of the potential adequacy of the mineral for removing contaminants from natural waters and because of its formation during the reduction of iron(III) (hydr)oxides under anaerobic conditions in the presence of organic matter or bacteria. This transformation could involve the release of contaminants previously sorbed on the iron(III) (hydr)oxides. In this work, the sorption of selenite on natural siderite (Bordes de Conflent, Lleida, Spain) is experimentally studied and the results obtained are compared to the previous results on selenite sorption on magnetite, hematite and goethite.Results indicate that the process of sorption was very fast; the equilibrium was reached in less than 1 hour, which indicates that sorption will not be kinetically controlled. The experimental data were fitted with a non-competitive Langmuir isotherm, which would indicate that the main process for the decrease of selenite in solution would be its sorption on siderite via monolayer coverage of the solid surface. The values of maximum sorption capacity of siderite obtained at pH 7,1 and 8,0 were 6,9 10-7 and 6,4 10-7 mol g-1, respectively and the same value of Langmuir constant was obtained for both pH values, 4,7 104 L mol-1.Postprint (published version

Influence of the interpellet space to the Instant Release Fraction determination of a commercial UO2 Boiling Water Reactor Spent Nuclear Fuel

The contact of the coolant with the fuel pin during irradiation produces a gradient of temperature in the fuel pellet that segregates the radionuclides (RN) depending on its volatility and reactivity. This segregation determines the Instant Release Fraction (IRF), an important source of radiological risk in the performance assessment (PA) of a Deep Geologic Repository (DGR). RN segregation was studied radially in previous papers. In the present work, it was studied axially, taking into special consideration the cutting position of the solid sample to be studied. Iodine and caesium were the RN with the highest release, while the contribution of rubidium, strontium, molybdenum and technetium to the IRF depended on their chemical state. The interpellet presence (known also as dishing) effect was clearly observed for caesium, increasing its release by one order of magnitude. According to these results, one of the major contributions to the IRF comes from the RN trapped in the dishing and has to be considered in the sampling and data interpretation that will be performed for the PA of the DGR.Peer ReviewedPostprint (published version

Water-air volatilization factors to determine volatile organic compound (VOC) reference levels in water

The goal of this work is the modeling and calculation of volatilization factors (VFs) from water to air for volatile organic compounds (VOCs) in order to perform human health risk - base d reference levels (RLs) for the safe use of water. The VF models have been developed starting from the overall mass - transfer coefficients ( K overall ) concept from air to water for two interaction geometries (flat surface and spherical droplets) in indoor a nd outdoor scenarios . For a case study with five groups of risk scenarios and thirty VOCs , theoretical VFs have been calculated by using the developed models. Results showed that K overall values for flat and spherical surface geometries were close to the m ass transfer coefficient for water ( K L ) when Henry ’s law constant ( K H ) was high. I n the case of s pherical drop geometry , the fraction of volatilization ( f V ) was asymptotical when increasing K H with f V values also limited due to K overall . VFs for flat surfa ces were calculated from the emission flux of VOCs , and results showed values close to 1000 K H for the most conservative indoor scenarios and almost constant values for outdoor scenarios. VFs for spherical geometry in indoor scenarios followed also constant VFs and were far from 1000 K H . The highest calculated VF values corresponded to the E2A, E2B, E3A and E5A scenarios and were compared with experimental and real results in order to check the goodness of flat and sphere geometry models. Results showed an ov erestimation of OPEN ACCESS Toxics 2014 , 2 277 calculated values for the E2A and E2B scenarios and an underestimation for the E3A and E5A scenarios. In both cases , most of the calculated VFs were from 0.1 - to 10 - times higher than experimental /real valuesPeer ReviewedPostprint (published version