Manuel González

The effect of the CO2 pressure on the thermal decomposition kinetics of calcium carbonate

Abstract The influence of the pressure of carbon dioxide on the thermal decomposition kinetics of calcium carbonate is studied. It is shown that it is possible to obtain meaningful and reliable kinetic parameters from isothermal and non-isothermal data provided that the pressure correction term is included in the kinetic equation.

Some considerations regarding the determination of the activation energy of solid-state reactions from a series of isothermal data

It has been demonstrated that the kinetic data on solid-state reactions show a good fitting to the expressiong(α)=kt, regardless of the nature of theg(α) function previously assumed for performance of the calculations. Moreover, the activation energy value obtained from the Arrhenius law is quite independent of the kinetic function assumed.ZusammenfassungEs wird gezeigt, daß die kinetischen, Daten von Festkörperreaktionen gut dem Ausdruckg(α)=kt entsprechen, ungeachtet der Natur der zur Ausführung der Berechnungen angenommen Funktiong(α). Darüber hinaus ist der nach dem Arrheniusschen Gesetz erhaltene Wert für die Aktivierungsenergie ganz unabhängig von der angenommenen kinetischen Funktion.РезюмеПоказано, что данные кинетики твердотельлых реакций хорощо описываются быражениемg(α)=kt, независимо от характера характера функцииg(α), ранее учитываемой при проведении вычислений. Кроме того, значение знергии активации, полученной из уравненил Аррениуса, польностью независимо от принимаемой кинетической функции.

A Marine Spatial Planning Approach to Select Suitable Areas for Installing Wave Energy Converters (WECs), on the Basque Continental Shelf (Bay of Biscay)

Recently, considerable interest has been generated in the wave energy production. As a new use of the ocean, a Spatial Planning approach is proposed to provide a mechanism to achieve consensus among the sectors operating at present, together with the identification of the most suitable locations to accommodate the Wave Energy Converters (WECs), in the near future. In this contribution: (a) a methodology for the establishment of a Suitability Index (SI) for WECs installation location selection is proposed; (b) the spatial distribution of the SI is mapped; and finally, (c) the accessible wave energy potential has been calculated for the entire Basque continental shelf. As the SI represents the appropriateness of several locations for WECs installation, while minimizing the conflict with other marine uses, the first step in the development of the analysis involved gathering all such information that may be likely to determine, or influence, the decision-making process. Seventeen information layers (among them 10 technical, 4 environmental, and 3 socioeconomical), corresponding to the identified key factors, including the theoretical wave energy in the study area, were generated to define their spatial distribution. Geographical Information System algorithms were used then in the assessment of the total theoretical energy potential and the accessible theoretical energy potential; these were calculated excluding areas where conflicts with other uses occur, such as navigation regulations or designated Marine Protected Areas. The resulting map indicates that, taking into account the zones not affected by “use conflicts,” together with the estimated energy performance of the most advanced WECs technology, the potential energy produced in the study area could supply between 37% and 50% of the electrical consumption of households in the Basque Country. This contribution could avoid the annual emission of 0.96 to 1.54 million tons of CO2 into the atmosphere.

Discrimination of the kinetic model of overlapping solid-state reactions from non-isothermal data

A method has been developed that allows the deconvolution of up to 15 overlapping solidstate reactions without previous assumptions. Both the kinetic parameters and the reaction mechanisms fitted by the unit reactions can be determined from a series of non-isothermal experiments carried out at different heating rates.ZusammenfassungEs wurde eine methode zur Dekonvolution von bis zu 15 einander überlappenden Festphasenreaktionen entwickelt, die keinerlei vorherige Annahmen notwendig macht. Mittels einer Reihe nichtisothermer Experimente mit unterschiedlichen Aufheizgeschwindigkeiten können sowohl die kinetischen Parameter als auch der Reaktionsmechanismus der Teilreaktionen bestimmt werden.РЕжУМЕРАжРАБОтАН МЕтОД, пОж ВОльУЩИИ РАжДЕлИть пЕРЕкРыВАУЩИЕсь тВЕ РДОтЕльНыЕ РЕАкцИИ с ЧИслОМ Их ДО 15. кИНЕтИЧЕскИЕ пАРАМЕ тРы И РЕАкцИОННыИ МЕхАНИж М кАжДОИ ЕДИНИЧНОИ РЕАкцИИ МОгУт Быть Оп РЕДЕлЕНы НА ОсНОВЕ Рь ДА НЕИжОтЕРМИЧЕскИх Иж МЕРЕНИИ пРОВЕДЕННых пРИ РАжлИЧНых скОРОстьх НАгРЕВА.

Biomonitoring of metals under the water framework directive: Detecting temporal trends and abrupt changes, in relation to the removal of pollution sources

Temporal trends in metal concentrations, i.e. Ag, Cd, Cu, Cr, Hg, Ni, Pb and Zn, measured in soft tissues of Mytilus galloprovincialis mussels and Crassostrea gigas oysters collected from estuarine waters within the Basque Country (Bay of Biscay), have been investigated to determine if actions undertaken have improved the environmental quality of rivers and estuaries. Data compiled between 1990 and 2010 have been analysed statistically, applying the Mann-Kendall and the Mann-Whitney-Wilcoxon tests. Moreover, in those cases with significant trends, the Kolmogorov-Zurbenko Adaptive (KZA) filter was applied to detect abrupt changes. Results showed significant decreasing trends for some metals, i.e. Ni, Cu, Pb and Zn, and differences between medians. Trend lines showed abrupt changes occurring between 1998 and 2002. Therefore, observed downward trends were related to increased wastewater treatment and diversions of discharges to ocean, implemented mainly during 2000-2002.

Influence of grinding on both the stability and thermal decomposition mechanism of siderite

Abstract It has been studied the influence of the comminution on the stability of a sample of siderite of the following composition: (Fe 0.692 Mg 0.308 )CO 3 . Both TG and XRD data seem to show that the above sample is decomposed by ball milling at room temperature with segregation of Fe 3 O 4 . On the other hand, it has been observed that the thermal decomposition under vacuum of the as received sample of siderite takes place in a single step giving FeO and MgO as final products. However two steps are observed in the thermal decomposition of the ground sample, the first one producing MgO and the second one MgO, FeO and Fe 3 O 4 . The ratio FeO/Fe 3 O 4 decreases by increasing the grinding time of the precursor until reaching the ratio FeO/Fe 3 O 4 = 0 after 8 hours of ball-milling. These results would be interpreted by assuming that the reactivity of the FeO and the CO 2 generated in the thermal decomposition of siderite yielding Fe 3 O 4 , increase by increasing the grinding time of siderite.

Skill Assessment of HF Radar–Derived Products for Lagrangian Simulations in the Bay of Biscay

AbstractSince January 2009, two long-range high-frequency (HF) radar systems have been collecting hourly high-spatial-resolution surface current data in the southeastern corner of the Bay of Biscay. The temporal resolution of the HF radar surface currents permits simulating drifter trajectories with the same time step as that of real drifters deployed in the region in 2009. The main goal of this work is to compare real drifter trajectories with trajectories computed from HF radar currents obtained using different methods, including forecast currents. Open-boundary modal analysis (OMA) is applied to the radar radial velocities and then a linear autoregressive model on the empirical orthogonal function (EOF) decomposition of an historical data series is used to forecast OMA currents. Additionally, the accuracy of the forecast method in terms of the spatial and temporal distribution of the Lagrangian distances between observations and forecasts is investigated for a 4-yr period (2009–12). The skills of the d...

Setting the maximum ecological potential of benthic communities, to assess ecological status, in heavily morphologically-modified estuarine water bodies.

Investigations on setting benthic macroinvertebrates reference conditions in natural waters have increased recently. Under the European Water Framework Directive, importance is given to research in morphological heavily-modified water bodies (HMWBs), which are very common in countries with high human pressure. However, research has not been undertaken on setting the maximum ecological potential (MEP), as a reference in HMWB. The objective of the present investigation is to set the MEP of two metrics (diversity and richness), used in assessing the ecological status in different benthic indices. The Oiartzun estuary (Basque Country) is used as a case study, which changed morphologically in the 19th Century, following harbour construction. Data obtained from 1874 and the present were used to model changes in currents, water residence time, salinity, volume, and intertidal area. Benthic macroinvertebrate data, from 1995 to 2011, were used to predict 19th Century and present MEP. Changes in the estuary were described: loss of all of the intertidal areas; doubling of the volume; residence time, changing from 2 to 95 days; current velocity reduced by 50%; salinity increase. All these factors have led to changes in the benthic communities and the structural variables. Predicted richness and diversity, for 1874, were lower (48-76%) than those at present. Taking into account the differences between natural and modified waters, it is proposed to utilize 75% of the natural reference conditions, as the MEP values for Basque HMWB.

Effect of grinding on the texture and kinetic stability of MnCO3, CdCO3 and PbCO3

Abstract The effect of grinding on both the texture and the kinetics of the thermal decomposition of MnCO 3 , CdCO 3 and PbCO 3 is studied. The particle size, the crystallite size and the activation energy of the thermal decomposition of these salts is determined as a function of the grinding time. It has been reported, firstly, that the activation energy decreases by increasing the grinding time and, secondly, that the continuous grinding of these materials does not lead to continuous increases of their BET surface but rather causes them to pass through a maximum. Moreover, the higher the lattice energy of these compounds, the lower the effect of grinding on the activation energy of their thermal decomposition and the higher the maximum value reached by the specific area during the grinding. These results have been explained on consideration that the deformation energy stored during the grinding of the MnCO 3 , CdCO 3 and PbCO 3 increases with decreasing lattice energy.

Validation of a numerical model for the study of anchovy recruitment in the Bay of Biscay

Some responses of the sea to the forcing agents actuating on it can be represented as differential equations in partial derivatives. Equations most frequently used to describe sea currents are the shallow water equations (SWE). These SWE are derived from the equations for the conservation of momentum and continuity making the assumptions that the pressure distribution is hydrostatic and that the terms referring to the vertical velocity are negligible. Unfortunately, the analytical resolution of the SWE is impossible and requires of the use of numerical approximation algorithms. The method used for the calculation of currents induced by the wind and by the astronomical tide in the area of the Bay of Biscay is the quasi-3D approximation using finite elements. Anchovy is a species of high economic interest for the Basque Countrys fleet. Eggs and larvae of this species behave as passive particles and are drifted around close to the surface (first 50 m) by sea currents. The behaviour of these particles can be represented by means of the general convection/diffusion equation, and by adding a source-decay term, the mortality of larvae can be represented. The Taylor-Galerkin technique adequate for problems in which convection dominates, allows the application of the finite element method to solve the dispersion in the marine environment. In this paper the preliminary results are presented concerning the numerical simulation of the drifting process of anchovy eggs and larvae from spawning areas, towards areas where they are fished. Results will be compared with survey data.