Estudio comparativo de la incidencia de la Directiva Seveso por ámbitos territoriales. El caso particular de la región de Andalucía

Desde la entrada en vigor de la primera Directiva Seveso en Europa, el concepto de prevención de accidentes graves por sustancias peligrosas ha evolucionado de forma diferente dependiendo de la transposición particular de cada Estado Miembro a su propio ordenamiento jurídico. Adicionalmente, cada región con competencias en materia de seguridad industrial o protección civil ha contribuido, aún más, a la dispersión normativa existente lo que no favorece una regulación de forma universal o estándar. Uno de los aspectos normativos merecedor de una profunda actualización ante la próxima puesta en vigor de la nueva Directiva Seveso III, es aquel que incide sobre las zonas de influencia donde existen establecimientos industriales afectados por la Directiva. En el presente trabajo se va a realizar una evolución histórica de la afectación por ámbito geográfico en la década 2002-2012. El análisis territorial comienza con la distribución geográfica de laafectación en la Unión Europea. De manera similar, se vadescendiendo geográficamente hasta estudiar el estadoespañol y, finalmente, alcanzará a la región de Andalucíadonde, se profundizará aún más, hasta alcanzar el nivelterritorial de provincias y, municipios. Del análisis se deducenunas primeras conclusiones particulares relativas tanto a las concentraciones de establecimientos Seveso y de los sectores industriales más significativos cubiertos por dicha normativa

A Spectroscopic Study of the Near-IR [SIII] Lines in a Sample of HII Galaxies: chemical abundances

A detailed spectroscopic study, from lambda 3700 A to 1 um, was performed for a sample of 34 HII galaxies in order to derive fundamental parameters for their HII regions and ionizing sources, as well as gaseous metal abundances. All the spectra included the nebular [SIII]9069,9532 A lines, given their importance in the derivation of the S/H abundance and relevant ionization diagnostics. A systematic method was followed to correct the near-IR [SIII] line fluxes for the effects of the atmospheric transmission.A comparative analysis of the predictions of the empirical abundance indicators R23 and S23 has been performed. The relative hardness of their ionizing sources was studied using the eta parameter, and exploring the role played by metallicity. For 22 galaxies of the sample a direct value of te[SIII] was derived, along with their ionic and total S/H abundances. Their ionic and total O/H abundances were derived using direct determinations of te[OIII].For the rest of the objects, the total S/H abundance was derived using S23. The abundance range covered by our sample goes from 1/20 solar up to solar metallicity. The mean S/O ratio derived is log (S/O)=-1.68+/-0.20 dex, 1 sigma below the solar S/O value. The S/O abundance ratio shows no significant trend with O/H over the range of abundance covered in this work, in agreement with previous findings.There is a trend for HII galaxies with lower gaseous metallicity to present harder ionizing spectra. We compared the distribution of the ionic ratios O+/O++ vs. S+/S++ derived for our sample with the predictions of a grid of photoionization models performed for different stellar effective temperatures. This analysis indicates that a large fraction of galaxies in our sample seem to be ionized by extremely hard spectra.Comment: 12 pages, 8 figures, accepted for publication in the A&A, minor gramatical corrections include

The Nitrogen-to-Oxygen evolution in galaxies: the role of the star formation rate

The main objective of the present work is to ckeck if the star formation efficiency plays a relevant role in the evolution of the relative abundance N/O. We analyze the evolution of the nitrogen-to-oxygen ratio as predicted by a set of computed theoretical models of simulated galaxies with different total masses which are evolved assuming different collapse time scales and different star formation efficiencies, thus producing different star formation histories. The stellar yield set we use for all of them (Gavil\'{a}n et al. 2005) have an important contribution of primary nitrogen proceeding from low and intermediate mass stars. It allows to obtain a dispersion of results in the N/O-O/H plane, when star formation efficiencies vary, in general agreement with observations. The model results for the N/O abundance ratio are in good agreement with most observational data trends: the extragalactic H{\sc ii} regions is well reproduced with present time resulting abundances and the low N/O values estimated for high-redshift objects, as well as the higher and constant values of N/O observed for irregular and dwarf galaxies or halo stars, can be simultaneously obtained with our models at the same low oxygen abundances. We conclude that differences in the star formation history of galaxies and regions within them are a key factor to explain the data in the N/O-O/H plane.Comment: 13 pages, 10 figures, accepted in MNRA

A photoionization model of the spatial distribution of the optical and mid-IR properties in NGC595

We present a set of photoionization models that reproduce simultaneously the observed optical and mid-infrared spatial distribution of the HII region NGC595 in the disk of M33 using the code CLOUDY. Both optical (PMAS-Integral Field Spectroscopy) and mid-infrared (8 mi and 24 mi bands from Spitzer) data provide enough spatial resolution to model in a novel approach the inner structure of the HII region. We define a set of elliptical annular regions around the central ionizing cluster with an uniformity in their observed properties and consider each annulus as an independent thin shell structure. For the first time our models fit the relative surface brightness profiles in both the optical (Halpha, [OII], [OIII]) and the mid-infrared emissions (8 mi and 24 mi), under the assumption of a uniform metallicity (12+log(O/H) = 8.45; Esteban et al. 2009) and an age for the stellar cluster of 4.5 Myr (Malumuth et al. 1996). Our models also reproduce the observed uniformity of the R23 parameter and the increase of the [OII]/[OIII] ratio due to the decrease of the ionization parameter. The variation of the Halpha profile is explained in terms of the differences of the occupied volume (the product of filling factor and total volume of the shell) in a matter-bounded geometry, which also allows to reproduce the observed pattern of the extinction. The 8 mi/24 mi ratio is low (ranging between 0.04 and 0.4) because it is dominated by the surviving of small dust grains in the HII region, while the PAHs emit more weakly because they cannot be formed in these thin HII gas shells. The ratio is also well fitted in our models by assuming a dust-to-gas ratio in each annulus compatible with the integrated estimate for the whole HII region after the 70 mi, and 160 mi Spitzer observations.Comment: Accepted for publication in MNRAS, 9 pages, 17 figure

On emission-line spectra obtained from evolutionary synthesis models I. Dispersion in the ionising flux and Lowest Luminosity Limits

(abriged) Stellar clusters with the same general physical properties (e.g., total mass, age, and star-formation mode) may have very different stellar mass spectra due to the incomplete sampling of the underlying mass function; such differences are especially relevant in the high-mass tail due to the smaller absolute number of massive stars. The dispersion in the number of massive stars also produces a dispersion in the properties of the corresponding ionising spectra. In this paper, we lay the bases for the future analysis of this effect by evaluating the dispersion in the ionising fluxes of synthetic spectra. As an important consequence, we found that the intensities of synthetic fluxes at different ionisation edges are strongly correlated, a fact suggesting that no additional dispersion will result from the inclusion of sampling effects in the analysis of diagnostic diagrams; this is true for HII regions on all scales. Additionally, we find convincing suggestions that the He II lines are strongly affected by sampling, and so cannot be used to constrain the evolutionary status of stellar clusters. We also establish the range of applicability of synthesis models set by the Lowest Luminosity Limit for the ionising flux, that is the lowest limit in cluster mass for which synthesis models can be applied to predict ionising spectra. This limit marks the boundary between the situations in which the ionising flux is better modeled with a single star as opposed to a star cluster; this boundary depends on the metallicity and age, ranging from 10^3 to more than 10^6 Mo. As a consequence, synthesis models should not be used to try to account for the properties of clusters with smaller masses.Comment: Replaced with accepted versio