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Russo A.,University of Lisbon | Trigo R.M.,University of Lisbon | Martins H.,University of Aveiro | Mendes M.T.,Instituto Portugues do Mar e da Atmosfera
Atmospheric Environment | Year: 2014

High levels of atmospheric pollutants are frequently measured in Portugal, a country which has been affected by several pollution episodes, exceeding PM10, O3 and NO2 legal limits repeatedly during the last decade. The occurrence of these episodes is often related to either local-scale conditions or regional-scale transport. In order to better understand the atmospheric factors responsible for poor air quality, the relationships between air pollution and meteorological variables or atmospheric synoptic patterns represent an important research area. Here an objective classification scheme of the atmospheric circulation affecting Portugal, between 2002 and 2010, is presented, where daily circulation is characterized through the use of a set of indices associated with the direction and vorticity of the geostrophic flow in the lower atmosphere. The synoptic characteristics and the frequency of ten basic circulation weather types (CWTs) are discussed and a framework that permits the identification of the main characteristics associated to the occurrence of pollution episodes is mapped based on the identified patterns. The relationship between CWTs and poor air quality allowed distinguishing between which types are most frequently associated to pollution episodes. It is shown that the anticyclonic and north types, although being the most frequent classes during the majority of the year, do not prevail during pollution episodes that are dominated by easterly types. In general, higher concentration of all three pollutants and the two extreme events analysed occur associated predominantly with synoptic circulation characterized by an eastern component and advection of dry air masses. Moreover, results on the link between CWTs and air quality for Lisbon and Porto urban areas suggest that air quality regimes are generally similar for the northern and southern regions considered with the exception of spring and autumn PM10. Results obtained highlight the existence of strong links between the interannual variability of daily air quality and interannual variability of CWTs. © 2014 Elsevier Ltd. Source


Wendling C.C.,Alfred Wegener Institute for Polar and Marine Research | Wendling C.C.,Leibniz Institute of Marine Science | Batista F.M.,Instituto Portugues do Mar e da Atmosfera | Wegner K.M.,Alfred Wegener Institute for Polar and Marine Research
PLoS ONE | Year: 2014

Bacteria of the genus Vibrio occur at a continuum from free-living to symbiotic life forms, including opportunists and pathogens, that can contribute to severe diseases, for instance summer mortality events of Pacific oysters Crassostrea gigas. While most studies focused on Vibrio isolated from moribund oysters during mortality outbreaks, investigations of the Vibrio community in healthy oysters are rare. Therefore, we characterized the persistence, diversity, seasonal dynamics, and pathogenicity of the Vibrio community isolated from healthy Pacific oysters. In a reciprocal transplant experiment we repeatedly sampled hemolymph from adult Pacific oysters to differentiate population from site-specific effects during six months of in situ incubation in the field. We characterized virulence phenotypes and genomic diversity based on multilocus sequence typing in a total of 70 Vibrio strains. Based on controlled infection experiments we could show that strains with the ability to colonize healthy adult oysters can also have the potential to induce high mortality rates on larvae. Diversity and abundance of Vibrio varied significantly over time with highest values during and after spawning season. Vibrio communities from transplanted and stationary oysters converged over time, indicating that communities were not population specific, but rather assemble from the surrounding environment forming communities, some of which can persist over longer periods. © 2014 Wendling et al. Source


Vale P.,Instituto Portugues do Mar e da Atmosfera
Photochemistry and Photobiology | Year: 2015

Mycosporine-like amino acids (MAAs) were analyzed in a Portuguese Gymnodinium catenatum strain when transferred to high salinity and high light conditions. Total MAA concentrations increased progressively between 30 and 36 psu, attaining at 36 psu 2.9-fold the 30 psu treatment. When abruptly transferred to solar light in an outdoor shadowed location, MAA concentration increased steadily along the day for most compounds. After 8 h, mycosporine-glycine, palythene and M-319 attained or surpassed 25-fold their initial concentration, while M-370 only attained 4-fold concentration. When transferred from halogen to fluorescent light, polar MAAs such as shinorine and porphyra-334, increased until day two and then declined, while M-370 increase slowly, becoming the dominant compound from the profile after 1 week. These experiments put into evidence the relation of palythene with M-319, which was further identified as its acid degradation product, palythine. Acid degradation of M-370 originated M-324, while M-311 seems to be the precursor of M-370. Under high salinity and high light conditions chain formation was altered toward shorter chains or solitary cells. This alteration can represent a morphological stress sign, which in the natural environment could affect average population speed during daily vertical migrations. Mycosporine-like amino acids concentration increased with salinity, in particular high polar MAAs. Abrupt changes in light intensity increased rapidly the low polar palythene. In both cases, mycosporine-glycine was one of the MAAs with the greatest increase, while biosynthesis of M370, a major MAA in G. catenatum, progressed slowly. Experiments put into evidence the biosynthetic relations between MAAs and its degradation pathways. MAAs might play a multifunctional role to cope with salinity (shinorine, porphyra-334) and photooxidative (mycosporine-glycine, palythene, M-370) stresses. High salinity and high light conditions also altered chain formation toward shorter chains or solitary cells. © 2015 The American Society of Photobiology. Source


Li Z.-L.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Li Z.-L.,French National Center for Scientific Research | Tang B.-H.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Wu H.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | And 6 more authors.
Remote Sensing of Environment | Year: 2013

Land surface temperature (LST) is one of the key parameters in the physics of land surface processes from local through global scales. The importance of LST is being increasingly recognized and there is a strong interest in developing methodologies to measure LST from space. However, retrieving LST is still a challenging task since the LST retrieval problem is ill-posed. This paper reviews the current status of selected remote sensing algorithms for estimating LST from thermal infrared (TIR) data. A brief theoretical background of the subject is presented along with a survey of the algorithms employed for obtaining LST from space-based TIR measurements. The discussion focuses on TIR data acquired from polar-orbiting satellites because of their widespread use, global applicability and higher spatial resolution compared to geostationary satellites. The theoretical framework and methodologies used to derive the LST from the data are reviewed followed by the methodologies for validating satellite-derived LST. Directions for future research to improve the accuracy of satellite-derived LST are then suggested. © 2012 Elsevier Inc. Source


Martins J.H.,University of Porto | Camanho A.S.,University of Porto | Gaspar M.B.,Instituto Portugues do Mar e da Atmosfera
Ocean and Coastal Management | Year: 2012

This paper provides a review of the literature on applications of the Driving forces, Pressure, State, Impact, Response (DPSIR) framework to fisheries. The interpretation given to each DPSIR category differs in existing studies, and as a result the indicators used to support fisheries management also vary considerably. This impairs comparisons concerning the state of different fishery systems, and does not provide a common base of knowledge concerning potential management measures that can be adopted in a given context. This paper clarifies the interpretation of each DPSIR category and proposes a set of indicators that can be applied in fishery contexts. The set of indicators proposed is also classified according to sustainability dimensions. It is argued that organising the indicators according to the DPSIR framework and sustainability dimensions (ecologic, economic, social and governance) is a positive contribution to serve as a guideline for future applications to adopt standardized indicators and improve fisheries management. © 2012 Elsevier Ltd. Source

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