79 research outputs found

    Use of the Sentinel‐2 and Landsat‐8 Satellites for Water Quality Monitoring: An Early Warning Tool in the Mar Menor Coastal Lagoon

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    During recent years, several eutrophication processes and subsequent environmental crises have occurred in Mar Menor, the largest hypersaline coastal lagoon in the Western Mediterranean Sea. In this study, the Landsat‐8 and Sentinel‐2 satellites are jointly used to examine the evolution of the main water quality descriptors during the latest ecological crisis in 2021, resulting in an important loss of benthic vegetation and unusual mortality events affecting different aquatic species. Several field campaigns were carried out in March, July, August, and November 2021 to measure water quality variables over 10 control points. The validation of satellite biogeochemical variables against on‐site measurements indicates precise results of the water quality algorithms with median errors of 0.41 mg/m3 and 2.04 FNU for chlorophyll‐a and turbidity, respectively. The satellite preprocessing scheme shows consistent performance for both satellites; therefore, using them in tandem can improve mapping strategies. The findings demonstrate the suitability of the methodology to capture the spatiotemporal distribution of turbidity and chlorophyll‐a concentration at 10– 30 m spatial resolution on a systematic basis and in a cost‐effective way. The multitemporal products allow the identification of the main critical areas close to the mouth of the Albujon watercourse and the beginning of the eutrophication process with chlorophyll‐a concentration above 3 mg/m3. These innovative tools can support decision makers in improving current monitoring strategies as early warning systems for timely assistance during these ecological disasters, thus preventing detrimental conditions in the lagoon.0,64

    CONSEQUENCES OF SINGULAR ENVIRONMENTAL EVENTS ON THE CYCLE OF METALS IN COASTAL LAGOONS AND THEIR INFLUENCE ON THE INCORPORATION OF METALS BY PRIMARY PRODUCERS

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    Coastal areas are valuable and sensitive environments subjected to great anthropogenic pressure. Among these pressures, metal pollution is of priority concern as these pollutants can reach concentrations that exceed the levels established to protect sensitive organisms in the ecosystem. In coastal lagoons, shallow systems with a reduced exchange with the open sea, metal concentrations are one or two orders of magnitude higher than in open-waters. In addition, these systems are subjected to physicochemical variations that can alter the biogeochemical cycling of the metals. Singular environmental events such as strong winds cause metal resuspension, torrential rain events provoke the entrance of solutes and pollutants, and phytoplankton blooms dramatically increase the concentration of organic matter. These events provoke alterations in the concentration and speciation of metals in the water column. This will have a direct impact in the organisms living in the area, since metal toxicity and bioavailability depends on the chemical speciation. Dissolved organic matter (DOM) is the most important variable influencing metal speciation and bioavailability in seawater. However, the effects of DOM on metal bioavailability have not been yet unravelled and contrasting results have been reported, some showing that DOM protects against metal toxicity and others showing the opposite. The present study was designed to study how the biogeochemical cycling of trace metals in the water column of coastal lagoons is influenced by these singular environmental events and how this affects the incorporation of metals by the primary producers, in this case, microalgae, with particular focus on the effect of dissolved organic matter on metal biouptake. The proposed work combines field sampling and analytical work in the Mar Menor lagoon (SE Spain). This project will substantially contribute to widen our knowledge about the behaviour of metals in coastal areas and to determine how the presence of DOM affects their toxicity

    COPPER AND LEAD COMPLEXATION BY DISSOLVED ORGANIC MATTER IN MAR MENOR COASTAL LAGOON

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    Mar Menor coastal lagoon is a shallow system with a reduced exchange with the open sea, that is affected by several anthropogenic pressures, mainly agriculture and mining. The mining sierra of Cartagena-La Unión has been historically discharging mining waste rich in heavy metals in the south area of Mar Menor, resulting in high metal concentrations in sediments (García and Muñoz-Vera., 2015). The nutrients reaching the lagoon, together with the high temperatures, also provoke phytoplankton blooms that lead to high concentrations of dissolved organic matter (DOM). It is well known that total metal concentrations are not good predictors of their bioavailability, and metal speciation should be taken into account. The presence of ligands, such as DOM in the water, may form metal-DOM complexes and protect against the deleterious effects of metals. The present study aims at studying the effect of DOM on the speciation of dissolved metals (Cu and Pb) in Mar Menor waters. With that aim, filtered water was sampled at five sites in Mar Menor lagoon at several sampling periods. Metal concentration was analysed by ICP-MS with Argon gas dilution, DOC was analysed in a carbon-specific infrared gas analyser and optical characterization of DOM was obtained from absorbance and fluorescence spectra. Complexiometric titrations of Cu and Pb were performed by anodic stripping voltammetry following Durán and Nieto (2011). Preliminary results show that Cu and Pb concentrations in Mar Menor waters are higher than in other coastal areas, especially in the south area of the lagoon, reaching concentrations of tens of nanomolar. DOC concentrations are also very high in Mar Menor waters, leading to high complexation capacities for Cu, therefore protecting aquatic biota from the deleterious effects of Cu. Pb, on the contrary, is poorly complexed by DOM, and almost all dissolved Pb is present in inorganic forms

    Identification of two new intimin types in atypical enteropathogenic Escherichia coli

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    Stool specimens of patients with diarrhea or other gastrointestinal alterations who were admitted to Xeral-Calde Hospital (Lugo, Spain) were analyzed for the prevalence of typical and atypical enteropathogenic Escherichia coli (EPEC). Atypical EPEC strains (eae+ bfp–) were detected in 105 (5.2%) of 2015 patients, whereas typical EPEC strains (eae+ bfp+) were identified in only five (0.2%) patients. Atypical EPEC strains were (after Salmonella) the second most frequently recovered enteropathogenic bacteria. In this study, 110 EPEC strains were characterized. The strains belonged to 43 O serogroups and 69 O:H serotypes, including 44 new serotypes not previously reported among human EPEC. However, 29% were of one of three serogroups (O26, O51, and O145) and 33% belonged to eight serotypes (O10:H–, O26:H11, O26:H–, O51:H49, O123:H19, O128:H2, O145:H28, and O145:H–). Only 14 (13%) could be assigned to classical EPEC serotypes. Fifteen intimin types, namely, α1 (6 strains), α2 (4 strains), β1 (34 strains), ξR/β2 (6 strains), γ1 (13 strains), γ2/θ (16 strains), δ/k (5 strains), ε1 (9 strains), νR/ε2 (5 strains), ζ (6 strains), ι1 (1 strain), μR/ι2 (1 strain), νB (1 strain), ξB (1 strain), and ο (2 strains), were detected among the 110 EPEC strains, but none of the strains was positive for intimin types μ1, μ2, λ, or μB. In addition, in atypical EPEC strains of serotypes O10:H–, O84:H–, and O129:H–, two new intimin genes (eae-νB and eae-ο) were identified. These genes showed less than 95% nucleotide sequence identity with existing intimin types. Phylogenetic analysis revealed six groups of closely related intimin genes: (i) α1, α2, ζ, νB, and ο; (ii) ι1 and μR/ι2; (iii) β1, ξR/β2B, δ/β2O, and κ; (iv) ε1, ξB, η1,η2, and νR/ε2; (v) γ1, μB, γ2, and θ; and (vi) λ. These results indicate that atypical EPEC strains belonging to large number of serotypes and with different intimin types might be frequently isolated from human clinical stool samples in Spain. [Int Microbiol 2006; 9(2):103-110

    Characteristics of the Shiga-toxin-producing enteroaggregative Escherichia coli O104:H4 German outbreak strain and of STEC strains isolated in Spain

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    A Shiga-toxin-producing Escherichia coli (STEC) strain belonging to serotype O104:H4, phylogenetic group B1 and sequence type ST678, with virulence features common to the enteroaggregative E. coli (EAEC) pathotype, was reported as the cause of the recent 2011 outbreak in Germany. The outbreak strain was determined to carry several virulence factors of extraintestinal pathogenic E. coli (ExPEC) and to be resistant to a wide range of antibiotics. There are only a few reports of serotype O104:H4, which is very rare in humans and has never been detected in animals or food. Several research groups obtained the complete genome sequence of isolates of the German outbreak strain as well as the genome sequences of EAEC of serotype O104:H4 strains from Africa. Those findings suggested that horizontal genetic transfer allowed the emergence of the highly virulent Shiga-toxin-producing enteroaggregative E. coli (STEAEC) O104:H4 strain responsible for theoutbreak in Germany. Epidemiologic investigations supported a linkage between the outbreaks in Germany and France and traced their origin to fenugreek seeds imported from Africa. However, there has been no isolation of the causative strain O104:H4 from any of the samples of fenugreek seeds analyzed. Following the German outbreak, we conducted a large sampling to analyze the presence of STEC, EAEC, and other types of diarrheagenic E. coli strains in Spanish vegetables. During June and July 2011, 200 vegetable samples from different origins were analyzed. All were negative for the virulent serotype O104:H4 and only one lettuce sample (0.6%) was positive for a STEC strain of serotype O146:H21 (stx1, stx2), considered of low virulence. Despite the single positive case, the hygienic and sanitary quality of Spanish vegetables proved to be quite good. In 195 of the 200 samples (98%), <10 colony-forming units (cfu) of E. coli per gram were detected, and the microbiological levels of all samples were satisfactory (<100 cfu/g). The samples were also negative for other pathotypes of diarrheagenic E. coli (EAEC, ETEC, tEPEC, and EIEC). Consistent with data from other countries, STEC belonging to serotypeO157:H7 and other serotypes have been isolated from beef, milk, cheese, and domestic (cattle, sheep, goats) and wild (deer, boar, fox) animals in Spain. Nevertheless, STEC outbreaks in Spain are rare

    La secuencia magmática Jurásico Superior-Cretácico Superior en la Cordillera Central, República Dominicana: sección cortical de un arco-isla intraoceánico.

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    The Late Jurassic-Late Cretaceous magmatic sequence exposed in the central-western sector of the Cordillera Central Dominican Republic, can be divided in five main lithostratigraphic units formed by plutonio, volcanic, volcanoclastic and sedimentary rocks. All rocks have suffered very heterogeneous ductile deformation and low-grade metamorphism with magmatic textures often preserved. From bottom to top, this magmatic sequence is made up of:: (1) Loma Caribe serpentinized peridotites, (2) the N-MORB volcano-plutonic assemblage of El Aguacate, of ophiolitic affinity, (3) the Duarte Complex oceanic plateau, (4) the arc-related volcanic and volcano-sedimentary sequence of the Tireo Formation, intruded by the Loma de Cabrera Batolith, and (5) the massive basaltic flows of Peña Blanca y Nalga de Maco. It is suggested that the magmatic sequence represents the crustal section of an intra-oceanic island arc, which was built onto a proto-caribbean oceanic crust and an overlying Lower Cretaceous oceanic plateau. The sequence is overlain by Upper Cretaceous basalts of the Caribbean oceanic plateau and limestones

    Volcanism and climate change as drivers in Holocene depositional dynamic of Laguna del Maule (Andes of central Chile – 36° S)

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    Late Quaternary volcanic basins are active landscapes from which detailed archives of past climate and seismic and volcanic activity can be obtained. A multidisciplinary study performed on a transect of sediment cores was used to reconstruct the depositional evolution of the high-elevation Laguna del Maule (LdM) (36∘ S, 2180 m a.s.l., Chilean Andes). The recovered 5 m composite sediment sequence includes two thick turbidite units (LT1 and LT2) and numerous tephra layers (23 ash and 6 lapilli). We produced an age model based on nine new 14C AMS dates, existing 210Pb and 137Cs data, and the Quizapú ash horizon (1932 CE). According to this age model, the relatively drier Early Holocene was followed by a phase of increased productivity during the mid-Holocene and higher lake levels after 4.0 ka cal BP. Major hydroclimate transitions occurred at ca. 11, 8.0, 4.0 and 0.5 ka cal BP. Decreased summer insolation and winter precipitation due to a southward shift in the southern westerly winds and a strengthened Pacific Subtropical High could explain Early Holocene lower lake levels. Increased biological productivity during the mid-Holocene (∼8.0 to 6.0 ka cal BP) is coeval with a warm–dry phase described for much of southern South America. Periods of higher lake productivity are synchronous to a higher frequency of volcanic events. During the Late Holocene, the tephra layers show compositional changes suggesting a transition from silica-rich to silica-poor magmas at around 4.0 ka cal BP. This transition was synchronous with increased variability of sedimentary facies and geochemical proxies, indicating higher lake levels and increased moisture at LdM after 4.0 ka cal BP, most likely caused by the inception of current El Niño–Southern Oscillation and Pacific Decadal Oscillation (ENSO–PDO) dynamics in central Chile.Postprin

    VISUAL PPINOT: A Graphical Notation for Process Performance Indicators

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    Process performance indicators (PPIs) allow the quantitative evaluation of business processes, providing essential information for decision making. It is common practice today that business processes and PPIs are usually modelled separately using graphical notations for the former and natural language for the latter. This approach makes PPI definitions simple to read and write, but it hinders maintenance consistency between business processes and PPIs. It also requires their manual translation into lower-level implementation languages for their operationalisation, which is a time-consuming, error-prone task because of the ambiguities inherent to natural language definitions. In this article, Visual ppinot, a graphical notation for defining PPIs together with business process models, is presented. Its underlying formal metamodel allows the automated processing of PPIs. Furthermore, it improves current state-of-the-art proposals in terms of expressiveness and in terms of providing an explicit visualisation of the link between PPIs and business processes, which avoids inconsistencies and promotes their co-evolution. The reference implementation, developed as a complete tool suite, has allowed its validation in a multiple-case study, in which five dimensions of Visual ppinot were studied: expressiveness, precision, automation, understandability, and traceability
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