Ecosistemas de alta montaña, las atalayas de la troposfera

La troposfera es el fluido en el que vivimos los organismos terrestres. La dinámica de este fluido hace posible el funcionamiento de los ecosistemas terrestres y acuáticos continentales tal como los conocemos. Factores locales como las precipitaciones atmosféricas (secas y húmedas) o la calidad de la radiación solar que llega al suelo, muy afectada por el contenido de aerosoles en la troposfera, dependen de fenómenos que pueden ocurrir a miles de kilómetros. Los ecosistemas de alta montaña, como la Sierra Nevada del sur ibérico, son los sensores más finos que poseemos para el estudio de los efectos de esos factores y para detectar pronto sus tendencias y cambios

Greenhouse gas fluxes from reservoirs determined by watershed lithology, morphometry, and anthropogenic pressure

EL-P was supported by a PhD fellowship FPU (Formación del Profesorado Universitario: 014/02917) from the Ministry of Education, Culture y Sports. This research was also funded by the Consejería de Economía, Conocimiento, Empresas y Universidad and European Regional Development Fund (ERDF), ref. SOMM17/6109/UGR. We specially thank to Jesús Forja, Teodora Ortega and Ana Sierra for helping with gas chromatography analysis and Eulogio Corral Arredondo for sampling support.Human population growth has increased the demand for water and clean energy, leading to the massive construction of reservoirs. Reservoirs can emit greenhouse gases (GHG) affecting the atmospheric radiative budget. The radiative forcing due to CO2, CH4, and N2O emissions and the relative contribution of each GHG in terms of CO2 equivalents to the total forcing is practically unknown. We determined simultaneously the CO2, CH4, and N2O fluxes in reservoirs from diverse watersheds and under variable human pressure to cover the vast idiosyncrasy of temperate Mediterranean reservoirs. We obtained that GHG fluxes ranged more than three orders of magnitude. The reservoirs were sources of CO2 and N2O when the watershed lithology was mostly calcareous, and the crops and the urban areas dominated the landscape. By contrast, reservoirs were sinks of CO2 and N2O when the watershed lithology was predominantly siliceous, and the landscape had more than 40% of forestal coverage. All reservoirs were sources of CH4, and emissions were determined mostly by reservoir mean depth and water temperature. The radiative forcing was substantially higher during the stratification than during the mixing. During the stratification the radiative forcings ranged from 125 mg CO2 equivalents m−2 d−1 to 31 884 mg CO2 equivalents m−2 d−1 and were dominated by the CH4 emissions; whereas during the mixing the radiative forcings ranged from 29 mg CO2 equivalents m−2 d−1 to 722 mg CO2 equivalents m−2 d−1 and were dominated by CO2 emissions. The N2O contribution to the radiative forcing was minor except in one reservoir with a landscape dominated by crops and urban areas. Future construction of reservoirs should consider that siliceous bedrocks, forestal landscapes, and deep canyons could minimize their radiative forcings.This research was funded by the project HERA (CGL2014-52362-R) and CRONOS (RTI2018-098849-B-I00) to IR and RM-B of the Spanish Ministry of Economy and Competitiveness and Spanish Ministry of Science, Innovation, and Universities, and the Modeling Nature Scientific Unit (UCE.PP2017.03) to IR co-financed with FEDER funds

Avances Recientes en la Síntesis de 3,4-Dihidropiran-2-Ones Organocatalizada por N-Carbenos Heterocíclicos

En los últimos años, los carbenos N-heterocíclicos (NHC) han ganado reconocimiento como moléculas versátiles capaces de actuar como organocatalizadores en diversas reacciones, en particular mediante la activación de aldehídos a través de aductos de tipo Breslow. Esta activación organocatalítica ha permitido la producción de numerosas 3,4-dihidropiran-2-onas y derivados relacionados. En esta revisión, ofrecemos una visión general de la producción de 3,4-dihidropiran-2-onas y derivados mediante procesos organocatalíticos con NHCs en los últimos ocho años. Estos procesos implican el uso de una diversa gama de sustratos, catalizadores y condiciones de reacción, que pueden clasificarse en cicloadiciones de tipo [4+2]-y [3+3]-, principalmente dirigidas a sintetizar este esqueleto debido a su actividad biológica y múltiples estereocentros. Estos procesos se escalan hasta la escala del gramo, y los productos resultantes se dirigen a menudo hacia la epimerización y funcionalización para producir moléculas más complejas con potenciales aplicaciones en el campo biológico. Por último, ofrecemos una perspectiva y las direcciones futuras de este tema en la síntesis orgánica.In recent years, N-heterocyclic carbenes (NHC) have gained recognition as versatile molecules capable of acting as organocatalysts in various reactions, particularly through the activation of aldehydes via Breslow-type adducts. This organocatalytic activation has enabled the production of numerous 3,4-dihydropyran-2-ones and related derivatives. In this review, we provide an overview of the production of 3,4-dihydropyran-2-ones and derivatives via organocatalytic processes involving NHCs over the past eight years. These processes involve the use of a diverse range of substrates, catalysts, and reaction conditions, which can be classified into [4+2]-and [3+3]-type cycloadditions, primarily aimed at synthesizing this skeleton due to its biological activity and multiple stereocenters. These processes are scaled up to the gram scale, and the resulting products are often directed towards epimerization and functionalization to produce more complex molecules with potential applications in the biological field. Finally, we provide a perspective and the future directions of this topic in organic synthesis

P inputs determine denitrifier abundance explaining dissolved nitrous oxide in reservoirs

This research was supported by the Ministerio de Economía y Competitividad (HERA project, grant no. CGL2014‐52362‐R), and the Ministerio de Ciencia, Innovación y Universidades (CRONOS project, RTI2018‐098849‐B‐I00) of Spain to IR and RM‐B. Elizabeth León‐Palmero was supported by a PhD fellowship from the Ministerio de Educación, Cultura y Deporte of Spain (grant nos. FPU014/02917), and a postdoctoral contract from CRONOS project, and later from Danmarks Frie Forskningsfond (DFF, 1026‐00428B) at SDU. This manuscript was improved through feedback from an anonymous reviewer, and Dr. Van Meter. Universidad de Granada/CBUA funded the open access of this article.Reservoirs are important sites for nitrogen processing, especially those located in agricultural and urban watersheds. Nitrogen inputs promote N2O production and emission, but the microbial pathways controlling N2O have been seldom studied in reservoir water columns. We determined N2O concentration in the water column of 12 reservoirs during the summer stratification and winter mixing. We explored the potential microbial sources and sinks of N2O by quantifying key genes involved in ammonia oxidation (bacterial and archaeal amoA) and denitrification (nirS and nosZ). Dissolved N2O varied up to three orders of magnitude (4.7–2441.2 nmol L−1) across systems, from undersaturated to supersaturated values (37%–24,174%) depending on reservoirs and depths. N2O concentration depended on nitrogen and oxygen availabilities, with the lowest and highest N2O values at suboxic conditions. Ammonia-oxidizing archaea dominated over ammonia-oxidizing bacteria but were not related to the dissolved N2O. In contrast, the abundance of the nirS gene was significantly related to N2O concentration, and three orders of magnitude higher than amoA abundance. Denitrifying bacteria appeared consistently in the water column of all reservoirs. The nirS and nosZ genes appeared in oxic and suboxic waters, but they were more abundant in suboxic waters. The nitrate concentration, and nirS and nosZ relative abundances explained the dissolved N2O. Besides, nirS abundance was related positively with total phosphorus and cumulative chlorophyll a, a proxy for fresh organic matter. Therefore, P inputs, not just N inputs, promoted N2O production by denitrification in the water column of reservoirs.Danmarks Frie Forskningsfond 1026‐00428BMinisterio de Ciencia, Innovación y Universidades RTI2018‐098849‐B‐I00Ministerio de Economía y Competitividad CGL2014‐52362‐RMinisterio de Educación, Cultura y Deporte of Spain FPU014/02917SDUUniversidad de Granada/CBU

Los géneros de hepáticas de las vertientes noroccidental y suroriental de la sierra nevada de santa marta, Colombia.

En este trabajo se realiza una revisión de la composición taxonómica de Hepáticas en las vertientes noroccidental y suroriental de la Sierra Nevada de Santa Marta en un gradiente altitudinal comprendido entre el nivel del mar hasta los 2300 msnm. Se realizaron siete viajes de recolección a la Sierra Nevada de Santa Marta, se recolectaron en total 222 muestras. Se separó y analizó el material correspondiente a hepáticas y cada muestra se determinó hasta nivel de género. Se describen, ilustran y establece la distribución geográfica de los géneros encontrados. Entre los resultados se mencionan que la composición de Hepáticas en las vertientes noroccidental y suroriental de la Sierra Nevada de Santa Marta es de 15 géneros, de los cuales 10 géneros constituyen nuevas citas. Aquí, cada uno de ellos se describe e ilustra con fotografías y se menciona su distribución. Del total de géneros encontrados en la Sierra Nevada de Santa Marta y con relación al hábito, predominan aquellos de hábito folioso, son 13 géneros y sólo 2 de hábito taloso, los primeros son epífito-cortícolas mientras que los géneros talosos son rupícolas. El mayor registro en las formaciones vegetales está en el bosque denso submontano entre los 1100 y 2300 msnm, con el 66% de Hepáticas, mientras que en el bosque denso tropical de tierras bajas entre los 700 y 1100 msnm fue del 60% y el menor registro se presentó en el bosque denso semideciduo desde el nivel del mar hasta 700 msnm con el 40% del total de los 15 géneros. Se evidencia una amplia distribución en el gradiente altitudinal de dos géneros foliosos: Plagiochila y Lejeunea. El total de géneros de Hepáticas registrados para la Sierra Nevada de Santa Marta es de 42 géneros y 24 familias de Hepáticas

Contribution of dust inputs to dissolved organic carbon and water transparency in Mediterranean reservoirs

The Mediterranean reservoirs receive frequent atmospheric Saharan dust inputs with soil-derived organic components mostly during the stratification periods, when run-off inputs are particularly limited. Here, we quantified and optically characterized the water-soluble organic carbon (WSOC) of the (dry and wet) atmospheric deposition in collectors placed near three reservoirs from the western Mediterranean Basin. In addition, we determined the WSOC contribution to the pool of dissolved organic carbon (DOC) in the reservoirs and the influence of dust-derived chromophoric organic components on the water transparency during their stratification periods. We found synchronous dynamics in the WSOC atmospheric inputs among the three collectors and in the DOC concentrations among the three reservoirs. The DOC concentrations and the WSOC atmospheric inputs were positive and significantly correlated in the most oligotrophic reservoir (Quéntar) and in the reservoir with the highest ratio of surface area to mixing water depth (Cubillas). Despite these correlations, WSOC atmospheric inputs represented less than 10% of the total DOC pool, suggesting that indirect effects of dust inputs on reservoir DOC may also promote these synchronous patterns observed in the reservoirs. Chromophoric components from dust inputs can significantly reduce the water transparency to the ultraviolet radiation (UVR). The depths where UVR at λ = 320 nm was reduced to ten percent of surface intensity (Z10%) decreased 27 cm in Béznar, 49 cm in Cubillas, and 69 cm in Quéntar due to the dust inputs. Therefore, the increasing dust export to the atmosphere may have consequences for the water transparency of aquatic ecosystems located under the influence of the global dust belt.This work was funded by the Spanish Ministry of Science and Technology (DISPAR, CGL2005-00076 to IR and CGL2008-06101/BOS to IdV) and by the Spanish Ministry of Education and Science (CICYT grant REN2003-03038 to RM-B)

Dissolved CH4 coupled to photosynthetic picoeukaryotes in oxic waters and to cumulative chlorophyll a in anoxic waters of reservoirs

Methane (CH4) emissions from reservoirs are responsible for most of the atmospheric climatic forcing of these aquatic ecosystems, comparable to emissions from paddies or biomass burning. Primarily, CH4 is produced during the anaerobic mineralization of organic carbon in anoxic sediments by methanogenic archaea. However, the origin of the recurrent and ubiquitous CH4 supersaturation in oxic waters (i.e., the methane paradox) is still controversial. Here, we determined the dissolved CH4 concentration in the water column of 12 reservoirs during summer stratification and winter mixing to explore CH4 sources in oxic waters. Reservoir sizes ranged from 1.18 to 26.13 km(2). We found that dissolved CH4 in the water column varied by up to 4 orders of magnitude (0.02-213.64 mu mol L-1), and all oxic depths were consistently supersaturated in both periods. Phytoplanktonic sources appear to determine the concentration of CH4 in these reservoirs primarily. In anoxic waters, the depth-cumulative chlorophyll a concentration, a proxy for the phytoplanktonic biomass exported to sediments, was correlated to CH4 concentration. In oxic waters, the photosynthetic picoeukaryotes' abundance was significantly correlated to the dissolved CH4 concentration during both the stratification and the mixing. The mean depth of the reservoirs, as a surrogate of the vertical CH4 transport from sediment to the oxic waters, also contributed notably to the CH4 concentration in oxic waters. Our findings suggest that photosynthetic picoeukaryotes can play a significant role in determining CH4 concentration in oxic waters, although their role as CH4 sources to explain the methane paradox has been poorly explored

Consultoría organizacional: Diagnóstico de la imagen corporativa y el servicio al cliente de la empresa SERVI FLEXO S.A.S.

La comunicación con los públicos de interés de las Compañías ha tomado cada vez mayor relevancia y es a través de ésta, que se crean intangibles invaluables como la imagen, la reputación y la identidad. Durante los últimos años, independiente de la razón social, el tamaño y las características organizacionales; las Empresas se han mostrado interesadas en conocer la percepción que sus públicos tienen sobre ellas; con el fin de crear propuestas de mejoramiento o cambio, tomar decisiones estratégicas y aumentar el número de negociaciones, clientes y ventas. En el presente trabajo se utilizaron diferentes metodologías para conocer la percepción de los públicos de interés de SERVI FLEXO S.A.S. y con sus los resultados obtenidos, se planteó una estrategia de imagen corporativa.The communication with the stakeholders Companies has taken more and more importance and it is through this, that invaluable intangibles are created as the image, the reputation and the identity. During the last years, independent of the company name, size and organizational characteristics; companies have shown interest in knowing the perception that their public has about them, in order to create proposals for improvement or change, make strategic decisions and increase the number of negotiations, customers and sales. In this text, different methodologies were used to know the perception of the stakeholders of SERVI FLEXO S.A.S. and with its results, a corporate image strategy was proposed.Especialización en Alta Gerenci