Photosynthetic activity buffers ocean acidification in seagrass meadows

Macrophytes growing in shallow coastal zones characterised by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH changes in shallow (5–12 m) seagrass (<i>Posidonia oceanica</i>) meadows spanning 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation state (&Omega;_Ar)) and O₂ within the meadows displayed strong diel variability driven by primary productivity, and changes in chemistry were related to structural parameters of the meadow, in particular, the leaf surface area available for photosynthesis (LAI). LAI was positively correlated to mean, max and range pH_NBS and max and range &Omega;_Ar. In June, vertical mixing (as Turbulent Kinetic Energy) influenced max and min &Omega;_Ar, while in September there was no effect of hydrodynamics on the carbonate system within the canopy. Max and range &Omega;_Ar within the meadow showed a positive trend with the calcium carbonate load of the leaves, pointing to a possible link between structural parameters, &Omega;_Ar and carbonate deposition. <br></br> Calcifying organisms, e.g. epiphytes with carbonate skeletons, may benefit from the modification of the carbonate system by the meadow. There is, however, concern for the ability of seagrasses to provide modifications of similar importance in the future. The predicted decline of seagrass meadows may alter the scope for alteration of pH within a seagrass meadow and in the water column above the meadow, particularly if shoot density and biomass decline, on which LAI is based. Organisms associated with seagrass communities may therefore suffer from the loss of pH buffering capacity in degraded meadows

Numerical simulation of the open-pool reactor coolant system using a multi-domain approach

The computational simulation of large-scale reactors is currently limited by the high computational cost. The system codes allow addressing these problems, although with the well-known loss of local information. The use of coupling domains to reduce the problems looks like a proper alternative to settle this issue. In the present paper, a multi-domain coupling 3-dimensional/0-dimensional method to solve the thermal hydraulics of the TRIGA Mark I IPR-R1 reactor was implemented into a Finite Volume suite. Despite of the broadly literature about coupling methods, even in the nuclear engineering community, most of them manage with different codes in a fully explicit way. In the other hand, the benefit of solve different domain approaches inside the same software is in the use of monolithic algorithms. The proposed method consists on using 3-dimensional full CFD to simulate the reactor pool and 0-dimensional modelling for the external cooling loop. This is made by implementing a set of ad hoc dynamics boundary conditions to model the momentum and energy balances along the pipeline. This strategy was used to perform long-time steady state simulations of the reactor at the design power of 100 kW as well as for the repowering up to 265 kW. The results demonstrated that the core is efficiently cooled at the higher power without need to increase the coolant mass flow rate of the external system. Moreover, two accidental events were simulated: the first case was the Station Black Out at full power of 265 kW. The results indicated that the loss of the external heat sink led to a slow pool heating, but the core remains being cooled by the natural circulation in the pool. In fact, the mass flow rate through the core is only reduced in 15% by the loss of the external loop circulation. Finally, a large-Loss of Coolant Accident for the operational power of 100 kW and keeping the pump running is performed. In this case, the pool is quickly empty if safety systems do not take action and the core is uncovered after 450 s completely losing the core cooling capacity.Fil: Corzo, Santiago Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; ArgentinaFil: Godino, Dario Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; ArgentinaFil: Costa, Antonella Lombardi. Universidade Federal de Minas Gerais; Brasil. Conselho Nacional de Desenvolvimiento Científico e Tecnológico; BrasilFil: Reis, Patricia A. L.. Universidade Federal de Minas Gerais; Brasil. Conselho Nacional de Desenvolvimiento Científico e Tecnológico; BrasilFil: Pereira, Claubia. Universidade Federal de Minas Gerais; Brasil. Conselho Nacional de Desenvolvimiento Científico e Tecnológico; BrasilFil: Ramajo, Damian Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones en Métodos Computacionales. Universidad Nacional del Litoral. Centro de Investigaciones en Métodos Computacionales; Argentin

Petrophysical properties in the Iberian Range and surrounding areas (NE Spain): 1-density

We introduce the first map of density data in Northeastern Spain which can help in the interpretation of gravimetric surveying. The background map is a simplified version of the Geode continuous geological cartography (scale 1:200.000) of the Iberian Range and Ebro basin. These maps are synthetic and homogeneous maps based on previous 1:50, 000 scale geological maps (MAGNA). The map uses the ETRS89 datum and UTM coordinates (30T northern zone) and covers an area of 140, 000 sq km. The compiled data shown in the map come from previous papers of the region (˜ 700 points) as well as from more than 800 additional points developed in the course of an exploratory project focused on the underground characterization of a potential CO2 reservoir in the so-called ‘Linking Zone''. The new data accomplish some basic criteria; they are accurately georeferenced and lithology, stratigraphic age and other technical details about the measurements (e.g. means and error) and methods are fully displayed

Pharmacological basis and clinical evidence of dabigatran therapy

Dabigatran is an emerging oral anticoagulant which is a direct inhibitor of thrombin activity. It has been approved in the European Union and the United States of America for the prevention of thrombosis after major orthopedic surgery. It has also been approved by the American Food and Drug Administration and the European Medicines Agency for the prevention of stroke in chronic atrial fibrillation. Dabigatran provides a stable anticoagulation effect without any need to perform periodical laboratory controls. Of note, there is a growing amount of clinical evidence which shows its safety and efficacy. For these reasons, dabigatran may suppose a revolution in oral anticoagulation. However, two important limitations remain. First, it is contraindicated in patients with end-stage renal disease. Second, there is no evidence of the prevention of thrombosis in mechanical heart valves

Anisotropy of magnetic susceptibility of the Pyrenean granites

In this paper, we report on a compilation of more than 2200 sites (more than 10,000 individual measurements) where anisotropy of magnetic susceptibility (AMS) was studied in granites from the Variscan Pyrenees. The standardization and homogenization of this information has allowed us to produce three Main Maps that synthesize all the information related with the AMS of the Pyrenean granites. We also describe the problems found during the construction of the database (variable geo-positioning, different published information, etc.). The information derived from 21 granite bodies, the database, and the synthesis maps (magnetic susceptibility, Km, and the orientation of the magnetic foliation, plane perpendicular to k3, and of the magnetic lineation, k1) allow us to see for the first time a complete image of this important kinematic and petrographic indicator

Southern Ocean pteropods at risk from ocean warming and acidification

Early life stages of marine calcifiers are particularly vulnerable to climate change. In the Southern Ocean aragonite undersaturation events and areas of rapid warming already occur and are predicted to increase in extent. Here, we present the first study to successfully hatch the polar pteropod Limacina helicina antarctica and observe the potential impact of exposure to increased temperature and aragonite undersaturation resulting from ocean acidification (OA) on the early life stage survival and shell morphology. High larval mortality (up to 39%) was observed in individuals exposed to perturbed conditions. Warming and OA induced extensive shell malformation and dissolution, respectively, increasing shell fragility. Furthermore, shell growth decreased, with variation between treatments and exposure time. Our results demonstrate that short-term exposure through passing through hotspots of OA and warming poses a serious threat to pteropod recruitment and long-term population viability