Search

Sampling for dissolved organic carbon (DOC) in the Arctic is challenging given the limited access and because it is not yet possible to measure with instruments deployed in situ. Compared to DOC, colored dissolved organic matter (CDOM) absorption spectroscopy is an easy‐to‐measure, relatively quick and cost‐effective approach which is often closely related to DOC concentrations in water samples. Here we present an algorithm based on quantitative and qualitative metrics of CDOM to provide DOC estimates derived from a Pan‐Arctic data set (n = 3,302) spanning rivers to deep ocean, with DOC ranging between 31 and 1,958 μM. The algorithm provided robust DOC estimates (r2 = 0.94; p < 0.0001) and could reproduce DOC profiles and mixing plots across different locations in the Arctic Ocean. Besides its simplicity, this method is capable of capturing the extremely broad range of DOC within the strong gradients observed between Arctic riverine and marine systems. Plain Language Summary: Surface waters in the Arctic Ocean have high content of dissolved organic carbon (DOC), which plays an important role in CO2 fluxes and absorbing heat, thus warming the ocean. Measuring DOC requires resource‐intensive lab analysis. The optical properties of colored dissolved organic matter (CDOM) are easier, quick and cost‐effective to measure, and can therefore be sampled at a higher frequency or with autonomous sensors. Here we develop an algorithm that uses CDOM optical properties to estimate DOC concentrations across the entire Arctic Ocean, spanning from rivers (high DOC) to the deep waters (low DOC). The algorithm provides reliable estimates and can reproduce regional features, which shows that the method is effective and can be employed to increase sampling efforts for DOC in remote Arctic waters. Key Points: Spectral properties of colored dissolved organic matter can predict dissolved organic carbon concentrations across a range of Arctic aquatic systemsWe developed a pan‐Arctic algorithm from a comprehensive data set spanning from rivers to the deep Arctic watersThe algorithm provides robust estimates allowing for reproduction of regional features such as vertical profiles and mixing lines [ABSTRACT FROM AUTHOR]

Objective: This retrospective study aimed to analyse the anatomical dimensions of the pterygomaxillary region, installation angulations of pterygoid implants and bone density in the pterygoid pillar region by cone beam computed tomography (CBCT) examinations used in planning dental rehabilitation with implant‐supported prostheses in patients with atrophic jaws. Materials and Methods: We analysed 360 CBCTs of patients with atrophic jaws using Xoran® software v.3.1.62 (Xoran Technologies). In addition, the angulation of virtual implants installed in the pterygomaxillary region was analysed in relation to the Frankfurt plan, as well as the length required for the installation of implants in this region. Results: The implant length installed in the pterygoid pillar varied between 13 and 20 mm, with an average of 16.17 mm (SD 2.16 mm). The pterygoid implant angulation on the latero‐lateral axis (frontal view) averaged 78.71° (SD. 3.58°) and 73.50° (SD 3.49°) in the anteroposterior direction (sagittal view). Bone density was found to be significantly higher in the pterygoid pillar region compared the maxillary tuberosity region (p < 0.05); the region of the tuberosity and pterygoid pillar had an average density value of 132.9 (SD 230.24) and 513.91 (SD 291.63) respectively. Conclusion: According to the results of this study, a pterygoid implant with a minimum length of 13 mm should be used in the pterygomaxillary region to reach the pterygoid bone pillar. [ABSTRACT FROM AUTHOR]

Electrochemical valorization of biomass waste (e.g., glycerol) for production of value‐added products (such as formic acid) in parallel with hydrogen production holds great potential for developing renewable and clean energy sources. Here, a synergistic effort between theoretical calculations at the atomic level and experiments to predict and validate a promising oxide catalyst for the glycerol oxidation reaction (GOR) are reported, providing a good example of designing novel, cost‐effective, and highly efficient electrocatalysts for producing value‐added products at the anode and high‐purity hydrogen at the cathode. The predicted CoMoO4 catalyst is experimentally validated as a suitable catalyst for GOR and found to perform best among the investigated metal (Mn, Co, Ni) molybdate counterparts. The potential required to reach 10 mA cm−2 is 1.105 V at 60 °C in an electrolyte of 1.0 m KOH with 0.1 m glycerol, which is 314 mV lower than for oxygen evolution. The GOR reaction pathway and mechanism based on this CoMoO4 catalyst are revealed by high‐performance liquid chromatography and in situ Raman analysis. The coupled quantitative analysis indicates that the CoMoO4 catalyst is highly active toward CC cleavage, thus presenting a high selectivity (92%) and Faradaic efficiency (90%) for formate production. [ABSTRACT FROM AUTHOR]

The Arctic Ocean receives a large supply of dissolved organic matter (DOM) from its catchment and shelf sediments, which can be traced across much of the basin's upper waters. This signature can potentially be used as a tracer. On the shelf, the combination of river discharge and sea‐ice formation, modifies water densities and mixing considerably. These waters are a source of the halocline layer that covers much of the Arctic Ocean, but also contain elevated levels of DOM. Here we demonstrate how this can be used as a supplementary tracer and contribute to evaluating ocean circulation in the Arctic. A fraction of the organic compounds that DOM consists of fluoresce and can be measured using in‐situ fluorometers. When deployed on autonomous platforms these provide high temporal and spatial resolution measurements over long periods. The results of an analysis of data derived from several Ice Tethered Profilers (ITPs) offer a unique spatial coverage of the distribution of DOM in the surface 800 m below Arctic sea‐ice. Water mass analysis using temperature, salinity and DOM fluorescence, can clearly distinguish between the contribution of Siberian terrestrial DOM and marine DOM from the Chukchi shelf to the waters of the halocline. The findings offer a new approach to trace the distribution of Pacific waters and its export from the Arctic Ocean. Our results indicate the potential to extend the approach to separate freshwater contributions from, sea‐ice melt, riverine discharge and the Pacific Ocean. Plain Language Summary: The Arctic Ocean has a layered structure with comparatively warm Atlantic waters (above freezing temperatures) separated from the surface by a cold layer of water called the halocline. This layer allows the surface waters to be cooled sufficiently for sea ice to form. Here we present a new approach to trace the origins of the halocline using organic matter fluorescence as a tracer. These measurements are made from autonomous profiling systems which offer an excellent opportunity to vastly expand our sampling coverage temporally and spatially. Key Points: Arctic surface waters with comparable temperature and salinity have contrasting in situ dissolved organic matter fluorescenceOrganic matter fluorescence can track low salinity waters feeding into the Transpolar Drift and halocline layersSiberian and Chukchi shelf waters can be separated based on their fluorescence to salinity relationship [ABSTRACT FROM AUTHOR]

The export of dissolved organic carbon (DOC) from the Arctic Ocean is expected to change due to warming and increased river runoff. Here we present a method to quantify DOC transport with the East Greenland Current combining synoptic and year‐round data (2009–2018). An algorithm based on quantitative and qualitative aspects of colored dissolved organic matter (CDOM) was developed to provide DOC estimates. Combined with mooring‐derived monthly Polar Surface Water (PSW) volume transports, we estimate DOC exports for the period from 2003–2017. For much of the period DOC exports have been reasonably constant at 46.8 (±6.2) Tg yr−1, while the reduction in PSW export in recent years has resulted in lower annual DOC exports (below 39 Tg C yr−1). We now have a technique to resolve seasonal and annual fluctuations in Arctic carbon export, offering a significant improvement over earlier bulk estimates and represents a baseline to detect future change. Plain Language Summary: The Arctic Ocean has higher concentrations of dissolved organic carbon (DOC) compared to the other oceans due to the supply from large Siberian rivers that drain expansive carbon‐rich watersheds. Climate change in the Arctic is altering the supply of river water and DOC to the Arctic Ocean. This is eventually expected to also be reflected in the subsequent export of DOC from the Arctic to the North Atlantic via a major gateway, the Fram Strait. Here we present a new approach to quantify the transport of DOC through the Fram Strait based on year‐round mooring data and spectroscopic measurements of colored dissolved organic matter (CDOM). We calculate DOC transports using our measurements over a 10‐yr period, and the results provide a baseline from which to observe future changes in the Arctic Ocean that were not resolved with earlier estimates based on bulk concentrations and bulk volume transports. Key Points: Spectral characteristics of CDOM can predict DOC concentrations in the Fram StraitDOC transports are strongly correlated with Polar Surface Water volume transports from the Arctic Ocean with the East Greenland CurrentAnnual DOC transport estimates for 2009 to 2018 varied between 27 and 60 Tg C yr−1 [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of using encapsulated nitrate product (ENP) replacing soybean meal in diets differing in concentrate to forage ratio on ruminal fermentation and methane production in vitro using a semi‐automatic gas production technique. Eight treatments were used in a randomized complete design with a 2 × 4 factorial arrangement: two diet (20C:80F and 80C:20F concentrate to forage ratio) and four levels of ENP addition (0%, 1.5%, 3.0%, and 4.5% of DM) replacing soybean meal. There was a diet × ENP interaction (p = 0.02) for methane production. According to ENP addition, diets with 80C:20F showed more intense reduction on methane production that 20C:80F. A negative linear effect was observed for propionate production with ENP addition in diet with 80C:20F and to the relative abundance of methanogens Archaea, in both diet. The replacement of soybean meal by ENP in levels up to 3% of DM inhibited methane production due to a reduction in the methanogens community without affecting the organic matter degradability. However, ENP at 4.5% of DM level affected fiber degradability, abundance of cellulolytic bacteria, and propionic acid production, indicating that this level of inclusion is not recommended for ruminant production. [ABSTRACT FROM AUTHOR]

The giant freshwater pearl mussel Margaritifera auricularia (GFPM) is one of the most endangered bivalve species in the world. Originally occurring in many European rivers, the GFPM is a relict now restricted to a few ageing populations in France and Spain in which natural reproduction is almost absent.Like most unionoid mussels, the GFPM needs host fish for the development of their parasitic larvae (glochidia). The European sturgeon (Acipenser sturio), the only known native host fish of the GFPM in France, is essentially extinct. Therefore, the aim of this study was to identify other hosts that could be responsible for the few cases of recent recruitment.Natural infestation of wild fishes in three French rivers was assessed to identify potential hosts of M. auricularia, while artificial infestation experiments were conducted on the sea lamprey (Petromyzon marinus) and the wels catfish (Silurus glanis) to determine their compatibility as hosts.Among the 29 fish species assessed for natural infestation, only the three‐spined stickleback (Gasterosteus aculeatus) and the European eel (Anguilla anguilla) carried M. auricularia glochidia. In the artificial infestation experiments, living juvenile mussels were collected from both P. marinus and S. glanis. The number of juveniles collected from a single P. marinus specimen (13,827) suggests that this species is a highly efficient host. As with previously known hosts, newly identified ones also appear to have a relationship with marine environments.The present findings suggest that P. marinus has played a key role in preventing the total extinction of M. auricularia in France, and indicate the potential use of P. marinus in conservation strategies aimed at reintroducing or stabilizing populations of this rare mollusc. [ABSTRACT FROM AUTHOR]

Abstract: We discuss here a unique flexible non‐carbonaceous layered host, namely, metal titanium niobates (M‐Ti‐niobate, M: Al3+, Pb2+, Sb3+, Ba2+, Mg2+), which can synergistically store both lithium ions and sodium ions via a simultaneous intercalation and alloying mechanisms. M‐Ti‐niobate is formed by ion exchange of the K+ ions, which are specifically located inside galleries between the layers formed by edge and corner sharing TiO6 and NbO6 octahedral units in the sol‐gel synthesized potassium titanium niobate (KTiNbO5). Drastic volume changes (approximately 300–400 %) typically associated with an alloying mechanism of storage are completely tackled chemically by the unique chemical composition and structure of the M‐Ti‐niobates. The free space between the adjustable Ti/Nb octahedral layers easily accommodates the volume changes. Due to the presence of an optimum amount of multivalent alloying metal ions (50–75 % of total K+) in the M‐Ti‐niobate, an efficient alloying reaction takes place directly with ions and completely eliminates any form of mechanical degradation of the electroactive particles. The M‐Ti‐niobate can be cycled over a wide voltage range (as low as 0.01 V) and displays remarkably stable Li+ and Na+ ion cyclability (>2 Li+/Na+ per formula unit) for widely varying current densities over few hundreds to thousands of successive cycles. The simultaneous intercalation and alloying storage mechanisms is also studied within the density functional theory (DFT) framework. DFT expectedly shows a very small variation in the volume of Al‐titanium niobate following lithium alloying. Moreover, the theoretical investigations also conclusively support the occurrence of the alloying process of Li ions with the Al ions along with the intercalation process during discharge. The M‐Ti‐niobates studied here demonstrate a paradigm shift in chemical design of electrodes and will pave the way for the development of a multitude of improved electrodes for different battery chemistries. [ABSTRACT FROM AUTHOR]

A significant obstacle to evaluating the importance of mangrove habitat to coral reef fishes has been the difficulty of disentangling its effects from other subtidal/nearshore habitats or human population pressures. Florida’s seascape, unlike most others, has been extensively surveyed and mapped, and there are reliable estimates of human population density. Despite many studies that have correlated reef fish abundance with nearby mangrove habitat, some researchers continue to question the importance of mangroves to reef fishes. Previous studies that have investigated the mangrove–reef fish subsidy effect have applied methods that either compared averages or examined linear relationships; yet there is a body of literature that indicates that the effects of habitat are characterized by thresholds and limiting functions. Here, we employed a generalized additive model to investigate whether species richness of 106 mangrove-associated reef fishes is related to thresholds in the extent of nearby mangrove forests along the Florida Keys Reef Tract. In addition, we used linear discriminant analyses (LDAs) to examine the relationships between the occurrence of 77 reef fish species and extent of Florida mangrove forests. We found that after accounting for confounding factors, at scales <20 km2 , species richness declines with decreasing mangrove extent, whereas richness increases with increasing mangrove extent at scales >80 km2. Results of our LDA suggested that at least 49 reef fish species (64% of focal species) were associated with higher nearby mangrove forest extent. Our results indicate that of all habitat attributes considered, mangroves played the most substantial role in the diversity of nearby reef fish populations. These apparent thresholds (i.e., non-linearities) in the extent of mangrove forests should be incorporated into fisheries critical habitat management and emphasize the need to consider non-linear relationships between fishes and their habitat. [ABSTRACT FROM AUTHOR]

The family Margaritiferidae is a small but widely distributed group within the Unionoida, or freshwater mussels, whose taxonomy and systematics has been the subject of numerous publications. Despite several efforts, there is no consensus on which characters reliably diagnose this family. Herein, we present the results of a phylogenetic analysis of the most comprehensive data set for Margaritiferidae in terms of taxa and phylogenetic markers assembled to date, including eleven out of the twelve margaritiferid species currently considered valid. In addition, we review the fossil record of the family and attempt to integrate fossil and DNA sequence data to provide a diagnosis of Margaritiferidae, identify its origin and biogeographic patterns, and determine the systematic relationships of its constituent species and their taxonomic affinities. We assembled a molecular data set comprised of five markers: COI, 16S, 28S, 18S and histone 3 for a total of 59 specimens representing eleven species of Margaritifera. Our results indicate that the family Margaritiferidae is a monophyletic group comprised of the single genus Margaritifera, which includes the following 12 species: M. dahurica, M. margaritifera, M. monodonta, M. middendorffi, M. laevis, M. marrianae, M. hembeli, M. falcata, M. laosensis, M. auricularia and M. marocana plus the unstudied M. homsensis. Estimates of divergence times using fossil calibrations or mean substitution rates produced dramatically different results. Divergence estimates based on the fossil calibrations were 10 times higher than those obtained applying the mean substitution rates. The current distribution of the family implies dispersal across marine or brackish waters by their host fish, leaving a fossil record on four continents that dates to the Mesozoic. Margaritiferidae appear to be derived from putative ancestor in the Silesunionidae, with a likely origin in Asia. We suggest that Margaritiferidae had spread along the Tethys margins and crossed the Atlantic already in the Late Triassic or Early Jurassic. Further dispersal events, in the Late Cretaceous or Eocene, may be linked to salinity-depleted coastal waters or freshwater layering. [ABSTRACT FROM AUTHOR]

ABSTRACT Freshwater mussels of the Order Unionida provide important ecosystem functions and services, yet many of their populations are in decline. We comprehensively review the status of the 16 currently recognized species in Europe, collating for the first time their life-history traits, distribution, conservation status, habitat preferences, and main threats in order to suggest future management actions. In northern, central, and eastern Europe, a relatively homogeneous species composition is found in most basins. In southern Europe, despite the lower species richness, spatially restricted species make these basins a high conservation priority. Information on freshwater mussels in Europe is unevenly distributed with considerable differences in data quality and quantity among countries and species. To make conservation more effective in the future, we suggest greater international cooperation using standardized protocols and methods to monitor and manage European freshwater mussel diversity. Such an approach will not only help conserve this vulnerable group but also, through the protection of these important organisms, will offer wider benefits to freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Freshwater mussels, historically a component of freshwater benthic invertebrate biomass, are one of the most imperilled animal groups on the planet. Margaritifera auricularia was once a common freshwater mussel inhabiting large rivers throughout Western Europe. It was believed to be extinct until 1996 when a few small populations were found in Spain and France., Currently M. auricularia is one of the most endangered species in the world. The current status of this mollusc in the Ebro River was surveyed, finding a few adult specimens at only two localities, and many old, empty shells throughout the river., Using a simple analysis of historical hydrological data, dramatic changes in water flow might have led to localized extirpation of this freshwater mussel., Other factors contributing to the slow extirpation of this long-lived invertebrate from other areas of the Ebro Basin include the continuous reduction of water levels during the reproductive season, overharvesting for nacre, construction of impoundments, extinction of fish hosts, and impaired water quality., Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A study was conducted to investigate effects of feeding encapsulated nitrate (EN) to beef cattle on ammonia (NH3) and greenhouse gas emissions from their manure. Eight beef heifers were randomly assigned to diets containing 0 (control), 1, 2, or 3% EN (55% forage dry matter; EN replaced encapsulated urea in the control diet and therefore all diets were iso-nitrogenous) in a replicated 4 x 4 Latin square design. Urine and feces collected from individual animals were reconstituted into manure and incubated over 156 h using a steady-state flux chamber system to monitor NH3, methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) emissions. Urinary, fecal, and manure nitrate (NO3-)-N concentration linearly increased (P < 0.001) with feeding EN, and urinary urea concentration tended to be lower (P = 0.078) for EN versus Control. The hourly emissions of NH3, CO2, and N2O (mg head-1 h-1) were not affected, although NH3 emission rates tended to be lower (P = 0.070) for EN compared with Control at 0 to 12 h. Cumulative NH3, CO2, and N2O emissions over 156 h were not affected, but CH4 emissions were less (4.5 vs. 7.4 g head-1; P = 0.027) for EN compared with Control. In conclusion, although NH3 emissions were initially lower for EN manures, total NH3 emitted over 156 h was not affected. Dietary EN lowered CH4 emissions from manure, and, despite greater NO3- concentrations in EN manure, N2O emissions were not affected in this short-term incubation. [ABSTRACT FROM AUTHOR]

Mediterranean-type streams are characterized by great seasonal and annual variation in flow. We studied the biology of the freshwater mussel Unio tumidiformis in such a stream, the Vascão River in southern Portugal, during a period of great interannual variation in hydrology. We studied growth patterns of the mussels between 2002-2008, and the reproductive cycle between 2005-2006. Life-history parameters were calculated and related to environmental variables and fish community patterns. Mark-recapture growth data confirmed that observed annuli were formed annually and are therefore reliable for use in growth studies of U. tumidiformis. The von Bertalanffy growth constant K and the asymptotic length L∞ were negatively correlated. K varied between 0.20 and 0.58 and was positively correlated with factors related to eutrophication. The maximum observed age was 7 years, and the maximum observed length was 52 mm. There was no apparent sexual dimorphism, and sexual maturity was reached at the age of 2 years. Fecundity was low, between 1500-15000 glochidia per female, and positively correlated with body length. Only one annual gametogenic cycle was identified, leading to a short-term reproductive period in spring (tachyticity). The reproductive cycle was similar in the two years sampled, between which hydrology and water quality differed greatly. The presence of glochidia was synchronized with the period when the proportion of fish hosts (genus Squalius) was higher in the fish community. Unio tumidiformis seems to be well adapted to the natural variability in flow in temporary Mediterranean-type streams. Modifications of the natural flow regime caused by climate change or increased water exploitation may lead to rapid declines in mussel populations. [ABSTRACT FROM AUTHOR]

ABSTRACT The use of natural fibers (NFs) in polymer composites for structural applications has increased greatly in the last years, owing to their abundance and biodegradability. In this work, an innovative and simple successive alkali treatment has been developed to improve the mechanical properties of NFs/polypropylene (PP) composites. Three different cellulosic fibers (curauá, jute, and flax) were used, with a fixed proportion of 10 wt %. The fibers were immersed several times in a 5 wt % NaOH solution. Thermogravimetric analysis data showed an improvement in thermal properties of the fibers, as well as the increase of the crystallinity degree was measured by X-ray diffraction. By Fourier transform infrared spectroscopy, disappearance of characteristics peaks of hemicelluloses and lignin was observed. Finally, mechanical behavior of the NF/PP composites was examined, using dynamic mechanical analysis. The results revealed that the curauá/PP mechanical properties were significantly improved, showing the positive effect of the successive alkali treatments. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41710. [ABSTRACT FROM AUTHOR]

In the present study, a new polypropylene (PP)/multi-walled carbon nanotube (MWCNT) masterbatch is synthesized by in situ polymerization and compared with a masterbatch obtained by melt mixing. Both masterbatches are used for the realization of PP/MWCNT nanocomposites by mixing with a commercial PP in a laboratory extruder. It is shown that the use of masterbatch synthesized in situ allows providing additional enhanced thermal stability and mechanical properties. Samples are characterized according to their thermo dynamicmechanical properties, thermal stability, and degree of crystallinity, as well as by scanning electron microscopy. DMA analysis shows that there is a sharp increase in both storage and loss moduli of materials even with very low CNT content, in comparison with the neat PP. By means of thermogravimetric analysis, it is found that the thermal stability of nanocomposites is also increased. Furthermore, the degree of crystallinity of the materials containing CNTs is increased to higher value than that of neat PP, suggesting that the carbon nanotubes act as nucleating agent. A sharper increase of Xc is observed in the composites with low CNT content prepared in the method using meltmasterbatch, suggesting that there are more agglomerations of CNTs in this material. [ABSTRACT FROM AUTHOR]

ABSTRACT [ABSTRACT FROM AUTHOR]

The article presents a study on the channel or ditch habitat as a sanctuary for naiads and its significance of this habitat for the long-term conservation of these bivalves. Several waterways fed by the mid Ebro River in Spain were sampled for naiad populations monitoring. Corresponding stretches of the waterways were meticulously inspected for mussel richness and density and the number of specimens per square meter were calculated. Results show that channel or ditch habitat harbour significant colonies of freshwater mussels.