The importance of biomass net uptake for a trace metal budget in a forest stand in north-eastern France

The trace metal (TM: Cd, Cu, Ni, Pb and Zn) budget (stocks and annual fluxes) was evaluated in a forest stand (silver fir, Abies alba Miller) in north-eastern France. Trace metal concentrations were measured in different tree compartments in order to assess TM partitioning and dynamics in the trees. Inputs included bulk deposition, estimated dry deposition and weathering. Outputs were leaching and biomass exportation. Atmospheric deposition was the main input flux. The estimated dry deposition accounted for about 40% of the total trace metal deposition. The relative importance of leaching (estimated by a lumped parameter water balance model, BILJOU) and net biomass uptake (harvesting) for ecosystem exportation depended on the element. Trace metal distribution between tree compartments (stem wood and bark, branches and needles) indicated that Pb was mainly stored in the stem, whereas Zn and Ni, and to a lesser extent Cd and Cu, were translocated to aerial parts of the trees and cycled in the ecosystem. For Zn and Ni, leaching was the main output flux (N95% of the total output) and the plot budget (input–output) was negative, whereas for Pb the biomass net exportation represented 60% of the outputs and the budget was balanced. Cadmium and Cu had intermediate behaviours, with 18% and 30% of the total output relative to biomass exportation, respectively, and the budgets were negative. The net uptake by biomass was particularly important for Pb budgets, less so for Cd and Cu and not very important for Zn and Ni in such forest stands

Évolution des émissions, de la qualité de l'air et des dépôts atmosphériques dans les espaces ruraux, notamment forestiers. Changes in atmospheric emissions, air quality and deposition in rural areas, especially in forests.

Les composés atmosphériques, qu'ils soient de sources naturelles ou anthropiques, peuvent être transformés, transportés sur de longues distances et transférés de l'atmosphère vers un autre réservoir via les retombées atmosphériques. Ces composés, bien que présents à l’état de trace, peuvent générer des événements de pollution, dont la prévision est utile à la protection de la santé publique, des milieux naturels et du climat. Au cours des trois dernières décennies, des politiques de réduction des émissions polluantes ont été mises en place en Europe et sur d’autres continents afin de limiter leurs effets. Pour un certain nombre de ces composés, l'efficacité de ces politiques peut être évaluée par le suivi à long terme de la chimie des retombées atmosphériques, ainsi que sur la définition de charges critiques pour un écosystème, définies (le milieu forestier dans cet article) comme le dépôt anthropique maximal qui ne conduira pas à un dépassement des concentrations critiques au sein du compartiment étudié, en l'état actuel des connaissances. En France, des observatoires nationaux (MERA, RENECOFOR/CATAENAT) sont dédiés à la surveillance des retombées atmosphériques depuis les années 90. Parmi les éléments majeurs inorganiques mesurés depuis l’origine, les ions sulfates (SO42-), nitrates (NO3-) et ammonium (NH4+) sont particulièrement suivis pour leurs impacts acidifiant et eutrophisant sur les écosystèmes. Ces ions solubilisés dans l’eau sont issus de la transformation des gaz précurseurs SOX, NOX, et NH3 émis majoritairement par les activités anthropiques. La mutualisation des mesures de ces observatoires offre un jeu de données inédit pour étudier l’évolution de la composition chimique des retombées atmosphériques au niveau national ou européen et permet une comparaison avec l’évolution des émissions des polluants primaires. Les variations sur les mêmes périodes des cartes de charges critiques et de leurs dépassements permettent de constater directement les effets des politiques de réduction des émissions mises en œuvre sur les écosystèmes terrestres. The atmospheric compounds which are emitted by natural or anthropogenic sources, can be transformed, transported on long range and transferred towards the ecosystems under the atmospheric deposition process. These compounds can generate pollution events which forecast is useful for public health and natural ecosystems protection. During the last three decades, the policies of reduction of polluting, emissions were organized in Europe and on other continents to limit their effects on the human health, the ecosystems and the climate. The efficiency of these policies can be estimated by the follow-up at long-term of the chemistry of the atmospheric deposition and in regards to critical loads defined for an ecosystem as "the highest load that will not cause chemical changes leading to long-term harmful effects in the most sensitive ecological systems", in the present state of the knowledge. In France, national monitoring networks (MERA, RENECOFOR/CATAENAT) were implemented to the monitoring of the atmospheric deposition from the beginning of the 90s. Among the inorganic major elements measured since the origin, the sulfate (SO4 2-), nitrate (NO3-) and ammonium (NH4+) ions are particularly followed for their acidifying and eutrophying impacts on the terrestrial ecosystems. These solubilized ions arise from the transformation of precursor gases SOx, NOx, and NH3 be mainly emitted by the anthropogenic activities. The combined measurements of these two monitoring networks offer a set of data to study the evolution of the chemical composition of the atmospheric deposition at the national or European level and allow a comparison with the evolution of the emissions of primary pollutants. The variations over the same periods of the maps of critical loads and their exceedances allow to estimate the effects of the emissions reduction policies

Side-Channel Analysis of Integrate-and-Fire Neurons within Spiking Neural Networks

Spiking neural networks gain attention due to low power properties and event-based operation, making them suitable for usage in resource constrained embedded devices. Such edge devices allow physical access opening the door for side-channel analysis. In this work, we reverse engineer the parameters of a feed-forward spiking neural network implementation with correlation power analysis. Localized measurements of electro-magnetic emanations enable our attack, despite inherent parallelism and the resulting algorithmic noise of the network. We provide a methodology to extract valuable parameters of integrate-and-fire neurons in all layers, as well as the layer sizes

Contrasted spatial and long-term trends in precipitation chemistry and deposition fluxes at rural stations in France

The long-distance effect of atmospheric pollution on ecosystems has led to the conclusion of international agreements to regulate atmospheric emissions and monitor their impact. This study investigated variations in atmospheric deposition chemistry in France using data gathered from three different monitoring networks (37 stations) over the period from 1995 to 2007. Despite some methodological differences (e.g. type of collector, frequency of sampling and analysis), converging results were found in spatial variations, seasonal patterns and temporal trends. With regard to spatial variations, the mean annual pH in particular ranged from 4.9 in the north-east to 5.8 in the south-east. This gradient was related to the concentration of NO3- and non-sea-salt SO42- (maximum volume-weighted mean of 38 and 31 µeq l-1 respectively) and of acid-neutralising compounds such as non-sea-salt Ca2+ and NH4+ In terms of seasonal variations, winter and autumn pH were linked to lower acidity neutralisation than during the warm season. The temporal trends in atmospheric deposition varied depending on the chemical species and site location. The most significant and widespread trend was the decrease in non-sea-salt SO42- concentrations (significant at 65% of the stations). At the same time, many stations showed an increasing trend in annual pH (+0.3 on average for 16 stations). These two trends are probably due to the reduction in SO2 emissions that has been imposed in Europe since the 1980s. Temporal trends in inorganic N concentrations were rather moderate and not consistent with the trends reported in emission estimates. Despite the reduction in NOx emissions, NO3- concentrations in atmospheric deposition remained mostly unchanged or even increased at three stations (+0.43 meq l-1 yr-1 on average). In contrast NH4+ concentrations in atmospheric deposition decreased at several stations located in western and northern areas, while the estimates of NH3 emissions remained fairly stable. The decrease in non-sea-salt SO42- and NH4+ concentrations was mainly due to a decrease in summer values and can in part be related to a dilution process since the precipitation amount showed an increasing trend during the summer. Furthermore, increasing trends in NO3- concentrations in the spring and, to a lesser extent, in NH4+ concentrations suggested that other atmospheric physicochemical processes should also be taken into account

The Effect of Increased Hip Rotation on Lower Body Anaerobic Power and Fatigue Index During the Wingate Anaerobic Power Test

https://scholarworks.moreheadstate.edu/student_scholarship_posters/1110/thumbnail.jp

Combined effect of atmospheric nitrogen deposition and climate change on temperate forest soil biogeochemistry: A modeling approach

International audienceAtmospheric N deposition is known to severely impact forest ecosystem functioning by influencing soil biogeochemistry and nutrient balance, and consequently tree growth and overall forest health and biodiversity. Moreover, because climate greatly influences soil processes, climate change and atmospheric N deposition must both be taken into account when analysing the evolution of forest ecosystem status over time. Dynamic biogeochemical models have been developed to test different climate and atmospheric N deposition scenarios and their potential interactions in the long term. In this study, the ForSAFE model was used to predict the combined effect of atmospheric N deposition and climate change on two temperate forest ecosystems in France dominated by oak and spruce, and more precisely on forest soil biogeochemistry, from today to 2100. After a calibration step and following a careful statistical validation process, two atmospheric N deposition scenarios were tested: the current legislation in Europe (CLE) and the maximum feasible reduction (MFR) scenarios. They were combined with three climate scenarios: current climate scenario, worst-case climate scenario (A2) and best-case climate scenario (B1). The changes in base saturation and inorganic N concentration in the soil solution were compared across all scenario combinations, with the aim of forecasting the state of acidification, eutrophication and forest ecosystem recovery up to the year 2100. Simulations highlighted that climate had a stronger impact on soil base saturation, whereas atmospheric deposition had a comparative effect or a higher effect than climate on N concentration in the soil solution. Although deposition remains the main factor determining the evolution of N concentration in soil solution, increased temperature had a significant effect. Results also highlighted the necessity of considering the joint effect of both climate and atmospheric N deposition on soil biogeochemistry

Composition chimique des dépôts atmosphériques à l’horizon 2020-2040

Les dépôts atmosphériques peuvent causer des dommages importants aux milieux naturels. Des mesures à long terme issues de la surveillance des dépôts atmosphériques en France ont été exploitées pour construire un modèle statistique prévisionnel afin d'estimer les changements de la composition chimique des dépôts atmosphériques à l'horizon 2020-2040. À partir de simulations d'évolutions possibles du climat et des émissions de polluants atmosphériques, les dépôts de sulfate non marin et les dépôts d'ammonium sont susceptibles de diminuer, mais ceux de nitrate pourraient augmenter de façons diverses selon les régions. Le changement des variations saisonnières de pluviométrie pourrait augmenter les flux de dépôts

On the pile-up effect and priors for L-inf and M/K: response to a comment by Hordyk et al. on "A new approach for estimating stock status from length frequency data" Reply

We thank Hordyk et al. (2019) for pointing out a typographical error in one of our equations, which has meanwhile been fixed in the online version of Froese et al. (2018) and addressed in a corrigendum for the printed version. We agree with Hordyk et al. (2019) that accounting for the pile-up effect in binned LF samples may be appropriate in, for example, tropical species with continuous reproduction, and we have provided for such correction as an option in the latest version of the LBB software. We note, however, that this correction as well as the LBSPR method of Hordyk et al. (2016) proposed by Hordyk et al. (2019) as an alternative to LBB leads to strong overestimation of exploitation and underestimation of stock status when compared with independent assessments of 34 real stocks from temperate and subtropical areas. As for the points raised by Hordyk et al. (2019) with regard to default priors for Linf and M/K, we maintain that these defaults are adequate for a wide range of exploited species. They can be easily replaced by users if better information is available. Warnings not to use LBB if LF samples do not show the typical asymmetric pattern were already provided in the original LBB paper and are repeated here.</p

A Hybrid Metaheuristic-Based Approach for the Aerodynamic Optimization of Small Hybrid Wind Turbine Rotors

This work presents a novel framework for the aerodynamic design and optimization of blades for small horizontal axis wind turbines (WT). The framework is based on a state-of-the-art blade element momentum model, which is complemented with the XFOIL 6.96 software in order to provide an estimate of the sectional blade aerodynamics. The framework considers an innovative nested-hybrid solution procedure based on two metaheuristics, the virtual gene genetic algorithm and the simulated annealing algorithm, to provide a near-optimal solution to the problem. The objective of the study is to maximize the aerodynamic efficiency of small WT (SWT) rotors for a wide range of operational conditions. The design variables are (1) the airfoil shape at the different blade span positions and the radial variation of the geometrical variables of (2) chord length, (3) twist angle, and (4) thickness along the blade span. A wind tunnel validation study of optimized rotors based on the NACA 4-digit airfoil series is presented. Based on the experimental data, improvements in terms of the aerodynamic efficiency, the cut-in wind speed, and the amount of material used during the manufacturing process were achieved. Recommendations for the aerodynamic design of SWT rotors are provided based on field experience

Structures, energetics, and dynamics of helium adsorbed on isolated fullerene ions

Helium adsorbed on C60+ and C70+ exhibits phenomena akin to helium on graphite. Mass spectra suggest that commensurate layers form when all carbon hexagons and pentagons are occupied by one He each, but that the solvation shell does not close until 60 He atoms are adsorbed on C60+, or 62 on C70+. Molecular dynamics simulations of C 60Hen+ at 4 K show that the commensurate phase is solid. Helium added to C60He32+ will displace some atoms from pentagonal sites, leading to coexistence of a registered layer of immobile atoms interlaced with a nonregistered layer of mobile atomsThis work was supported by MICINN projects FIS2010-15127, ACI2008-0777, CTQ2010-17006, Consolider-Ingenio CSD2007-00010, CAM program NANOBIOMAGNET S2009/MAT1726, the Austrian Science Fund, Wien (FWF, projects P19073, L633, and I200 N29), the European Commission, Brussels (ITS-LEIF), and the European COST Action CM0702