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International audience; Precise structural information collected from plots is significant in the management of and decision-making regarding forest resources. Currently, laser scanning is widely used in forestry inventories to acquire three-dimensional (3D) structural information. There are three main data-acquisition modes in ground-based forest measurements: single-scan terrestrial laser scanning (TLS), multi-scan TLS and multi-single-scan TLS. Nevertheless, each of these modes causes specific difficulties for forest measurements. Due to occlusion effects, the single-scan TLS mode provides scans for only one side of the tree. The multi-scan TLS mode overcomes occlusion problems, however, at the cost of longer acquisition times, more human labor and more effort in data preprocessing. The multi-single-scan TLS mode decreases the workload and occlusion effects but lacks the complete 3D reconstruction of forests. These problems in TLS methods are largely avoided with mobile laser scanning (MLS); however, the geometrical peculiarity of forests (e.g., similarity between tree shapes, placements, and occlusion) complicates the motion estimation and reduces mapping accuracy.Therefore, this paper proposes a novel method combining single-scan TLS and MLS for forest 3D data acquisition. We use single-scan TLS data as a reference, onto which we register MLS point clouds, so they fill in the omission of the single-scan TLS data. To register MLS point clouds on the reference, we extract virtual feature points that are sampling the centerlines of tree stems and propose a new optimization-based registration framework. In contrast to previous MLS-based studies, the proposed method sufficiently exploits the natural geometric characteristics of trees. We demonstrate the effectiveness, robustness, and accuracy of the proposed method on three datasets, from which we extract structural information. The experimental results show that the omission of tree stem data caused by one scan can be compensated for by the MLS data, and the time of the field measurement is much less than that of the multi-scan TLS mode. In addition, single-scan TLS data provide strong global constraints for MLS-based forest mapping, which allows low mapping errors to be achieved, e.g., less than 2.0 cm mean errors in both the horizontal and vertical directions.

International audience; Polymorphism commonly exists in the preparation of cocrystals and has attracted widespread attention from both the pharmaceutical industry and academia. However, few studies have examined how to discover polymorphic cocrystals and their potential formation mechanism. In this study, we report the novel discovery of salicylic acid: 3-nitrobenzamide (SA-3NBZ) polymorphic cocrystals by thermal methods. The formation mechanism is elucidated based on theoretical calculations. SA-3NBZ polymorphic cocrystals with molar ratio of 1:1 and 2:2 were discovered using the combination of differential scanning calorimetry and hot stage microscopy. Single-crystal X-ray diffraction analysis confirmed this discovery. Density functional theory calculations corrected with dispersion were conducted to illustrate the energetic stabilization of SA polymorphic cocrystals. Compared with the starting materials, formation of the cocrystals at 1:1 and 2:2 present a weak stabilization with overall energy reduction of −0.01 and −0.05 eV/molecule, respectively. The calculated noncovalent interactions index further suggests that intralayer hydrogen bonds and van der Waals forces contribute to these weak interactions. The density functional theory calculations are in good agreement with the X-ray diffraction data. Hence, thermal analysis is a simple and reliable method to discover polymorphic cocrystals.

International audience; The efficiency of zero-valent iron (Fe-0)for the degradation of contaminants in water or soil can be highly reduced by side reactions with oxygen or water. This work was conducted to test whether this drawback can be effectively suppressed by the carbonation of Fe-0 with pyrolyzed biomass, which forms a Fe3C composite. The composite Fe3C was characterized and its reactivity and stability were assessed in batch tests with methyl orange (MO) as a model pollutant. The results indicated that the removal rate of MO on Fe3C composite was higher than that of Fe-0 (7.587 mg/(g.min) vs. 4.306 mg/(g.min)) at pH 4, where the degradation mechanism was confirmed by high-performance liquid chromatography-mass spectrometry. More importantly, the produced iron oxide in the Fe3C composite was highly suppressed. Regeneration studies showed that after three times of cycling, the removal efficiency of MO on Fe3C composite was kept to 99.42%, but Fe-0 almost lost its reactivity. In situ chemical reduction of a colorimetric redox probe (indigo-5, 5'-disulfonate, I2S) quantitatively demonstrated that Fe3C composite has the reduction kinetics of I2S obviously slower than Fe-0, indicating that Fe3C composite improved the stability of incorporated Fe-0 to resist the side oxidation.

We apply the regional chemistry-transport model WRF-Chem to investigate the air pollution characteristics in three Chinese metropolitan areas (Beijing, Shanghai and Guangzhou) and assess the model performance in wintertime (January 2010) and summertime (July 2010) conditions. Three simulations utilizing the HTAPv2, REASv2 and MACCity anthropogenic emission inventories are conducted and compared with satellite and ground-based measurements to assess the sensitivity of the model predictions to anthropogenic emissions. Model-predicted surface meteorological fields are overall in good agreement with surface observations. However, the model tends to overestimate maximum surface wind speed, a feature also found in previous WRF-Chem modelling studies. Large discrepancies between the three emission inventories are found, specifically in the spatial distribution and the magnitude of the emissions (e.g. over 98%, 86% and 85% differences in some regions for carbon monoxide (CO), nitrogen oxide (NO) and organic carbon (OC) emissions, respectively). As a result, we find large differences between the simulations. When compared to satellite and surface observations, the HTAPv2-and REASv2-based simulations better reproduce the magnitude and spatial patterns of CO total columns and NO2 tropospheric columns derived from MOPITTv6 and GOME2 satellite observations, respectively. The simulations satisfactorily reproduce the air pollution characteristics in January 2010 as observed at surface monitoring stations in Beijing and Shanghai. The HTAPv2-based simulation better captures the pollution episode that occurred in Beijing in mid-January 2010, which is found to be related to a combination of different meteorological factors that led to the build-up of pollution. The high photochemical activity and convective turbulence in July 2010, in addition to differences in the emissions used, led to more pronounced differences between the simulations and lower statistical skills in particular for trace gases. This study shows that a considerable part of uncertainties in air quality model predictions for China can be attributed to uncertainties in current anthropogenic emission inventories. It highlights the need for more accurate and highly resolved emissions in order to improve the accuracy of model predictions. However, this study reveals that in some cases, model-observation discrepancies cannot be attributed only to inaccuracies in the emissions. For example, we found that regardless of the adopted emissions, all of the simulations fail to capture the temporal variability of particulate matter in Guangzhou during January 2010, indicating that factors other than emissions have a considerable influence on the atmospheric composition in this region. This work shows that inaccuracies in the predicted meteorological parameters (e.g. wind speed/direction, relative humidity, etc.) significantly affect the model performance, as found for example in the model predictions for Shanghai for July 2010, which show high and abrupt increases of NOx and particulates due to rapid decreases in wind speed in the model.

International audience; Hyperaccumulator plants are new alternative sources for elements of interest e.g., nickel, rare-earth elements(REEs), as concentrations in their aerial parts are higher than in common low-grade ores. The fern Dicranopterislinearis naturally grows on former mine tailings in Southern China and is classified as a REE hyperaccumulator.The efficient recovery of REEs is fundamental to ensure economic viability and to limit the environmental impactof the process. This study presents a novel approach for the treatment of the Dicranopteris biomass after incinerationto ash to drastically improve the “bio-ore” grade and to generate heat. Ash structure and composition isdescribed, and challenges for efficient recovery of REEs are discussed. A pre-processing step, aiming at renderingthe REEs available for extraction, was designed to dissolve aluminum (Al) using concentrated sodium hydroxide(6 M) at an average temperature (80 ◦C). The operating parameters were investigated through experimentmethodology design and parametric studies to build an empirical model. Additional experiments revealed thatthe formation of insoluble aluminosilicate compounds limited the removal of aluminium. Rinsing the REE-richresidue proved to be effective to increase the REE concentration and was carefully designed. Subsequently,the REEs were extracted under mildly acidic conditions using nitric acid (25 ◦C, pH 4.8), producing a valuablesolution devoid of aluminium and containing 74% of the REEs.

International audience; Understanding the formation of the Qilian Shan in the NE Tibetan Plateau provides insights into the growth mechanisms of the northern portion of the plateau through time. The onset time of exhumation in the Qilian Shan is still debated. The Qinghai Nan Shan subrange, located in the southeastern Qilian Shan, is cut by the Yellow River that forms Longyang Gorge, providing a good vertical profile for thermochronological investigation of exhumation. In this paper, we reconstruct the cooling and exhumation history of the Eastern Qinghai Nan Shan using apatite fission-track(AFT) and apatite (Usingle bondTh)/He(AHe) thermochronological dating on basement rocks. The fission-track data display a marked age-elevation trend from Early Cretaceous (114–122 Ma) ages at the bottom of the canyon to Early-Middle Jurassic ages (165–180 Ma) at the top. Mean (Usingle bondTh)/He ages are mainly Early Cretaceous (97–128 Ma) with one Eocene outlier (42 Ma). Combined with fission track lengths, Dpar values and thermal modeling results, these data indicate that the study area resided above the closure temperature of AFT and AHe until Early Cretaceous. Rapid cooling occurred during the Early Cretaceous and early Cenozoic likely driven by the Lhasa and Indian blocks collision with the southern margin of the Asian continent. Nonetheless, since then exhumation was limited to less than a few kilometers in the study area. Combined with regional geological studies, the thermochronological analysis demonstrates that, since the Mesozoic, intense exhumation occurred simultaneously along the northern and southern margins of the Qilian Shan. Hence, we suggest that the geomorphic framework of the northeast margin of the Tibetan Plateau was established during the Early Cretaceous-early Cenozoic.

International audience; Building roof extraction from airborne laser scanning point clouds is significant for building modeling. The common method adopts a bottom-up strategy which requires a ground filtering process first, and the subsequent process of region growing based on a single seed point easily causes oversegmentation problem. This paper proposes a novel method to extract roofs. A top-down strategy based on cloth simulation is first used to detect seed point sets with semantic information; then, the roof seed points are extracted instead of a single seed point for region-growing segmentation. The proposed method is validated by three point cloud datasets that contain different types of roof and building footprints. The results show that the top-down strategy directly extracts roof seed point sets, most roofs are extracted by the region-growing algorithm based on the seed point set, and the total errors of roof extraction in the test areas are 0.65%, 1.07%, and 1.45%. The proposed method simplifies the workflow of roof extraction, reduces oversegmentation, and determines roofs in advance based on the semantic seed point set, which suggests a practical solution for rapid roof extraction.

Phytoextraction is a promising technology for decontamination and recovery of rare earth elements (REEs) from REE-rich wastes. However, the improvement of REE phytoextraction efficiency on ion-adsorption REE mine tailings remains a challenge because the substrate can hardly support the growth of hyperaccumulators. In this study, REE phytoextraction using a REE hyperaccumulator, Phytolacca americana, grown on ion-adsorption REE mine tailing materials amended with organic material (OM) and biochar (BC) was explored through a pot experiment. Results show that under 1% OM, 5% OM, 1% BC, and 5% BC treatments, the shoots biomass of P. americana was 4.17, 7.85, 3.41, and 5.14 times higher than the control (without organic amendment) respectively, whereas the REE concentrations in shoots were 2.02, 68.4, 0.16, and 1.98 times lower than the control (524 ± 82.8 mg kg−1) respectively. The highest REE yield was obtained under 1% BC treatment and was 3.56 times that of the control. Both OM and BC treatments largely improved the soil physico-chemical properties. However, compared with OM and 5% BC treatments, 1% BC treatment induced a smaller increase in pH, and the amount of organic carbon and nutrients in the soil solution, thereby minimizing the reduction of REE bioavailability. We conclude that amendment with a low dosage of BC could be a potential way to improve REE phytoextraction efficiency by P. americana on ion-adsorption REE mine tailings.

International audience; Co-option of RAG1 and RAG2 for antigen receptor gene assembly by V(D)J recombination was a crucial event in the evolution of jawed vertebrate adaptive immunity. RAG1/2 are proposed to have arisen from a transposable element, but definitive evidence for this is lacking. Here, we report the discovery of ProtoRAG, a DNA transposon family from lancelets, the most basal extant chordates. A typical ProtoRAG is flanked by 5-bp target site duplications and a pair of terminal inverted repeats (TIRs) resembling V(D) J recombination signal sequences. Between the TIRs reside tail-to-tail-oriented, intron-containing RAG1-like and RAG2-like genes. We demonstrate that ProtoRAG was recently active in the lancelet germ-line and that the lancelet RAG1/2-like proteins can mediate TIR-dependent transposon excision, host DNA recombination, transposition, and low-efficiency TIR rejoining using reaction mechanisms similar to those used by vertebrate RAGs. We propose that ProtoRAG represents a molecular "living fossil" of the long-sought RAG transposon.

Metal tailings are potential sources of strong environmental pollution. In situ remediation involves the installation of a plant cover to stabilize materials and pollutants. Whether metal(loid)s are effectively immobilized in remediated tailing ponds submitted to heavy rainfall remains uncertain. In this study, tailing materials were collected from bare tailings (control), grass-planted (G) and grass-shrub planted (GS) areas on a former Pb/Zn mine site. Batch column experiments were performed with three rainfall intensities of 0.36, 0.48, and 0.50 mL min−1 for 18 d in the lab. The pH, Eh, Cd, Pb, Zn and As concentration in leachate were recorded. Selected leached tailing materials were finally characterized. Results showed that leachates from control were strongly acidic (pH 3.11–4.65), and that Cd, Pb, Zn and As were quickly released at high rate (e.g., 945 mg L−1 Zn). During the experiment up to 4% Cd present in the material was released and almost 1% Zn. With material collected from the G area, leachates were even more acidic (2.16–2.84) with a rainfall intensity of 0.50 mL min−1 and exhibited a high redox potential (588–639 mV). However, concentrations of metals in leachates were much lower than that in the control, except for Zn (e.g., 433 mg L−1), and they tended to decrease with time. Cumulative leaching rate was still relatively high (e.g., 0.68% Cd; 0.75% Zn) during the first eight days (stage I). However, with the GS treatment, leachate pH gradually raised from acid to alkaline values (3.9–8.2) during stage I, then remained high until the end of the experiment (stage II). Also, amounts of elements released during the 18 d were low in general. The releasing ratios of Cd (R2 > 0.95), Pb (R2 > 0.95), As (R2 > 0.87), and Zn (R2 > 0.90) fitted well with a two-constant model. In conclusion, under subtropical climate with heavy rainfall, phytostabilization is effective but immobilization of metals is higher with a combination of grass and shrub than with only grass to reduce leaching of As and Zn.

International audience; We evaluate the topographic evolution of the southwestern Alps using Eocene to Pleistocene pollen data combined with existing sedimentological, petrographic and detrital geo-and thermochronological data. We report 32 new pollen analyses from 10 sites completed by an existing dataset of 83 samples from 14 localities situated across the southwestern Alps, including both the pro-and the retro-foreland basins. The presence of microthermic tree pollen (mainly Abies, Picea) indicates that this part of the mountain belt attained elevations over 1900 m as early as the Oligocene. Inferred rapid surface uplift during the mid-Oligocene coincided with a previously documented brief phase of rapid erosional exhumation, when maximum erosion rates may have reached values of up to 1.5–2km/Myr. Slower long-term average exhumation rates of ∼0.3km/Myr since the Late Oligocene helped maintaining the high Alpine topography of the southwestern Alps until today. The relative abundances of meso-microthermic tree pollen (Cathaya, Cedrusand Tsuga) and microthermic tree pollen (Abies, Picea) in the pro-and retro-foreland basin deposits, indicate that the present-day asymmetric topography, with a relatively gentle western flank and steeper eastern flank, was established early in the southwestern Alps, at least since

The well-documented energy balance dynamics within forest ecosystems are poorly implemented in studies of the biophysical effects of forests. This results in limitations to the accurate quantification of forest cooling/warming on local air temperature. Taking into consideration the forest air space, this study proposes a three-layered (canopy, forest air space and soil [CAS]) land surface energy balance model to simulate air temperature within forest spaces (Taf) and subsequently to evaluate its biophysical effects on forest cooling/warming, i.e., the air temperature gradient (∆Ta) between the Taf and air temperature of open spaces (Tao) (∆Ta = Taf − Tao). We test the model using field data for 23 sites across 10 cities worldwide; the model shows satisfactory performance with the test data. High-latitude forests show greater seasonal dynamics of ∆Ta, generating considerable cooling of local air temperatures in warm seasons but minimal cooling or even warming effects during cool seasons, while low-latitude tropical forests always exert cooling effects with less interannual variability. The interannual dynamics of ∆Ta are significantly related to the seasonality of solar geometry and canopy leaf phenology. The differences between forest canopy temperature (Tc) and Tao, which are the two most important terms attributed by the CAS model in impacting Taf, explain a large part of forest cooling and warming (May–July: R2 = 0.35; November–January: R2 = 0.51). The novel CAS model provides a feasible way to represent the energy balance within forest ecosystems and to assess its impacts on local air temperatures globally. Keywords: Forest cooling/warming, Forest biophysical effects, Radiative transfer equation, Land-atmosphere model, Local environmental health, Climate warming mitigation

A high-resolution pollen record obtained from Pingnan County, Fujian province in China, provides new insights into the nature of ecosystem changes and the relative importance of human disturbances during the last 1300 years. Pollen and stable carbon isotope data indicate that prior to about 800 cal BP the study area was covered by a natural forest, dominated by evergreen broad-leaved trees (Castanopsis and Quercus). This primeval vegetation was then progressively replaced by the secondary vegetation after similar to 800 cal BP. Increases of Gramineae pollen since similar to 800 cal BP and a sharp rise in Pinus pollen after similar to 450 cal BP clearly express the expansion of human impacts, reflecting the expansion of farming and the succession of a now-widespread Pinus massoniana after alteration of the primeval vegetation. Taxonomic diversity analysis also shows that the floristic diversity is higher during the period of human disturbances than in the earlier part of the record, a phenomenon that has been observed in temperate pollen records where human activities increased.

International audience; Wind plays an important role in regulating mixing/stratification, estuarine circulation, and transport timescale in estuaries. A three-dimensional model was used to investigate the effect of wind on transport time by using the concept of water age (WA) in the tidal Rappahannock River, a western tributary of the Chesapeake Bay, USA. The model was calibrated for water level, current, and salinity. A series of experiments regarding the effects of wind on WA was conducted under various dynamic conditions. The effect of wind on transport timescale depends strongly on the competition between the wind and buoyancy forcings, and on the pre-status of the circulation. A down-estuary wind generally decreases WA along the estuary. An up-estuary wind increases WA substantially because it changes the vertical mixing and estuarine circulation more significantly. When the buoyancy forcing increases, the up-estuary wind effect decreases whereas the down-estuary wind effect increases. A 2-day period wind pulse with a maximum speed of 15 ms can alter WA for 3 days; but the wind influence on WA lasts up to 40 days in the simulation. Both local and non-local wind forcings alter WA distribution. The local wind enhances vertical mixing and changes the gravitational circulation in the downstream portion of the estuary whereas it enhances transport in the freshwater portion of the estuary. Consequently, the local wind has a significant impact on WA distribution. In contrast, the non-local wind does not change the gravitational circulation significantly by imposing setup (setdown) of water level at the open boundary, resulting in a lesser impact on WA distribution.

International audience; Given a (possibly improper) edge-colouring $F$ of a graph $G$, a vertex colouring $c$ of $G$ is \emph{adapted to} $F$ if no colour appears at the same time on an edge and on its two endpoints. If for some integer $k$, a graph $G$ is such that given any list assignment $L$ of $G$, with $|L(v)| \ge k$ for all $v$, and any edge-colouring $F$ of $G$, there exists a vertex colouring $c$ of $G$ adapted to $F$ such that $c(v) \in L(v)$ for all $v$, then $G$ is said to be \emph{adaptably $k$-choosable}. The smallest $k$ such that $G$ is adaptably $k$-choosable is called the \emph{adaptable choice number} and is denoted by $ch_{ad}(G)$. This note proves that $ch_{ad}(G) \le \lceil {Mad}(G)/2 \rceil +1$, where ${Mad}(G)$ is the maximum of $2|E(H)|/|V(H)|$ over all subgraphs $H$ of $G$. As a consequence, we give bounds for classes of graphs embeddable into surfaces of non-negative Euler characteristics.