bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon alleviated manganese toxicity in cucumber by cell wall compartmentation
Authors: Dragisic Maksimovic Jelena , Maksimovic Vuk
Published: March 2020

As a consequence of normal root growth and development, a considerable range of organic and inorganic substances are exchanged between the root and soil, which causes changes in the biochemical and physical properties of the rhizosphere. Plants modify their rhizosphere in response to various environmental signals and stresses. Low-molecular-weight metabolites are commonly detected in this region and their exudation from plant roots has been associated with abiotic stress, such as inorganic form of manganese (Mn). In this study we investigated the root exudate constituents (phenolics and enzymes) of cucumber (Cucumis sativus L.) plants grown in Mn-free and Mn-contaminated nutrient solutions (0.5 and 100 μM, respectively) with (+Si) or without silicon (–Si) supplied as 1.5 mM silicic acid. High external Mn supply induced both growth inhibition of the whole plant and the appearance of Mn-toxicity symptoms in the leaves, while the simultaneous application of Si alleviated toxicity symptoms. At high Mn supply, concentration of phenolic compounds, as plant-borne substrates for peroxidase (POD) and polyphenol oxidases (PPO), depended on Si application. The increased concentrations of phenolic compounds (e.g., coniferyl alcohol, p-coumaric and isoferulic acid) in –Si plants were in agreement with enhanced POD and PPO activities. The activities of both enzymes were kept at a lower level in +Si plants grown at higher Mn concentrations. These results suggest that Si nutrition modulates the metabolism and utilization of phenolic compounds most probably as a consequence of the formation of Si-polyphenol complexes and their subsequent cross-linking with cell wall polymers. In –Si plants increased activity of the PPO and POD/H2O2 systems lead to the formation of highly reactive compounds, while in +Si plants, lignin biosynthesis is favored. H2O2 in the presence of elevated Mn concentrations produced potentially toxic •OH and Mn3+ in the Fenton reaction, which was efficiently suppressed by Si application. Silicon thus prevented the formation of toxic intermediates (•OH and Mn3+) and accumulation/oxidation of free phenolics leading to oxidative browning, the initial indicator of Mn-toxicity symptoms. In summary, we presented the knowledge about how cucumber can overcome hyperaccumulation of Mn by means of Si-complexation suggesting ways of improving future phytoremediation strategies.
Logging residue produces greenhouse gases in boreal forests
Authors: Laihonen Antti , Tiirola Marja
Published: March 2020

Living trees are recognized as sources of greenhouse gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). However, less is known about greenhouse gas exchange in deadwood during its decay, and especially in logging residue. During the logging process, logging residue is produced in large amounts. Even though residue can be harvested for energy production, significant amounts of logging residue is still left in forests. In Finland, 30 % of the logging residue is recommended to be left on the logging site. It has been estimated, that in the European Union, annually over 200 million cubic meters of logging residue is produced, which of approximately one sixth is produced solely in Finland. As an example, only 2.7 million cubic meters of logging residue was recovered from Finnish forests and used for energy production in 2018.

We hypothesized that logging residue left in forests produces various greenhouse gases – CO2, CH4 and N2O – during its decay. We studied greenhouse gas exchange in logging residue of spruce (Picea abies) and birch (Betula sp.) with focus on logs with average diameter of 5 – 10 cm. Residue was collected from 18 different research areas, covering approximately 47 hectares of spruce-dominated forest in Central Finland. All research areas were clear cuts, with known cut ages; the studied logs had decayed between 0 and 10 years. The study was carried out in 2019 during an eight-month period from May to December. In addition to greenhouse gas flux, dry matter content of logs was determined. All studied logs were a source of CO2, with CO2 flux correlating with log decay time and dry matter content. CO2 emission was observed to be dependent on ambient temperature. In general, we detected low CH4 emissions from logging residue; opposite to CO2, no clear trend was found between CH4 flux and log decay time or dry matter content. N2O results were similar to CH4, with low overall emissions. Dry matter content of logs correlated well with log decay time, with dry matter content decreasing as the logs were more decayed. Our study is an important step in understanding greenhouse gas exchange in logging residue and decaying wood in forests.
Impacts of monocyclic aromatics on regional and global tropospheric gas-phase chemistry
Authors: Sander Rolf , Cabrera-Perez David , Bacer Sara , Gromov Sergey , Lelieveld Jos , Taraborrelli Domenico , Pozzer Andrea
Published: March 2020

Aromatic compounds in the troposphere are reactive towards ozone
(O3), hydroxyl (OH) and other radicals. Here we present an
assessment of their impacts on the gas-phase chemistry, using the
general circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry). The
monocyclic aromatics considered in this study comprise benzene, toluene,
xylenes, phenol, styrene, ethylbenzene, trimethylbenzenes, benzaldehyde
and lumped higher aromatics bearing more than 9 C atoms. On a global
scale, the estimated net changes are minor when aromatic compounds are
included in the chemical mechanism of our model. For instance, the
tropospheric burden of CO increases by about 6 %, and those of OH,
O3, and NOx (NO + NO2) decrease between
2 % and 14 %. The global mean changes are small partially because of
compensating effects between high- and low-NOx regions. The
largest change is predicted for glyoxal, which increases globally by 36
%. Significant regional changes are identified for several species. For
instance, glyoxal increases by 130 % in Europe and 260 % in East Asia,
respectively. Large increases in HCHO are also predicted in these
regions. In general, the influence of aromatics is particularly evident
in areas with high concentrations of NOx, with increases up
to 12 % in O3 and 17 % in OH. Although the global impact of
aromatics is limited, our results indicate that aromatics can strongly
influence tropospheric chemistry on a regional scale, most significantly
in East Asia.
Anthropogenic changes in internal climate variability can cause the most extreme climate extremes
Authors: Olonscheck Dirk , Notz Dirk
Published: March 2020

 
The influence of velocity gradients choice in deep alluvial basin seismic site response
Authors: Cascone Valeria , Boaga Jacopo
Published: March 2020

The characterization of seismic site response represents one of the most important issues of seismic hazard assessment and risk mitigation planning. Characterizing the site conditions involves the measurement of several soil properties such as the shear-wave velocity (Vs), density and damping properties as a function of depth. Therefore, most of the site-effect studies in earthquake ground motions are based on the properties of the upper 30 meters and the anti-seismic building codes propose in most cases a simplified analysis based on shear wave velocity of the shallow subsoil. From a seismological perspective, the upper 30 meters would almost never represent more than 1% of the distance from the source. This should be taken into account especially for large and deep alluvial basins, representing the most inhabited geological environment of the world, where could be difficult to estimate the thickness and the velocity profile of the soft sediment overlying the rigid seismic bedrock.

The common approach adopted to characterize greater depths is then an extrapolation of shear wave velocity in depth, considering a selected linear or non-linear velocity gradients till the depth of the considered seismic bedrock (usually set to Vs ≥ 800 m/s). These gradients are generally derived from geological information or from literature, but how much the gradients choice affects the final site response analyses is often a neglected aspect.

In this work we try to investigate the generic case of deep alluvial basins. We consider the shallow subsoil as characterized by several in-situ tests in northern Italy. We extrapolate the deeper soil structure considering different literature velocity gradients obtained for deep basins in different geological contests: tectonic basins (Lower Rhine Basin and Po Plain) and Alpine basins (Grenoble and Lucerna Basins). We perform one-dimensional analysis of shear waves with the Linear Equivalent Method. The study demonstrates how relevant can be the role of velocity gradient choice for the ground response scenario. Starting from the same shallower Vs structures, the computed seismic motion at surface can present variation in the order of 50% varying the velocity gradients in depth. The results are of relevant interest for the analysis of seismic hazard in the deep alluvial basins environments, which host the main urban areas around the world.
Three-dimensional geological mapping and modelling at the Geological survey of Sweden
Authors: Wendelin Eva , Bastani Mehrdad , Persson Lena , Curtis Phil , Sopher Daniel , Daniels Johan
Published: March 2020
Modification of cometesimal interiors by early thermal evolution and collisions
Authors: Jutzi Martin , Golabek Gregor
Published: March 2020

In the early solar system radiogenic heating by 26Al and collisions are the two prominent ways expected to modify the internal composition of cometesimals, building blocks of comets, by removing highly volatile compounds like CO, CO2 and NH3. However, observations indicate that even large comets like Hale-Bopp (R ≈ 70 km) can be rich in these highly volatile compounds [1].

Here we constrain under which conditions cometesimals experiencing both internal heating and collisions can retain pristine interiors. For this purpose, we employ both the state-of-the-art finite-difference marker-in-cell code I2ELVIS [2] to model the thermal evolution in 2D infinite cylinder geometry and a 3D SPH code [3] to study the interior heating caused by collisions among cometesimals. For simplicity we assume circular porous cometesimals with a low density ( ≈ 470 kg/m3) based on measurements for comet 67P/Churyumov-Gerasimenko [4].

For the parameter study of the thermal history we vary (i) cometesimal radii, (ii) formation time and the (iii) the silicate/ice ratio. For the latter we keep the mean density fixed and change the porosity of the cometesimal. For the impact models we use porous, low-strength objects and vary (i) target and (ii) projectile radii, (iii) impact velocity as well as (iv) impact angle. Potential losses of volatile compounds from their interiors are calculated based on their critical temperatures taken from literature [5]. Our combined results indicate that only small or late-formed cometesimals remain mostly pristine, while early formed objects can even reach temperatures high enough to melt the water ice.

 

REFERENCES

[1] Biver et al., Nature 380, 137-139 (1996).

[2] Gerya & Yuen, Phys. Earth Planet. Int. 163, 83-105 (2007).

[3] Jutzi, Planet. Space Sci. 107, 3–9 (2015).

[4] Sierks et al. Science 347, 1044 (2015).

[5] Davidsson et al. Astronomy & Astrophysics 592, A63 (2016).
The characteristics and evolution of accommodation zone in Xihu Sag, East China Sea Shelf Basin
Authors: Xu Bin , Wu Zhiping , Cheng Yanjun , Dai Yining
Published: March 2020

Accommodation zone is an important deformation structure in sedimentary basin, which is significant to understanding the basin structure. The formation and evolution of the Xihu Sag is controlled by the NNE-striking faults, whereas the NNE-striking deformation is offset by the NW-striking accommodation zone. However, the structure and evolution of the accommodation zone are poorly known. Based on the dips and activation rates of related NNE-striking faults on two sides of the NW-striking accommodation zone, 8 styles of NW-striking accommodation zones are divided in this sag, including the synthetic approaching style, synthetic broken line style, synthetic overlapping style, reverse approaching style, reverse broken line style, composite approaching style, composite broken line style, composite overlapping style. The relative accommodation ratio of the accommodation zone can be reflected by the difference-value of the faults activation rate of the NNE-striking faults. The results show that: (1) the most of the NW-striking accommodation zones formed at Early Cretaceous with low relative accommodation ratio, and reached its peak at Eocene, and disappeared at Late Oligocene. (2) The temporal and spatial differences of the NW-striking accommodation zones are very common in the Xihu Sag. Spatially, the accommodation zones are mainly developed in the western slope of Xihu Sag, and rarely developed in the middle and eastern of the Xihu Sag. Temporally, the accommodation zones developed in the northern area of the western slope of the Xihu Sag during the early stage, whereas, these zones migrated to the southern area of the western slope of the Xihu Sag during the late stage. This study on the tectonic evolution of the accommodation zone provides significant support to the study on the tectonic evolution of the Xihu sag.
A fast and robust approach for simulating the pressure diffusion in three-dimensional discrete fracture networks applied to inversion problems
Authors: Ringel Lisa Maria , Somogyvári Márk , Jalali Mohammadreza , Bayer Peter
Published: March 2020

This study is aimed at the characterization of discrete fracture networks (DFN) by a transdimensional inversion methodology. It has been demonstrated that the reversible-jump Markov chain Monte Carlo (rjMCMC) is suitable for the inversion of two-dimensional (2D) DFNs. Based on given statistical information and measured data, the algorithm identifies the main characteristics of a DFN correctly.

For this reason, the method will be extended to the inversion of three-dimensional (3D) DFNs which allows more realistic examples. Two main difficulties arise here. First, further constraints have to be defined to limit the number of unknowns due to the high dimensionality of the inversion problem. Second, the forward modelling is a restricting factor concerning the computational costs and the robustness of the iteration. The assumptions made to simplify the governing fluid equations are to be evaluated and the resulting limitations are presented, e.g. small Reynolds number, smooth fracture walls, impermeable rock matrix. Moreover, the errors caused by the numerical solution of the partial differential equation are estimated to verify the correctness of the implementation.
Strain localization associated with brittle faulting in a natural clinoptilolite-tuff (open-pit mine Nižný Hrabovec, Slovak Republic)
Authors: Hou Zhaoliang , Rice A. Hugh N , Tschegg Cornelius , Berger Thomas , Grasemann Bernhard
Published: March 2020

Clinoptilolite, a micro-porous natural zeolite comprising tetrahedra of silica and alumina that commonly occurs in volcanic tuffs through devitrification of natural glasses, has numerous uses in the manufacturing, agriculture and building industries; it also has applications in veterinary and human medicines. Field observations and microstructural investigations in the natural clinoptilolite-tuff from Nižný Hrabovec (Slovak Republic) – one of the world’s economically most important high-quality clinoptilolite deposits – show evidence of strain localization. Brittle faults formed along pre-existing joints with plumose structures that had acted as a pathway for local infiltration of iron-, manganese- and potassium-rich fluids. Fault displacement formed structures that are indicative of both velocity hardening, with dissolution precipitation creep (SC/SCC’ foliation), and velocity weakening, with several phases of ultra-cataclasites forming along principal slip surfaces. Rock-fluid interaction is characterized by a high-mobility of K, with K-feldspar decorating SC/SCC’ foliations, infiltrating fractures in fault damage zones and precipitating as idiomorphic crystals in open cavities and along fault surfaces. Microstructures such as polished slickensides, injection of fluidized cataclasites, clast cortex grains in cataclasites and truncated grains along principal slip surfaces suggest that seismic slip probably occurred along some of the faults.
Amazon rainforest increases photosynthesis in reponse to atmospheric dryness
Authors: Green Julia K. , Gentine Pierre , Zhang Yao , Berry Joe , Ciais Philippe
Published: March 2020

Earth system models predict that atmospheric dryness reduces photosynthesis due to its reductive effect on stomatal conductance. However, while this representation may be appropriate in many environments, in the wet Amazonian tropical rainforest, this is not the case. Using remote sensing data combined with machine learning techniques (k-means clustering and artificial neural networks), we show that in the wettest parts of the Amazon rainforest, gross primary production and evapotranspiration continue to increase alongside atmospheric dryness, i.e. vapor pressure deficit, despite reductions in ecosystem conductance. On the other hand, Earth system models have the opposite photosynthetic response to vapor pressure deficit in the wettest part of the Amazon, overestimating its reductive effect on tropical vegetation photosynthesis and evapotranspiration, leading to an exaggerated carbon source to the atmosphere. As vapor pressure deficit is expected to increase with climate change, our study highlights the importance of reframing how we understand and represent the response of ecosystem photosynthesis to atmospheric dryness in the wettest ecosystems, to accurately quantify the future land carbon sink and atmospheric CO2 growth rate.
Water fluxes and coupled nitrogen export in a managed prealpine grassland: identifying the effects of climate change and agricultural management
Authors: Schneider Katrin , Kiese Ralf
Published: March 2020

It is generally accepted that climate change likely alters the ratio of water balance components in mid-latitude environments. Higher temperatures and an elevated water vapour deficit may increase evapotranspiration rates and reduce groundwater recharge rates. At the same time, agricultural management may interfere these effects, e.g. through reduced plant transpiration rates due to a high cutting frequency.

The study analyses climate change and agricultural management effects on the water fluxes and coupled nitrogen export in a prealpine grassland. It makes use of the grassland lysimeters, which are part of the TERENO preAlpine observatory in southern Bavaria (Germany). In a “space-for-time” approach, soil cores with an area of 1 m² and a depth of 1.5 m have been excavated and translocated to lower elevations. Furthermore, soil cores from the same area (that have not been translocated to lower elevations) act as control plots in the lysimeter network. The elevation gradient between the highest (864 m a.s.l.) and lowest (695 m a.s.l.) lysimeter station accounts for a temperature increase of approx. 2°C, while precipitation decreases from approx. 1350 mm a-1 to approx. 960 mm a-1. Following local agricultural practice, intensive as well as extensive grassland management is applied at the lysimeters: intensive management refers to a higher frequency of cutting (up to five times per year) and manure application (approx.. 250 kg N ha-1 a-1) than extensive management (two cuts and approx. 80 kg N ha-1 a-1).

The study compares the effects of temperature and precipitation changes (i.e. elevated temperature and decrease in precipitation) and different agricultural management on water balance components (evapotranspiration, groundwater recharge, Ammonia and Nitrate fluxes) measured at the lysimeters. Preliminary result show that the ratio of evapotranspiration to precipitation increases in the climate change treatment. Water-bound nitrogen fluxes are comparably low on all sites, indicating that nitrogen uptake by plant plants is dominating over nitrogen leaching.
Palynology of Holocene Lake Baikal sediments
Authors: Labes Alienor , Mazzini Adriano , Akhmanov Grigorii G. , Kürschner Wolfram M.
Published: March 2020

The Class@Baikal 2019 expedition led by UNESCO-Moscow State University Educational-Scientific Center for Marine Geology and Geophysics (the Department of Geology, Moscow State University Lomonosov) sailed several transects between the southern and central part of the Lake Baikal, Russia. Seismic profiles were made to map the lake bottom sediments and structures as well as several short piston cores were drilled. The drilling sites were located a) following a nearshore to offshore transect to study the sedimentary processes and b) in areas where mud volcanoes were located in the geophysical data. Intriguingly, the sediments retrieved from the cores contained a high amount of plant debris, such as wood and conifer needles. The present palynological study has been started with the goal to better understand the sedimentological processes resulting in these distinct horizons of plant fossil rich sediments. Another goal is to obtain a stratigraphic age for the mud clasts and the surrounding matrix sediments of the presumed mud volcano structures. The first sediment samples appear to be rich in pollen and spores which allows to establish a palynostratigraphic framework for the studied cores.

 
Mesospheric fronts in airglow images and the variation of the bottomside sodium layer densities measured by a sodium lidar at Tromsø, Norway
Authors: Narayanan Viswanathan Lakshmi , Nozawa Satonori , Mann Ingrid , Oyama Shin-ichiro , Shiokawa Kazuo , Otsuka Yuichi , Saito Norihito
Published: March 2020

Mesospheric frontal systems are waves extending to hundreds of kilometers along their phase fronts and appear like a boundary. They are observed in the upper mesospheric airglow imaging observations of OH, sodium and OI greenline nightglow emissions. It is believed that the fronts result from gravity wave dynamics associated with favorable background conditions like thermal ducting. Many of the frontal systems are identified as mesospheric bores when they are accompanied with sudden airglow intensity changes across the frontal boundary. Most of the frontal systems propagate with phase locked undulations following the leading front, while some induce turbulence behind the front. Though the existence of the frontal systems in the mesosphere is known for more than two decades, their role and importance is not understood properly. In this work, we use airglow data from an all-sky imager located at Tromsø to identify the frontal systems, particularly using OH images. Collocated five-beam sodium lidar measurements are used to identify the structuring in sodium densities around time of passage of the frontal systems. The sodium lidar at Tromsø is a versatile system capable of measuring sodium densities, temperatures and winds in the upper mesospshere region. Hence, we obtain the wind and temperature information to study the background conditions during passage of the intense frontal systems. Though, mostly we focus on OH airglow images as they are observed with broad pass band resulting in higher signal strength, we also utilize images from other emissions like OI greenline and sodium whenever they are available and free from auroral features. Interestingly, we find formation of some unusual structuring in the bottomside sodium layer around the passage of the frontal systems. We show different cases during winter months of the years 2013-14 and 2014-15 and investigate the relationship between unusual bottomside structuring in the sodium layer and passage of the frontal systems.
A Businger Mechanism for Intermittent Bursting in the Stable Boundary Layer
Authors: van der Linden Steven , van de Wiel Bas , Petenko Igor , van Heerwaarden Chiel , Baas Peter , Jonker Harmen
Published: March 2020

High-resolution large-eddy simulations of the Antarctic very stable boundary layer reveal a mechanism for systematic and periodic intermittent bursting. A non-bursting state with a boundary-layer height of just 3 m is alternated by a bursting state with a height of ≈5 m. The bursts result from unstable wave growth triggered by a shear-generated Kelvin-Helmholtz instability, as confirmed by linear stability analysis. The shear at the top of the boundary layer is built up by two processes. The upper, quasi-laminar layer accelerates due to the combined effect of the pressure force and rotation by the Coriolis force, while the lower layer decelerates by turbulent friction. During the burst, this shear is eroded and the initial cause of the instability is removed. Subsequently, the interfacial shear builds up again, causing the entire sequence to repeat itself with a timescale of 10 min. Despite the clear intermittent bursting, the overall change of the mean wind profile is remarkably small during the cycle. This enables such a fast erosion and recovery of the shear. This mechanism for cyclic bursting is remarkably similar to the mechanism hypothesized by Businger in 1973. In his proposed mechanism, the momentum in the upper layer is increased by the downward turbulent transport of high-momentum flow. From the results, it appears that such transfer is not possible as the turbulent activity above the base flow is negligible. Finally, it would be interesting to construct a climatology of shear-generated intermittency in relation to large-scale conditions to assess the generality of this Businger mechanism.
Airmass analysis of the processes driving the progression of the Indian summer monsoon
Authors: Volonté Ambrogio , Turner Andrew G. , Menon Arathy
Published: March 2020

The Indian summer monsoon is a vital source of water and a cause of severe impacts for more than a billion people in the Indian subcontinent. The INCOMPASS project investigates the mechanisms driving its onset and progression through an observational field campaign supplemented by high-resolution numerical simulations for the 2016 season using UK Met Office models. A 4.4 km resolution convection-permitting limited-area model simulation (driven at its boundaries by a daily-initialised global model) is used in this study, and verified against observations, along with short-lead-time operational global forecasts.

These data show that the monsoon progression towards northwest India in June 2016 is a non-steady process, modulated by the interaction between moist low-level southwesterly flow from the Arabian Sea and a northwesterly incursion of descending dry air from western and central Asia. The location and extent of these two flows are closely linked to mid-latitude dynamics, through the southward propagation of potential vorticity streamers and the associated formation of cyclonic circulations in the region where the two air masses interact. Particular focus is devoted to the use of Lagrangian trajectories to characterise the evolution of the airstreams and complement the Eulerian monsoon progression analysis. The trajectories confirm that the interaction of the two airstreams is a primary driver of the general moistening of the troposphere associated with monsoon progression. They also indicate the occurrence of local diabatic processes along the airstreams, such as turbulent mixing and local evaporation from the Arabian Sea, in addition to moisture transport from remote sources.

In summary, this combined Eulerian-Lagrangian analysis reveals the non-steady nature of monsoon progression towards northwest India. This process is driven by the interaction of different air masses and influenced by a synergy of factors on a variety of scales, such as mid-latitude dynamics, transient weather systems and local diabatic processes.

This work has recently been accepted for publication on the Quarterly Journal of the Royal Meteorological Society.
Quantifying active deformation within the Southwestern Foothills of Taiwan, from incised fluvial terraces and sedimentary data
Authors: Steer Philippe , Lefils Valentine , Simoes Martine , Shyu J. Bruce H. , Rizza Magali , Siame Lionel
Published: March 2020

The Taiwan mountain range stands as one of the most active regions on Earth. With an overall shortening rate of ~40 mm/yr and an average erosion rate of ~4 mm/yr, this mountain range appears ideal to better understand the interactions between tectonics and surface processes, and how these shape active landscapes. Here we explore the geomorphic and sedimentary record of active deformation within the Southwestern Foothills of Taiwan, and we quantify from there the kinematics of active faults. In particular, we investigate the downstream portion of the meandering Tsengwen river - one of the largest rivers of this region - where we identify and correlate remnants of 7 terrace levels, progressively abandoned over the last ~5 kyr. The incision of these terraces is interpreted as being controlled to the first-order by folding and uplift related to underlying active faults. The evolution of the river is reconstructed from correlated terrace remnants, and our results indicate that the overall river sinuosity and gradient did not vary significantly during the past ~5 kyr in response to tectonics. Incremental tectonic uplift is retrieved from terrace incision corrected for sedimentation at the mountain front, and is used to derive the incremental shortening since terrace abandonment. Downstream, within the Coastal Plain, the Tsengwen river reaches its base level and aggrades. Sedimentary facies within boreholes of the Coastal Plain record vertical displacements relative to sea level, spatially consistent with potential blind active faults. When corrected for eustatic variations, these data allow for quantifying tectonic uplift rates within the Coastal Plain over the last ~20 kyr. Taken altogether, our quantitative analysis of the Tsengwen river record, from terrace incision to dowsntream aggradation, reveals that the most frontal active faults absorb a shortening rate of at least ~35 mm/yr, that is most of - if not all -  the shortening rate to the absorbed across the whole mountain range.
Capability of maize water use efficiency estimation at field scale using Sentinel-2 data
Authors: Ma Zonghan , Wu Bingfang , Yan Nana , Zhu Weiwei
Published: March 2020

Water use efficiency (WUE) is defined as the ratio between gross primary production (GPP) and evapotranspiration (ET) at ecosystem scale, which can help understand the mechanism between water consumption and crop production in guiding field water management. Water consumption control is important in precision agriculture development. Mapping WUE at field scale using remote sensing data could provide crop water use status at high resolution and acquire the WUE spatial distribution. In this study we proposed a method to estimate field-scale maize WUE with Sentienl-2 data. The GPP of maize is estimated by a light use efficiency model with RS observed albedo, sunshine radiation, fraction of photosynthetically active radiation (fpar) fitted using in site observation. Maize ET is modelled using FAO-PM model with crop coefficient simulated using vegetation indexes acquired from Sentinel-2 bands. We compared the GPP, ET and final WUE estimation with eddy covariance (EC) observations in a maize field of North China Plain where water scarcity is a main limit factor of crop development. Comparation results show a high correlation between in site observation and modelled results. Combining the phenology development of maize, the temporal characteristics of maize WUE change is associated with phenology. WUE was low after sowing, then increased during Elongation stage. Maize WUE peaked at Heading and Grouting period and decreased in Maturation stage. Our WUE estimation method with high resolution could guide adopting various irrigation strategies based on different WUE conditions at field scale. This research could help shed light on the future WUE development under climate change background and improve our knowledge of precise water management.
Evidence that viscous shear zones spontaneously establish hydro-mechanical anisotropy
Authors: Gilgannon James , Waldvogel Marius , Poulet Thomas , Fusseis Florian , Berger Alfons , Barnhoorn Auke , Herwegh Marco
Published: March 2020

We revisit large shear strain deformation experiments on Carrara marble and observe that anisotropic porous domains develop spontaneously during shearing. Specifically, as samples are deformed periodic porous sheets are documented to emerge and are found to transfer mass. These results imply that viscous shear zones may naturally partition fluids into highly anisotropic bands. As this hydro-mechanical anisotropy is produced by creep, each porous sheet is interpreted to represent a transient dynamic pathway for fluid transport. It is unclear how long each porous domain is uniquely sustained but it is clear that sheets are persistently present with increasing strain. Our results forward the idea that viscous shear zones have dynamic transport properties that are not related to fracturing or chemical reaction. We believe these new results provide experimental foundation for changing the paradigm of viscosity in rocks to include dynamic permeability. In our view making this change in perspective could alter many classical interpretations in natural banded mylonite zones, for example shear zone parallel syn-kinematic veining may be the result of pore sheet instability and ductile fracturing.
EUHFORIA in the ESA Virtual Space Weather Modelling Centre
Authors: Poedts Stefaan
Published: March 2020

The goal of the ESA project "Virtual Space Weather Modelling Centre - Part 3" (2019-2021) is to further develop the Virtual Space Weather Modelling Centre (VSWMC), building on the Part 2 prototype system and focusing on the interaction with the ESA SSA SWE system. A first, limited version went operational in May 2019 under the H-ESC umbrella on the ESA SSA SWE Portal. The objective and scopes of this new project include: the efficient integration of new models and new model couplings, including daily automated end-to-end (Sun to Earth) simulations, the further development and wider use of the coupling toolkit  and front-end GUI, making the operational system more robust and user-friendly. The VSWMC-Part 3 project started on 1 October 2019.

EUHFORIA (‘European heliospheric forecasting information asset’) is integrated in the VSWMC and will be upgraded with alternative coronal models (Multi-VP and Wind-Predict) and flux-rope CME models, and new couplings will be made available, e.g. to more advanced magnetospheric models and radiation belt models, geo-effects models, and even SEP models. The first results will be discussed and put into perspective.
Experimental detection of subsurface particle transport in coarse steep vineyard soils
Authors: Iserloh Thomas , Seeger Manuel , Ries Johannes B.
Published: March 2020

The Mosel wine region (Rhineland-Palatinate, Germany) is the largest steep vineyard region in the world. Due to extreme slopes (>17°), tillage with heavy machinery, increase in extreme precipitation events and new planting of vines, these vineyards are among the agricultural systems most affected by soil erosion.

Due to viticulture since the Roman period and their special characteristics, almost all vineyard soils in the Mosel region are classified as Terric Anthrosols. Soils are characterized by a very high rock fragment content (schists and fluvial sediments) and a loose surface layer over a compact layer due to tillage or weathered parent material. This structure enables subsurface flows between these two layers, especially in periods of very high soil moisture.

There is a knowledge gap in the identification and quantification of transported soil particles in this subsurface flow. If these soil particles reach relevant amounts, superficial protective measures may be partially ineffective and the soil degrades despite the existing protection. In consequence, there is a need to develop a method to determine this subsurface particle transport in situ.

Here, we present a first experimental approach for assessing the occurrence of sub surface erosion of fine-grained soil particles within soils. With this, it is possible to prove this process and the development of a sediment trap prototype, based on a drainage pipe, for in situ measurements of subsurface soil erosion.
Real-time estimation of multi-GNSS and multi-frequency integer recovery clock with undifferenced ambiguity resolution
Authors: Xiong Yun , Yuan Yongqiang , Wu Jiaqi , Li Xin , Huang Jiaxin
Published: March 2020

Precise clock product of global navigation satellite systems (GNSS) is an important prerequisite to support real-time precise positioning service. The developments of multi-constellation and multi-frequency GNSS open new requirements for real-time clock estimation. In this contribution, the estimation model of multi-GNSS and multi-frequency integer recovery clock (IRC) is developed to improve both the accuracy and efficiency of real-time clock estimates. In the proposed method, the undifferenced ambiguities are fixed to integers, thus the integer properties of the ambiguities are recovered and the accuracy of the clock estimates is also improved. Moreover, benefitting from the removal of large quantities of ambiguity parameters, the computation time is greatly reduced which can guarantee high processing efficiency of real-time clock estimates. Multi-GNSS observations from 150 globally distributed Multi-GNSS Experiment (MGEX) tracking stations were processed with the proposed model. Compared to the float satellite clocks, the precision of the real-time IRC with respect to CODE 30 s final multi-GNSS satellite clock products were improved by 53.0%, 42.7%, 63.7% and 33.9% for GPS, BDS, Galileo and GLONASS, respectively. The average computation time per epoch with multi-GNSS observations was improved by 97.1% compared to that of standard float clock estimation. Kinematic precise point positioning (PPP) ambiguity resolution was also performed with the derived real-time IRC products. Compared to the float PPP solutions, the position accuracy of the multi-GNSS IRC-based fixed solutions was improved by 77.2%, 49.7% and 52.7% from 24.2, 13.3 and 30.7 mm to 5.5, 6.7 and 14.5 mm for the east, north and up components, respectively. The results indicate that ambiguity fixing can be successfully achieved by using the derived the IRC products. In addition, the estimation model of multi-frequency IRC products is also investigated to promote the capability and application of real-time PPP AR under multi-frequency signals.
Influence of orographic precipitation on the co-evolution of landforms and vegetation
Authors: Srivastava Ankur , Yetemen Omer , Kumari Nikul , Saco Patricia M.
Published: March 2020

Topography plays an important role in controlling the amount and the spatial distribution of precipitation due to orographic lift mechanisms. Thus, it affects the existing climate and vegetation distribution. Recent landscape modelling efforts show how the orographic effects on precipitation result in the development of asymmetric topography. However, these modelling efforts do not include vegetation dynamics that inhibits sediment transport. Here, we use the CHILD landscape evolution model (LEM) coupled with a vegetation dynamics component that explicitly tracks above- and below-ground biomass. We ran the model under three scenarios. A spatially‑uniform precipitation scenario, a scenario with increasing rainfall as a function of elevation, and another one that includes rain shadow effects in which leeward hillslopes receive less rainfall than windward ones. Preliminary results of the model show that competition between increased shear stress due to increased runoff and vegetation protection affects the shape of the catchment. Hillslope asymmetry between polar- and equator-facing hillslopes is enhanced (diminished) when rainfall coincides with a windward (leeward) side of the mountain range. It acts to push the divide (i.e., the boundary between leeward and windward flanks) and leads to basin reorganization through reach capture. Our findings suggest that there exists a strong coupling between climate and landform evolution processes, and that orographic precipitation can imprint its influence on landforms in semi-arid ecosystems.  
Origin and the Silurian odyssey of the Brunovistulian terrane: paleomagnetic evidence from the Brno Massif (central Europe).
Authors: Nawrocki Jerzy , Leichmann Jaromir , Pańczyk Magdalena
Published: March 2020

The Brno Massif forms a part of larger tectonostratigraphic unit named the Brunovistulian Terrane (BVT) that is one of crustal block of Europe with the Neoproterozic basement.  However, the Neoproterozoic orogenic belt was developed in wide area i.e. along the Gondwana margin and near the present day eastern and southern edge of the East European Craton. For more than 20 years, the problem of primary setting of the BVT inside the Neoproterozic orogenic  belt have been discussed. Also the path of their drift and  time of their final accretion have been a matter of debate. To solve these problems the paleomagnetic and isotope studies of vertical intrusions cutting the BVT basement near Brno in Moravia have been undertaken. Preliminary isotope dating of granitic and basaltic intrusions points to the early Silurian age of them. Results of demagnetization of paleomagnetic samples from three localities revealed the presence of stable components with a steep inclination, at that time characteristic for the northern margin of Gondawana but not for the Baltica paleocontinent that during the Silurian was situated between the equator and 30oS. The Emsian  “old red” type deposits may indicate that final amalgamation of the BVT took place some-time between the Silurian and the Devonian. This time of joining of the BVT  to Baltica and quite high (50 – 60oS) paleolatitudes obtained from the early Silurian rocks of the Brno Massif  point to a rapid drift of the BVT across the Rheic Ocean during the Silurian.
Assessing and ameliorating edge effects in magnetic data transformations
Authors: Lelièvre Peter , Fournier Dominique , Walker Sean , Williams Nicholas , Farquharson Colin
Published: March 2020

Reduction to pole and other transformations of total field magnetic intensity data are often challenging to perform at low magnetic latitudes, when remanence exists, and when large topographic relief exists. Several studies have suggested use of inversion-based equivalent source methods for performing such transformations under those complicating factors. However, there has been little assessment of the importance of erroneous edge effects that occur when fundamental assumptions underlying the transformation procedures are broken. In this work we propose a transformation procedure that utilizes magnetization vector inversion, inversion-based regional field separation, and equivalent source inversion on unstructured meshes. We investigated whether edge effects in transformations could be reduced by performing a regional separation procedure prior to equivalent source inversion. We applied our proposed procedure to the transformation of total field magnetic intensity to magnetic amplitude data, using a complicated synthetic example based on a real geological scenario from mineral exploration. While the procedure performed acceptably on this test example, the results could be improved. We pose many questions regarding the various choices and control parameters used throughout the procedure, but we leave the investigation of those questions to future work.
Pluvial flooding in urban areas: Parsimonious hazard mapping for a case study in Berlin, Germany
Authors: Seleem Omar , Heistermann Maik , Bronstert Axel
Published: March 2020

Urban pluvial floods are increasingly recognized as a ubiquitous hazard. They are caused by short and intense rainfall, followed by rapid runoff concentration. But while flood hazard maps for rivers have been widely implemented under the EU Flood Directive, corresponding efforts for pluvial flooding are rare, yet: pluvial floods are not to the existence of a river channel. They could occur anywhere, subject to the existence of minimal areas for surface runoff generation and concentration. That concentration could be dominated by small features of urban landscapes, which makes identification of flow paths uncertain even with highly-resolved digital elevation models (DEM) and full hydrodynamic simulations (which are computationally expensive). At the same time, sub-surface sewer and drainage systems – an additional complication in an already complex environment – will typically be subject to overcharge for extremely heavy rainfall events. That, however, allows us to focus on the surface in order to assess the hazard from such events. In the present study, we present a low-(computational)-cost approach to identify areas at risk of pluvial flooding. Common GIS operations are used to detect flood-prone depressions from a high-resolution 1m x 1m DEM, identify contributing watersheds, and represent runoff concentration by a fill-spill-merge approach. The approach is applied to a study area in Berlin, which has been repeatedly subject to pluvial flooding in the past years.
Ecological impacts of apple orchards on China's Loess Plateau
Authors: Yang Min , Wang Shaofei , Zhao Xining , Gao Xiaodong
Published: March 2020

Due to their great economic benefits, there are many apple orchards on the Loess Plateau and aggressive expansion is planned. However, little is known about their ecological impact in relation to the deep soil water, soil organic carbon and soil particle aggregation. An accurate evaluation of the ecological impact of apple orchards is crucial to ensure the establishment of sustainable ecosystems on the Loess Plateau. We, therefore, measured the soil water content variation in deep layers (WCAD) (200-800 cm), soil organic carbon (SOC) content and density (0-800 cm) and, soil aggregate stability (0-40 cm) in apple (Malus pumila) orchards and ecological plantations of black locust (Robinia pesudoacacia) and korshinsk peashrub (Caragana korshinskii). The results suggested that (1) the soil water in deep soil was generally lower under apple orchards (13.29%), black locust (12.4%) and korshinsk peashrub (13.46%) than under arable land (18.35%), both in the semiarid and semihumid regions. This finding implied that apple orchard, black locust and korshinsk peashrub plantations caused intense reductions in soil moisture compared with the arable land, leading to severe soil desiccation. (2) Apple orchards (1.85 to 5.49 g kg-1) had significantly (p <0.05) lower SOC density than ecological plantations (2.15 to 8.95 g kg-1), especially in 0-100 cm soil layer, in both semiarid and semihumid regions. This result suggests that apple orchards have no profitless for SOC sequestration over the long-term because their clean cultivation management increase the risk of SOC loss by soil erosion. (3) In semiarid and semihumid regions, soil aggregate stability (the mean weight diameter, MWD) in apple orchards (0.26-0.63 mm) was significantly (p <0.05) lower than under black locust (0.63-2.97 mm) and korshinsk peashrub (0.72-2.13 mm) plantations in 0-40 cm layers, and even lower than in arable land in the 0-20 cm layer in most regions, which means that apple orchards have low anti-erodibility. Our results suggest that continued expansion of apple orchards and ecological plantations both consumed much deep soil water, but the ecological effect (e.g., SOC sequestration, soil and water conservation) brought by apple orchard is much lower than that of ecological plantations. In the interest of sustainable development in the region, apple cultivation should be undertaken with caution, especially in semiarid regions.