bluuebunny/crossref_metadata_2025 huggingface dataset:
Decadal Prediction of Indian Ocean Dipole
Authors: Francis Feba , Karumuri Ashok , Collins Matthew
Published: March 2020

 

Decadal Prediction is the prediction of climate for the next 5–20 years. Decadal Prediction has gained great importance as it tries to bridge the gap between seasonal and Centennial (50-100 year) predictions creating a balance between initial conditions and boundary conditions. We analysed the model output from CMIP5 decadal runs of nine models. Our results show that two of the decadal hindcasts show prediction skills of significance for the Indian Ocean Dipole for up to a decade. The Indian Ocean Dipole is one of the leading modes of climate variability in the tropics, which affects global climate. As already established, the models also show year-long lead predictability of the El Niño Southern Oscillation. We found no significant skills for the Indian Summer Monsoon. We are presently looking for the source of the lead predictability of Indian Ocean Dipole which appears to be due to links from the Southern Ocean. These decadal prediction skills and predictability for a climate driver like the Indian Ocean Dipole have immense helpfulness for climate science and society in general.
Characteristics of shale oil reservoirs in Qianjiang Formation, Qiangjiang Depression, Jianghan Basin, China
Authors: Luo Jing , Wang Furong
Published: March 2020

The Jianghan Basin is a typical eastern fault depression salt lake basin in China, in which the Paleogene strata of the Qianjiang Sag are rich in shale oil resources. As a salt lake sedimentary basin, the developed Qianjiang Formation is a set of inter-salt oil-bearing strata, in which the salt rock strata are especially developed. There are many salt rhythms in the study area and a salt rhythm consists of a argillaceous dolomite layer between a salt rock formation and a salt rock formation. This study focuses on the 10th rhythm of the Qian 34 section of Qianjiang Depression (Eq3410). The samples were investigated by organic geochemical analysis and X-ray diffraction, and the pore structure characteristics of the reservoir were studied by argon ion polishing scanning electron microscope and low temperature nitrogen adsorption test. The research indicates that the average TOC of Eq3410 in Qianjiang Depression is 2.11% and the main distribution is 1%~3%; the type of organic matter is mainly Type II2 and Type II1; the overall maturity of organic matter is low maturity stage(Tmax is 412~441℃with an average of 423℃). The XRD data indicates that the mineral composition of the Qianjiang Formation shale oil reservoir is complex and have strong heterogeneity(quartz content in 2.3%~18.6% with an average of 9.5%, calcite content in 6.9~43.8% with an average of 12.8%, dolomite content in 2.5%~ 61.2% with an average of 27.2%, clay mineral content in 1.0%~45.2% with an average of 20.5%, glauberite content from 7.1% to 92.7% with an average of 22.9%). The pore types of shale oil reservoirs in Qianjiang Sag are complex and diverse and mostly are intergranular pores, which are mainly developed between detrital minerals or between detrital minerals and carbonate minerals. In carbonate mineral particles and quartz particles, some intragranular pores are visible, including calcite dissolution pores, internal pores of calcite and clay minerals, and internal pores of pyrite particles. And organic pores are rare in reservoirs due to the low maturity(Ro ranges between 0.5% and 0.7%). Nitrogen adsorption experiments showed that the pore size distribution of Eq3410 samples was dominated by mesopores and macropores. And the pore volume of the Eq3410 sample was most affected by the macropore pore volume, averaging 66.22%, followed by the mesopore pore volume with an average of 31.45%. To study and understand the characteristics of shale oil reservoir in Qianjiang Depression is conducive to mastering the regularity of shale oil enrichment and provides a basis for the exploration and development of shale oil.
Reprocessing of aeromagnetic data under consideration of satellite data for interpretation and modelling
Authors: Ebbing Jörg , Yixiati Dilixiati , Baykiev Eldar , Haas Peter , Ferraccioli Fausto , Scheiber-Enslin Stephanie
Published: March 2020

We analyse aeromagnetic and satellite data for Australia, Antarctica and Southern Africa. For all these areas, high-resolution aeromagnetic surveys have been released in recent years, which are of major interest as these areas form formerly adjacent parts of Central Gondwana. The compilations are based on surveys with varying line spacing and flight altitude, merged into a single grid. However, processing and merging can adversely affect the long-wavelength parts of these compilations. Satellite models of the lithospheric magnetic field typically provide more accurate long wavelength data down to ca 300 km wavelengths. Comparison of the corresponding spectral part of the aeromagnetic compilations shows similarities, but also some discrepancies. An example is the South African compilation, where a jump in the amplitude of the magnetic signal corresponds to the edges of regional compilations. When reconstructed into a pre-break-up Gondwana configuration, the same jump is observed between Antarctica and Southern Africa. However, such a jump is not present in satellite data and can be adjusted by combination of the datasets. A pitfall is that some of the signal in the long-wavelength range of the aeromagnetic data still corresponds to shallow level geological features, while satellite data may reflect the deeper tectonothermal setting. The implications of the airborne-satellite data integration are discussed and examples for modelling lithospheric magnetisation provided.
VM-ADCP backscatter data management using QGIS
Authors: Picco Paola , Nardini Roberto , Pensieri Sara , Bozzano Roberto , Repetti Luca , Demarte Maurizio
Published: March 2020

VM-ADCP (Vessel Mounted Acoustic Doppler Current Profiler) are regularly operating on board of several research vessels with the aim of providing 3-D ocean currents fields. Along with ocean currents, these instruments also measure acoustic backscatter profile on a known frequency, that can be of great advantages for other environmental investigations such as the zooplankton migrations. The presence of zooplankton can be detected by a variation of acoustic backscatter changing  with the depth at a periodic (diurnal or semidiurnal) variability, related to the vertical  migration of these organisms. GIS has proven to be a powerful tool to manage the huge amount of VM-ADCP backscatter data obtained during the oceanographic campaigns. Moreover, this allows to extract relevant information on zooplankton distribution and abundance, even when the monitoring strategy of the experiment does not completely meet the temporal and spatial resolution required for these studies. The application here described has been developed on QGIS and tested on the Ligurian Sea (Mediterranean Sea). In order to obtain the comparability of data from instruments operating at different frequencies and sampling set-up, echo intensity data are converted into volume backscatter strength and corrected for the slant-range. Using high-resolution bathymetry rasters acquired and processed by the Italian Hydrographic Institute, allows to discard the anomalous high backscatter values due to presence of the bottom. Another advantage of the GIS is the possibility to easily identify night-collected data from the daily ones and their spatial distribution, as well as those from the surface and the deeper layer. All the possible combinations can be then visualised and analysed.
Effects of Water-soluble Organic Carbon on Aerosol pH
Authors: Hennigan Christopher , Battaglia, Jr. Michael , Weber Rodney , Nenes Athanasios
Published: March 2020

Water soluble organic carbon (WSOC) is a ubiquitous and significant fraction of fine particulate matter.  Despite advances in aerosol thermodynamic equilibrium models, there is limited understanding on the comprehensive impacts of WSOC on aerosol acidity (pH).  We address this limitation by studying submicron aerosol that represent the two extremes in acidity levels found in the atmosphere: strongly acidic aerosol from Baltimore, MD, and weakly acidic conditions characteristic of Beijing, China. These cases are then used to construct mixed inorganic/organic single-phase aqueous particles, and thermodynamically analyzed by the E-AIM and ISORROPIA models in combination with activity coefficient model AIOMFAC to evaluate the effects of WSOC on the H+ ion activity coefficients (γH+) and activity (pH).  We find that addition of organic acids and non-acid organic species concurrently increases γH+ and aerosol liquid water.  Under the highly acidic conditions typical of the eastern U.S. (inorganic-only pH ~1), these effects mostly offset each other, giving pH changes of < 0.5 pH units even at organic aerosol dry mass fractions in excess of 60%.  Under conditions with weaker acidity typical of Beijing (inorganic-only pH ~4.5), the non-acidic WSOC compounds had similarly minor effects on aerosol pH, but organic acids imparted the largest changes in pH compared to the inorganic-only simulations.  Organic acids affect pH in the order of their pKa values (oxalic acid > malonic acid > glutaric acid).  Although the inorganic-only pH was above the pKa value of all three organic acids investigated, pH changes in excess of 1 pH unit were only observed at unrealistic organic acid levels (aerosol organic acid concentrations > 35 µg m-3) in Beijing.  The model simulations were run at 70%, 80%, and 90% relative humidity (RH) levels and the effect of WSOC was inversely related to RH.  At 90% RH, WSOC altered aerosol pH by up to ~0.2 pH units, though the effect was up to ~0.6 pH units at 70% RH.  The somewhat offsetting nature of these effects suggests that aerosol pH is sufficiently constrained by the inorganic constituents alone under conditions where liquid-liquid phase separation is not anticipated to occur.
Why and when can biosolids be used as a soil amendment for ecosystem reclamation and rehabilitation?
Authors: Fraser Lauchlan
Published: March 2020

Biosolids are a source of nutrient-rich organic material that can be used to improve degraded or disturbed soils. However, public perception of the use of biosolids on land is both positive and negative and can change over time and be different in different regions of the world. Research on the land application of biosolids has increased in the past 20 years, but there is little consensus on how the environment responds to biosolids applications. Here, I (1) present public perception research on the use of biosolids in land application in British Columbia, Canada, (2) present a review of the literature on the effects of biosolids in land application with a particular focus on plant community development, and (3) provide recommendations for the use of biosolids in land application depending on potential differences in ecosystem reclamation goals. In the public perception research, many citizens see the value in the use of biosolids as a sustainable fertilizer, especially in mine reclamation, but some have expressed concerns about pathogens in biosolids and their effect on humans and animals. The literature review revealed that biosolids increase plant productivity but have no effect on plant diversity. The research suggests that climatic conditions and seeding are influential in altering ecosystem and community level responses to biosolids application.
Understanding the sources and transit times of water contributing streamflow from intermittent headwater catchments in semi-arid areas
Authors: Barua Shovon , Cartwright Ian , Daly Edoardo , Morgenstern Uwe
Published: March 2020

Intermittent headwater catchments constitute a significant proportion of many stream networks. In semi-arid climates, intermittent headwater streams flow only following periods of sustained rainfall. There is commonly a rapid response of streamflow to rainfall; however, whether this is the input of recent rainfall or displacement of water stored in the catchments for several years is not well known. Understanding the sources and transit times of water that contribute to streamflow is important for the maintenance of stream health and predicting the response of land-use changes.

The study focuses on two intermittent streams from two contrasting land-use (pasture and forest) in southeast Australia. The native eucalyptus forests in this region were originally cleared for grazing following European settlement ~180 years ago and then partially replaced by plantation in the last ~15 years. Stream water and groundwater from the riparian zone adjacent to the streams were sampled between May and October 2018.

The stream water has 3H activities of 1.30 to 3.17 TU in the pasture and 1.84 to 3.99 TU in the forest, with higher activities recorded during the higher winter flows. Groundwater from the riparian zone has 3H activities of 0.16 to 0.79 TU in the pasture and 2.01 to 4.10 TU in the forest. Aside from one riparian zone groundwater sample, all 3H activities of groundwater in the riparian zone are lower than those of recent local rainfall (~2.79 TU). The single high 3H activity in riparian zone possibly reflects recharge by winter rainfall with higher 3H activities.

The mean transit times (MTTs) of water were estimated using a range of tracer lumped parameter models. The riparian zone groundwater has greater MTTs of hundreds of years in the pasture and up to 9 years in the forest. At high streamflow, the stream water has MTTs of <6 years in the pasture and the forest. The MTTs of stream water at low streamflow vary from 15 to 42 years in the pasture and from 3 to 16 years in the forest. The long MTTs of water from streams indicate that the source water is not just recent rainfall, rather water stored in the riparian zone is mobilised at the commencement of flow and recent rainfall makes a larger contribution at higher flows. The observation is consistent with the major ion geochemistry of the stream water, which most closely represents that of the riparian zone groundwater. The differences in MTTs of stream water between two contrasting land-use imply that the streamflow has been being most likely impacted by land-use changes. Thus, it is necessary to improve the strategies for catchment management to protect stream health from land-use practices.
How far can we estimate pluvial flood damage risk by statistical learning?
Authors: Laaha Gregor , Nocker Clemens
Published: March 2020

Pluvial flooding is getting increasing attention around the world, but there are very limited studies on how to estimate pluvial flood damage risk at a regional scale. In this paper, we evaluate the value of statistical methods for pluvial flood risk estimation. One objective is to assess if statistical methods can deliver significant relationships between precipitation indices, soil and landscape characteristics, and pluvial flood damage risk in agricultural areas. Additionally, we want to explore if the statistical methods could be a cost-efficient alternative to deterministic surface run-off models. The analyses are performed for agricultural landscapes in Upper Austria where flood damage location reports of the Austrian hail insurance are available for the 2007 to 2013 period. We assess the relative performances of a generalized linear model (GLM) and a random forest (RF) model to estimate pluvial flood occurrence based on presence/absence raster data set, where the imbalance of the binary target variable and multicollinearity of predictors pose specific challenges. The analysis reveal that within the study area the most severe agricultural damages were triggered by intense rain events, but in one case the damage was caused by longer lasting low intense rain. By means of log-linear models and random forests the relationships between the location characteristics and damage events are investigated. A specific focus is laid on comparing the skills of continuous versus classified parameters, and on methods for dealing with collinearity. We compare the performances of both models based on cross-validation statistics and the process-realism of results. We finally discuss how far the statistical methods appear appropriate for quantifying pluvial flood damage risk at a regional scale.
New constraints on the role of late Variscan extension in the origin of the Eastern Galicia Magnetic Anomaly (NW Spain)
Authors: Ayarza Puy , Villalaín Juan José , Martínez Catalán Jose Ramón , Alvarez Lobato Fernando , Durán Oreja Manuela , Recio Clemente
Published: March 2020

The Eastern Galicia Magnetic Anomaly (EGMA) is one of the most conspicuous and, definitively, the best studied of all the magnetic anomalies in the Central Iberian Arc (CIA). This is probably due to its location, on the thoroughly researched Lugo-Sanabria gneiss dome and to the unique fact that its source rocks crop out in the Xistral Tectonic Window. Multiple studies and models of this anomaly have been carried out in the last 25 years and still, new results keep on shedding more light on its understanding. Rock magnetic analyses, natural remanent magnetization, anisotropy of the magnetic susceptibility and stable isotopes geochemistry carried out on the rocks that produce this anomaly have provided new insights on the processes that led to magnetization and on its age. Results suggest that magnetization of source rocks is a consequence of the increase in oxygen fugacity underwent by metamorphic and magmatic rocks affected by late-Variscan extensional tectonics. Extensional detachments were the pathways that allowed the entrance of fluids that led to syn-tectonic crystallization of magnetite and hematite in S-Type granites. Accordingly, magnetization is not really linked to primary lithologies but mostly to extensional structures. This process took place in the late Carboniferous to earliest Permian, during the Kiaman reverse superchron. Natural remanent magnetization exhibited by hematite-bearing samples confirms the age of the magnetization and adds complexity to the interpretation of the EGMA, where remanence has been often largely ignored or underestimated. Understanding the origin of the EGMA contributes to the interpretation of other anomalies existing in the CIA, also located on thermal domes. Furthermore, it provides new hints to interpret magnetic anomalies located in extensional tectonic contexts worldwide
Application of a dynamic terrestrial landslide early warning system in a wide high-voltage transmission line coverage area
Authors: Liu Shuhao , Yin Kunlong , Zhang Yiyue , Xiao Ting , Lin Wei
Published: March 2020

The power grid is one of the most important lifeline projects in modern society. However, the complex transmission network was fixed to the ground through millions of transmission towers, which were inevitably being affected by various types of geohazard. The failure of local facilities may further cause large-scale power outages, leading serious social impact and economic loss. From this perspective, this study aims to develop a territorial landslide early warning system (Te-LEWS) for the high-voltage transmission line coverage area by introducing a novel method, combining landslide inventory and susceptibility maps, rainfall thresholds and real time rainfall forecast, transmission tower vulnerability analysis and GIS-based dynamic alert system. To this objective, the power grid system consisting of over 130,000 high-voltage transmission towers and covering an area of 7 provinces in China was selected as study objective to conducted susceptibility mapping with different classification methods (information value, random forest and support vector). The rainfall threshold of each county was calculated through analyzing a 7 consecutive day rainfall data for the major historical landslide event. Instead of an ordinary landslide risk assessment practice within the transmission line coverage area, this study mainly focuses on the landslide risk over transmission towers and tries to generate an risk assessment result over a specific risk bearing element with linear distribution characteristic, in this case the electricity transmission lines. With real-time predicted rainfall value as input variable, a dynamic landslide warning system was established on a pixel basis, to identify the transmission towers that are potentially vulnerable to landslide disasters. The performance of the proposed Te-LEWS system were validated through the historical rainfall data and the landslides events from 2015-2019, to gain a comprehensive evaluation on its warning accuracy. Results suggest that the system has a high warning success rate and the false alarm was significantly reduced. In such case, the proposed To-LEWS would greatly support the grid authorities in reducing disaster risks and retrieving huge economic loss. The study shed a new light on the risk analysis method of a specific linear distributed risk bearing element towards geohazard, to demonstrate its potential over wide areas, an application to a huge area in China was shown and discussed.

Keywords: Landslides; GIS; early warning system; disaster risk reduction; high-voltage transmission line
Spatial Distribution of Particle Precipitation in Terms of Energy Channels under Different Geomagnetic Conditions
Authors: Shen Han-Wen , Shue Jih-Hong , Dombeck John , Li Hsien-Ming
Published: March 2020

The geomagnetic activity can modulate the number and energy fluxes of precipitation and their spatial distributions. Most previous studies examined precipitation in terms of energy spectrum types associated with quasi-static potential structures (QSPS) acceleration, Alfvénic acceleration, and wave scattering under various geomagnetic conditions. In this study, we instead categorize precipitation according to energy channels of particles. The spatial distribution of the precipitation for various energy channels is also derived under different geomagnetic conditions. Our results indicate that regardless of active and quiet times, low-energy (high-energy) precipitation is mostly distributed on the dayside (nightside). By comparing with past results, we infer that electron precipitation is mainly caused by QSPS and Alfvénic acceleration for most cases; however, the high-energy electrons during quiet times are predominantly created by wave scattering. For high-energy precipitation, the dawn-dusk asymmetry of the spatial distribution during active times is found to be opposite of that during quiet times. Based on their spatial distributions, we suggest that the high-energy precipitation during quiet times is dominated by the curvature and gradient drifts, while that during active times is mainly affected by physical processes related to substorms in the magnetotail.
Spatiotemporal variations of organic matter sources in two mangrove-fringed estuaries in Hainan, China
Authors: Chu Mengfan , Sachs Julian P. , Zhang Hailong , Ding Yang , Jin Gui’e , Zhao Meixun
Published: March 2020

Mangrove systems represent important long-term sinks for carbon since they have much higher carbon burial rates than terrestrial forests or typical coastal ecosystem. However, quantifying the sources of organic matter (OM) in estuarine and coastal sediments, where mangroves occur but are not the only source of OM, is challenging due to the variety of OM sources and diverse transport processes in these dynamic environments. The sources of OM in surface sediments of two mangrove-fringed estuaries in Hainan Province, China, were investigated using the mangrove specific biomarker taraxerol and other lipid biomarkers, as well as stable carbon isotopes. Mixing models based on the concentration of taraxerol, plant wax n-alkanes and δ13 COM indicate that terrestrial non-mangrove plant OM accounted for 52-72% of the OM in the two estuaries, aquatic OM from phytoplankton and/or seagrass accounted for 8-29%, and OM from mangroves comprised 16-26% of the total. Terrestrial plants contributed 16-20% more of the OM to sediments of Bamen Bay, which is on the wetter, eastern side of Hainan Island, than to Danzhou Bay, but aquatic OM (algae plus seagrass) fraction was 17% lower than that in Danzhou Bay sediments. In both estuaries, mangrove and aquatic OM fractions increased seaward while the terrestrial OM fraction decreased. Terrestrial fraction in BMB sediments is 12% higher in summer compared to autumn, which is offset by a comparable reduction in the mangrove OM fraction, as well as higher aquatic OM fractions in both estuaries. This may be caused by enhanced river discharge, more efficient mangrove leaf litter transport offshore, and/or higher aquatic productivity. The biomarker and carbon isotope approach used here can be applied to semi-quantitatively estimate spatial and temporal variations of the sources of organic carbon in tropical estuarine and coastal sediments, a major sink for carbon in the ocean.
Does changing connectivity due to beaver engineering result in changing hydrological function? Understanding the impacts of the return of the Eurasian beaver to Great Britain.
Authors: Puttock Alan , Graham Hugh , Brazier Richard
Published: March 2020

The connectivity of landscapes is increasingly recognised as being a key control over their hydrological function and provides a valuable conceptual approach for understanding the environmental impacts of the return of beaver to European landscapes.

Beavers are the archetypal keystone species, which can profoundly alter ecosystem structure and function through their engineering activity, most notably the building of dams. Beaver dams, associated ponds and other structures such as canals can reduce downstream connectivity. However, conversely beaver engineering can also increase lateral connectivity pushing water sideways, connecting the channel and floodplain, creating complex wetland environments.

Changes in hydrological connectivity associated with beaver, has the potential to alter flow and sediment regimes, biogeochemical cycling and freshwater ecology. Results will be presented from hydrological monitoring across a range of sites in Great Britain where the Eurasian beaver (Castor fiber) has been reintroduced. Analysis will consider (1) does beaver engineering result in flow attenuation across scale and landuse? (2)  Is flow attenuation manifested during both low and high flow conditions?

The return of beaver to intensively managed European landscapes may provide ecosystem service benefits, including natural flood management, water quality, sediment storage and habitat creation (Puttock et al., 2017, 2018). However, beaver activity such as damming and tree felling can also cause management issues (Auster et al., 2019). Therefore, it is critical to understand where and in what density beaver damming may occur. A modelling approach will be presented for determining beaver habitat suitability and dam capacity, which in conjunction with empirical monitoring aims to provide understanding at management and policy relevant scales.

References

Auster, R. E., Puttock, A., & Brazier, R. (2019). Unravelling perceptions of Eurasian beaver reintroduction in Great Britain. Area, area.12576. https://doi.org/10.1111/area.12576

Puttock, A., Graham, H. A., Cunliffe, A. M., Elliott, M., & Brazier, R. E. (2017). Eurasian beaver activity increases water storage, attenuates flow and mitigates diffuse pollution from intensively-managed grasslands. Science of The Total Environment, 576, 430–443. https://doi.org/10.1016/j.scitotenv.2016.10.122

Puttock, A., Graham, H. A., Carless, D., & Brazier, R. E. (2018). Sediment and Nutrient Storage in a Beaver Engineered Wetland. Earth Surface Processes and Landforms. https://doi.org/10.1002/esp.4398
Kinetic theory and simulation of electron-strahl scattering in the solar wind
Authors: Verscharen Daniel , Jeong Seong-Yeop , Chandran Benjamin , Salem Chadi , Pulupa Marc , Bale Stuart
Published: March 2020

We investigate the scattering of strahl electrons by microinstabilities as a mechanism for creating the electron halo in the solar wind. We develop a mathematical framework for the description of electron-driven microinstabilities and discuss the associated physical mechanisms. We find that an instability of the oblique fast-magnetosonic/whistler (FM/W) mode is the best candidate for a microinstability that scatters strahl electrons into the halo. We derive approximate analytic expressions for the FM/W instability threshold in two different βc regimes, where βc is the ratio of the core electrons' thermal pressure to the magnetic pressure, and confirm the accuracy of these thresholds through comparison with numerical solutions to the hot-plasma dispersion relation. We find that the strahl-driven oblique FM/W instability creates copious FM/W waves under low-βc conditions when U0s>3wc, where U0s is the strahl speed and wc is the thermal speed of the core electrons. These waves have a frequency of about half the local electron gyrofrequency. We also derive an analytic expression for the oblique FM/W instability for βc~1. The comparison of our theoretical results with data from the Wind spacecraft confirms the relevance of the oblique FM/W instability for the solar wind. In addition, we find a good agreement between our theoretical results and numerical solutions to the quasilinear diffusion equation. We make predictions for the electron strahl close to the Sun, which will be tested by measurements from Parker Solar Probe and Solar Orbiter.
Isotope labeling experiment to infer ecohydrological travel times
Authors: Mennekes David , Rinderer Michael , Seeger Stefan , de Boer Hugo , Orlowski Natalie , Weiler Markus
Published: March 2020

Stable water isotopes are promising tracers to study soil-tree interactions and root water uptake. Traditionally, destructive sampling techniques are applied to measure the isotopic signature in soils and plant tissues but these methods are limited in their temporal resolution. For calculating ecohydrological travel times from soil water to transpiration, high frequent isotope measurements are required. Recently, in-situ water isotope probes have been successfully applied in beech trees to yield high-frequent isotope measurements under field conditions but the complexity and heterogeneity of natural field conditions can make a systematical method testing difficult. Here, we test whether the new probes are capable of capturing tree species-specific differences in root water uptake and associated travel times.
We test this in a controlled experiment using large pots with three 4-6 meter high and 20 year old coniferous and deciduous trees: Pinus pinea, Alnus x spaethii and Quercus suber that are expected to have different water uptake strategies. We applied deuterated irrigation water to the homogeneous soils in the pots and traced the water flux from the soils through the trees with in-situ isotope probes in high temporal resolution.
This contribution presents preliminary results on ecohydrological travel times in relation to environmental parameters such as sap flow, photosynthetic activity, matrix potential, soil water content, water vapor pressure deficit and solar radiation.
Our in-situ isotope probes were capable to capture the breakthrough of the isotope tracer in all trees. The calculated travel times were shorter for the Pinus and Alnus compared to the Quercus which suggests differences in root water uptake. Detailed results from such controlled experiments are fundamental for testing new measurement techniques such as the in-situ isotope probes. Such results are important to better interpret results measured under natural and therefore more complex and heterogeneous field conditions.
Long-term monitoring with spring-based gravimeters: tilt-control benefits and application to the Rochefort Cave Laboratory (Belgium)
Authors: Fores Benjamin , Watlet Arnaud , Van Camp Michel , Francis Olivier
Published: March 2020

Spring-based gravimeters are light and easy to install, with a precision around 5 μGal/√Hz. However, they are still not used for long-term gravity monitoring. The main reason for that is the non-linear drift of those instruments, which is very difficult to correct without removing geophysical signals. We will show that when the tilt is actively controlled, a gPhone spring-based gravimeter shows a quasi-linear drift and can reach a long-term stability at the µGal level.

This allows experiments such as the one in the Rochefort Cave Laboratory (Belgium). Thanks to the size of the gPhone and its low facility requirements, a monitoring from inside a cave was possible. Coupled with another gravity monitoring at the surface, it reveals new information on the local hydrology of this karstic site.
The Geogarden of the University Roma Tre: creation of a prototype of a Geological Garden of Lazio for the dissemination of Geological Sciences in Rome
Authors: Corrado Sveva , Bollati Andrea , Fabbri Marina
Published: March 2020

Between 2017 and 2019, a prototype of a geological garden for the dissemination of Geological Sciences to the general public was created in the open-air spaces of the Department of Sciences of the Roma Tre University. This first nucleus is the result of a Citizen Science activity carried out by students of the High Schools of Rome and its province, conceived and guided by a group of University researchers and high school teachers, in collaboration with local institutions and some mining companies operating in the surroundings of Rome. Currently the prototype consists of six large rock samples representative of lithotypes cropping out in the Roman Campaign and in the nearby Central Apennines that allow to tell the evolution of the territory surrounding the city of Rome since about 15 Ma ago, with particular reference to the history of the Roman countryside in the Quaternary period. Guided tours for schools and a general public and events popularizing scientific culture at various scales have represented the main dissemination activities carried out so far. Currently the garden is being expanded and integrated with numerous plant species representative of the botanical heritage of the Lazio region.
Evaluation of altimeter undersampling in estimating global wind and wave climate using virtual observation
Authors: Jiang Haoyu
Published: March 2020

Altimeters can provide global long-duration observations of oceanic wind speed and wave height. However, altimeters face the undersampling problem in estimating wind and wave climate because of their sparse sampling pattern and the changing number of in-orbit satellites. In this study, the undersampling error of altimeters was studied by sampling the ERA5 oceanic wind speed and wave height data using the track information of multiplatform altimeters. Comparisons were made between the statistics (mean, 90th and 99th percentiles, and long-term trends of them) of the original ERA5 data and the gridded along-track sampling of the ERA5 data. The results show a large discrepancy with respect to the extreme values (90th and 99th percentiles). The undersampling of altimeters can lead to significant underestimations of monthly extreme values of oceanic wind speed and wave height. Meanwhile, this underestimation is alleviated with the increase of the number of in-orbit altimeters, leading to very large overestimations of long-term trends of these extreme values over the period 1985-2018. In contrast, the annual extreme values of oceanic wind speed and wave height and their long-term trends are more reliable, although slight aforementioned biases of extreme values still exist and the data from GEOSAT are not suitable for computing annual statistics. For altimeter data, the annual values are a better option to compute long-term trends than the monthly data. This study also presents a correction scheme of using model data to compensate for the wind and wave events missed by altimeter tracks. After the correction, the global trends in oceanic wind speed and wave height over 1992-2017 are recomputed using annual statistics. The results show a clear discrepancy between the trends of wind speed and wave height during this period: the wind speed increased, while the wave height decreased. However, the reason for this discrepancy is unknown at this stage.
Fast cooling of normal-fault footwalls: rapid fault slip or thermal relaxation?
Authors: Wolff Reinhard , Hetzel Ralf , Dunkl István , Anczkiewicz Aneta A. , Pomella Hannah
Published: March 2020

Rapid rock exhumation in mountain belts is often associated with crustal-scale normal faulting during late-orogenic extension. The process of normal faulting advects hot footwall rocks towards the Earth's surface, which shifts isotherms upwards and increases the geothermal gradient. When faulting stops, this process is reversed and isotherms move downwards during thermal relaxation. Owing to these temporal changes of the geothermal gradient, it is not straightforward to derive the history of faulting from mineral cooling ages (Braun, 2016). Here, we combine thermochronological data with thermokinematic modeling to illustrate the importance of syntectonic heat advection and posttectonic thermal relaxation for a crustal-scale normal fault in the European Alps. The N–S trending Brenner fault defines the western margin of the Tauern Window and caused the exhumation of medium-grade metamorphic rocks during Miocene orogen-parallel extension of the Alps (Rosenberg & Garcia, 2011; Fügenschuh et al., 2012). We analyzed samples from a 2-km-thick crustal section, including a 1000-m-long drillcore. Zircon and apatite (U-Th)/He ages along this transect increase with elevation from ~8 to ~10 Ma and from ~7 to ~9 Ma, respectively, but differ by only ~1 Myr in individual samples. Thermokinematic modeling of the ages indicates that the Brenner fault became active 19±2 Ma ago and caused 35±10 km of crustal extension, which is consistent with independent geological constraints. The model results further suggest that the fault slipped at a total rate of 4.2±0.9 km/Myr and became inactive 8.8±0.4 Ma ago. Our findings demonstrate that both syntectonic heat advection and posttectonic thermal relaxation are responsible for the cooling pattern observed in the footwall of the Brenner normal fault.

References

Braun, J., 2016, Strong imprint of past orogenic events on the thermochronological record: Tectonophysics, v. 683, p. 325–332.

Fügenschuh, B., Mancktelow, N., Schmid, S., 2012, Comment on Rosenberg and Garcia: Estimating displacement along the Brenner Fault and orogen-parallel extension in the Eastern Alps: Int. J. Earth Sci., v. 101, p. 1451–1455.

Rosenberg, C.L., Garcia, S., 2011, Estimating displacement along the Brenner Fault and orogen-parallel extension in the Eastern Alps: Int. J. Earth Sci., v. 100, p. 1129–1145.

Wolff, R., Hetzel, R., Dunkl, I., Anczkiewicz, A.A., Pomella, H. 2020, Fast cooling of normal-fault footwalls: rapid fault slip or thermal relaxation? Geology, v. 48, doi:10.1130/G46940.1.
Urov endemic disease: peculiarities of biogeochemical food chains
Authors: Ermakov Vadim , Gulyaeva Uliana , Danilova Valentina , Safonov Vladimir , Tyutikov Sergey , Degtyarev Alexander
Published: March 2020

The comparative assessment of the levels of content and migration parameters of biologically active chemical elements in the biogeochemical food chains of the main localities of the Urov  endemic disease in the Eastern Transbaikalia: rocks-soils-plants-animal hair, milk was conducted. The differentiated polyelement microelementosis with an excess of Sr [1], Mn, Cr, Ni, in some cases – P, Ba, As, Zn  and deficiency of Se, J, Cu, and Mo is typical in Urov biogeochemical provinces of Eastern Transbaikalia against the background territories. Soil landscapes are not much different in content of selenium, but its migration in plants was reduced in places of spread of Urov disease. Parameters of migration of chemical elements in the soil-plant complex reflected on their content in wheat, hair cover of animals and milk cows. The sources of this imbalance are soil-forming rocks, specific conditions of soil formation (accumulation of organic matter in freezing soils of narrow valleys with a high degree of moisture and low flow, and selective concentration by plants). For floodplain soils with a high level of organic matter is characterized by a high content of micromycetes of the genus Fusarium as their species composition and abundance. The data obtained are consistent with the results of research by Chinese scientists on the assessment of the chemical elemental composition of hair in healthy children and with Urov Kashin-Beck pathology [2] and considered as risk factors in the genesis of this endemic disease.

Funding

This study was supported by the Russian Foundation for Basic Research, project No. 19-05-00054

 

References

Ermakov V.V., U. A. Gulyaeva, S. F. Tyutikov, T. G. Kuz’mina, and V. A. Safonov. Biogeochemistry of Calcium and Strontium in the Landscapes of Eastern Transbaikalia. Geochemistry International, 2017, 55 (12). P. 1105–1117. https://link.springer.com/article/10.1134%2FS0016702917090026

Wang X., Ning Y., Zhang P., Li C., Zhou R., Guo X. Hair multi-bioelement profile of Kashin-Beck disease in the endemic regions of China. J Trace Elem Med Biol., 2019. 54 (July 2019). P. 79-97. https://rareomics.healx.io/disease/kashin-beck-disease.
Metrological calibration strategies and uncertainty assessments for spectroscopic mid-IR isotope ratio measurements in carbon dioxide
Authors: Prokhorov Ivan , Chubchenko Ian , Werhahn Olav , Ebert Volker
Published: March 2020

Optical isotope ratio spectroscopy (OIRS) has recently gained popularity and maturity in isotope research because it simplifies the measurement process and makes isotope ratio measurements in atmospheric greenhouse molecule gases, e.g. CO2, N2O, CH4, more accessible to field research and monitoring networks. OIRS is advantageous in terms of high time resolution, possibility of in-situ measurements and simplified sampling process. However, compared to traditional, high accurate isotope ratio mass spectrometry (IRMS), spectroscopic methods are not yet well established for the highest precision quantification of delta values and agreed recommendations for best practices are still missing. From a metrological point of view, the concept of uncertainty assessment in OIRS field measurements needs to be reported in accordance to the terms of the “Guide to the expression of uncertainty in measurement” (GUM, ISO/IEC Guide 98-3:2008). GUM compliant uncertainty estimation is necessary to assess the metrological comparability of OIRS measurement results. 

In this study we discuss calibration strategies for δ13C-CO2 and δ18O-CO2 measurements with commercial mid-IR OIRS instrumentation (Thermo Scientific Delta Ray), an uncertainty budget for OIRS measurements estimated according to the GUM, and compare the calibration strategies recommended by the manufacturer with our new metrological calibration procedure, which considers aspects so far limiting the accuracy as, e.g., matrix gas effects, CO2 concentration dependence, instrumental drift corrections, and isotope calibration gas uncertainties.

Acknowledgments. This study has received funding from the European Metrology Programme for Innovation and Research (EMPIR) co-financed by the EURAMET Participating States and from the European Union's Horizon 2020 research and innovation programme as of the SIRS project (16ENV06).  PTB is a member of the European Metrology Network for Climate and Ocean Observation.
Have we misunderstood the Shields curve?
Authors: Duran Vinent Orencio , Pähtz Thomas
Published: March 2020

The Shields curve, which compiles measurements of fluvial sediment transport thresholds in terms of the nondimensionalized threshold fluid shear stress and shear Reynolds number, is a standard reference in geophysics and hydraulic and coastal engineering and commonly thought to describe the critical flow conditions that are required for flow-driven entrainment of bed sediment. However, recent findings from several independent research groups have challenged this belief on various grounds: (i) particle-bed impacts predominately trigger sediment entrainment [1]; (ii) such impact-triggered entrainment can sustain continuous transport even when flow-driven entrainment events are (almost) completely absent [2, 3, (4)]; and (iii) extrapolating measurements of the transport rate of such impact-sustained continuous transport to zero yields transport thresholds that still fall on the Shields curve [5]. The question that thus emerges from these findings is, if not flow-driven entrainment, then what is the physics behind the thresholds shown in the Shields curve? We will try to give an answer to this question based on our latest research.

 

[1] Vowinckel et al., Journal of Hydraulic Research, 2016, doi: 10.1080/00221686.2016.1140683

[2] Pähtz & Duran, Physical Review Fluids, 2017, doi: 10.1103/PhysRevFluids.2.074303

[3] Lee & Jerolmack, Earth Surface Dynamics, doi: 10.5194/esurf-6-1089-2018

[4] Heyman et al., Journal of Geophysical Research: Earth Surface, 2016, doi: 10.1002/2015JF003672
Coastal to Abyssal Vertical Sediment Accumulation Rates Predicted via Machine-Learning: Towards Sediment Characterization on a Global Scale
Authors: Restreppo Giancarlo , Wood Warren , Phrampus Benjamin
Published: March 2020

Observed vertical sediment accumulation rates (SARs; n = 1166) were gathered from ~55 years of peer reviewed literature.  Original methods of rate calculation include long-term isotope geochronology (14C, 210Pb, and 137Cs), pollen analysis, horizon markers, and box coring. These observations are used to create a database of contemporary vertical SARs. Rates were converted to cm yr-1, paired with the observation’s longitude and latitude, and placed into a machine-learning based Geospatial Predictive Seafloor Model (GPSM). GPSM finds correlations between the data and established global “predictors” (quantities known or estimable everywhere; e.g. distance from coast line, river mouths, etc.).  The result, using a k-nearest neighbor (k-NN) algorithm, is a 5-arc-minute global map of predicted vertical SARs.  The map generated provides a global reference for vertical sedimentation from coastal to abyssal depths.  Areas of highest sedimentation, ~3-8 cm yr-1, are generally river mouth proximal coastal zones and continental shelves on passive tectonic margins (e.g. the Gulf of Mexico, eastern United States, eastern continental Asia, the Pacific Islands north of Australia), with rates falling exponentially towards the deepest parts of the oceans.  Coastal zones on active tectonic margins display vertical sedimentation of ~1 cm yr-1, which is limited to near shore when compared to passive margins.  Abyssal depth rates are functionally zero at the time scale examined (~10-4 cm yr-1), and increase one order of magnitude near the Mid-Atlantic ridge and at the conjunction of the Pacific, Nazca, and Cocos tectonic plates.  Predicted sedimentation patterns are then compared to established quantities of fluvial sediment discharge to the oceans, calculated by Milliman and Farnsworth in River Discharge to the Coastal Ocean: A Global Synthesis (2011).