bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanoscale STXM imaging of soil fungal exudates and organo-mineral interfaces
Authors: Pucetaite Milda , Persson Per , Hammer Edith
Published: March 2020

Soils act as a major sink for atmospheric carbon (C) and, correctly managed, can help counterbalance the excessive CO2 emissions. Organic C in soils can be physically stabilized and ‘hidden’ from its decomposers within soil aggregates and it is thought that soil fungi play a decisive role in “gluing together” and redistributing soil mineral particles and existing organic matter to form them (M. W. I. Schmidt et al., Nature 478(7367), 49–56, 2011). A significant contribution to the early aggregation process is adsorption of fungal exudates to the reactive surfaces of mineral particles. To uncover the mechanisms of C stabilization processes and to be able to increase the C sink potential of our soils, we need a deepened understanding of which fungi play key roles in the process, what mineral properties promote it, and what type of fungal exudates are involved.

For this purpose, we have grown saprotrophic and symbiotic (both arbuscular mycorrhizal (AM) and ectomycorrhizal (EM)) fungi under sterile conditions in contact with different principal soil components: quartz, goethite and muscovite, on top of X-ray transparent silicon nitride membrane windows and analyzed fungal hyphae by high lateral resolution synchrotron based scanning transmission X-ray microscopy (STXM) in combination with near edge X-ray fine structure (NEXAFS) spectroscopy at absorption edges of C(K), K(L), N(K) and Fe(L). We performed our experiments in the SM beamline at Canadian Light Source, Saskatoon, Canada and I08 beamline at Diamond Light Source, Oxfordshire, UK. In the resultant chemical images, we were able to differentiate the mostly proteinaceous hyphal material, the exudate layer constituting of mixtures of polysaccharides and proteins, and the organo-mineral interfaces consisting of a higher protein and carboxyl to sugar ratio than in the exudate layer. We also observed heterogeneous distributions of the exudate materials around the fungal hypha, indicating presence of exudation channels in the cell wall. Finally, we specifically analyzed NEXAFS spectra at Fe(L) absorption edge of goethite containing samples and were able to show changes in iron speciation in the mineral particles that were in contact with the fungal exudates. These results provide us with better insights to both nanoscale processes of fungal exudation and their role in the formation of organo-mineral interfaces subsequently responsible for soil aggregation.
Lateral particle supply as a key vector in the oceanic carbon cycle
Authors: Kim Minkyoung , Hwang Jeomshik , Eglinton Timothy I. , Druffel Ellen R. M.
Published: March 2020

Despite the potential importance in the oceanic carbon cycle and benthic ecosystem, global feature of lateral supply of aged organic matter hosted on lithogenic particles derived from sediment resuspension has not been systematically examined. We compiled concentrations and fluxes of lithogenic material in the ocean in a global-scale by using literature data of sediment trap studies to understand the contribution of resuspended sediment to sinking particulate matter. We find that these contributions are significant in various oceanic settings, particularly over continental margins. Lithogenic material flux decreased with increasing distance from the margins and above the seafloor. Examination of Δ14C values of sinking POC revealed strong relationships with parameters that represent contribution of resuspended sediment. We then derive estimates for the contribution of aged POC from sediment resuspension to sinking POC based on these relationships and global lithogenic material flux data.
Stochastic simulation of water demands within water resources management
Authors: Bairaktaris Ioannis Michail , Lemonis Anastasios , Mantzouranis Emmanouil , Rontiris Georgios , Nikolopoulos Dionysios , Kossieris Panagiotis , Tsoukalas Ioannis , Efstratiadis Andreas
Published: March 2020

Traditionally, the use of stochastic models within water resources management aim to provide synthetically-generated inflow time series that reproduce the statistical regime of the historical data. On the other hand, the water uses are typically handled as steady-state elements, which follow a constant seasonal pattern over the entire simulation horizon. However, given that the demands are associated with highly uncertain hydroclimatic and socioeconomic factors, they should also be considered as random variables, as made for inflows. Using as example a complex hydrosystem in Western Thessaly, Greece, comprising both surface and groundwater resources to serve irrigation, water supply, environmental and hydroelectric uses, we demonstrate the advantages of a fully stochastic setting of the water management problem over its traditional configuration. Among others, we investigate the use of synthetic demands that are correlated with inflows, given that both are driven by hydroclimatic processes. Data syntheses are employed with the recently introduced AnySim stochastic simulation package (https://www.itia.ntua.gr/en/softinfo/33/).
Sensitivity studies of the 4.8 micron carbon dioxide absorption band for high temperature events
Authors: Romaniello Vito , Spinetti Claudia , Silvestri Malvina , Buongiorno Maria Fabrizia
Published: March 2020

Measuring the sources of carbon dioxide is of high interest in order to know the distribution of this greenhouse gas and quantify the natural/anthropogenic emissions. The aim of the present study is to understand the capability of the absorption band at 4.8 µm to detect and measure the CO2 emissions from different HTEs (High Temperature Events) like degassing plumes from active volcanic sources, fires and industrial emissions. The performance of this channel was investigated by using the MODTRAN (MODerate resolution atmospheric TRANsmission) radiative transfer model. Simulations of the TOA (Top Of Atmosphere) radiance have been performed by using real input data to reproduce realistic scenarios on a volcanic high elevation point source (>2 km). The sensitivity of the channel has been analysed varying CO2 concentrations (in the range 0-1000 ppm) and surface temperatures from standard (300 K) to high temperature (1000 K). Moreover, typical response functions of imaging sensors carried on aircraft and operating in the Middle Wave InfraRed (MWIR) spectral region were used: the channel width values of 0.15 µm and 0.30 µm were tested. Simulations provide results about the sensitivity necessary to appreciate carbon dioxide concentration changes considering a target variation of 10 ppm in the gas column concentration. The results show the strong dependence of at-sensor radiance on the surface temperature: radiances sharply increase, from 1 Wm-2sr-1µm-1 (in the standard condition) to >1200 Wm-2sr-1µm-1 (in the warmest case). The highest sensitivity has been obtained considering the channel width equal to 0.15 µm with noise equivalent delta temperature (NEDT) values in the range from 0.045 to 0.560 K at surface temperatures ranging from 300 to 1000 K. Furthermore, data acquired by the multispectral MASTER (Modis ASTER) airborne simulator on Kilauea volcano (Hawaii), during the January/February 2018 campaign, were considered. The aim is to estimate lava flow/lake temperatures and to test the channel at 4.8 µm for retrieving CO2 emissions on volcanic craters.
Prediction of Power Output in a Large Wind Farm Using the WRF Model
Authors: Teng Wei-Guang , Wu Yu-Ting , Lin Chun-Yao
Published: March 2020

A weather research and forecasting (WRF) model, offline coupled with the Jensen’s wake model in WASP, is used to predict the power output in a large wind farm located within the Changhua Coastal Industrial Park, Taiwan. The wind farm has 31 Vestas V80 wind turbines with a hub height of 67 m installed in the park area (about 8 by 8 square km). A WRF simulation can provide simulation results of wind speed, wind direction, pressure, and temperature every 30 minutes for model validation. We chose December 2015 as the main simulation scenario, because that month was mainly northeast monsoon, and the wind speed could change from 2-3 m/s to more than 25 m/s every 3 to 7 days. The WRF results are then used in Jensen’s wake model in WASP to estimate the turbine power output. The simulation results show that as long as the turbine is under normal operating conditions, the predicted and actual measured power outputs have an acceptable agreement. The comparison of wind speed and wind direction is also quite consistent. The predicted temperature is lower than the measured temperature at the actual hub position. This discrepancy is mainly because the hub generator generates a lot of heat during the power generation process, which causes the air temperature near the hub to rise.
How do grain size and dose of sunflower husk biochar influence the water retention of sandy soil?
Authors: Rafalska-Przysucha Anna , Szlązak Radosław , Vitková Justina , Gluba Łukasz , Lukowski Mateusz , Szewczak Kamil , Usowicz Bogusław
Published: March 2020

Biochar is a carbon-rich material obtained from the process of biomass pyrolysis. Due to its desirable properties, it is discussed as a soil amendment to improve soil quality; for example, adding biochar can change soil water retention by modifying soil textural and structural properties. However, the optimal fabrication conditions and proportions of biochar particles sizes, that would improve soil properties are still not precisely known. In our research, we investigated the influence of grain size and a dose of biochar on water retention of sandy soil. For this purpose, water retention curves (pF) were measured, as it indicates such important properties as plant available water, field water capacity, wilting point. The studies were carried out on podzol soil samples taken from meadow located in Sekow, Poland, mixed with different percentage mass content of sunflower husk biochar produced in 650-750°C (0.95, 2.36, 4.76 and 9.52% of sample weight). Samples contain one of biochar granulometric fraction: 250-100, 100-50 or less than 50 µm. The control included soil samples with the addition of mixed fractions of biochar and soil without biochar. The research method we used allows obtaining information about plant available water content by comparing differences in water content between 0.06 and 5 bar pressure points which corresponding to a 1.85-3.7 pF. In this range, most plants can use water for their growth and development. Our results revealed that, surprisingly, soil with all fractions of biochar reduces the amount of available water for plants compared to the control (soil without biochar), regardless of the biochar dose applied. However, fractionated biochar can both increase or decrease the soil water content, depending on the particle size and dose. Small doses of sunflower husk biochar (0.95 and 2.36%) and the finest fraction (<50μm) have the most beneficial effects for water retention of investigated soil. Our research may strongly suggest the biochar producers that the production of biochar with the right fraction may be more favourable for increasing soil water retention. 

Research was partially conducted under the project “Water in soil - satellite monitoring and improving the retention using biochar” no. BIOSTRATEG3/345940/7/NCBR/2017 which was financed by Polish National Centre for Research and Development in the framework of “Environment, agriculture and forestry” – BIOSTRATEG strategic R&D programme.
Web-based hydrological modelling tool - Hidro-Odtu
Authors: Karaman Çağrı Hasan , Akyürek Zuhal , Bolat Kenan
Published: March 2020

Bucket-type conceptual hydrological models are widely popular, because of their relatively low data and computational demands. With the improved computational techniques and advances in computer sciences, web based hydrological modelling tools are becoming available too. Conceptual rainfall-runoff (CRR) models are designed to approximate the general physical mechanisms which govern the hydrologic cycle and found practical by many hydrologists and engineers. In this context, a web based, open-source, platform independent, easily accessible hydrological modelling tool Hidro-Odtu has been designed. Aiming at providing fast and accurate results, Hidro-Odtu utilize lumped and semi-distributed hydrological modelling capabilities. The design of the Hidro-Odtu contains pre-processing using the tools to automatically delineate the river network and basin boundaries, input the forcing data, lumped hydrological modelling with parameter calibration capability, hydrological overland flow routing and dynamic result visualization. Moreover, web-based technologies allow remotely prepare model input files, run model calculation and display model results for rainfall-runoff calculations. Bucket storage lumped, conceptual rainfall-runoff model is selected as core feature for hydrological model and it is enhanced to a semi-distributed model by including the Muskingum-Cunge flow routing method to simulate overland flow. Model results are evaluated by several performance indices such that Nash–Sutcliffe Efficiency Index (NSE), Sum of Square of Error (SSE) or Kling-Gupta Efficiency (KGE).

Hydrological modelling, calibration and routing algorithms have been implemented by using Python programming language for the back-end calculations and Node.js framework, html, JavaScript have been utilized for front-end side to handle data preparation and results visualization.

Hidro-Odtu have been evaluated with numerous data sets with different study areas and found successful to delineate sub basins and river network, to define rainfall-runoff relationship on the basis of the sub-basins. With this tool, it is aimed to obtain practical hydrological modelling results using web technologies.
Impact of the Wintertime Meteor Showers on the Sporadic E Layer Activity at Midlatitudes
Authors: Barta Veronika , Mosna Zbysek , Kouba Daniel , Igaz Antal , Sárneczky Krisztián
Published: March 2020

The impact of meteor showers and individual meteors on the ionosphere has been investigated during wintertime meteor showers using synchronised measurements of two DPS-4D Digisondes installed at Pruhonice (50°, 14.5°) and at Sopron (47.63°, 16.72°). Rather short distance between Pruhonice and Sopron allow us to perform special joint campaigns of vertical and oblique sounding under the high sampling rate to detect fine structures within ionospheric plasma.

 

High cadence campaigns have been performed to observe behavior of sporadic E layer (Es) during the Leonids, Geminids and Quadrantids meteor showers in 2018 and 2019. The time resolution of the ionograms have been set to approximately 0.5 - 2 ionograms per minute. We used vertical and oblique reflections to investigate the fine structure and the movement of Es layer. Based on the first results the oblique sounding is a good technique to detect the Es activity between two stations, however there were periods (typically 10 to 40 minutes of duration) when the Es was observed using oblique trace but there was no observation of Es layer in vertical ionograms. Furthermore, double Es structures have been detected more times for tens of minutes during the observation nights.

 

Beside the regular behavior of Es we concentrated on observation of intervals of increased plasma frequency in the Es region presumably directly induced by the meteors. In the framework of GINOP-2.3.2-15-2016-00003 (“Kozmikus hatások és kockázatok") an optical camera has been installed at the MTA Széchenyi István Geophysical Observatory (Sopron) in September 2019 with the cooperation of the Konkoly Observatory to monitor the meteors. Therefore, we were able to compare the ionograms measured during meteor showers with the optical data to determine the plasma trails of individual meteors. In the 20-25% of the observed meteors a faint Es layers were detected on the ionograms during and after (< 1 min) the optical record. The direction of the detected plasma traces determined by the SAO Explorer was in good agreement with the direction of the optically observed meteors in most of the cases. Consequently, the plasma trace of individual meteors could be detected on the high time resolution ionograms.
Adaptation of the MMF (Morgan-Morgan-Finney) model to Mediterranean forests subject to wildfire and post-fire rehabilitation measures
Authors: Zema Demetrio Antonio , Nunes Joao Pedro , Lucas-Borja Manuel Esteban
Published: March 2020

The hydrological effects of wildfire are very difficult to predict in Mediterranean forests, due their intrinsic semi-arid climate and soil characteristics. The Morgan-Morgan-Finney (MMF) model has shown generally accuracy and reliability in predicting surface runoff and soil erosion in several environmental contexts. In spite of its ease use and limited input requirements, few applications exist in Mediterranean forests with or without post-fire rehabilitation measures; therefore, its applicability to those conditions may be questionable without purposed verifications.

To fill this gap, the MMF model has been verified at the seasonal and plot scales in areas affected by a wildfire of a Mediterranean forest, with and without post-fire straw mulch treatment. The application of MMF with input parameters set up according to the original guidelines of the model’s developers led to poor performance in every soil condition. Subsequently, the model has been adapted to burned soils and Mediterranean climate characteristics, introducing changes in input data for both the hydrological and erosive components (seasonal values of evapotranspiration, reduction of the soil hydrological depth, including soil water repellency effects in burned soils, and modelling erosive precipitation only). By these adaptations, MMF was able to predict seasonal runoff volumes and soil loss with good reliability in all the experimented conditions.  

This modelling experiment has shown the capacity of the MMF model to simulate the seasonal hydrological response of the burned and mulched soils of Mediterranean forests. Therefore, the potential applicability of the model is promising as a management tool for predicting and controlling the erosion risk in semi-arid forest ecosystems threatened by wildfire as well as to evaluate the efficiency of post-fire treatments.
The scholar seismic network of Tenerife: technical and scientific issues
Authors: Domínguez Vidal , Barrancos José , D'Auria Luca , Peréz Nemesio M.
Published: March 2020

Currently thousands of seismic sensors, managed by different national and international institutions, are deployed throughout the planet. In the last decades, thanks to scientific and technological advances, broadband sensors are being produced at costs affordable for most institutions that operate a seismic network. At the same time, advances in nanotechnology led to the development of MEMS sensors which allowed the development of accelerometers of very reduced dimensions and low costs. The seismic data obtained by the commercial MEMS sensors, can be sampled, synchronized, stored and transmitted through low cost microcontrollers such as RaspberryPi or Arduino. This allows the development of a complete seismic station of very small size and cost with respect to the traditional ones, although of lower sensitivity and quality.

Since 2019, Instituto Volcanológico de Canaria (INVOLCAN) is developing a low cost seismic network: the Red Sísmica Escolar Canaria (RESECAN, Scholar Canarian Seismic Network) with multiple purposes. The main aims of RESECAN are:

supporting the teaching of geosciences

promoting the scientific vocation

strengthening the resilience of the Canarian communities by improving awareness of the Canary volcanism and the associated hazards.

The project aims at realizing and distributing low-cost stations in various educational institutions of the Canary Islands, complementing them with didactic material on the topics of seismology and volcanology. Each school will be able to access the data of its own station, as well as other centers, being able to locate some of the recorded earthquakes. The data recorded by RESECAN will be fully integrated with the data of the Red Sísmica Canaria (C7), a permanent broadband seismic network operated by INVOLCAN. This will make RESECAN also an instrument of scientific interest able to contribute effectively to the volcanic monitoring of the Canary Islands, strengthening its resilience in facing future volcanic emergencies.
Kinetic Vlasov simulations of contact discontinuities
Authors: Umeda Takayuki , Tsujine Naru , Nariyuki Yasuhiro
Published: March 2020

The stability of contact discontinuities formed by the relaxation of two Maxwellian plasmas with different number densities but the same plasma thermal pressure is studied by means of a one-dimensional electrostatic full-Vlasov simulation. Our simulation runs with various combinations of ion-to-electron ratios of the high-density and low-density regions showed that transition layers of density and temperature without jump in the plasma thermal pressure are obtained when the electron temperatures in the high-density and low-density regions are almost equal to each other. However, the stable structure of the contact discontinuity with a sharp transition layer on the Debye scale is not maintained. It is suggested that non-Maxwellian velocity distributions are necessary for the stable structure of contact discontinuities. A direct comparison between full- and hybrid-Vlasov simulations is also made.
Derivation of 3D deformation fields for the 2019 Ridgecrest Earthquakes (USA) based on Sentinel-1 TOPS data
Authors: Horvath Roland , Magyar Balint , Kenyeres Ambrus
Published: March 2020

The advances of Sentinel-1 SAR data, like its open access policy and short revisit time, gives an outstanding opportunity to conduct in-situ mapping of large scale deformations. After the requisite calibrations and corrections (radiometric, terrain), geocoding, coregistration and phase unwrapping; the unwrapped phase can be converted to Line-of-site (LOS) displacements. Although it gives a characteristic picture of the investigated phenomena only in one-dimension, but to obtain tree-dimensional (East/North/Up – ENU) deformation, it requires a more complex approach.

To obtain the complete tree-dimensional displacement field, both ascending and descending LOS displacements shall be retrieved. As well as, the corresponding unit-vector of LOS look-vectors and its parallel, along-track azimuth vector in the direction of the azimuth offsets, from the SAR sensor to all measurements (pixel) in ENU format. This lead to four observations with different incident angles for each measurements, which can be generalized as an over-determined inverse problem. The estimated model vector of the complete tree-dimensional displacement can be obtained, if the Jacobi-matrix can be represented as the look-vectors in ENU basis and the observation vector as LOS deformations acquired from the unwrapped phase of the interferogram. Then the over-determined linear equation system can be solved in the L2 norm via the Gaussian Least Squares (LSQ) approach combined with Singular Value Decomposition (SVD).

Demonstrating the aforementioned, we present the continuation of DInSAR results of the two strike-slip earthquakes between 2019.07.04-06. with foreshock MW =6.5 and mainshock M W =7.1 in the Eastern Californian Shear Zone near Ridgecrest (US).
Projected precipitation changes over China for global warming levels at 1.5°C and 2°C in an ensemble of regional climate simulations: Impact of bias-correction algorithms
Authors: Guo Lianyi
Published: March 2020

Four bias-correction methods, i.e. Gamma Cumulative Distribution Function (GamCDF), Quantile-Quantile Adjustment (QQadj), Equidistant CDF Matching (EDCDF) and Transform CDF (CDF-t), were applied to five daily precipitation datasets over China produced by LMDZ4-regional that was nested into five global climate models (GCMs), BCC-CSM1-1m, CNRM-CM5, FGOALS-g2, IPSL-CM5A-MR and MPI-ESM-MR, respectively. A unified mathematical framework can be used to define the four methods, which helps understanding their nature and essence in identifying the most reliable probability distributions of projected climate. CDF-t is shown to be the best bias-correction algorithm based on a comprehensive evaluation of different rainfall indices. Future precipitation projections corresponds to the global warming levels of 1.5°C and 2°C under RCP8.5 were obtained using the bias correction methods. The multi-algorithm and multi-model ensemble characteristics allow to explore the spreading of results, considered as a surrogate of climate projection uncertainty, and to attribute such uncertainties to different sources. It was found that the spread among bias-correction methods is smaller than that among dynamical downscaling simulations. The four bias-correction methods with CDF-t at the top all reduce the spread among the downscaled results. Future projection using CDF-t is thus considered having higher credibility.
Observation and Quantification of CO2 passive degassing at sulphur Banks from Kilauea Volcano using thermal Infrared Multispectral Imaging
Authors: Boubanga Tombet Stephane , Gatti Sylvain , Eisele Andreas , Morton Vince
Published: March 2020

The formation of Earth atmosphere and oceans have been primarily deeply influenced by volcanic emissions. In addition, the planet radiative balance and stratospheric chemistry can be affected by materials injected into the atmosphere by large explosive eruptions. Volcanic emission often contain water vapor (H2O), carbon dioxide (CO2), and depending on the type of volcano they may contain varying proportions of toxic/corrosive gases such as Sulphur dioxide (SO2), hydrogen fluoride (HF) and silicon tetrafluoride (SiF4). CO2 is generally the most abundant gas with the lowest solubility among the volatile compounds of magmatic liquids and the less susceptible than most other magmatic substances such as SO2 and HF. Thanks to those properties, the volcanic CO2 emission rates could play an important role for assessing volcanic hazards and for constraining the role of magma degassing in the biogeochemical cycle of carbon. However, measurements of CO2 emission rates from volcanoes remain challenging, mainly due to the difficulty of measuring volcanic CO2 against the high level of CO2 in the atmosphere. Thermal Infrared (TIR) imaging is now a well-established tool for the monitoring of volcanic activity since many volcanic gases such as CO2 and SO2 are infrared-active molecules. High speed broadband cameras give valuable insight into the physical processes taking place during volcanic activity, while spectrally resolved cameras allow to assess the composition of volcanic gases.

In this work we conducted TIR imaging and quantification of CO2 passive degassing at Sulphur Banks from Kilauea volcano using Telops Midwave Infrared time-resolved multispectral imager. The imager allows synchronized acquisition on eight channels, at a high frame rate, using a motorized filter wheel. Using appropriate spectral filters measurements allows estimation of the gas emissivity parameters in addition to providing selectivity regarding the chemical nature of the emitted gases. Our results show CO2 measurements within the volcano’s plume from its distinct spectral feature. Quantitative chemical maps with local CO2 concentrations of few hundreds of ppm was derived and mass flow rates of few g/s were also estimated. The results show that thermal infrared multispectral imaging provides unique insights for volcanology studies.
Establishment of Digital mapping for Slope Maintenance
Authors: Kim Wooseok , Koo Kiyoung , Kwon Oil , Kim Jinhwan
Published: March 2020

In Korea, basic safety management and maintenance are performed with budget support and done systematically in the case of common general national road, highway and railroad slopes. However, in the case of local governments with a low fiscal self-reliance ratio, even the current state of slopes is not assessed. With this in mind, research development for the maintenance of various slopes to enable analysis within a budget and management automation is required.
This research aims to build an digital mapping production platform to be used as a part of the slope investigation and maintenance on slopes affecting national highways. Digital mapping produced through this platform are used as input data for the automatic identification of slope weak points. For this, an analysis was performed for the adaptability of the drawing products using Open-source photogrammetry S/W which is known to have excellent performance. The performance of this S/W was verified using LIDAR data for small size bedrock, and its adaptability was verified using measured data for actual slopes.
The utilization of the results of this research are adjudged and made available for actual slope image data. The results also are available for the foundation of utilizing operation guidelines for supporting using multiple resolutions (Project Number: 20SCIP-C151408-02).
Physical drivers of oxygen depletion in the Central and Eastern Baltic Sea
Authors: Liblik Taavi , Stoicescu Stella-Theresa , Laanemets Jaan , Samlas Oliver , Salm Kai , Suhhova Irina , Lilover Madis-Jaak , Lips Urmas
Published: March 2020

Eutrophication and consequent increase in biomass production and sedimentation of organic material cause oxygen depletion of the deep layers and an increase in hypoxic bottom areas in the Baltic Sea.

The Baltic Sea – a semi-enclosed brackish sea – has restricted water exchange with the North Sea. High fresh water runoff and sporadic inflows of saline water through the Danish Straits maintain stratification. Seasonal thermocline and quasi-permanent halocline, their vertical location, shape and strength are sensitive to atmospheric forcing and influence the oxygen depletion in the near-bottom layer. Physical processes altering deoxygenation in the three sub-basins of the Baltic Sea (Baltic Proper, Gulf of Finland and Gulf of Riga) are under scope of the present overview. Permanent halocline is present in the deep Baltic Proper, while in the Gulf of Finland, it occasionally vanishes during winter. Complete mixing occurs in each winter in the shallow Gulf of Riga separated from the Baltic Proper by the sill. We show that the bathymetry, combined with physical drivers, causes distinct spatial and temporal patterns of oxygen depletion in the basins. The results presented here are a summary of in-situ measurement campaigns conducted by the research vessel, underwater glider, autonomous vertical profiler and bottom moorings in 2011–2020.

Large barotropic inflows from the North Sea temporarily ventilate the deep layer of the Central Baltic Proper, but rather intensify hypoxia in the Northern Baltic Proper and the Gulf of Finland. Wind-driven estuarine circulation alterations shape the hypoxic area and volume in the Gulf of Finland considerably. Seaward winds support estuarine circulation and the advection of hypoxic saltier water of the Northern Baltic Proper into the gulf deep layer. The landward wind can reverse estuarine circulation, the collapse of stratification and mixing of the whole water column in winter (when the seasonal thermocline is absent), thus, temporarily improving oxygen conditions in the deep layer of the gulf. Intrusion of cold saltier water of the Baltic Proper over the sill into the Gulf of Riga deep layer strengthens water column stratification and supports hypoxia formation in summer. Such a water exchange regime is related to the northerly wind forced upwelling along the eastern coast of the Baltic Proper. The role of submesoscale processes on vertical mixing and deep layer ventilation is still unclear, and the data of high-resolution in situ measurements in the Baltic Sea is limited yet. Preliminary results from the dedicated underwater glider surveys conducted at the coastal slope of Eastern Baltic Proper in 2019-2020 will be presented.
Applying the denitrification method to 15N and 18O analysis of nitrate in natural groundwater samples
Authors: Stock Patricia , Roder Susanne , Burghardt Diana
Published: March 2020

This study aims to develop a simplified denitrification method for the δ15N and δ18O analysis of nitrate (NO3–) in natural groundwater samples following Zhu et al. (Sci Total Environ. 2018; 633: 1370–1378) and Sigman et al. (Anal Chem. 2001; 73: 4145–4153). With the help of Pseudomonas aureofaciens bacteria, the simplified method induced denitrification of the sample and completely converted the NO3– into measurable N2O while avoiding sample fractionation. In contrast to the classic denitrification method (Sigman et al., 2001), which is based on anaerobic cultivation, the bacteria are cultivated aerobically in the simplified method (Zhu et al., 2014). In this study, aerobic cultivation was performed in a nitrate-free medium. Unlike the other two methods, aerobic cultivation was performed without the addition or removal of nitrate in the liquid medium. This eliminates the need for another preparation step, saving time. There was no contamination with external NO3–. After further optimising the influencing factors, the method yielded high accuracy and precision (standard deviations were generally ≤ 0.7‰ for δ18O and ≤ 0.3‰ for δ15N), confirming the suitability of this procedure. Finally, the potential applicability of the method was demonstrated by measuring the isotopic composition of NO3– in natural groundwater samples.
A Research on Technology Development in response to Slope Reinforcing Facility (Anchor) Aging
Authors: Park Byungsuk , Kwon Oil , Kim Seunghyn , Lee Jonghyun , Woo Yonghoon
Published: March 2020

Recently, various drawbacks have been pointed out on the aspects of design, construction, and maintenance of anchor-reinforced slopes, and in some research the causes of increases and decreases of the tension force of the anchor are analyzed. However, research on the development of technology to cope with increases and decreases of the tension force in terms of maintenance is rare. In case that slipping occurs on an anchor-reinforced slope, shear and bending stress will occur in the shear section along the slip surface, and the anchor force may increase when slipping persists due to the deformation of the anchor body. Additionally, if shear deformation occurs in the anchor, cracks will occur in the grout at a relatively low deformation rate, and when deformation continues, the tension force may be further reduced due to the destruction of the grout. We tried to define investigation methodologies and safety plans through the analysis of case studies on functional loss sections, such as fractures of strands due to the excessive load placed on the anchors. From the results of the anchor lift-off test of 466 holes, the number of anchors that could not be retensioned was 177 holes, and the number of anchors with an increased tension force was 49 holes. From the results of ground exploration, it was found that soiled weathering zones or weathering zones with fractured bedrock were distributed at depths of 30m or more. It is analyzed that most anchor settlement with insufficient anchor forces were located in the slip surface and lacked anchor length. It is found that the safety of the slope can be secured if additional reinforcing anchors are installed around anchors with poor strand strength or anchors that cannot be retensioned.(Project Number: 20SCIP-C151408-02).
A unified typology for small European rivers
Authors: Jupke Jonathan , Schäfer Ralf
Published: March 2020

A large number of chemicals such as pharmaceuticals, pesticides and industrial chemicals are in daily use. In Europe alone, an estimated 100,000 chemicals are in current use, of which 30,000 are produced in quantities larger than one ton per year. Chemicals can enter freshwater ecosystems as an intended (e.g. deliberate emission as in the case of pesticides) or unintended (e.g. wastewater discharge as in the case of pharmaceuticals) byproduct of their use. In the environment, many chemicals (hereafter called toxicants) can exert adverse toxic effects on freshwater organisms and in turn on ecosystem functions. The potential toxic effects of chemicals are often examined within the context of Ecological Risk Assessment (ERA). ERA consists of standardized procedures and methods to evaluate the environmental risks of ecological systems. An open question is to what extent ERA needs to account for differences between recipient ecosystems that are subject to chemical exposure. For example, in the European context, is a single ecological threshold concentration per substance sufficient or is the sensitivity of the organism’s dependent on water body size, geology or climate.

As previous studies have shown that the latter factors influence the community composition of algae and invertebrates, we aim to compare the sensitivity of communities across macroecological gradients. 

We established a typology of small streams for eight European countries that captures the major macroecological gradients and identified typical ecological assemblages for each type. The typology is based on the Catchment & Characteristics Modelling 2 database and incorporates catchment properties such as climate, geology, and altitude as well as river attributes such as sinuosity and flow regime statistics. The latter are derived from modeled daily discharge values. Through CLARA-clustering of the resulting data, we obtained a classification into 14 stream classes. We focused on smaller rivers as they constitute the majority of river length, host a higher share of biodiversity than large rivers, and are more susceptible to pollution. The presented typology is built from the ground up with openly accessible data. All code will be made publicly available; thus, it will be easy to update, modify, and extend the typology. Beyond our application the typology can be used to regionalize ecological and hydrological models, to inventory the number and state of different river types or to develop individualized conservation programs.

Based on the identified typical assemblages we can also present preliminary relative sensitivities of stream types towards different toxicants.
Assessment of turbulent scales over complex terrain in central Spain
Authors: García-Pereira Félix , Maqueda Gregorio
Published: March 2020

In this work, a micrometeorological assessment of Atmospheric Boundary Layer paremeters is carried out in order to determine the characteristic turbulent scales over complex terrain in the Sierra de Guadarrama, a range in central Spain. Observational data series of temperature and wind velocity measured at high frecuency (10 Hz) are available. These data come from two different stations located in the Bosque de La Herrería and belonging to GuMNet (2020) (Guadarrama Monitoring Network).

Integral scales, both time and spatial, have been determined for different atmospheric conditions, defined by parameters such as wind direction or stability of stratification. Also, energy cascade phenomenon occurence is assessed. In order to carry this out, different time series analysis tools are used, such as autocorrelation functions in time, and normalised power spectra or wavelets. Results obtained are compared with previous works.

In general, results show that under no synoptic forcing there is a clear dependency on diurnal cycle, giving rise to the development of big integral scales at nighttime, while they are small during the day. When synoptic forcing prevails, the scales are also small, both at daytime and nighttime. Moreover, a correlation patterns method has been implemented for scales obtained at two different heights (4 and 8 meters) on the one hand and at two locations on the other. In the first case, integral scales are highly correlated, exceeding the threshold of 0.5. In the second case, temporal scales show high correlation values, but spatial ones do not.  In addition, the slopes of the spectra in the inertial subrange have  been obtained and compared to those over homogeneous terrain (Kaimal et al., 1972), getting similar results for velocity turbulent components but not in case of vertical kinematic momentum and heat fluxes.

 

References

GuMNet: Guadarrama Monitoring Network (UCM), https://www.ucm.es/gumnet/, 2020.

Kaimal, J. C., Wyngaard, J. C., Izumi, Y., and Coté, O. R.: Spectral characteristics of surface- layer turbulence, Quart. J. R. Met. Soc., 98, 563–589, 1972.
Experimental time constraints on the kinetic and chemistry of amphibole at deep crustal levels
Authors: Bonechi Barbara , Perinelli Cristina , Gaeta Mario , Tecchiato Vanni , Fabbrizio Alessandro
Published: March 2020

Aiming to improve the current knowledge about amphibole growth kinetics at deep crustal levels, new amphibole growth rate data are provided. Our findings, indeed, may be useful to correctly interpret the textural features of amphibole-bearing mafic cumulates and rocks, and for a better constraining of the timescales of magmatic processes at upper mantle-lower crustal depths. Experiments were performed to determine the amphibole growth rates in a primitive alkaline basalt from Procida island (Campi Flegrei Volcanic District, southern Italy) at the following conditions: temperature of 1030 and 1080 °C, pressure of 0.8 GPa, water content in the range 3.3-4.2 wt%, and variable dwell time from 0.25 to 9 h. Amphibole growth rates range from 1.5·10-7 to 2.9·10-8 cm·s-1 with increasing the duration of the experiments. It is observed that, keeping a constant dwell time, an increase of the experimental temperature or of the water content results in comparable growth rate increase. Coexisting synthetic amphibole and clinopyroxene show a faster growth rates in favour of amphibole regardless of the dwell time, since the chemical and structural similarities of these minerals cause kinetic competition. Moreover, the chemical composition of amphibole is influenced mainly by the experimental time; in detail, in the shortest (≤3 h) and low temperature runs edenite is the prevailing composition whereas the magnesiohastingsitic term becomes dominant at higher temperature and longer run duration. Based on the interpretation of the Fe-Mg exchange coefficient values between amphibole and coexisting liquid, the magnesiohastingsitic amphibole is considered to be the stable term at the investigated run conditions. Finally, the resulting growth rates have been applied to constrain the crystallization time of natural amphiboles and clinopyroxenes from the Oligo-Miocene cumulates of north-western Sardinia (i.e., Capo Marargiu  Volcanic District, Italy), yielding crystallization times in the range 1.46-3.12 yr.
Improved estimates of non-tidal environmental loading contribution into Zenith Total Delay series over Europe
Authors: Bogusz Janusz , Klos Anna , Pacione Rosa , Humprey Vincent , Dobslaw Henryk
Published: March 2020

The motivation of this study is to assess the spatio-temporal patterns in the Zenith Total Delay (ZTD) time series estimated within the second re-processing campaign (1996-2014) of the EUREF Permanent GNSS Network (EPN, http://www.epncb.oma.be) for a set of European stations. In particular we used AS0 solution provided by the EPN analysis center ASI (Agenzia Spaziale Italiana Centro di Geodesia Spaziale, Italy), and GO1 and GO4 solutions provided by the EPN analysis center GOP (Geodetic Observatory Pecny, Czech Republic) along with the combined EPN Repro-2 products. Solutions differ by processing options and number of stations processed. We find that all individual ZTD solutions are characterized by pure autoregressive noise, which is reduced during the combination, meaning that some part of information is lost in the combination procedure. Combination procedure does not however affect spatial patterns of ZTD residuals (trend and seasonal signals are removed beforehand). They are almost the same for both individual and EPN Repro-2 combined solutions. This means that regional ZTD estimates reflect tropospheric dynamics even at very high-frequency signals of small variance. Therefore, we compute ZTD differences from the two GOP solutions GO1 and GO4, which only differ by unmodelled non-tidal atmospheric loading. We find that there is a similarity between the ZTD differences and non-tidal atmospheric loading which is strongly demonstrated in terms of unusual loading events, as significant non-linear trends or large seasonal peaks. As these similarities are only observed for GO1 and GO4 differences, this indicates that unmodelled vertical loading effects contribute 50% of the ZTD noise, affecting errors of trends.
Flow signatures and basin parameters for Hierarchical tunisian Catchments clustering and similarity assessement.
Authors: Cherif Rim , Gargouri Ellouze Emna
Published: March 2020

Regional frequency approaches are frequently proposed in order to estimate runoff quantiles for non-gauged catchments. Partitioning methods such as cluster analysis are often applied in order to regionalize catchments.

This study presents an investigation based on the hierarchical clustering method related to watershed Hydro-geomorphic descriptors and aims to compare types of distances signatures involved in the clustering approach.

The delineation pooling groups (regions) is based on distances calculated between sites in multidimensional space: hydrological, physiographical and geomorphological characteristics.

Resulting clusters are then checked for homogeneity level by silhouette index.

We consider in this work A data set from nineteen (19) catchments situated in the Tunisian ridge, monitored since 1992, is used to apply this comparison. 

 Latitudes vary from 35°N to 37°N and longitudes from 8°E to 11°E; areas range between 1 km2 and 10 km2. These catchments are located in a semi-arid zone; with annual average rainfall fluctuating between 280 mm and 500 mm. The relief is moderately high to-high for the majority of the basins, which helps rapid runoff. These catchments are little permeable to impermeable. The rain gauge network consists of 20 gauges.

The delineation of regions in multidimensional space involves hydrological signatures, physiographical and geomorphological catchment characteristics. The last ones are : area, perimeter, maximum altitude, minimum altitude, specific height, global slope index, equivalent rectangle length, equivalent rectangle width, Gravellus index, the percentage of pasture land ; the percentage of forest cover, the percentage of cereal culture area, the percentage of arboriculture area and the percentage of area affected by anti-erosive practices. Hydrological signatures are: specific maximum discharge, runoff volume, time to peak, base time, infiltration index and runoff coefficient.

Hierarchical culstering are applied with several distances calculated from these signatures and characteristics. Two clusters are considered for basin regions. Nine distances are compared (euclidean , Spearman, Cheybechev, cityblock, correlation, cosine, hamming, Jaccard, Minkowsky).

Silhouettes values are calculated for each cluster based on the distances calculated. All distances give satisfying results and correlation and Cosine distance give relative best silhouette values.

 