bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Formaldehyde Measurements by HANTZSCH, CRDS and DOAS instruments in the SAPHIR Chamber
Authors: Glowania Marvin , Fuchs Hendrik , Rohrer Franz , Dorn Hans-Peter , Holland Frank , Tillmann Ralf
Published: March 2020

Three instruments using different measurement techniques were used to measure formaldehyde (HCHO) concentrations during experiments in the atmopshere simulation chamber SAPHIR at the Forschungszentrum Juelich. An AL4021 instrument by Aero Laser GmbH uses the wet-chemical Hantzsch reaction for efficient gas stripping, chemical conversion and fluorescence measurement. An internal permeation gas source provides daily calibrations characterized by sulfuric acid titration. A G2307 analyzer by PICARRO INC. uses Cavity Ring-Down Spectroscopy (CRDS) technique to determine concentrations of HCHO, water and methane. A high-resolution laser differential optical absorption spectroscopy (DOAS) instrument provided HCHO measurements along the central chamber axis using an optical multiple reflection cell. The measurements were conducted from June to December 2019 in experiments when ambient air was flowed through the chamber and also in photochemical experiments in synthetic air with mixtures of different reactants, water vapour, nitrogen oxides, and ozone concentrations. Results demonstrate the importance for a linear base line interpolation between zero measurements for the Hantzsch instrument. In addition, a strong water dependence of the baseline of CRDS measurements was found. After correction for the baselines, the correlation analysis of measurements demonstrate good agreement (R > 0.98) between the instruments.
Characteristics of daytime medium scale traveling ionospheric disturbances (MSTIDs) as observed by SWARM
Authors: Nayak Chinmaya , Buchert Stephan
Published: March 2020

This paper studies the daytime medium scale traveling ionospheric disturbances (MSTIDs) in the mid- and low-latitude ionosphere for a period of nearly half a solar cycle (2014-2019) using SWARM observations. We specifically focus on daytime MSTIDs to rule out any contribution from nighttime plasma irregularities. Fluctuations in electron density are primarily used to identify the MSTIDs. These wave like structures are independently observed in both electron density and magnetic fluctuations, although they do not always show one to one correlation. In most cases, the structures are observed by both satellite ‘A’ and ‘C’, suggesting that their zonal extent is more than 140 km. The study makes an attempt to understand and explain the magnetic conjugate nature of the MSTIDs. To have a better understanding of the dynamics of the MSTIDs, ground based GPS-TEC and ionosonde data has been used on case to case basis, wherever available. Additionally, spatio-temporal statistics of MSTID distribution is presented.
Origin and behavior of contamination of Lake Neusiedl with PAH and PFAS
Authors: Zessner Matthias , Zoboli Ottavia , Reif Daniela , Kittlaus Steffen , Krampe Jörg , Wolfram Georg
Published: March 2020

Lake Neusiedl is the largest endorheic lake in Central Europe, straddling the Austrian–Hungarian border. The lake has an area of 315 km2, 52% of which is covered by a reed belt representing the second largest contiguous reed population in Europe. The lake's drainage basin has an area of about 1,120 km2 and is strongly impacted by intensive agricultural production and urban settlements, especially in the catchment of the main inflow River Wulka. On average, the lake's surface lies 115.45 m above the Adriatic Sea and the lake is no more than 1.8 m deep. Due to its chemical composition Lake Neusield can be characterized as soda lake with typical pH values of 9.0-9.3 in the open lake.

In this contribution, we present results from investigations on selected PAH (Benzo(a)pyrene, Fluoranthene) and PFAS (PFOS and PFOA) in the lake with specific focus on sediment associated transport and legacy processes. We apply a holistic approach, by combining emission modelling, targeted monitoring, adsorption and mobilization experiments as well as a lake’s mass balance. We describe the current state of contamination of River Wulka and the lake, we identify the main emission pathways into both river and lake and we shed light on the complex environmental behavior within the coupled system lake - reed belt.

While PFOA and PFOS emissions into the river are dominated by effluents from waste water treatment plants, atmospheric deposition on the lake surface adds a significant contribution to the contamination of the lake. On the contrary, agricultural erosion is the dominant pathway of the contamination of river and lake for Benzo(a)pyrene, Fluoranthene. Our results show that the reed belt at the entrance of River Wulka to the lake acts as a significant sink for these substances due to suspended solid sedimentation.

Persistent chemicals entering the lake may undergo different fates. They may concentrate in water, because in this peculiar lake evaporation exceeds precipitation. They may also be stored in the sediments of the reed belt, from where they might be later re-mobilized. The fate of Benzo(a)pyrene and Fluoranthene is clearly dominated by the latter processes. While these processes cannot be neglected for PFOS and PFOA as well, PFOA shows a strong enrichment in the lake water. The behavior of PFOS is even more complex. Though highly persistent, its removal from the lake water cannot be explained by suspended solid associated transport to and sedimentation in the reed belt. It is removed from the lake water through degradation or conversion to metabolites to a significant extent as well.
Large-scale industrial cloud perturbations confirm bidirectional cloud water responses to anthropogenic aerosols
Authors: Trofimov Heido , Toll Velle
Published: March 2020

Aerosols offset poorly quantified fraction of anthropogenic greenhouse gas warming, whereas the aerosol impact on clouds is the most uncertain mechanism of anthropogenic climate forcing. In this research, we extend satellite observations of polluted cloud tracks from Toll et al. (2019, Nature, https://doi.org/10.1038/s41586-019-1423-9) with analysis of larger scale polluted cloud areas detected in MODerate-resolution Imaging Spectroradiometer satellite images. We demonstrate that large-scale anthropogenic aerosol-induced cloud perturbations exist at various major industrial aerosol source regions. The areal extent of the polluted cloud areas detected in MODIS satellite images extended to hundreds by hundreds of kilometres. Polluted clouds detected in satellite images in the global anthropogenic air pollution hot spot of Norilsk, Russia, and in other regions show close compensation between aerosol-induced cloud water increases and decreases. On average, there is relatively weak decrease in cloud water in the large areas with strong decreases in cloud droplet radii. This is in very good agreement with previous results based on small-scale polluted cloud tracks (Toll et al., 2019) and strongly disagrees with unidirectionally increased liquid water path in global climate models.
Modeling the effects and feedbacks of irrigation on the regional climate in Northern Italy
Authors: Asmus Christina , Hoffmann Peter , Rechid Diana , Böhner Jürgen
Published: March 2020

Large parts of the earth’s land surface are modified by humans. Since the land surface and the atmosphere are constantly in energy exchange and in interactions with each other, anthropogenic modifications of the land’s surface can lead to effects on the climate. The objective of this study is to quantify and investigate the effects and feedbacks of irrigation on the local to regional climate. Irrigation is a land use practice, which does not change the land cover type but changes the biophysical properties of the land’s surface and the soil and thus alters energy and moisture fluxes. These local to regional process responses, detectable in different meteorological variables, are investigated using the regional climate model REMO. High resolution simulations at convection permitting scales will be performed in order to particularly investigate irrigation effects on the spatiotemporal behavior of moist convection. Newly developed parameterizations of different types of irrigation are tested on the example of a northern Italian model domain, where cropland and rice paddies are the dominating land cover. The focus of the sensitivity study is on the impact of the parameterizations on the surface moisture and energy balance as well as on heavy rainfall events.
Swimming-induced non-Fickian transport of bacteria in porous media
Authors: Dentz Marco , Auradou Harold , Creppy Adama , Clément Eric , Carine Douarche
Published: March 2020

Progress in experimental techniques and imaging methods have led to a leap in the understanding of 
microscopic transport and swimming mechanisms of motile particles in porous media. This is very different 
for the understanding and characterization of large scale transport behaviors, which result from the 
interaction of motility with flow and medium heterogeneity, and the upscaling of microscale behaviors. 
Only few works have investigated large scale dispersion of active particles in porous media, 
which mainly operate in the framework of Brownian dynamics and effective dispersion or 
are completely data driven. In this work, we use the particle tracking data of Creppy et al. [1] 
to derive the stochastic dynamics of small scale particle motion due to hydrodynamic flow variability 
and the swimming activity of bacteria. These stochastic rules are used to derive a 
continous time random walk (CTRW) based model for bacteria motion. The CTRW naturally accounts for 
persistent advective motion along streamlines [2]. In this framework, particle motility is modeled 
through a subordinated Ornstein-Uhlenbeck process that accounts for the impact of rotational diffusion on 
 particle motion in the fluid, and a compound Poisson process that accounts for the motion toward and around 
grains. The upscaled transport framework can be parameterized by the distribution of the Eulerian 
pore velocities, and the motility rules of the bacteria. The model predicts the propagators of the 
ensemble of bacteria as well as their center of mass position and dispersion for bacteria transport under different
flow rates. 

[1] A. Creppy, E. Clément, C. Douarche, M. V. D’Angelo, and H. Auradou. Effect of motility on the transport of bacteria populations through a porous medium. Phys. Rev. Fluids, 4(1), 2019.

[2] M. Dentz, P. K. Kang, A. Comolli, T. Le Borgne, and D. R. Lester. Continuous time random walks for the evolution of Lagrangian velocities. Physical Review Fluids, 1(7):074004, 2016.
The Mt. Gamalama Instability in Generating Landslides in Ternate Island, Indonesia
Authors: Saaduddin Saaduddin , Neuberg Jurgen , Thomas Mark , Hill Jon
Published: March 2020

Mt. Gamalama has a history of volcanic tsunamis that have occured in 1608 and 1840. Regarding its geomorphology, Mt. Gamalama has very steep flanks, and landslides entering the sea could be the potential mechanism of tsunami generation which could threaten the coastal population and submarine infrastructure in the vicinity of Mt. Gamalama.

The potential volumes and types of landslides are estimated by a study of the Mt. Gamalama instabilities using the Generalized Hoek-Brown failure criterion which is applied in Slide2D (Rocscience), a 2D slope stability program using limit equilibrium methods. This procedure will result in a so-called Factor of Safety or FoS which represents a value of the Mt. Gamalama slope stability level.

The critical FoS values ranging from 1.945 to 3.361 have been obtained for four sections i.e., north, south, west and east side of the Mt. Gamalama edifice and are considered in relatively stable condition. These values hold for a static condition only under the force of gravity and in the absence of any volcanic activities. The application of seismic coefficients of 0.103 and 0.658, magma pressure of 2-17 MPa, and various angles of a dyke intrusion decreases the Mt. Gamalama stability and might cause landslides. Based on posture parameter analysis of modeled landslides, the landslide volumes could reach 106 -109 m3. Furthermore, regarding the morphometric characteristic parameter analysis, the landslide mobility could enter the Molucca seaand generate tsunamis.

Keywords: Gamalama, volcanic instability, volcanic landlsides, volcanic tsuamis
Towards deep learning based flood forecasting for ungauged basins
Authors: Kratzert Frederik , Klotz Daniel , Shalev Guy , Nevo Sella , Klambauer Günter , Nearing Grey , Hochreiter Sepp
Published: March 2020

Floods are among the most destructive natural hazards in the world. To reduce flood induced damages and casualties, streamflow forecasts should be as accurate as possible.

As of today, streamflow forecasts are usually made with either conceptual or process-based hydrological models. The problem these models usually have is that they perform best when calibrated for a specific basin, and performance degrades drastically if the models are used in places without historic streamflow measurements. To make things worse, some of the most devastating floods occur in developing and low-income countries, where historic records of streamflow measurements are scarce. Therefore, a central task for enhancing flood forecasts and helping local authorities to manage these areas is to provide high-quality streamflow forecasts in ungauged rivers. Although the IAHS dedicated an entire decade (2003-2012) to advance the problem of Prediction in Ungauged Basins the central goal remains largely a challenge.

In this talk, we will present a novel approach for tackling the problem of prediction in ungauged basins using a data-driven approach. More concretely, we show that the Long Short-Term Memory network (LSTM), which is a special type of a deep learning model, can serve as a generalizable rainfall-runoff simulation model. We will present recent results indicating that the LSTM gives on average better out-of-sample predictions (ungauged prediction) than e.g. the SAC-SMA in-sample (gauged) or the US National Water Model (Kratzert et al., 2019).

One place where these research results are already finding their way into operation is Google’s Flood Forecasting Initiative. The goal of this initiative is to provide (enhanced) flood warnings, where needed, starting with a pilot project in India. And as mentioned above, historic streamflow records in those regions are scarce, which motivates new and innovative approaches for enhanced streamflow forecasting.

References:

Kratzert, F., Klotz, D., Herrnegger, M., Sampson, A. K., Hochreiter, S., & Nearing, G. S.: Toward improved predictions in ungauged basins: Exploiting the power of machine learning. Water Resources Research, 55. https://doi.org/10.1029/2019WR026065, 2019.
Tuning IMS station processing parameters and detection thresholds to increase detection precision and decrease detection miss rate
Authors: Saragiotis Christos , Kitov Ivan
Published: March 2020

Two principal performance measures of the International Monitoring System (IMS) stations detection capability are the rate of automatic detections associated with events in the Reviewed Event Bulletin (REB) and the rate of detections manually added to the REB. These two metrics roughly correspond to the precision (which is the complement of the false-discovery rate) and miss rate or false-negative rate statistical measures of a binary classification test, respectively. The false-discovery and miss rates are clearly significantly influenced by the number of phases detected by the detection algorithm, which in turn depends on prespecified slowness-, frequency- and azimuth- dependent threshold values used in the short-term average over long-term average ratio detection scheme of the IMS stations. In particular, the lower the threshold, the more the detections and therefore the lower the miss rate but the higher the false discovery rate; the higher the threshold, the less the detections and therefore the higher the miss rate but also the lower the false discovery rate. In that sense decreasing both the false-discovery rate and the miss rate are conflicting goals that need to be balanced. On one hand, it is essential that the miss rate is as low as possible since no nuclear explosion should go unnoticed by the IMS. On the other hand, a high false-discovery rate compromises the quality of the automatically generated event lists and adds heavy and unnecessary workload to the seismic analysts during the interactive processing stage.

A previous study concluded that a way to decrease both the miss and false-discovery rates as well as the analyst workload is to increase the retiming interval, i.e., the maximum allowable time that an analyst is allowed to move an arrival pick without having to declare a new arrival. Indeed, when a detection needs to be moved by an interval larger than the retiming interval, not only is this a much more time-consuming task for the analyst than just retiming it, but it also affects negatively both the associated rate (the automatic detection is deleted and therefore not associated to an event) and the added rate (a new arrival has to be added to arrival list). The International Data Centre has increased the retiming interval from 4 s to 10 s since October 2018. We show how this change affected the associated-detections and added-detections rates and how the values of these metrics can be further improved by tuning the detection threshold levels.
RCP 8.5 Ghana. High-end climate change impacts on crop production
Authors: Tramberend Sylvia , Fischer Günther , van Velthuizen Harrij
Published: March 2020

Climate change threatens vulnerable communities in sub-Saharan Africa who face significant challenges for adaptation. Agriculture provides the livelihood for the majority of population. High-resolution assessments of the effects of climate change on crop production are urgently needed for targeted adaptation planning. In Ghana, next to food needs, agriculture plays an important role on international cocoa markets. To this end, we develop and apply a National Agro-Ecological Zoning system (NAEZ Ghana) to analyze the impacts of high-end (RCP8.5) global warming on agricultural production potentials until the end of this century. NAEZ Ghana uses an ensemble of the CORDEX Africa Regional Climate Model, a regional soil map, to assess development trends of crop production potentials for 19 main crops. Results highlight differential impacts across the country. Especially due to the significant increase in the number of days exceeding high-temperature thresholds, rain-fed production of several food and export crops could be reduced significantly compared to the historical 30-year average (1981-2010). Plantain production, an important food crop, could achieve under climate change less than half of its current potential already in the 2050s and less than 10% by the 2080s. Suitable areas for cocoa production decrease strongly resulting in only one third of production potential compared to today. Other crops with detrimental effects of climate change include oil palm, sugarcane, coffee, and rubber. Production of maize, sorghum, and millet cope well with a future warmer climate. The NAEZ Ghana database provides valuable high-resolution information to support agricultural sector development planning and climate change adaptation strategies. The expansion of irrigation development will play a central role in some areas. This requires further research on Ghana’s linkages between food, water, and energy, taking into account climate and socio-economic changes.
The carbon footprint of a tropical reservoir: measured versus modeled values highlight the underestimated key role of downstream processes
Authors: Soued Cynthia , Prairie Yves
Published: March 2020

Reservoirs are important sources of greenhouse gases (GHGs) to the atmosphere and their number is rapidly increasing, especially in tropical regions. Accurately predicting their current and future emissions is essential but hindered by fragmented data on the subject, which often fail to include all emission pathways (surface diffusion, ebullition, degassing, and downstream emissions) and the high spatial and temporal flux variability. Here we conducted a comprehensive sampling of Batang Ai reservoir (Malaysia), and compared field-based versus modeled estimates of its annual carbon footprint for each emission pathway. We further explored the processes fuelling and regulating emissions downstream of the dam, which are important but commonly overlooked. Carbon dioxide (CO2) surface diffusion and methane (CH4) ebullition were lower than predicted, whereas moderate surface CH4 diffusion was accurately predicted. Most GHGs present in discharged water were degassed at the turbines, and the remainder were gradually emitted along the outflow river, leaving time for CH4 to be partly oxidized to CO2. Overall, the reservoir emitted 2475 gCO2eq m-2 yr-1, of which 89 % occurred downstream of the dam, mostly in the form of CH4. These emissions, largely underestimated by predictions, are mitigated by CH4 oxidation upstream and downstream of the dam, but could have been drastically reduced by slightly raising the water intake elevation depth. Degassing and downstream emissions are largely due to the accumulation of GHGs under the permanent thermocline. Studying the interplay between the processes regulating CO2 and CH4 concentrations in the reservoir deep layer highlighted the key role of physical factors on GHGs dynamics. Overall, our results show that exploring morphometry, soil type, and stratification patterns as predictors can improve modeling of reservoir GHGs emissions at local and global scales.  
JPI_URBANWAT project. Tools and criteria for URBAN groundWATer management
Authors: Scheiber Laura , Vazquez-Suñé Enric , Bogaard Thom , Bofill Mas Sílvia , Pérez Sandra , Ginebreda Martí Antoni , Luquot Linda , Rusiñol Marta , Criollo Rotman , Girones Rosina , Fores Eva , Gómez Elena , Duporté Geoffroy , Garcia-Rios Maria
Published: March 2020

According to the European Union, half of the human population will live in cities, one of the main water spend zones and focus of pollutants it is expected by 2050. Considering the growing pressure on water resources whole world, a better knowledge for its management is needed to face this situation.

URBANWAT is a project funded by the EU Commission under the call “Closing the Water Cycle Gap” of the Water JPI Strategic Research and Innovation Agenda. The goal of this project is to come up with an improvement of tools and criteria for groundwater management in urban areas to guarantee the urban water resources sustainability, identify their potential uses and their risks related to groundwater use from both environmental and human health perspectives by an integral approach developing novel technologies and methodologies.

The project will involve a multidisciplinary approach integrating the research of the natural state of the hydrological cycle and pollutants identification (general chemistry, pollutants of emerging concern (CECs) and microorganisms, with emphasis in viruses).

To achieve that goal, URBANWAT proposes to use innovative approaches based on liquid chromatography high resolution mass spectrometry (HLC-RMS) to: (1) detect differences in degradation in different anoxic conditions employing CECs as indicators of contamination and their transformation products (TPs) as indicators of degradability; (i2)  analyse fate and transport of chosen contaminants in the soil-plant as a remediation system utilizing picked infrastructures; (3) understand the contaminants movement applying encapsulated DNA nanoparticles; (4)  scout the presence of new and emergent viruses in groundwater samples employing viral metagenomics. Viral concentration methods from water samples will be also optimized in this research. To do so, column experiments will be carried out.

URBANWAT project will focus on Barcelona city. In parallel, several studies will be carried out at full-scale in the demonstration facility called ‘WaterStreet’ at TUDelft. The expected results will help to provide novel and cost-efficient technologies for urban groundwater management with beneficial environmental, economic and societal impacts for the European Union (EU) facilitating their application worldwide.
Space debris monitoring based on inter-continental stereoscopic detections
Authors: Sozza Alessandro , Cencini Massimo , Parisi Leonardo , Acernese Marco , Santoni Fabio , Piergentili Fabrizio , Melillo Stefania , Cavagna Andrea
Published: March 2020

The monitoring of space debris and satellites orbiting around Earth is an essential topic in the space surveillance. The impact of debris, even of small size, against active spatial installations causes serious damage, malfunctions and potential service interruptions. Collision-avoidance maneuverings are often performed but they require increasingly complex protocols. Density of space debris is now so high that even astronomical observations are often degraded by it. Although it does not affect space weather, it may interfere with weather satellites.
We have developed an innovative experimental technique based on stereometry at intercontinental scale to obtain simultaneous images from two optic observatories, installed in Rome (at the Urbe Airport and in Collepardo on the Apennines) and in Malindi (Kenya). From the observations on Earth, it's possible to reconstruct the three-dimensional position and velocity of the objects. The distance between the two observatories is crucial for an accurate reconstruction. In particular, we have considered the sites of Urbe and Collepardo, with a baseline of 80 km, to detected Low-Earth orbits (LEO), while we have considered a baseline of 6000 km, between Urbe and Malindi, to observe geostationary orbits (GEO).
We will present the validation of the three-dimensional reconstruction method via a fully synthetic procedure that propagate the satellite trajectory, using SGP4 model and TLEs data (provided by NASA), and generate synthetic photographs of the satellite passage from the two observatories. Then we will compare the synthetic results with the experimental results obtained using real optic systems. The procedure can be automatized to identify unknown space objects and even generalized for an arbitrary number of sites of observation. The identified debris will be added to the catalogue DISCOS (Database and Information System Characterizing Objects in Space) owned by the European Space Agency (ESA) to improve the space surveillance and the ability to intervene in the case of potential risks. 
Coastal inundation hazard in the North Adriatic Sea under Climate Change
Authors: Hrast Essenfelder Arthur , Amadio Mattia , Bagli Stefano , Mazzoli Paolo
Published: March 2020

On the 12th of November of 2019, flood levels in the Venice Lagoon have reached the mark of 1.87 metres, the second-highest level since records began in 1923. Although a recurrent problem in Venice, the significance of this event have raise awareness of the issue of coastal inundation hazard in Italy, particularly at the highly vulnerable territory of the regions facing the North Adriatic Sea. Several are the processes that contribute to a costal inundation event. On the short term, processes such as high tide and storm surge events can result in sea levels, potentially triggering devastating impacts on human settlements and activities. On the long term, the land subsidence and mean sea level (MSL) changes are important factors; in fact, in some regions such as Jakarta and Bangkok the land is expected to subside by more than 1 meter, while MSL is expected to rise during the next decades, reaching global mean absolute values ranging from 0.3–0.6m (RCP 2.6) to 0.5–1.1m (RCP 8.5) by the end of the century. The combined effect of global sea level rise, local subsidence, and short term phenomena can potentially increase the frequency and intensity of extreme sea levels (ESL), posing a major threat to coastal areas. Currently, almost 700 million people live in low-lying coastal areas, and about 13% of them are exposed to a 100-year flood. In Italy, a territory that is highly vulnerable to coastal flooding are the Regions facing the North Adriatic Sea, mainly due to two factors: the morphological characteristic of this territory, characterised by low-lying areas, and the bathymetry and shape of the Adriatic basin, which cause water level to accumulate and increase rapidly during storm surge events, especially during winter. In this paper, we evaluate two different coastal inundation modelling techniques, one hydrostatic (as part of the EIT Climate-KIC SaferPLACES project) and another hydrodynamic (the ANUGA model), by stressing the models with different ESL, both for the historical mean sea level and for MSL projections at 2050 and 2100. The two different inundation models are tested on three pilot sites particularly vulnerable to coastal flooding located in the North Adriatic Sea: Venice, Cesenatico, and Rimini. We compare our modelling results with existing hazard records and previous hazard and risk assessments. Finally, we apply a flood damage model developed for Italy to estimate the potential economic damages linked to the different flood scenarios, and we calculate the change in expected annual damages according to the relative extreme sea levels.
Lateral carbon export from polygonal tundra catchments on Samoylov Island, Lena River Delta
Authors: Beckebanze Lutz , Walz Josefine , Runkle Benjamin R.K. , Holl David , Fedorova Irina V. Fedorova , Helbig Manuel , Kutzbach Lars
Published: March 2020

Permafrost-affected soils contain a large quantity of soil organic carbon (SOC). Two processes control the amount of carbon stored in soils. The photosynthetic activity of plants produces biomass that may accumulate in the soil, while microorganism’s respiration leads to a depletion of the soil carbon stocks through decomposition. The carbon balance defines whether a soil acts as a source or sink of carbon. In recent decades, many researchers observed and analyzed the carbon balance of permafrost soils. In most cases, the focus lays on observations of the vertical carbon flux (CO2 and CH4) to estimate the carbon balance. However, there is lack of information regarding the lateral losses of carbon via dissolved organic carbon (DOC) or dissolved inorganic carbon (DIC) in ground- or rainwater.

In this study, we estimate the lateral carbon fluxes from a permafrost-affected site in north-eastern Siberia, Russia. Long-term measurements of vertical carbon fluxes have been conducted at this study site. By considering both, the vertical and the lateral carbon fluxes, we estimate the complete carbon balance for one growing season in 2014 and discuss the contribution of the lateral carbon flux to the overall carbon balance.

The results show that the vertical CO2 fluxes dominate the carbon balance during the growing season from June 8th – September 8th (-19 ± 1.2 kg-C m-2). The lateral fluxes of DOC and DIC reached values of +0.1 ± 0.01 and +1.4 ± 0.09 kg-C m-2, respectively, whereas the vertical fluxes of CH4 had values of +0.7 ± 0.02 kg-C m-2 integrated over this time. By considering the lateral carbon export, the net ecosystem carbon balance of the study area was reduced by 8%. On shorter time scales of days, the relationship between lateral and vertical flux changes within the growing season. Early in the growing season, the lateral carbon flux outpaces the weak vertical CO2 uptake for a few days and converts the estimated carbon balance from a sink to a source.

We conclude that lateral carbon fluxes have a larger influence on the carbon balance of our study site on time scales of days (early and late growing season) and that this influence decreases with annual time scales. Therefore, the vertical carbon flux can be seen as a good approximation for the carbon balance of this study site on annual time scales.
Microscale characterisation of damage evolution in curling stones used in international competition
Authors: Leung Derek , Fusseis Florian , Butler Ian
Published: March 2020

The rocks used to produce curling stones for international competition are only sourced from two localities in the world: Ailsa Craig, Scotland and Trefor, Wales. Curling stones consist of two components: (1) the running band (the ring-shaped bottom surface of the stone which rests on the ice) and (2) the striking band (the convex band on the profile of stones which collides with those of other stones). With a focus on the striking bands, we aim to document the damage evolution of curling stones using synchrotron microtomography (3D characterisation of pristine samples and 4D damage evolution), optical and scanning electron microscopy (quantitative characterisation of pristine samples and microfracture characterisation of damaged striking bands), and petrophysical testing (fracture characteristics and comparative data). These data will be complemented by an on-ice experiment that will determine the mechanics (e.g., stress distribution, contact area, and velocity) of curling stone impacts. Out of four curling stone varieties (from Ailsa Craig and Trefor), we observe the striking bands of three varieties to show macroscopic, incipient to mature, curvilinear fractures. The curvature of these fractures is consistent and does not vary significantly between individual stones and between curling stone varieties. However, the degree of macroscopic fracture development differs between aged striking bands of curling stone types: Blue Trefor (macroscopic fractures not observed), Red Trefor (weakly incipient), Ailsa Craig Common Green (incipient to juvenile), and Ailsa Craig Blue Hone (juvenile to mature). Unfortunately, it is not possible to determine the degree of usage (age) of the selected samples and thus it is not possible to normalize these apparent differences in damage. Given that the striking band limits the lifetime of curling stones, understanding the damage evolution of curling stones can contribute valuable information to the maintenance of curling stones. The rock physics of curling stone impacts is linked to dynamic spalling and more broadly to rock failure, as these processes are ultimately related to the initiation and propagation of fractures.
Groundwater circulation and mixing inferred from age dating with dissolved gas tracers in a complex Mediterranean karstic and thermal aquifer (Thau lagoon area, Montpellier, France).
Authors: de Montety Véronique , Lemaitre Laurie , Ladouche Bernard , Bailly-Comte Vincent , Pérotin Laïna , Hery Marina , Guilhe-Batiot Christelle , Pétré Marie-Amélie , Seidel Jean-Luc
Published: March 2020

Groundwater in coastal area is a strategic but fragile resource since it undergoes high anthropogenic pressure that can lead to saltwater intrusion. Therefore the use of coastal groundwater needs a thorough understanding of the groundwater flow and mixing to assure a suitable management of the resource.

The coastal and thermal karstic hydrosystem of the Thau basin (South of France) shows a good example of the pressure that can undergoes coastal groundwater as it is a strategic resource for drinking water, spa activities as well as shellfish aquaculture. In this aquifer, groundwater originates from 3 different naturally sources with contrasted mean residence time (MRT): 1) cold and young karstic water, 2) warm and mineralized thermal waters with long MRT, and 3) marine waters (Thau lagoon and/or seawater). In this context, age dating tracers can be valuable tools for the characterization of the groundwater flow circulations, the estimation of their residence time but also of the mixing which can affect the thermal system.

We used dissolved gases (CFCs and SF6) and 3H age dating tracers to characterize the young end-member, as these tracers are particularly suitable for identifying and quantifying water mixing of different ages (Newman et al., 2010). Strategic locations representative of each component of the system (surficial and deep karst, springs and thermal boreholes) were sampled during different hydrogeological contexts (high flow/base flow).

The first results show that as expected, in general, the thermal component has a very low level of dissolved gas indicating long MRT and few mixing whereas karstic springs show high contents of dissolved gas. However, some thermal wells show important and variable gas content indicating mixing with the karstic component and rapid circulation in some parts of the system. These data will contribute to determine the groundwater transfer model(s) in the Thau system and to estimate the contribution of the current karst water to the Balaruc thermal system. These results will in turn, be used within the framework of the “Dem’Eaux Thau project” to develop tools for groundwater resources management allowing decision-makers to take on the challenges of this region.
The effect of vegetation dynamics on erosion processes, sediment dynamics, and landscape evolution in semiarid areas with sparse plant cover
Authors: Saco Patricia , Quijano Juan , Moreno-de las Heras Mariano , Willgoose Garry , Rodriguez Jose
Published: March 2020

Vegetation not only controls but is also controlled by erosion processes. This tight feedback effect leads to the coevolution of vegetation and erosion patterns that modulate landform shape, and regulate many other landscape processes. These tight interactions are particularly important in semiarid landscapes. We have studied these interactions using a landform evolution model that accounts for the effect (and feedbacks) of spatially and temporally varying hydrologic and vegetation patterns.

We apply the modelling framework to improve our understanding of the coevolution of landforms and vegetation patterns in different semiarid landscapes in Australia. The vegetation of the selected sites is Acacia Aneura (Mulga) which covers vast areas of Australia.  These sites display a sparse vegetation cover and strong patterns of water redistribution, with sources located in the bare areas and sinks in the vegetation patches which characterize the observed hydrologic connectivity. This effect triggers high spatial variability of erosion/deposition rates that affects the evolving topography and induces feedbacks to the dynamic vegetation patterns. We run simulations for 1000 years using local rainfall and erosion and vegetation parameters previously calibrated for similar sites in the Northern territory. Our numerical modelling results are validated by comparing simulated and observed patterns of vegetation and landforms obtained from satellite, airborne remote sensing and field data. We further investigate the effect of alterations in hydrologic connectivity induced by climate change and/or anthropogenic activities, which affect water and sediment redistribution and can be linked to loss of resources leading to degradation.

Our simulations are able to reproduce observed banded vegetation and landform patterns for the Northern territory in Australia. We show that an increase in hydrologic connectivity can trigger changes in vegetation patterns inducing feedbacks with landforms leading to degraded states. These transitions display non-linear behaviour and in some cases can lead to thresholds with an abrupt reduction in productivity. Critical implications for effective long-term restoration efforts are discussed.
Multi-scale and multi-disciplinary investigation of the southwest Portuguese Continental shelf, the MINEPLAT project
Authors: Terrinha Pedro , Ribeiro Carlos , Noiva João , Rosa Marcos , Brito Pedro , Magalhães Vitor , Neres Marta , Nogueira Pedro , Velez Sandra , Pacheco Ângela , Mil-Homens Mário , Luis Mariana , Andrade Laura , Carvalho André , Afonso Paula , Silva Mariana
Published: March 2020

The MINEPLAT project (Assessment of the mineral resources potential in the continental shelf of Alentejo and of the environmental conditions caused by the tectonic uplift in the Pliocene-Quaternary) allowed acquisition of 1700 km of ultra- high resolution seismic profiles, and full coverage of multibeam bathymetry  and acoustic  backscatter of 1450 km2 and 1940km of magnetic data of the Alentejo continental shelf, SW Portugal. 270 sediment samples were collected (Smyth-Macyntire dredges and multicores) and processed for sediment, geochemical and mineralogical analyses (granulometry, Xray diffractometry, major and trace metals analysis).

The wealth of data is meeting its full processing phase. Preliminary interpretation of the large dataset has already allowed to understand various novel contributions: i) identification of various sea level stand stills in Pliocene-Quaternary times; ii) drainage network during low stand sea levels; iii) grainsize dependency on submarine relief and inherited morphology from low stand periods; iv) eustatic,  oceanographic, fluvial and depth dependency of the post-alpine orogeny deposits of Pliocene-Quaternary age; v) location of deposits with high-quality sand for beach nourishment; and vi) identification of submarine harbor waste disposal sites and their environmental impact and dispersal; vii) high resolution mapping of magnetic anomalies related with magmatic events that can be source of heavy minerals.

The authors would like to acknowledge the FCT financial support through project UIDB/50019/2020 – IDL and MINEPLAT project ALT20-03-0145-FEDER-000013
Farmers’ decision-making strategies for dealing with hydro-climatic risks in the Kilombero Valley, Tanzania
Authors: Höllermann Britta , Näschen Kristian , Tibanyendela Naswiru , Kwesiga Julius , Evers Mariele
Published: March 2020

At present, the seasonally flooded wetland of the Kilombero River is mainly used by small-scale farmers who predominantly produce rice and maize during the wet season. Some community-based irrigation systems do exist, which reduce the consequences and risks of climate variabilities regarding e.g. the onset of the rainy season and which allow year-round farming. Like other sub-Saharan wetlands, the Kilombero Valley floodplain is a highly dynamic environment, which is amplified due to increasing variability in the onset and intensity of the wet season.

In this study, we identify drivers of change and farmers’ decision-making strategies using focus group discussions with different types of farmers. In particular, we examine the differences between farmers from rain-fed and irrigated agriculture in terms of their agricultural practices and decision-making strategies for dealing with hydro-climatic risks. The results map the perceptions and visions of the people whose actions shape this highly dynamic environment and identify a range of options for action that go beyond the optimality paradigm.

Understanding how aspirations and visions about the future shape agricultural practices and hence human-water interaction is crucial to understand possible changes and dynamics of coupled socio-ecological systems. Therefore, this study is embedded into a wider multi-method approach integrating qualitative and quantitative data to inform and modify hydrological modelling. Here, the qualitatively collected data and findings of this research provide ground for developing additional scenarios for hydrological models and allow for contextualizing model results. Thus, human-water interactions can be better represented and the local populations’ perception and reactions to hydro-climatic risks can be assessed.

This research is part of the Collaborative Research Centre 228 “Rural Future Africa” funded by the German Research Foundation (DFG).
Denitrifier communities differ in mangrove wetlands across China
Authors: Li ruili
Published: March 2020

Denitrifier communities differ in mangrove wetlands across China

Ruili Li*, Sijie Wu, Minwei Chai, Xiaoxue Shen, Lingyun Yu

Key Laboratory for Heavy Metal Pollution Control and Reutilization, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, Guangdong, PR China

*Corresponding author. E-mail address: liruili@pkusz.edu.cn

Abstract:

Denitrification plays an important role in the removal of nitrogen from coastal wetlands. However, knowledge regarding the dynamics of denitrifier communities in mangrove wetlands is limited, and the corresponding influential factors lack quantitative analysis. To explore the geographical variations in the nosZ-denitrifier community and the underlying influential factors, surface sediments in mangrove forest and adjacent mudflat were collected from six mangrove wetlands across China, including high-latitude Yunxiao (YX) and Futian (FT) mangroves, middle-latitude Fangchenggang (FCG), Zhanjiang (ZJ) and Dongzhaigang (DZG) mangroves, and low-latitude Dongfang (DF) mangrove. The nosZ gene abundance in mangrove sediments varied from 1.60×105–1.17×106 copies g-1 dry sediment, with a higher density in Avicennia marina forest than the mudflat. Denitrifier community richness and diversity increased with decreasing latitude based on the Chao1 richness and Shannon diversity index, with the highest diversity being observed in the DF mangrove. The denitrifier communities could be classified into three groups including low-latitude DF mangrove, middle-latitude FCG, ZJ and DZG mangroves, and high-latitude YX and FT mangroves based on HCA and PCA analysis. The nosZ OTUs could be divided into seven distinct clusters with different proportionality characteristics among mangroves. Environmental factors (TN, TOC, and salinity) could collectively shape denitrifier communities in mangrove sediments.
Beyond Sea Surface Temperatures: a Holistic Approach to Addressing Pliocene Tropical Conditions
Authors: Ford Heather L. , Burls Natalie , Chandan Deepak , LaRiviere Jonathan , Fedorov Alexey , Ravelo A. Christina
Published: March 2020

The tropical Pacific thermocline structure is critical to tropical sea surface temperatures (SSTs) and variability. During the mid-Pliocene warm period (~3 Ma), the zonal SST gradient was reduced due to relatively warm SST in the Eastern Equatorial Pacific; we call this mean state “El Padre.” How did the equatorial thermocline contribute to this reduced zonal SST gradient? Here we summarize published Mg/Ca (surface and subsurface dwelling foraminifera) and alkenone records and generate new SST estimates from Mg/Ca and alkenones. The subsurface dwelling Globorotalia tumida Mg/Ca-based temperature records from the eastern and western equatorial Pacific show mid-Pliocene warm period subsurface temperatures warmer than today; El Padre included a basin-wide thermocline that was relatively warm, deep, and weakly tilted. We compare the published and newly generated SST and subsurface temperature records to the Pliocene Modeling Intercomparison Project (PlioMIP1) and show that few models capture the magnitude and spatial pattern suggested by the temperature records. Those models that do corroborate the temperature records have warm subsurface temperatures in the Eastern Equatorial Pacific that dynamically link to warm SSTs in the cold tongue. This highlights the need to accurately model thermocline dynamics and mid-latitude conditions, where equatorial thermocline waters originate, in order to gain an understanding of the underlying processes that explain the mid-Pliocene warm period.