bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrological variability of Finnish free-flowing rivers
Authors: Lintunen Karoliina , Bertacchi Uvo Cintia , Alho Petteri , Kasvi Elina
Published: February 2023

River discharges and ice cover strongly impact biotic and abiotic processes in fluvial environments. Hydrometeorological circumstances affect discharges and under climate change, they are changing in high-latitude areas of the globe. During the past decades, spring snowmelt has started earlier in Northern Europe, leading to a shift in the timing of floods and discharge peaks. Also, higher wintertime discharges have been measured. However, little is known about how these changes in the variability and trends have occurred during the past decades (up to 100 y.) and how they will evolve in the future.The goal of this paper is to understand how the hydrological variability of free-flowing rivers has changed from the past to the present in Finland. To achieve the goal, long-term data on flood magnitude, frequency, and timing are statistically analyzed to identify the hydrological variability of Finnish free-flowing rivers. Previous works showed that discharge parameters work as reliable indicators for assessing long-term changes caused by climate change when combined with weather parameters, teleconnection patterns, and river ice data. Open-access data from 45 gauging stations in 25 different watershed areas were used. The timespan of datasets varies between 40 and 100 years. The results of this paper can be applied when future changes and adaptation methods related to river discharges are considered in the boreal-subarctic climate region.
The CAIRT earth explorer 11 mission: a way towards global gravity wave momentum budgets
Authors: Preusse Peter , Polichtchouk Inna , Osprey Scott , Ungermann Joern , Rhode Sebastian , Chipperfield Martyn , Errera Quentin , Friedl-Vallon Felix , Funke Bernd , Godin-Beekmann Sophie , Hoffmann Alex , Malavart Alizee , Raspollini Piera , Sinnhuber Björn-Martin , Verronen Pekka , Walker Kaley
Published: February 2023

Retrieving global observations of gravity waves (GW) from recent satellite missions is challenging. Nadir viewing satellites such as AIRS provide directional momentum fluxes, but lack fine vertical resolution and hence observe only those GW with exceptionally high intrinsic phase speed. Limb scanning instruments such as HIRDLS and SABER have only a single measurement track and hence provide only an estimate of absolute GW momentum flux. In addition, the sparse along-track sampling of these limb sounders introduce uncertainties in horizontal wavelength. GPS-RO can provide GW profile triplets, allowing in principle the horizontal direction of GW propagation to be inferred, but these triplets are rare. Finally, direct wind measurements from Aeolus are restricted in altitude to less than ~25km and only provide the wind component in the direction of the lidar beam from one observational track. In consequence, also Aeolus cannot reveal horizontal propagation direction and GW momentum flux.This situation could be dramatically improved by bringing a limb imager into space. A limb imager combines the very dense spatial sampling of a nadir viewing instrument with the high vertical resolution of a limb sounder. This will provide an almost complete description of the vertical spectrum of GWs, necessary for inferring drag estimates. Such global GW momentum flux data would for the first time allow to retrieve a global momentum budget from the mid-troposphere to the upper mesosphere.The changing-atmosphere infra-Red Tomography (CAIRT) mission candidate for ESA's earth explorer 11 proposes a limb imager for spatial sampling of 25 km across-track, 50 km along-track and 1 km in the vertical. From this we expect to infer directional GW momentum fluxes from the tropopause to 70 km or higher. This will allow longstanding scientific questions to be addressed such as the quantification of tropospheric GW sources and their related phase speed spectra and the identification of secondary wave generation in the stratosphere and lower mesosphere. Considering the momentum flux at higher altitudes, secondary wave generation competes with oblique GW propagation which allows GWs from low latitude sources to reach the high latitudes mesosphere and thus avoid critical levels. In general, two-way interaction with the background flow will be considered via the modulation of the GW spectrum by the winds and the mean wind accelerations by the GWs. In this contribution we will outline the CAIRT instrument concept, give an overview of the mission’s objectives and demonstrate its potential using simulated observations.
Separating fundamental and harmonic sources in LOFAR solar type III radio burst images
Authors: Vocks Christian , Zucca Pietro , Bisi Mario , Dabrowski Bartosz , Morosan Diana , Gallagher Peter , Krankowski Andrzej , Magdalenic Jasmina , Mann Gottfried , Marque Christophe , Rothkaehl Hanna , Matyjasiak Barbara
Published: February 2023

LOFAR low band interferometric images of type III solar radio bursts during an M class flare on 7 September 2017 show distinct sources with variations in their positions and intermittent dual source structures. We identify these as fundamental and harmonic emission, with the one or other being dominant at times. The data show that transport effects due to refraction and scattering play a significant role, both in source separation and drift of their apparent positions. We present a method of automatically separating fundamental and harmonic contributions that allows for obtaining separate lightcurves. Comparing the lightcurves of fundamental and harmonic pairs, e.g. 35 MHz and 70 MHz, enables studies of radio wave propagation in the solar corona. Harmonic sources at the lowest observable frequencies are relevant for the transition into the solar wind, and for joint observing campaigns with Parker Solar Probe and Solar Orbiter that are currently investigating the inner heliosphere.
Citizen science and the exploration of solar data
Authors: Musset Sophie , Glesener Lindsay , Sankar Ramana , Fortson Lucy , Jol Paloma , Lasko Kekoa , Zhang Yixian , Panesar Navdeep , Fleishman Gregory , Jeunon Mariana , Hurlburt Neal , Zheng Yuping
Published: February 2023

Citizen science provides a way to analyze large and complex data sets, complementary to contemporary tools such as machine learning. Indeed, while trained algorithms excel in the task they are trained for, humans can spot outliers and make serendipitous discoveries. With recent and new instruments, we are able to observe the Sun and the heliosphere at high cadence and high resolution, providing large amounts of data, revealing complexity in the observed features, and leading to the discovery of new features on small scales. We will present how citizen science, while still under-utilized in solar and heliospheric physics, is particularly adapted to explore, and analyze solar data sets. The “Solar Jet Hunter”, a citizen science project launched one year ago to build a catalog of coronal jets, will be presented as an example, and other science cases for which citizen science is the most adequate tool will be highlighted. Finally, the opportunities raised by citizen science to create strong relationships between academia and society will be discussed.
Detection capabilities of a multi-satellite wide-swath altimetry conceptual mission
Authors: Vergara Oscar , Dibarboure Gérald , Treboutte Anaëlle , Faugère Yannice , Boy François
Published: February 2023

The soon-to-be available swath altimetry observations from the SWOT mission are expected to drastically improve our capacity to observe fine-scale ocean processes (wavelengths shorter than 100 km). With its increased observing capacity and lower signal-to-noise (SNR) ratio in comparison to conventional nadir altimetry, this new technology is expected to deliver unprecedented high-resolution two-dimensional observations of the ocean surface circulation and surface water bodies. Benefiting from the technological maturity acquired during the preparation for SWOT, a new constellation concept composed of swath altimeters has been proposed to carry on the European operational observing system towards the end of the decade. In the present work, we focus on evaluating the ocean observing capabilities of a novel swath altimeter concept (WiSA – Wide Swath Altimeter). Using the observed surface wave field (SWH – Significant Wave Height) and the instrumental characteristics, we compute global estimates of the SNR. We observe an average global observability around 40 km wavelength over 50% of the global ocean, and 47 km on average over 80% of the globe. Little or no seasonality is observed in the SNR, related to the seasonal compensation of the two competing factors that contribute to the observability, namely the instrumental noise levels and the observed spectral slopes. The performance of recently developed data-driven filtering techniques is also evaluated, considerably increasing the purely instrumental observing capabilities. The results are also discussed from an operational perspective, considering the contribution of a constellation of swath altimeters over a mono-satellite mission.
The dark side of the moon: A glimpse into the future of the microbiome structure and function of glacier-fed streams
Authors: Michoud Gregoire , Kohler Tyler , Ezzat Leila , Peter Hannes , Nattabi Juliet , Nalwang Rosemary , Bourquin Massimo , Busi Susheel , Battin Tom
Published: February 2023

Glaciers are receding at an unprecedented rate with expected losses of up to half their masses by 2100. Such changes will profoundly effect the physicochemical characteristics of glacier-fed stream (GFS) water, such as the composition of organic matter, turbidity, conductivity, and patterns in discharge. Hence, direct effects are anticipated for the microbial communities and assemblages inhabiting these environments. High-elevation tropical glaciers are already responding to these enhanced changes (e.g. temperature) and thus are a proxy to study the ecology of GFSs in the future. Here, we sampled and studied the Mt Stanley glacier in Africa’s ‘Mountains of the Moon’ (Rwenzori National Park, Uganda). We showed that the benthic microbiome from this GFS is distinct at several levels from other GFSs worldwide. Specifically, several novel taxa were present, and usually, common groups such as Chrysophytes and Polaromonas exhibited lower relative abundances compared to higher-latitude GFSs, while cyanobacteria and diatoms were more abundant. The rich primary producer community in this GFS likely results from the greater environmental stability of the Afrotropics, and accordingly, heterotrophic processes dominated in the bacterial community. Metagenomics revealed that almost all prokaryotes in the Mt. Stanley GFS are capable of organic carbon oxidation, while >80% have the potential for fermentation and acetate oxidation. Our findings suggest a close coupling between photoautotrophs and other microbes in this GFS and provide a glimpse into the future for high-latitude GFSs globally where primary production is projected to increase with ongoing glacier shrinkage.
Analysis of airborne-derived sea ice emissivities up to 340 GHz in preparation for future satellite missions
Authors: Risse Nils , Mech Mario , Prigent Catherine , Spreen Gunnar , Crewell Susanne
Published: February 2023

Passive microwave radiometers onboard polar-orbiting satellites provide global information on the atmospheric state. The underlying retrievals require accurate knowledge of the surface radiative properties to distinguish atmospheric from surface contributions to the measured radiance. Polar surfaces such as sea ice contribute up to 400 GHz to the measured radiance due to the high atmospheric transmissivity under cold and dry conditions. Currently, we lack an understanding of sea ice parameters driving the variability in its radiative properties, i.e., its emissivity, at frequencies above 200 GHz due to limited field data and the heterogeneous sea ice structure. This will limit the use of future satellite missions such as the Ice Cloud Imager (ICI) onboard Metop-SG and the Arctic Weather Satellite (AWS) in polar regions.To better understand sea ice emission, we analyze unique airborne measurements from 89 to 340 GHz obtained during the ACLOUD (summer 2017) and AFLUX (spring 2019) airborne campaigns and co-located satellite observations in the Fram Strait. The Polar 5 aircraft carried the Microwave Radar/radiometer for Arctic Clouds (MiRAC) cloud radar MiRAC-A with an 89 GHz passive channel and MiRAC-P with six double-sideband channels at 183.31 GHz and two window channels at 243 and 340 GHz. We calculate the emissivity with the non-scattering radiative transfer equation from observed upwelling radiation at 25° (MiRAC-A) and 0° (MiRAC-P) and Passive and Active Microwave radiative TRAnsfer (PAMTRA) simulations. The PAMTRA simulations are based on atmospheric profiles from dropsondes and surface temperatures from an infrared radiometer.The airborne-derived sea ice emissivity (O(0.1km)) varies on small spatial scales (O(1km)), which align with sea ice properties identified by visual imagery. High-resolution airborne-derived emissivities vary more than emissivities from co-located overflights of the GPM constellation due to the smaller footprint size, which resolve sea ice variations. The emissivity of frozen and snow-free leads separates clearly from more compact and snow-covered ice flows at all frequencies. The comparison of summer and spring emissivities reveals an emissivity reduction due to melting. We will also conduct evaluations of emissivity parameterizations (e.g. TELSEM²) and provide insights into observations at ICI and AWS frequencies over Arctic sea ice. Findings based on the field data may be useful for the assimilation of radiances from existing and future microwave radiometers into weather prediction models in polar regions.
Dissolved gases in groundwater as tracer for gas-water interaction and volcanic system evolution: a case study at island of Vulcano (Italy)
Authors: De Gregorio Sofia , Camarda Marco , Capasso Giorgio , Di Martino Roberto M.R. , Prano Vincenzo
Published: February 2023

Water-gas interaction is an ordinary process occurring in volcanic areas because of gases released from magma reservoir at depth interact and dissolve in groundwater and/or are discharged from the soils or fumaroles. At the island of Vulcano (Aeolian Islands), both thermal and geochemical anomalies in groundwater were detected along lines of structural weakness in the volcanic edifice behaving as preferential pathways for up-flows of heat and fluids discharged by the deep magmatic system.The interaction between deep volcanic/hydrothermal gases and groundwater can develop at various extent due to both local hydrogeological conditions and volcano-tectonic setting, resulting in different dissolved gas concentrations. Herein, we report a comprehensive study of chemical and stable isotope composition of dissolved gases in thermal groundwater at island of Vulcano.The data were acquired with systematic sampling in four selected well since 2010, and include data on dissolved helium isotopes and carbon isotope composition of dissolved CO2. The chemistry and isotopic data (C and He) of dissolved gases reveal the magmatic origin of the gas interacting with the aquifer and point out as the pristine magmatic composition varies upon gas ascent because of either dilution by a soil-atmospheric component or fractionation processes during interaction with groundwater. Further we discussed dissolved gases variations recorded during the period of unrest which onset at Vulcano on September 2021 and is still ongoing. The period of unrest was characterized by huge increase, orders of magnitude over the background, of degassing activity both from main crater and in pericrateric area. The variations detected in the chemical and isotopic composition of the dissolved gases occurred at different times and intensities in relation to the location of the wells.
Zonal Momentum Balance in South Asian Summer Monsoon: Forces and Changing Winds
Authors: Upadhyaya Pankaj , Mishra Saroj K.
Published: February 2023

The balance of forces for the South Asian Summer Monsoon (SASM) gives valuable insights for the understanding of the mean circulation and the changes it has undergone in the past. In this study, we have analyzed the zonal momentum balance for SASM for the last few decades (1950-2010) using reanalysis data to understand the changes in different forces and relate them with the changes in the associated circulation. In the lower level (925 hPa), the Pressure Gradient Force (PGF), Coriolis Force (CF), and Residual Force (RF, which includes the unresolved sub-grid scale process and frictional terms) are found to be the dominant terms of the zonal momentum balance for SASM with a magnitude of order 10-4m sec-2 whereas, horizontal advection and eddy force terms are negligible with one or more order lesser in magnitude. The residual force can be estimated by Rayleigh friction induced by turbulence, particularly over ocean points, which, however, is not a good measure of the same over the land points because of high irregularity. The momentum balance at the upper level (200 hPa) is between the PGF, CF, and the advection term, unlike the lower level, where the residual force does not seem to be dominant. In the free troposphere, the Convective Momentum Transfer or in other words convective friction is a good estimator of the RF, which represents the vertical transport of momentum. The changes in SASM circulation in the past can be apprehended by looking into the changes in these vital forces that drive the motion.
Data-Driven Modelling of Steppe Wetland Variability in Eastern Austrian Seewinkel Using Satellite-Derived Water Extent and Climatological and Groundwater Data
Authors: Schauer Henri Isidor , Schlaffer Stefan , Bueechi Emanuel , Dorigo Wouter
Published: February 2023

Seewinkel salt pans are a unique wetland ecosystem in eastern Austria that serves as habitat for a diverse range of e.g. birds and halophilic species. Due to groundwater drainage by channels and wells, the salt pans are in an increasingly vulnerable state as they are decisively conditioned by duration and timing of water abundance. However, water gauge data are merely given for three salt pans. The dynamics of salt pans in Seewinkel, locally referred to as Salzlacken, remain insufficiently understood in the context of continuously changing seasonal and long-term hydrological, meteorological, and climatological patterns. Based on previous results on salt pan mapping and monitoring, this work advances inundation state prediction for 34 salt pans by using high-resolution remote sensing data and machine learning methods. The random forest classification models build on hydrological and meteorological predictors in 12-monthly temporal resolution, as, e.g., reduced precipitation sums during the preceding winter season affect the recharge rates of salt pans and groundwater and, as a result, drying state in summer. Four models predict summer drying state at respective four points in time, namely in March, April, May, and June of each year between 1984 and 2022. We first show that remotely sensed water extent products, retrieved from Landsat data can serve as a target variable for data-driven modelling of small-scale salt pan water-dynamics. Secondly, we show that the applied models can successfully predict summer drying state and inundation periods of individual salt pans achieving a maximum F1-score of 0.81. Finally, it is demonstrated that very similar model results can be attained without in-situ groundwater measurements. Research based on water gauge measurements with similar model-designs has been done in the context of lakes, whereas the combination of satellite-derived water extent and salt pans, especially for ecosystems of small size, remains underrepresented. As the data retrieval in this work is based on global and freely available remote sensing data, this method is transferable to comparable salt pan ecosystems in other parts of the world. 
Quartz solubility in low-density aqueous fluids: evaluation and development of thermodynamic models
Authors: Salomone Federica , Dolejš David
Published: February 2023

Solubility of quartz in aqueous fluids over a wide range of temperatures and pressures is crucial for our understanding of water–rock interaction. Experimental data cover a temperature range of 20 to 1130 °C and pressures from 1 to 20 kbar, and this dataset provides a useful basis for critical comparison and development of thermodynamic models for mineral solubility and aqueous solutes. Thermodynamic models for quartz solubility in pure water (1982-2021) are based on one of the following approaches: (1) successive hydration of solute, (2) correlation with solvent density, (3) virial equation of state for solute-solvent mixtures, or (4) Helgeson-Kirkham-Flowers (HKF) electrostatic equation of state. Predictions from these models generally converge at hydrothermal and supercritical temperatures in the fluid density range of 0.6-1.0 g cm-3. At high temperatures and fluid densities, the models based on successive hydration or virial expansion loose their physical meaning; the electrostatic approaches tend to overestimate the quartz solubility, although the large number of parameters in the HKF equation of state offers remarkably large calibration flexibility. At low pressures and low fluid densities, the individual approaches diverge: the density and virial models correctly approach the limiting case of ideal gas, but the virial equations of state tend to predict consistently higher solubilities. In this study we develop a more physically rigorous density-based model for quartz and test its performance in low-pressure aqueous fluids. Thermodynamic properties of aqueous solute are formulated as a function of hydration number that is typically variable at very low pressures (< 400 bar). At partial hydration, the thermodynamic properties of species are mainly controlled by enthalpy of stepwise hydration reactions and long-range solute-solvent interactions are minimal. At complete inner-sphere hydration the thermodynamic properties of aqueous species become a combined contribution of unhydrated species properties, mechanic interaction in the hydration sphere and standard-state conversion terms. When complete hydration of a species is achieved, Gibbs energy of species becomes linear with log water density at constant temperature, thus mimicking the linear log K – log density relationship for the mineral solubility equilibrium.
Responses of C/N Coupling to Nutrient Additions in Subtropical Mountainous Rivers in Taiwan
Authors: Huang Yu-Hsiang , Lee Li-Chin , Huang Jr-Chuan
Published: February 2023

C-N (carbon-nitrogen) coupling in streams which reflects ecosystems’ demand for energy and nutrients can help understand the ecosystem status and health. However, the DON (dissolved organic nitrogen) response to different nutrient addition is not clear, particularly in the C-limited streams. In this study, incubations with nutrient additions (DIN, dissolved inorganic nitrogen and/or DOC, dissolved organic carbon) were conducted using water samples from agricultural and pristine watersheds in northern Taiwan to examine the responses of C-N coupling to different disturbance levels. Results showed that during the incubation, DON concentration only increased when DIN was added, whereas no significant changes was found in DON with DOC addition. Specifically, DON could increase up to 360% - 460% in the pristine watersheds, while it only increased by 20% - 80% in the agricultural watersheds. Compared to DOC, DON significantly responded to DIN addition, indicating apparent nutrient demand in pristine watersheds. Besides, the DOC:DON ratio in the pristine watersheds dropped from around 10 to 2, while the ratio in the agricultural watersheds only dropped from 0.8 to 0.5. Such decrease might indicate that DIN addition can greatly increase DOM (dissolved organic matters) lability in pristine watersheds. Interestingly, all DOC concentrations dropped to around 0.4 to 0.5 mg/L in all different addition combinations, including DOC addition. Although DIN and/or DOC addition can stimulate relevant biogeochemical processes, a presumable limitation of DOC (0.4 to 0.5 mg/L) might be a tipping point of these processes, which required further investigation.

Keywords: carbon-nitrogen coupling, small mountainous rivers (SMRs), Taiwan
An AI hybrid predictive tool for extreme hurricane forecasting
Authors: Martinez Amaya Javier , Radin Cristina , Nieves Veronica , Longépé Nicolas , Muñoz-Marí Jordi
Published: February 2023

Hurricanes, and more generally tropical cyclones, are among the most destructive natural hazards, and are arguably changing under climate change influences. Applying the power of AI to predict the extreme behavior of these events could be key to helping minimize hurricane damage. AI tools are a significant opportunity to: 1) identify non-linear relationships between changing hurricane-related characteristics and tropical storm intensification, and 2) anticipate responses to these changes. Another key part of this AI-based system is uncertainty quantification for decision-making processes. In this context, we present an improved ML hybrid model for predicting the development of extreme hurricane events, which includes effective information on spatio-temporal evolution variations of structural parameters extracted from IR satellite images. This approach, which combines Convolutional Neural Networks (CNNs) and a Random Forest (RF) classification framework, has been trained/tested with data from 1995 over the North Atlantic and NorthEast Pacific regions. Results from the CNN-RF model shows a performance of 80% or better considering lead-times of up to three days ahead (every 6 hours). With the proposed configuration, the overall precision has increased by at least 8%. This model could be yet further improved with the inclusion of new variables linked to environmental factors to be progressively explored. 
Toward improved food security under compound shocks in Lebanon: A Water-Energy-Food Nexus Approach
Authors: Daher Bassel , Bachour Roula , F. Yanni Sandra , Koo-Oshima Sasha , H . Mohtar Rabi
Published: February 2023

The current challenges in Lebanon are multifaceted, and among them is an impending food security crisis. Much of this can be attributed to a lack of sustainable planning within the agricultural sector. Decision-makers in agriculture and other connected sectors are disconnected and further hindered by the absence of national platforms and methods for assessing the trade-offs of potential interventions. This study aims to: (1) identify and quantify the critical interconnections between water, energy, nutrition, and food systems in Lebanon; (2) develop a framework to quantify the trade-offs associated with adopting interventions within current water, energy, and agriculture portfolios and practices; (3) evaluate producers' perceptions toward their willingness to implement proposed changes in crop production, renewable energy, and water reuse. The research shows that investing in local production of broad beans, lentils, chickpeas, and peas can lead to cost savings, increased nutritional value in locally produced foods, and reduced reliance on foreign markets. However, this also leads to increased water, energy, land and carbon usage which needs to be taken into account. Given the volatility of future currency exchange rates, it is increasingly important to identify a strategic food basket that can be produced locally to reduce dependence on imports. The findings of this study can aid in shaping policy and planning in Lebanon, and may also be adapted and applied in other countries in the MENA region.
Pressure drop as a forecasting tool of eruption duration: 2021 La Palma eruption
Authors: Charco Maria , González Pablo J. , Garcia-Cañada Laura , del Fresno Carmen
Published: February 2023

One of the main goals of the modern volcanology is produce accurate eruption forecastings. Not only from a scientific point of view, but considering that approximately 30 million people live in the vicinity of active volcanic areas and tens of thousands of people have lost their lives as a result of the direct effects of historical eruptions. Thus, in 2017 "The US National Academies of Sciences, Engineering and Medicine" considered the forecast of eruptions as one of the great challenges of Volcanology. Generally, the focus is on forecasting the eruption onset, however, forecasting the style, size and duration becomes relevant and properly manage long-duration eruption, e.g., during the 2021 La Palma (Canary Islands) eruption, whose main hazards were air pollution, ash fall and lava flows. In particular, the 2021 eruption of La Palma lava flows caused extensive devastation to the surrounding community: more than 2800 buildings and almost 1000 hectares of banana plantations and farmland were destroyed. In this study, we use co-eruptive GNSS series of deformation data to estimate the eruption's end. The forecast was based on the relationship between displacements and pressure changes provided by a purely elastic model of the medium. We also estimated the location of a magma reservoir. A depth of 10-15 km is inferred. This reservoir is consistent with the main seismogenic volume during the eruption. We interpret that the reservoir pressure dropped due the progressive withdrawal of magma that fed the eruption. We assumed that the magmatic plumbing responsible for the eruption was a closed system and that the magma contributions in this zone do not cause detectable deformations. Thus, we used the pressure drop as an indicator of the end of an eruption. With the benefit of the hindsight, we extensively tested our model considering different deformation time series spams in order to evaluate the feasibility of making near-real time predictions of the duration of the eruption, and derive some constraints about the magma system.
The submarine Congo Canyon as a conduit for microplastics to the deep sea
Authors: Pohl Florian , Hildebrandt Lars , O’Dell Joey , Talling Peter , Baker Megan , El Gareb Fadi , La Nasa Jacopo , De Falco Francesca , Mattonai Marco , Ruffell Sean , Eggenhuisen Joris , Modugno Francesca , Proefrock Daniel , Pope Ed , Silva Jacinto Ricardo , Heijnen Maarten , Hage Sophie , Simmons Stephen , Hasenhündl Martin , Heerema Catharina
Published: February 2023

The increasing plastic pollution of the world’s oceans represents a serious threat to marine ecosystems and has become a well-known topic garnering growing public attention. The global input of plastic waste into the oceans is estimated to be approximately 10 million tons per year and predicted to rise by one order of magnitude by 2025. More than 90% of the plastic that enters the oceans is thought to end up on the seafloor, and seafloor sediment samples show that plastics are concentrated in confined morphologies and sedimentary environments such as submarine canyons. These canyons are occasionally flushed by powerful gravity-driven sediment flows called turbidity currents, which transport vast volumes of sediment to the deep sea and deposit sediment in deep-sea fans. As such, turbidity currents may also transport plastics present in the canyon and bury plastics in deep-sea fans. These fans may therefore act as sinks for seafloor plastics. Here we present a comprehensive dataset showing the spatial distribution of microplastics in seafloor sediments from the Congo Canyon, offshore West Africa. Multicores taken from 16 locations along the canyon, sampled different sedimentary sub-environments including the canyon thalweg, canyon terraces, and distal lobe. Microplastics were extracted from the sediments by density separation and the polymer type, size, and shape of all individual microplastic particles were analysed using laser-direct infrared-spectroscopy (LDIR). Microplastic number concentrations in the sediments of the distal lobe are significantly higher than in the canyon, indicating that the Congo Canyon system is a highly efficient conduit for microplastic transport to the deep sea. Moreover, microplastic concentrations of >20,000 particles per kg of dry sediment were recorded in the lobe, which represent some of the highest ever recorded microplastic number concentrations in seafloor sediments. This shows that deep-sea fans can serve as hotspots and potential terminal sinks for seafloor microplastics.
Do tree-rings match the low-frequency patterns represented in climate models?
Authors: McPartland Mara , Hébert Raphaël , Laepple Thomas
Published: February 2023

Whether tree-rings faithfully archive the low-frequency variability (LFV) in climate remains debated. In theory, trees are fundamentally limited by being relatively short-lived and therefore unable to capture variations in the climate that are longer than their own lifespans. In addition, near universal practices of “detrending” tree-ring records to remove individualistic age-growth trends place further constraints on the amount of LFV that is maintained in final chronologies. Detrending methods designed to boost LFV may increase low-frequency signals, but how well those patterns reflect true variations in climate as opposed to long growth trends is still unclear. In this study, we first compared the spectral properties of the PAGES North America 2k dataset of temperature-sensitive tree-ring records against long temperature records to determine how much variability is retained in tree-rings after detrending, and how detrending method influences agreement in tree-ring power spectra across space. Then, we compare the spectral properties of tree-rings to the CMIP6 last millennium simulation to validate climate models against long proxy records. This research works to resolve discrepancies between temperature proxies and climate models on long timescales in order to improve our understanding of centennial-scale variability in the Earth’s climate system.
Mapping mining environmental impacts using PRISMA hyperspectral imagery: Acid mine drainage (AMD) example
Authors: Kopackova-Strnadova Veronika
Published: February 2023

Acid mine drainage (AMD) is considered as one of the main factors causing water pollution in regions with historic or current mining activities. Its generation, release, mobility, and attenuation involves complex processes governed by a combination of physical, chemical, and biological factors. Clearly this phenomenon is highly dynamic depending on other external factors such as precipitations and ground water table fluctuations and conventional monitoring is time and resource-demanding. Recent research studies proved that imaging spectroscopy represents an alternative to conventional methods and an efficient way to characterize mines and assess the potential for AMD discharge while focusing on mapping those minerals serving as indicators of sub-aerial oxidation of pyrite (‘hot spots’) and the subsequent formation of AMD. In this study a potential of new PRISMA hyperspectral satellite sensor for multi-temporal AMD mappng was evaluated. The PRISMA AMD mineral mapping results were compared with existing ground truth data and other validated AMD maps derived using aerial high-resolution hyperspectral imaging data (e.g., CASI/SASI). To conclude, a spectral and spatial resolution of the PRISMA satellite data is sufficient to map this phenomenon at multi-temporal scale and PRISMA data has a potential to be operationally used in remediation projects and other environmental applications.
Effectiveness of Sentinel-2 imagery, apparent electrical conductivity and topography for delineating site-specific management zones in an olive grove in southern Spain.
Authors: Vanderlinden Karl , Martínez García Gonzalo , Ramos Rodríguez Mario , Mateos Iñiguez Luciano
Published: February 2023

Variable rate irrigation (VRI) shows attractive cost/benefit ratios, as compared to drip irrigation, when implemented in large orchards with suitable field and planting geometries. To evaluate the effectiveness of apparent electrical conductivity (ECa), elevation (Z), topographic wetness index (TWI) and time-series of Sentinel-2 NDVI imagery for delimiting VRI zones in olive groves, a study was conducted in a 40-ha commercial plot in southern Spain (Ecija, Seville), equipped with a linear move sprinkler irrigation system and with trees on a 4 × 7 m grid. Soil samples were collected at 140 points on a regular grid with depth intervals of 0.3 m down to 1.2 m and analyzed for soil texture. Relationships between soil texture, topography, ECa and NDVI were analyzed using correlation analysis and regression trees. Time series of correlation between ECa and NDVI showed a seasonal pattern because of the growth-decline pattern of the grass soil cover. The regression tree analysis showed that ECa and elevation were most relevant for classifying NDVI (R2=0.70). Fuzzy k-means classification using ECa+Z yielded 4 classes while for ECa, ECa+Z+TWI and ECa+Z+TWI+NDVI 2 classes were obtained. The zoning based on ECa+Z classified clay content and the 0.95 percentile NDVI successfully. This classification was adopted for VRI since the involved variables can be related to soil water availability. Confounding effects of coarse fragments and soil water content on the clay-ECa relationship could be resolved in future studies by measuring theses variables to improve further the classification.AcknowledgementThis work is funded by the Spanish State Agency for Research through grants PID2019-104136RR-C21 and PID2019-104136RR-C22/AEI/10.13039/501100011033 and by IFAPA/FEDER through grant AVA2019.018.
Deformation of epidote and plagioclase in the semi-brittle regime
Authors: Incel Sarah , Mohrbach Katharina , Renner Jörg
Published: February 2023

In the plagioclase-rich lower continental crust, hydrous epidote-group minerals will, among other phases, replace plagioclase in the presence of minor amounts of fluids. It has previously been shown that this reaction has a significant impact on the strength of plagioclase aggregates, with reacting aggregates being much weaker than their unreacted counterparts (Stünitz and Tullis, 2001). Hence, reactions taking place in the lower continental crust may have a strong influence on its deformation behaviour and thus on its strength. Yet, it still remains unclear if the observed weakening is due to the nucleation and growth of inherently weaker product phases, e.g., epidote-group minerals, or due to inhibited grain growth in a polyphase aggregate as a result of Zener pinning. We experimentally investigated the relative strength of pure epidote and pure plagioclase aggregates at a confining pressure of 1 GPa, two different temperatures (550 and 650 °C) and two different strain rates (5·10-5 and 5·10-6 s-1) using a solid-medium Griggs-deformation apparatus. Furthermore, we also investigated potential strength differences due to differences in grain size by deforming aggregates with a grain-size range of either 90-135 μm or <25 μm. After deformation under 650 °C, the epidote aggregates reveal the nucleation and growth of new phases indicating that epidote was no longer stable. The amount of product phases found in the epidote aggregates scales with the duration of deformation. At the explored experimental conditions, the compressive strength of plagioclase and epidote aggregates depends on temperature and strain rate with a decrease in strength with an increase in temperature or a decrease in strain rate. At identical conditions, the epidote aggregates are either significantly stronger or show a similar strength as the plagioclase aggregates. Microstructural analyses of the recovered samples reveal that deformation in both aggregates was almost exclusively accommodated by grain fracturing and occasionally slip along cleavage planes, and remained non-localized except for the epidote aggregate deformed at 650 °C with a strain rate of 5·10-6 s-1, exhibiting kinetically-controlled faulting due to reaction. Stünitz, H. and Tullis, J. (2001). Weakening and strain localization produced by syn-deformational reaction ofplagioclase. International Journal of Earth Sciences, 90(1):136{148.
On building a general framework for assessing food security risk under probabilistic socioeconomic scenarios
Authors: Papayiannis Georgios , Koundouri Phoebe , Vassilopoulos Achilleas , Yannacopoulos Athanasios
Published: February 2023

Food security is a key issue in sustainability studies. In this work, a general framework for providing detailed probabilistic socioeconomic scenarios as well as predictions concerning food security is proposed. Our methodology builds (a) on the Bayesian probabilistic version of world population prediction model and (b) on the dependencies of food needs and food system capacities on key drivers, such as population, gross domestic product (GDP) and other socioeconomic and climate indicators. In this perspective, the concept of the recently developed convex risk measures involving model uncertainty is employed for the construction of a risk assessment framework in the context of food security. The proposed method provides within and across the various probabilistic scenarios predictions and evaluations for food security risk. Our methodology is illustrated by studying food security and quantifying the occurring risk in Egypt and Ethiopia up to the year 2050, in the combined context of the Shared Socioeconomic Pathways (SSPs) and the Representative Concentration Pathways (RCPs).
Hair-ice, fungal guttation droplets, ice ribbons and needle ice from a chemical perspective
Authors: Hofmann Diana , Preuss Gisela , Fontana Pietro , Mätzler Christian
Published: February 2023

As a result of global warming, now evident also in temperate latitudes, longer periods of snow-free winters, instead with plenty of precipitation are becoming increasingly common. If the temperatures then fall below freezing point, one can, with a little luck, discover hair ice - hair-like, flexible structures reaching up to 10 cm in length without any ramifications.This natural phenomenon, already described in 1918 by Alfred Wegener, was a mystery for a long time. Only in the 21st century a fungus (Exidiopsis effusa) was discovered as the causative agent [1].Hair ice develops exclusively on rotten hardwoods on/in which this fungus is present, at high humidity, preferably windless, and temperatures slightly below freezing. Once infected, corresponding branches can be repeatedly elicited hair-rise growth under optimal conditions (field & climate chamber). Hair ice, unlike frost needles, arises from the base. At the onset of hair-ice melt a very thin fibre becomes apparent, which carries brownish water drops. Melting water samples show complex mass spectra similar to dissolved organic carbon e.g. from terrestrial/ marine waters, soil extracts or aerosols.Hair ice samples of various tree species were desalted, concentrated by solid phase extraction and subsequently analyzed by flow injection analysis in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer, equipped with an ESI source and a 7 T supra-conducting magnet (LTQ-FT Ultra, ThermoFisher Scientific) - the key technique for the analysis of complex samples, simultaneously providing molecular level details of thousands of compounds. As main result, complex, but almost identical spectra were found. For their chemical characterization van Krevelen diagrams, typical to classify samples regarding polarity and aromaticity were plotted. By comparison with references biopolymer substance classes were derived. As result, lignin and tannin could be detected as the main hair-ice substance classes, supposed to act as freezing catalyst as well as recrystallization inhibitor.For the question, if and what happens in summer, we sampled in several years guttation droplets, too – of this fungus and for comparison from a fungus of another family. Both samples were carbon riche, but only the samples from Exidiopsis effusa show such a complex DOC-spectrum, but in contrast to hair ice peak depleted with mainly tannin assignment.Popular scientific publications have led to an increasing interest in hair ice and related phenomena in recent years. We have received spectacular photos of various ice structures, followed by first samples of needle ice and ice ribbons. After initial measurements for their C content, HPLC-MS investigations still with a triple quadrupole mass spectrometer have been performed. For final analyses a cooperation with a FTICRMS working group is now sought.[1] D. Hofmann, G. Preuss and C. Mätzler (2015) Biogeosciences 12: 4261–4273
Land degradation estimation by SDG 15.3.1 computed at the local scale: the case of the six Mediterranean study sites of the NewLife4Drylands project
Authors: Tarantino Cristina , Vicario Saverio , Adamo Maria , Labadessa Rocco , Assennato Francesca , Alessi Nicola , Riitano Nicola , Vitale Marcello , Perez Martina , Domingo-Marimon Cristina , Montero Pau , Carabassa Vicenc
Published: February 2023

In 2015, during the 12th Conference of the Parties (COP) a new overall vision objective of the United Nations Convention to Combat Desertification (UNCCD) and the Sustainable Development Goals (SDGs) for 2030 called “Achieving Land Degradation Neutrality (LDN)” was incorporated. NewLife4Drylands (NL4DL; https://www.newlife4drylands.eu/), the LIFE Preparatory project, focuses on the use of remote sensing for the identification of a framework for the monitoring of land degradation and results of nature-based restoration interventions for achieving LDN. With this aim, Indicators and/or their proxies have been extracted from satellite data as essential variables for land degradation status assessment. Six Mediterranean Natura 2000 study sites located in Italy, Greece and Spain were considered as case studies and pressures and threats affecting each of them were analysed as land cover mappings, burn severity mappings, time series of climatic and phenology spectral indices, precipitation indices, soil organic carbon mappings.  Freely available satellite data from Landsat and Sentinel-2 programs were considered: in the case of sites less than 50 hectares in size, commercial satellite data at very high spatial resolution were used for evaluation. The indices analyzed will be integrated for the computation of SDG 15.3.1 indicator “proportion of land that is degraded over the total land area” according to the 2030 Agenda for Sustainable Development and UNCCD guidelines. SDG 15.3.1 standard formula considers sub-indicators to be integrated: trends in land cover, primary productivity and soil organic carbon. The novelty in the project outcomes is two-fold: 1) the estimation of drivers/disturbance (drought, fire, etc.) of LDN together with sub-indicators will allow to give practical indication to land manager; 2) sub-indicators have been computed at the local scale. For each study site, short-term and long-term analyses will be approached. Results will be part of a protocol for the assessment of land degradation and monitoring restoration interventions of degraded land.