bluuebunny/crossref_metadata_2025 huggingface dataset:
Magma oceanography of the dense, ultrashort-period sub-Earth GJ 367 b
Authors: Golabek Gregor J. , Lichtenberg Tim , Bartels Lotte M. , Tackley Paul J. , Meier Tobias , Bower Dan
Published: March 2024

The dawn of high-resolution observations with the James Webb Space Telescope will enable spatially resolved observations of ultrashort-period rocky exoplanets. Some of these planets orbit so closely to their star that they lack an atmosphere [1], which gives direct access to their surfaces and opens a window to infer their geodynamics [2]. The physical parameters of the ultrashort-period sub-Earth GJ 367 b have been observationally constrained to a planetary radius of about 0.72 to 0.75 Earth-radii and a mass between 0.48 and 0.55 Earth-masses, implying a density of 6200 to 8500 kg/m3 [3, 4], which puts this planet in a Mercury-like interior regime with a thin mantle overlying a fractionally large core.The dayside temperature ranges between 1500 to 1800 K, thus suggesting the presence of a permanent magma ocean or dayside magma pond on the surface, induced by stellar irradiation. The large uncertainty on the age of the stellar system, between 30 Myr [4] and about 8 Gyr [3], however, introduce severe uncertainties related to the compositional and thermal evolution of the planetary mantle. In this study we perform global 2D spherical annulus StagYY simulations [5, 6] of solid-state mantle convection and surface melting with the goal to constrain the geometric and compositional properties of the planet. Constraining the spatial dimensions of thermodynamic properties of partially molten, atmosphere-less planets like GJ 367 b offers unique opportunities to constrain the compositional fractionation during magma ocean epochs and provides avenues to constrain the delivery and loss cycle of atmophile elements on strongly irradiated exoplanets.References:[1] L. Kreidberg and 18 co-authors. Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b. Nature, 573:87–90, 2019.[2] T. G. Meier, D. J. Bower, T. Lichtenberg, P. J. Tackley, and B.-O. Demory. Hemispheric Tectonics on LHS 3844b. Astrophys. J. Lett., 908:L48, 2021.[3] K.W.F. Lam and 78 co-authors. GJ 367 b: A dense, ultrashort-period sub-earth planet transiting a nearby red dwarf star. Science, 374:1271–1275, 2021.[4] W. Brandner, P. Calissendorff, N. Frankel, and F. Cantalloube. High-contrast, high-angular resolution view of the GJ367 exoplanet system. Mon. Notices Royal Astron. Soc., 513:661–669, 2022.[5] J. W. Hernlund and P. J. Tackley. Modeling mantle convection in the spherical annulus. Phys. Earth Planet. Int., 171:48–54, 2008.[6] P. J. Tackley. Modelling compressible mantle convection with large viscosity contrasts in a three-dimensional spherical shell using the yin-yang grid. Phys. Earth Planet. Int., 171:7–18, 2008.
Advancing understanding of Holocene rock glacier dynamics
Authors: Lehmann Benjamin , Anderson Robert S. , Cusicanqui Diego , Valla Pierre G.
Published: March 2024

Rock glaciers, major cryospheric features in alpine landscapes, pose formidable challenges in extracting climatic information over recent to Holocene timescales. This presentation delves into an integrative multi-method approach, striving to replicate modern motion through feature tracking, exposure ages from 10Be concentrations, and observations of rock glacier morphology. Applying a novel numerical model for rock-glacier dynamics, our study focuses on the Holocene to modern activity of a prominent rock glacier flowing northeast from a 300-m tall headwall on the Mt. Sopris (West Elk Mountains, Colorado USA).The Mt. Sopris rock glacier spans 2 km from its headwall avalanche source cone to a 25 m tall terminus, adorned with metric size granitic blocks exhibiting systematic variations in lichen cover and weathering. Fine-grained material fills voids between blocks in the lowermost reaches, supporting tree clusters. The 10Be-based exposure ages of block surfaces range from 1.5 to 12 kyr, with ages older than 6 kyr being compressed into the bottom quarter of the rock glacier. Modern rock-glacier surface velocities, ranging from 0.6 to 2 m/yr, can be explained by the internal deformation of a 25-m thick ice core beneath the rocky surface. However, interpreting the 10Be exposure age profile proves challenging, leading to the development of a new numerical model for rock-glacier dynamics.Our model simplifies the mass balance to an avalanche cone accumulation zone, and the rock cover is assumed to damp melting of underlying ice over the remaining areas of the rock glacier. Climate forcing is achieved through a proposed history of the snow avalanche activity. The rock glacier velocity is calculated assuming Glen’s flow law in the interior ice and acknowledges the role of debris cover in augmenting the stress profile throughout. Preliminary modeling suggests that an avalanche cone history with two independent pulses, one in the early Holocene and the other simulating the Neoglacial, captures dominant features of the 10Be exposure age structure. The first manifestation of the rock glacier extends to approximately 1.5 km in lengths, then extends, thins, and slows over the mid-Holocene lull in input, before being overtaken and re-accelerated by the Neoglacial pulse.This study contributes new insights into rock glacier dynamics, bridging multiple timescales and quantitatively assessing physical processes in action. Rock glaciers, key players in alpine landscape evolution, exhibit a response to climate that differs from typical glacier systems in that they never retreat, and can survive long periods of low snow input. Our numerical simulations allow investigation of dynamic responses to variations in both climate and headwall backwearing erosion. Success of our approach on the Mt. Sopris rock-glacier system suggests its utility in developing a deeper understanding of how different high mountain landscapes respond to climatic fluctuations over Holocene timescales.
Delineation of microseism noise sources in the Indian Ocean.
Authors: Pradhan Gyanasmita , Reddy Ramakrushna , Singha Roy Paresh Nath
Published: March 2024

Microseisms are the continuous oscillations of the earth originated from the interaction of ocean waves with the solid earth. It is divided into two types, primary microseism and secondary microseism. Primary microseisms are generated by the interaction of ocean waves in the shallow coastal part and secondary microseisms are generated due to the interaction of two waves traveling opposite towards each other in the deeper or shallower part. Secondary microseism is also known as double frequency microseism band which is divided into two parts, long period double frequency microseism band and short period double frequency microseism band.We have taken data from IRIS DMC for ten seismic stations of the year 2018. Our study area is on the Indian Ocean. Indian ocean is considered as one of the global sources of microseism noise. In comparison to the North Indian Ocean, the Southern Ocean generates very strong amplitudes of microseism noise. Storm activity of Southern Ocean is very hazardous and destructive. In addition to that, the Antarctic circumpolar current brings warm water to the Ocean. Therefore, every year it experiences multiple cyclones which play a major role in the generation of microseism noise.In this study, we are using the frequency-dependent polarization analysis method. Our aim is to understand the spatial variation of noise and their possible sources. Power spectral density (PSD) is calculated using the spectral covariance matrix. Diagonal elements of the matrix represent the power spectra of each component (EW, NS, and Z). For analysing the spatial variation of PSD, we have used the vertical component (Z). We have observed higher PSD in the stations that are present close to the Southern Ocean and comparatively lower amplitudes are observed in the stations far away from the Southern Ocean. Back azimuth is used to determine the dominant source direction of the noise. From our results, major source direction of noise is from the Southern Ocean while minor sources are from Bay of Bengal and Arabian Sea. Clear seasonal variation in the source direction is not observed but seasonal variation in the number of polarized signals is observed indicating maximum polarized signal in the winter season and minimum polarized signals in the summer season. Combined results of spatial variation of PSD and back azimuth analysis help us to better understand the noise sources.  
U-Pb geochronology of Quaternary pedogenic carbonates and teeth from archaeological sites of Zarqa Valley, Jordan
Authors: Cerqueira João Carlos , Roberts Nick M. W , Scardia Giancarlo , Parenti Fabio , Ladeira Francisco , Neves Walter
Published: March 2024

Dating Quaternary carbonates and phosphates beyond the range of U-series geochronology is challenging, but recent studies have shown potential using the method of LA-ICP-MS U-Pb geochronology. Terrestrial materials altered and produced by pedogenic processes are particularly challenging, as they are usually rich in common Pb and poor in U; however, they provide some of the rare opportunities to directly date important archaeological artefacts. Our aim is to advance the age constraints of the hominin presence in the Zarqa Valley, Jordan, an important geomorphological feature with the oldest hominin artefact outside Africa. Along with new Ar-Ar geochronology of sequence-bounding basalts and new palaeomagnetic constraints, our approach is to: (1) review published U-Pb data of 2019; (2) conduct LA-ICP-MS U-Pb analyses in various pedogenic carbonates (calcrete) that cap the artefact-bearing deposits along with mammoth fossil remains; and (3) review the regional 234U/238U activity ratio estimate required for calculation of accurate U-Pb ages.A previous attempt to date hominin artifacts in the valley yielded an age of 1.98 ± 0.20 Ma for calcrete material, which is a weighted mean of several individual U-Pb isochrons derived from laminated calcretes, cracks, pore spaces and cement, and corrected by an initial 234U/238U activity ratio of 1.5 ± 0.5. We calculated an alternative, statistically favourable, age based on pooling the data into a single Tera-Wasserburg regression, resulting in 1.93 ± 0.44 Ma.Our LA-ICP-MS analysis thus far has not yielded a new significant age, but we have focussed on understanding the U and Pb compositions in a range of materials, including calcretes, rhizoliths, fossil coatings and Mammalian fossils. Biogenic spherulite laminae in laminar calcrete have higher U (0.56 ± 0.064 ppm) and lower Pb contents (0.61 ± 0.15 ppm) compared to abiogenic cracks and cement (0.33 ± 0.084 and 0.9 ± 2 ppm, respectively). Although far from desirable for U-Pb geochronology, for now, the spherulite laminae seems to be the most suitable micromorphology to date calcrete. Coarse spar of rhizoconcretions have very low U contents (0.07 ± 0.35 ppm), leading to unfavourable U/Pb ratios. Two fragments of a mammoth molar from an artefact-bearing deposit have been analysed; one is part of the crown having dentine and enamel, and the other one is dentine of the root. The crown and root fragments have high U concentrations of 33 ± 11 and 13.7 ± 9.9 ppm, respectively, but with their high Pb contents they still yield a low spread in U/Pb ratios and very imprecise lower intercept ages. Using LA-ICP-MS mapping to better identify areas of alteration, we pooled U-Th-Pb spot data from regions with low Y (
The Effect of Time-Varying Soil Properties Caused by Ploughing and Consolidation on Pesticide Fate in Soil and Groundwater
Authors: Cornelissen Pavan , Wipfler Louise , Braakhekke Maarten , Heinen Marius
Published: March 2024

Soil properties such as the dry bulk density and soil hydraulic parameters can significantly affect the environmental fate of pesticides. These properties are often assumed to remain constant in time in numerical models. In reality, however, these properties change over time due ploughing and consolidation. In this study, we modeled the time-varying soil properties induced by ploughing and consolidation and assessed its effect on pesticide accumulation in the topsoil and leaching to the groundwater. For this purpose, time-dependent soil properties have been implemented in the hydrological model SWAP and the pesticide fate model PEARL. Ploughing instantaneously decreases the bulk density, after which it gradually increases again to its original value due to consolidation caused by rainfall. The time-dependent soil properties are modelled based on empirical relationships between the dry bulk density and the Mualem-Van Genuchten parameters found in the literature.Ploughing leads to a short-term deviation of the soil water content and concentration compared to the reference case (i.e., the case with constant soil properties). We included mixing of pesticide over the ploughing layer due to ploughing in both cases. However, under Central European climate conditions, the effect of ploughing vanishes within several months in the entire soil profile. For assessing the impact on the leaching of pesticide to groundwater, we evaluated the pesticide concentration in pore water at 1 meter depth. The effect of time-varying soil properties due to ploughing and consolidation on the leaching concentration was found to be small for both a tracer and an adsorbing solute. Even for an extreme case with three ploughing events per year, the effect on the 90th-percentile of daily leaching concentration was smaller than 0.3%. For assessing the impact on the exposure of soil organisms to pesticides, we considered the pesticide concentration in pore water averaged over the upper 20 centimeters of the soil. For the tracer, ploughing resulted in a 1.2% decrease of the 90th-percentile of daily topsoil concentration data for the extreme case of three ploughing events per year. Interpretation of the results for adsorbing solutes in the topsoil is hampered by the fact that soil mass is not conserved in the current approach. More advanced models must be developed that allow for conservation of soil mass for assessing the impact of time-dependent soil properties on concentrations in the topsoil.
Tree species effects on stocks and stability of soil carbon: Links to mycorrhizal association and soil biota composition and functioning
Authors: Vesterdal Lars , Steffens Christina , Peng Yan , Zheng Haifeng , Yi Huimin , Hedênec Petr
Published: March 2024

Tree species with leaf litter traits driving slow rates of leaf litter decomposition have traditionally been associated with accumulation of higher soil organic carbon (SOC) stocks than tree species with fast litter decomposition rates. This hypothesis has mainly been based on observations of thick C-rich forest floors under tree species associated with ectomycorrhizae (ECM). However, a recent hypothesis suggested that tree species with foliar litter traits conducive to fast decomposition will lead to more pronounced microbial transformation and stabilization of litter C. The latter tree species are often associated with arbuscular mycorrhizae (AM) and may enhance deeper incorporation of C by more active soil fauna communities and by higher belowground rates of litter input. The Danish multi-site common garden tree species experiment includes ECM and AM tree species that differ widely in traits such as foliar litter chemistry. The experiment has been studied over the last 15 years to document and explain soil C stocks supported by emerging studies of soil fauna and soil microbial community composition and functioning.The six common European tree species formed distinct groups in soil carbon characteristics as well as in soil biota community composition and functioning that partly reflected their mycorrhizal association. Forest floor C stocks were consistent with the traditional perception of slowly decomposing leaf litter in ECM species being conducive to high C stocks. However, an intriguing pattern of higher C stocks in the mineral soil in AM tree species with high litter quality and characteristic soil biota functioning supported the recent microbial stabilization hypothesis and suggested deeper incorporation of C in more stable forms.Based on new results on microbial, macro- and mesofauna communities and their functioning, and on repeated soil sampling, this talk will revisit the common garden experiments for a synthesis of processes and patterns in organic matter formation that may explain observed patterns in quantity and quality of SOC.
From a white paper to an adventure gamebook: engaging practitioners in climate change impact studies on hydrology
Authors: Vidal Jean-Philippe , Héraut Louis
Published: March 2024

Scientific methodological guides are usually rather boring. However, numerous methodological challenges and pitfalls can be encountered in carrying out a climate change impact study on hydrology, and there is an urgent need to transfer data and related expertise from scientists to practitioners. This communication presents a hopefully less boring white paper written in the style of an adventure gamebook (see Jackson & Livingstone, 1982). This book is tailored for French water managers and consultants in hydrology, taking into account their specific language, datasets, and institutional context. It gathers good practice and up-to-date knowledge from scientists, and real-life experience of studies designed by local water managers and conducted by consultants within the EU LIFE Eau&Climat project (2021-2024).The book starts with the traditional warnings to the reader which is then invited to define her quest given the evolving context of the catchment of interest, and to prepare her equipment, gathering existing reports/adventurers’ accounts, collecting data/parchment maps, and listing available models/forest pathways. The core of the book is organized around two missions, the first of which consists in recovering the past evolution of water resources, through analyzing trends and potentially implement hydrological models. The second mission aims at composing the future of water resources in the catchment, through understanding and making use of possible climate and hydrology futures, through exploring the latest national climate and hydrology services and associated web portals to future worlds (see Kirk and Sangster, 2023, notably Part 4: “Portals and Worlds”). This book should serve as a basis for the reader to then develop robust adaptation strategies, in order for her to neither drown in a future flooding nor seeing her vital harvest compromised by recurring severe droughts.This book is designed in R markdown with the bookdown package (Xie, 2023). This work is funded by the EU LIFE Eau&Climat project (LIFE19 GIC/FR/001259).Jackson S. & Livingstone, I. (1982) The Warlock of Firetop Mountain. Puffin, Harmondsworth. 170 p. ISBN 978-978-0-14-031538-7Kirk T. & Sangster M. (2023) Realms of Imagination. Essays from the Wide Worlds of Fantasy. British Library, London. 271 p. ISBN 978-978-0-7123-5449-3Xie Y. (2023) bookdown: Authoring Books and Technical Documents with R Markdown. R package version 0.37, https://github.com/rstudio/bookdown
An analytical framework to understand flash drought mechanisms
Authors: Singh Vishal , Apurv Tushar
Published: March 2024

Understanding the physical mechanisms which contribute towards the rapid intensification of flash droughts is crucial for improving their forecasts. These mechanisms are difficult to elucidate using statistical techniques due to the complex interactions between land surface and atmospheric processes. In order to overcome this limitation, we use a slab model to model the coupled energy and water balance of the land and atmosphere. We develop an analytical framework to disentangle the influence of external forcings and system response driven by the state variables using the energy and water balance equations of the model. We apply the model to six locations selected from different climate regions of India to identify the physical mechanisms of flash droughts. We find that most flash droughts in India happen during the monsoon season, with higher frequency in humid regions of Northeast India and southern peninsular India. We find that all flash droughts occur during periods of deficient rainfall and the drying is predominantly driven by net shortwave radiation. However, the flash droughts differ in terms of contribution of winds towards drying, based on which we classify the flash drought mechanisms into three types: (a) Category 1: flash droughts with wind-driven intensification due to land-atmospheric feedback (b) Category 2: flash droughts with minimal contribution of winds towards drying and (c) Category 3: flash droughts with wind-driven intensification due to advected heat. We also show that although the enhanced vapor pressure deficit is a frequently recurring feature of flash droughts, it is not necessarily the most relevant contributor in their development.  
Submarine geomorphology of the Diamantina Trench (SE Indian Ocean) based on high-resolution multibeam sonar bathymetry and push core sediments
Authors: Yang Xun , Huang Xiaoxia , Zhou Peng , Peng Xiaotong
Published: March 2024

Diamantina Trench in the southeast Indian Ocean is one of the less unexplored hadal trenches (> 6000 m) of our planet, which develops the second deepest point (Dordrecht Deep, ca. 7019 m depth) in the Indian Ocean. Humans did not visit its ocean floor until the Chinese submersible Fendouzhe reached its deepest point in January 2023. This expedition collected high-resolution multibeam sonar bathymetry data covering about 3000 nautical miles and conducted 28 scientific dives with high-resolution videos and push core sediments of the upper seafloor (max. 40 cm) at a wide range of submarine geomorphology. This study combines these materials to fully assess the morphological variability of the trench and the causative factors and processes determining such characteristics.Bathymetry data indicate a rugged and complex landscape with various seamounts and debris deposits in the Diamantina Trench which could be classified into three sections. Bounded by the Broken Ridge to the north, the western section contains a series of basins and gorges, as well as parallel intruded ridges (WNW striking). The eastern section shows deeper and steeper slopes compared to the western section. The transitional area of the two sections (the Dordrecht Deep area, 270 km2) is the deepest part of the trench.Four push core sediment profiles were analyzed from the most west and east locations, the Dordrecht Deep area, and the western trend with foraminifera oozes. Layers of foraminifera and calcareous nannofossil oozes occur at the western section, whereas brownish pelagic sediments with occasionally coarse-grained Fe-Mn nodules develop at the eastern section. The preliminary results of total carbon (TC) and total nitrogen (TN) suggest distinct differences among and within profiles. TC values reach 12% in foraminifera oozes and less than 1.2% in the pelagic sediments. TC values decrease rapidly at the upper 10 cm and remain low (0.1–0.2%) at the lower part in the profiles from the eastern section and Dordrecht Deep area. An analogous trend applies to the TN graphs. The sediment profile from the western section, however, shows decreasing TC and TN values within depth.This research provides the first knowledge of the highly spatial heterogeneity of submarine geomorphological characteristics and sediment dynamics in the Diamantina Trench. The ongoing measurements of organic matter content, carbon isotope, and grain size from different topographic locations with the potential of dating methods (e.g., 14C and paleontological data) will further aid in reconstructing the spatial variations of paleoenvironmental changes and organic cycling process, as well as in understanding the relationship with tectonic activities and catastrophic events in hadal zones.
Accounting for Spatial Dependencies in Flood Hazard Assessment
Authors: Rotaru Ana Maria , Radice Alessio
Published: March 2024

Flood hazard assessments commonly employ either scenario-based or event-based approaches, assuming uniform return periods for peak flows throughout the entire watershed. However, due to the spatial and temporal heterogeneity inherent in flood events, relying on uniform scenarios can yield inaccurate outcomes. While employing uniform return periods may be advantageous at the local level, it proves to be inadequate for large-scale assessments. For example, assuming a 100-year return period for the entire river network is unrealistic, given the rarity of a singular event of such magnitude occurring across the entire watershed. This approach may lead to an overestimation of flood risk, as it fails to accurately capture the intricacies of floods on a broader scale.Regardless of the chosen methodology to account for these dependencies and variations, synthesizing flood hazard emerges as a primary need to provide decision-makers with adequate knowledge. When no uniform return period is used, this synthesis may be realized using probabilistic maps, which, unlike deterministic approaches, may represent the inherent complexity of the considered hydrogeological system. This would enable the stochastic nature of flood hazard to be captured, ensuring a more reliable analysis.Several methods are available for generating flood events accounting for the spatial dependence and the variability of occurrence probability at the watershed scale. A comprehensive review of existing studies that have proposed alternative methods for generating flood events, considering the spatial dependence, will be presented. Noteworthy methodologies include approaches based on the conditional exceedance model by Heffernan and Tawn, the application of a multivariate multisite weather generator coupled with continuous hydrological simulation, the use of simplified stochastic rainfall generators, and models grounded on copulas.Furthermore, a sample application is presented of inferring a dependency structure for an area northern to Milan, considering spatial dependencies for contributing sub-basins, and prospects for stochastic hazard mapping are discussed.
Delivery of organic matter to the Galilean moons
Authors: Benest Couzinou Tom , Amsler Moulanier Alizée , Mousis Olivier
Published: March 2024

The presence of carbonaceous matter is envisaged on the surface of many outer solar system bodies, including the Galilean moons. Density and moments of inertia of icy moons and dwarf planets also suggest the presence of this material in their refractory cores. The initial carbonaceous matter would have been composed of complex organic molecules (COMs) that possibly formed when the building blocks of the moons were in the forms of pebbles and icy grains in the protosolar nebula. Experimental studies indeed show that COMs can be formed from the UV irradiation of icy grains under nebular conditions.A baseline scenario is the formation of the Galilean moons in a circumplanetary disk that was too cold to vaporize the solids originating from the protosolar nebula. In this scenario, only the thermodynamic conditions of the protosolar nebula play a crucial role in determining the composition of the building blocks of the moons. Here we aim to assess the thermodynamic conditions of the protosolar nebula that enable the formation and the delivery of COMs to the formation location of the Galilean moons in the context of the aforementioned scenario. To do so, we have developed a two-dimensional model that describes the transport of pebbles/dust particles during the evolution of the protosolar nebula, using a Lagrangian scheme. This allows us to calculate the interstellar flux received by the particles as they migrate through the nebula.
Exploring mathematical formulations for a next-generation compatible finite element dynamical core
Authors: Witt Daniel , Shipton Jemma , Bendall Thomas
Published: March 2024

Compatible finite element methods are attractive for modelling geophysical fluids because they can replicate many of the desirable properties of the Arakawa C-grid, such as good wave dispersion. Compatible finite elements also facilitate alternative grid structures which avoid the clustering of grid points at the poles without the associated downsides these grids have with a finite difference scheme. For this reason compatible finite element methods are used in the Met Office's next-generation dynamical core, GungHo. The mathematical formulation used in GungHo is designed to be similar to that used in the Met Office's previous dynamical core, ENDGame. For instance, GungHo uses an advective form of the momentum equation and the lowest-order finite element spaces   We present an investigation into formulation options, carried out in Gusto, a geophysical fluid toolkit built upon Firedrake, an automated code generation framework for solving PDEs via finite element methods. Gusto shares the same fundamental compatible finite element formulation as GungHo but provides greater flexibility to investigate other choices Specifically, we investigate the effects of increasing the finite element order on the model. Due to the flexibility of Gusto, we can consider a generally higher order model as well as separately altering the horizontal and vertical orders. Additionally we investigate the effects brought about by writing the advective term in the momentum equation in its vector invariant form. We evaluate the impacts of these choices by conducting several test cases considering the short-term fluid dynamics and long-term statistical climate properties.  Understanding how these options impact the dynamical core will inform future research directions and improvements for GungHo.
Stem and soil methane fluxes of different ecosystems in Central Amazon
Authors: F. V. Cunha Hellen , P. Jones Sam , Van Asperen Hella , Botía Santiago , Komiya Shujiro , Rosalem Lívia , Schöngart Jochen , Fernandez Piedade Maria Teresa , Magnabosco Marra Daniel , Wittmann Florian , Trumbore Susan
Published: March 2024

Trees can significantly influence the net exchange of methane between forests and the atmosphere but what controls this behaviour in hyper-diverse ecosystems of the Central Amazon is not well defined. Variations in topography and rainfall cause predictable, but poorly documented, changes to the balance between methanotrophy and metanogenesis in soils and sediments across the landscape and between seasons. Trees can act as conduits for methane produced below-ground, however, the rate of such transport is mediated by inter and intra-species traits that need to be understood.To better understand the relationships among methane exchange, topographic position, seasonal rainfall and tree species in forests of the Central Amazon, we are conducting two related studies within the Uatumã Sustainable Development Reserve and Amazon Tall Tower Observatory, Amazonas, Brazil. The first is measuring soil and stem fluxes in six plots (6 trees / plot) along a topographic transition from a well-drained plateau, through slopes to a waterlogged valley. The second study is focusing on stem fluxes from six different species (5 trees / species), with differences in wood density and phenology, growing at a similar elevation in an Igapó forest of the adjacent Uatumã river. These observations, starting in September 2023, are being made every 2-3 months to capture the influence of seasonal rainfall and inundation.During the dry season (September, 2023), soils in the plateau (-1.4 ± 0.27 nmol m-2 s-1) and slope (-1.66 ± 0.11 to -1.20 ± 0.29 nmol m-2 s-1) plots acted as a sink for methane, whilst, those in the valley plot where a source (11.40 ± 2.56 nmol m-2 s-1 ). Reflecting this pattern, stem emissions were mostly observed in the valley (10.7 ± 4.71 nmol m-2 s-1) and in particular from the palm Mauritia flexuosa. Stem fluxes in the plateau and slope plots were marginal (0.0028 ± 0.0039 to 0.224 ± 0.0554 nmol m-2 s-1). In the Igapó (November, 2023), the exposed soil behaved as a sink for methane. Differences were observed among the species studied, with the largest emissions from Nectandra amazonum – low wood density group (0.64 ± 0.14 nmol m-2 s-1 ) and Inga sp. – high wood density group (0.39 ± 0.049 nmol m-2 s-1), while the other 4 species had lower emissions (0.0023 ± 0.01 to 0.10 ± 0.01 nmol m-2 s-1). Together these results support methane produced below-ground as the main source of tree emissions across this landscape and highlight the need to take species composition into account when considering the net exchange of methane from these ecosystems.
Variability of turbulent carbon dioxide flux netto at different time scales in an apple orchard ecosystem in Central Poland
Authors: Pawlak Izabela , Kleniewska Małgorzata
Published: March 2024

The impact of increasing CO2 on global temperature and strengthening of the greenhouse effect makes the measurements of gas exchange between the Earth’s surface and the atmosphere particularly important. Observational data on greenhouse gases exchange between different types of ecosystem and the atmosphere are crucial in thorough understanding the global climate mechanisms. Fruit tree ecosystems constitute an important kind of land use in Central Europe and apple is very extensively cultivated fruit tree crop in the world. Because intensively used apple orchards have a potential for carbon (C) sequestration and to be an important sink of atmospheric CO2 the continuous measurements of processes of ecosystem-atmosphere exchange are necessary for properly determining of global carbon (C) budget.This work presents the results of continuous closed-path EC measurements of carbon dioxide (CO2) fluxes in the apple orchard located near Grójec in the Masovian voivodeship on the largest orchard area in Poland. These are the results of the first and the only measurements of the net CO2 fluxes (started in February 2023) carried out in the apple orchard ecosystem in Poland. The main goal of the work is to present variations of CO2 flux at different time scales at different stages of fruit tree growth and during different climatic conditions. The turbulent fluxes of CO2 were calculated on a 30-min basis. The raw data were computed using the EddyPro -7.0.9 software taking into account the necessary corrections and procedures to correct the obtained results. CO2 fluxes were characterized by clear daily variability with negative values during the day (CO2 uptake in the photosynthesis process) and positive at night (CO2 release in plants respiration processes). The most intensive CO2 absorption took place between May and September (phases of flowering and fruit development and ripening) the with a maximum in June. Negative 30 min mean CO2 flux value reached for this month was around 12 µmol ּ m-2 ּ s-1 around noon. In the remaining months the CO2 absorption processes were lower and ranged around a few µmol ּ m-2 ּ s-1. 
Interaction of fault slip with fast fluid pressure transients in subduction zones
Authors: Gupta Avinash , Shapiro Nikolai M. , Ampuero Jean-Paul , Farge Gaspard , Jaupart Claude
Published: March 2024

This study investigates the dynamic interplay between fluids and fault slip transients in the portion of subduction zones subject to slow earthquakes. The permeable subduction interface in this region is believed to be saturated with fluids supplied by metamorphic dehydration reactions in the downgoing plate. Following Farge et al. (2021), we consider a model of a heterogeneous subduction channel filled with low-permeability plugs that behave as elementary fault-valves. Such a system is characterized by an intermittent fluid transport and rapid and localized pressure transients. Episodic rapid build-ups and releases of the fluid pressure affect the frictional strength on the fault and can result in transient slip accelerations. To study the possible effect of episodic fast fluid pressure variations on fault slip, we use numerical simulations in a 2D in-plane shear geometry. The fault is governed by rate-and-state friction, with velocity-strengthening steady-state properties, and is forced with time and spatially variable pore fluid pressure. In an initial set of tests, we show that periodic pore pressure oscillations can accelerate the fault slip akin to observed slow slip events. We then investigate how the fault slip responds to more complex and “realistic” pore pressure histories generated by the dynamic permeability model of Farge et al. (2021). Our results underscore the possible role of input fluid flux and permeability structure in determining the variations of fault slip and, in particular, in facilitating the slow slip events. 
Dynamic interaction between thermal insulation by cratonic keels and asthenospheric convection: insights from numerical experiments
Authors: Macedo Silva João Pedro , Sacek Victor , Manatschal Gianreto
Published: March 2024

The conductive heat transport in the lithosphere is less efficient than the convective heat transport in the asthenospheric mantle. Therefore, the lithosphere behaves as a thermal insulation above the asthenospheric mantle. As a consequence, the temperature in the mantle can increase, also affecting the rheological structure of the mantle, both in the asthenosphere and at the base of the lithosphere. As the thickness of the thermal lithosphere can vary laterally from less than 100 km to more than 200 km under cratonic domains, the impact of thermal insulation can vary geographically. Therefore, the variation of lithospheric thickness may affect the efficiency of the heat transport from the asthenosphere to the lithospheric mantle. Using thermo-mechanical numerical models, we investigate how lateral variation of lithospheric thickness affects the heat flow to the surface, the convective pattern inside the asthenospheric mantle and the impacts of thermal evolution of cratonic keel over time scales of hundreds of million years. We test scenarios considering different lateral positions for the cratonic keel, scenarios with relative movement between lithosphere and asthenospheric mantle to emulate lateral movement over geological time. We also test the impacts of assuming different mantle potential temperatures for the asthenosphere. Additionally, yield strength envelopes are calculated in different portions of the lithosphere in the numerical domain to assess the impact of the thermal insulation to the rheological structure of the lithosphere. The preliminary results indicate that rising/hot thermal anomalies tend to concentrate at the base of cratonic keels, which may eventually act as a weakening effect in the lithosphere. In scenarios with relative movement, we observe a systematic shift in the location of hot thermal anomalies in the opposite direction of the relative movement.
Coupling Leaching-Bioremediation for Petroleum-Contaminated Soils
Authors: Qin Bing , Ren Liming
Published: March 2024

Petroleum-contaminated soils are difficult to remediate due to a wide range of point/nonpoint sources of pollution and complex components. Here, a new leaching agent system was developed and synthesized, including oligomers, to construct the leaching process and optimize the soil leaching process parameters. The new agent has improved skeleton structure, green bio-based surfactant molecules, and synergists. Based on the characteristics of the leaching soil and its flora structure, more than 60 strains of petroleum degradation bacteria were isolated and screened. Furthermore, suitable bacteria for degradation were cultivated, the nutritional formula and process flow were optimized, and the microbial agent formula for heavy oil, polycyclic aromatic hydrocarbons and other pollutants were established. According to the physical characteristics of different types of oily sludge and soil, an economical and efficient remediation technology system and supporting implementation process were established, and finally, a "leaching-bioremediation" coupling treatment process was formed. The PHs content of the actual contaminated soil after the treatment was lower than 0.45%, and 12,000 t of PHs contaminated soil was remediated. Through the study of the elution-bioremediation process, the establishment of economical and environmentally friendly remediation technology and the process will improve our knowledge to solve the sudden oil pollution in contaminated areas and the environmental protection solution of historical problems.
Disentangling local processes at the Strait of Gibraltar and their climatic influence on Mediterranean hydrography
Authors: Gonzalez Nicolas , Waldman Robin , Somot Samuel , Sevault Florence , Chanut Jérôme , Giordani Hervé
Published: March 2024

The Mediterranean Sea is a semi-enclosed basin losing heat and freshwater to the atmosphere. As such, Mediterranean volume, heat, and salt budgets are strongly constrained by water mass exchanges with the global Ocean. Most of these exchanges take place through a shallow and narrow channel: the Strait of Gibraltar (SoG), making local processes at stake in its vicinity impact on a larger scale. Among these, tidal and fine-scale dynamics are known to influence Mediterranean hydrography, but their combined effects remain unclear.In this study, we address this question by comparing a set of four 30 year-long fully-coupled hindcast simulations of the Mediterranean region (CNRM-RCSM6 regional climate model, ~ 7km ocean horizontal resolution) differing only by the inclusion or omission of explicit tidal forcing and refined resolution (~ 1.5km) at the SoG. We show that tidal and fine-scale processes are equally relevant to Mediterranean hydrography and that their interplay is essential over climatic scales. On the one hand, tides drive the water mass transformations across the strait and the zonal slope of the interface between the exchanged flows. On the other hand, fine-scale dynamics, shaped by the abrupt topography of the strait, drive the Atlantic layer thickness and the magnitude of its inflow. These results highlight that kilometric-scale and tidal dynamics at the SoG are essential components of the physical system shaping the Mediterranean mean state and climatic trends. As such, they should be explicitly included in numerical models or parameterized when this is numerically unaffordable.
Scientific core drilling of the Lower Palaeozoic succession in the Swedish sector of the Baltic Sea – investigation of the CO2 storage potential
Authors: Erlström Mikael , Rosberg Jan-Erik , Dahlqvist Peter , Hjerne Carl-Erik , Lorenz Henning
Published: March 2024

With an aggregated thickness of c.100 m, a porosity of up to 15 % and a permeability above hundred millidarcy, previous studies have assessed the three widely distributed Cambrian sandstone members in the Swedish sector of the Baltic Sea as the most potential CO2-storage candidates in Sweden. Existing models indicate an effective storage capacity between 450–1500 Mt CO2. However, these rough numbers are uncertain as they are related to vintage and partly inadequate data sets, especially regarding physical property values needed for a more certain evaluation of the storage capacity. Hence, as part of a larger screening and evaluation programme, launched by the Swedish government to identify and quantify potential storage sites in Sweden, two scientific core drillings were completed in 2023 on the southernmost part of the island of Gotland in the Baltic Sea. The primary aim was to collect complementary and missing data on the Lower Palaeozoic succession including both caprocks and reservoirs. The scientific evaluations and results of the core drillings on south Gotland will together with geophysical logging of the boreholes, new seismic data and 3D models constitute an essential part in improving the models of the effective storage capacity of the Cambrian reservoirs in the Swedish sector of the Baltic Sea. The coring, monitoring and investigations were managed by the Geological Survey of Sweden and the Swedish national research infrastructure for scientific drilling, “Riksriggen”, operated by the department of Engineering Geology at Lund university. H-dimension triple tube coring (96/61 mm hole/core diameter) was successfully performed with an Atlas Copco CT20C rig. The two wells, Nore-1 and Nore-2, penetrate 470 m of Silurian marlstone and claystone, 85 m of Ordovician argillaceous limestone and 225 m of Cambrian sandstone, siltstone and shale before finishing in the Precambrian crystalline basement of potassium porphyritic granite at 791.5 m and 787.7 m, respectively. The operation managed to reach the set goals despite challenges of over pressured formations and up to metre-thick bentonites. Initial results show a thick, tight, and homogenous caprock and that the Faludden Sandstone, one of the three Cambrian sandstone members, have hydraulic properties that qualifies it as a possible storage reservoir. The preliminary results from the two wells are here presented together with evaluations of drilling performance, monitoring programme, logging and test operations. 
Exceptional eruptive CO2 emissions from intra-plate alkaline magmatism in the Canary volcanic archipelago
Authors: Burton Mike ,   Tajogaite 2021 Gas Team
Published: March 2024

Alkaline mafic magmas forming intra-plate oceanic islands are believed to be strongly enriched in CO2 due to low-degree partial melting of enriched mantle sources. However, until now, such CO2 enhancement has not been verified by measuring CO2 degassing during a subaerial eruption. Here, we provide evidence of highly CO2-rich gas emissions during the 86-day 2021 Tajogaite eruption of Cumbre Vieja volcano on La Palma Island, in the Canary archipelago. Our results reveal sustained high plume CO2/SO2 ratios, which, when combined with SO2 fluxes, melt inclusion volatile contents and magma production rates at explosive and effusive vents, imply a magmatic CO2 content of 4.5 ± 1.5 wt%. The amount of CO2 released during the 2021 eruptive activity was 28 ± 14 Mt CO2. Extrapolating to the volume of alkaline mafic magmas forming La Palma alone (estimated as 4000 km3 erupted over 10 Ma), we infer a maximum CO2 emission into the ocean and atmosphere of 1016 moles of CO2, equivalent to 20% of the eruptive CO2 emissions from a large igneous province eruption, suggesting that the formation of the Canary volcanic archipelago produced a CO2 emission of similar magnitude as a large igneous province.
Surprising megafloods in Europe – learning from the big picture
Authors: Bertola Miriam , Blöschl Günter ,   Team members
Published: March 2024

Megafloods that far exceed previously observed records at a given location can take citizens and flood managers by surprise. Existing methods based on local and regional information rarely go beyond national borders and cannot predict these floods well because of limited data on megafloods, and because flood generation processes of such extremes differ from those of smaller, more frequently observed events. Here we analyse the most comprehensive dataset of annual maximum discharges in Europe available to date, to assess whether recent locally surprising megafloods could have been anticipated using observations in hydrologically similar catchments across the continent.We base our analysis on annual maximum river discharge observations from 8023 gauging stations for the period 1810–2021. We identify about 500 “target” catchments where recent (i.e., after 1999) megafloods have occurred that are surprising based on local data. We perform a hindcast experiment of predicting their peak discharge with regional envelope curves, using flood observations from similar “donor” catchments up to the year before their occurrence. From this group of donor catchments we construct an envelope curve which we compare with the megaflood that occurred later in the target catchments. We repeat this analysis for all the detected megafloods in the target catchments.Our analysis shows that, in 95.5% of the target catchments, the discharge of the envelope is larger than that of the observed megaflood, suggesting that, from a European perspective, almost none of the events can be considered a regional surprise. Similar results are obtained by repeating the analysis on two consecutive sub-periods, indicating that megafloods have not changed much in time relative to their spatial variability. In conclusion, our findings show that recent megafloods could have been anticipated from observations in other parts of Europe, which would not be possible using only national data.