bluuebunny/crossref_metadata_2025 huggingface dataset:
The capturing of flocs by migrating subaqueous dunes
Authors: de Lange Sjoukje , van der Wilk Anne , Chassagne Claire , Ali Waqas , Hoitink Ton , Borne Maximilian , Brodersen Kristian , Waldschläger Kryss
Published: March 2024

Flocculated particles, formed by the aggregation of clay particles, are common in rivers. These flocs exhibit a different behaviour than primary particles: they can deform and break apart, and they have greater settling velocities than the particles of which they are composed. The latter allows flocs, unlike primary clay particles, to deposit on the river bed in mildly turbulent conditions, potentially leading to interactions with the bed. Particularly in sand-bedded rivers, where bedforms shape the riverbed, there exists a potential interaction between flocs and the riverbed.Physical experiments were carried out in an annular flume, using a flocculant to induce flocculation. Different amounts of flocculant and various shear stress conditions were applied, and the resulting floc characteristics and bedform geometry were measured.Under lower shear conditions, the flocs were larger and transport rates were lower than under high shear conditions. However, under both shear conditions, flocs were transported via saltation and in suspension, and they became integrated within the sediment bed either as individual flocs, clusters, or sheets. Deposition occurred predominantly on the leeward side of the dune, revealing distinct stratigraphy patterns. The presence of flocs had a negligible impact on the actual geometry of the bedforms.This investigation highlights the active role of flocculated clay particles in sediment transport in riverine systems, contrary to the general assumption that clay particles behave passively as wash load. This finding has the potential to affect sediment transport rates of fines and contaminants and could have far-reaching impacts on the interpretation of mud deposits in the sedimentary rock record. For modelling and predicting the sediment dynamics in river systems a comprehensive understanding of the transport mechanisms of clay flocs is essential and should be taken into account.
Monazite ﬁssion-track thermochronology as a possible proxy for low-magnitude erosion
Authors: Jepson Gilby , Carrapa Barbara , Jones Sean , Kohn Barry , Gleadow Andrew , George Sarah , Gehrels George , Howlett Caden , Triantafyllou Antoine
Published: March 2024

Conventional low-temperature thermochronology can resolve cooling typically associated with ~2 – 6 km of erosion. Lower magnitudes of erosion produced by surface processes and climatic variations are often difficult to quantify. Here, we apply a new, low-temperature thermochronometer (closure temperature
The use of nature-based solutions (NbS) for coastal restoration actions and biodiversity protection: the A-AAgora project for Ireland.
Authors: Biausque Melanie , O'Suilleabháin Darragh , Wah-Pay Lee , Verling Emma
Published: March 2024

Nature-based solutions (NbS) at the coast are, by definition, methods developed to work with nature to sustainably protect, restore and/or manage the shore. They can be classified into 4 main categories such as fully natural solutions, managed natural solutions, hybrid solutions and ‘green’ engineering solutions. As part of the EU Mission: ‘Restore our ocean and waters by 2030’, the Horizon Europe-funded Atlantic-Arctic Agora (A-AAgora) project identifies innovative solutions, including NbS, to co-develop coastal restoration actions in association with nature and people, throughout 3 demonstration areas. In this context, Demo Ireland locally adapted the ‘living lab’ approach via community-led actions undertaken at Harper’s Island, Co. Cork. Managed and hybrid NbS, for instance livestock grazing, control of invasive species (Spartina), development of pollinator areas, etc…, were successfully tested, supporting coastal wetland restoration and significantly enhancing local biodiversity. NbS deployed by communities at Harper’s Island, with the support of Cork County Council, were then described and reported, allowing their replication to the whole island of Ireland, and overseas. Moreover, additional sites facing coastal erosion and tidal flooding issues were selected and monitored along the Co. Cork coastline. Preliminary results allowed us to identify the main coastal challenges for each site in association with local geomorphological patterns and hydrodynamics, in a context of climate change. The next step for the A-AAgora project in Ireland is to identify suitable NbS as sustainable solutions and long-term management actions, to tackle coastal challenges in those areas. Moreover, this ongoing work is carried-out with the collaboration of multiple stakeholders, such as scientists, decision makers and communities. While these methods have been developed at local scales in the south of Ireland, they can be reproduced and upscaled in other areas, further raising global awareness about coastal adaptation and coastal sustainable solutions/managements.
Water Resources Assessment of the Mountainous Upper Syr Darya Catchment
Authors: Alcamo Lucas , Schaffhauser Timo , Huang Jingshui , Disse Markus
Published: March 2024

Water is a strategic and highly contested resource in Central Asia. This is exasperated by a highly uneven distribution of this resource within the region as most of the water originates from the high-mountainous regions. In this study we evaluate the current water resources of the highly mountainous headwaters of the Syr Darya River. Trends in hydrometeorological data are investigated and the dominant hydrological processes are studied using hydrologic modeling. The Syr Darya is one of the two tributaries of the Aral Sea, which has been of high interest due to its drastic decrease. The headwaters investigated in this study include the Naryn and Karadarya Rivers, which originate in the mountainous regions of Kyrgyzstan and flow into the Ferghana Valley where they form the Syr Darya River. The discharge regime is dominated by nivo-glacial processes and therefore highly susceptible to climate change.Streamflow and climatological data spanning from 1889 until 2018 is statistically analyzed and evaluated with regard to trends and change points. For example, at the gauge in Naryn City, an increase in streamflow can be observed, while precipitation peaks tend to shift to earlier months. The observed temperature increase is above the global average.For a more comprehensive understanding of the water resources of the region the fully revised version of the Soil Water Assessment Tool (SWAT+) is used to represent the hydrological cycle of the catchments. The model is calibrated using daily streamflow gauges at several locations. In addition, evapotranspiration is calibrated using remotely sensed data from the Global Land Evaporation Amsterdam Model (GLEAM). The model is driven by three different sets of reference data from three ensembles of General & Regional Circulation Models (GCM and RCM, respectively). In detail, we used one RCM, (REMO) and the two sets of GCMs from ISIMIP2 (Inter-Sectoral Impact Model Intercomparison Project) and ISIMIP3. The ISIMIP data is based on the 5th and 6th phase of the Coupled Model Intercomparison Project (CMIP5 and CMIP6), respectively. The different driving climatological data sets are investigated with respect to multiple variables essential for an understanding of the water resources, such as streamflow, evapotranspiration, snow and soil moisture. Besides, observed trends and signals are investigated with respect to their dominant physical controls.
The study on the distribution properties of NWC transmitter signals based on CSES observation
Authors: YaLu Wang , BinBin Ni , Wei Xu , Zhima Zeren , Zheng Xiang , ZhongXing Wang
Published: March 2024

Very-low-frequency (VLF) signals from ground-based transmitters could penetrate through the ionosphere, and even leak into the Earth's magnetosphere, leading to the precipitation of inner radiation belt electron. Therefore, detailed information about the distribution characteristics of VLF transmitter signals in geo-space is of great importance for in-depth understanding of their driven radiation belt electron loss processes and consequences. Based on data from DEMETER, CSES and Van-Allen Probes, the VLF signals emitted from NWC transmitter located in Australia, were analyzed firstly to validate CSES data. The we distinguished the NWC signals in the ionosphere and statistically investigate the day-night asymmetry, geographic distributions, seasonal and geomagnetic activity dependence, and wave propagation features, using the electric field measurements from CSES during the period from 2019 to 2022. The results indicated that, on the night-side and during the months of local winter, VLF transmitter signals are stronger due to the smaller ionosphere electron density. In contrast, the amplitudes of these signals are weakly affected by the level of geomagnetic activity. The distribution properties of NWC signals at the conjugate region, showed that the signals propagate to the conjugate hemisphere both in the non-ducted mode and ducted mode.
Timing and rates of salt movement in the Romanian Eastern Carpathians: insights from Radiocarbon and OSL dating
Authors: Tamas Dan Mircea , Tamas Alexandra , Sava Gabriela Odilia , Avram Anca , Timar-Gabor Alida
Published: March 2024

Salt, an age-old resource, holds significance in human history and emerges as a potential solution in transitioning from fossil fuels to sustainable energy, due to its unique properties. Its geological fluidity results in formations like salt diapirs, influencing deformation in the past and present. Understanding the details and timing of such deformation is crucial for certain energy transition projects like hydrogen storage in salt caverns.Salt tectonics in the Romanian Eastern Carpathians has long been studied. Initially, it was studied for its significance as a natural resource, but its implications for the hydrocarbon industry were later explored. Techniques such as seismic interpretation, well-log analysis, analogue and numerical modelling, and field observations are used to examine salt movement and interaction with sediment. In order to understand the Quaternary uplift rates of salt diapirs and the timing of salt movement in the Eastern Carpathians, we use radiocarbon and optically stimulated luminescence (OSL) dating.This innovative combination of radiocarbon and OSL dating marks a breakthrough in understanding salt diapir uplift rates in the area of interest, shedding light on the historical dynamics of geological formations and erosion processes.
Effects of glaciations on the tectonics of active continental margins: Insights from force-balance models and implications for the North Patagonian Andes
Authors: Dielforder Armin , Matthies Fiene , Hampel Andrea
Published: March 2024

Force-balance models show that the stress state at active continental margins is largely controlled by the gravitational force and the megathrust shear force and remains unchanged as long as subduction proceeds undisturbed. Glacially induced changes in mountain topography and mass redistribution by glacial erosion, sediment transport and deposition alter the force balance but the impact on the upper-plate stress state and tectonics remains quantitatively poorly constrained. Here, we use numerical force-balance models (Matthies et al., 2024) and investigate upper-plate stress changes resulting from (i) a reduction in mountain height in the arc by glacial erosion, (ii) a steepening of the arc front, (iii) a decrease in the megathrust shear force due to increased sediment subduction and fault weakening, (iv) an increase in sediment thickness in the trench, and (v) the load of an ice cap. Our model results show that each process causes distinct stress changes that affect different parts of the upper plate. The largest stress changes result from a reduction in mountain height, which increases the deviatoric compression in the arc, and a decrease in megathrust shear force, which reduces the deviatoric compression in the entire upper plate. Smaller stress changes occur for a steepening of the arc front, increased sediment deposition in the trench and the load of an ice cap. The different stress changes may promote or suppress faulting in different parts of the upper plate. Application of our model to the North Patagonian Andes indicates that glacial erosion during late Cenozoic cold periods may have localized the deformation in the arc interior but did not significantly reduce the mean elevation of the mountain range. Moreover, the reduced activity of thrust faults in the forearc and backarc likely reflect reduced compression of the upper plate due to a decrease in megathrust shear force. Matthies, F., Dielforder, A., & Hampel, A. (2024). Force-balance modelling of the impact of glacial erosion, trench sedimentation, megathrust weakening and glacial loading on the stress state of the crust at active continental margins. Tectonophysics, 871, 230180. https://doi.org/10.1016/j.tecto.2023.230180. 
Grain-scale simulation of olivine phase transition under stress: implications for mantle discontinuities
Authors: Lu Lucy , Wheeler John
Published: March 2024

Olivine and its polymorphs are the dominant minerals in the upper mantle and transition zone. The olivine phase transitions, determined primarily by pressure and temperature, control mantle discontinuities and influence mantle dynamics. Pressure is a first-order control on olivine phase transition and relates primarily to depth; therefore, it is commonly used to interpret the depths of mantle discontinuities. However, mantle dynamic models predicted stress levels of 100-300 MPa or as high as 1 GPa. Previous work has provided a complete picture of how such stresses would affect the positions where mineral reactions occur (and hence large-scale mantle structure). In this work, we plan to focus on the feedback between pressure and stress on the olivine phase transition at grain scale, and then the results can be extrapolated and upscaled to mantle scale deformation. We use the Open Phase Studio software based on the phase field model to simulate olivine phase transitions. The phase field model uses order parameters to distinguish different phases and describe their evolution. The parameter value of 1 indicates the bulk of the phase, and a value of 0 indicates the absence of this phase and is a smooth function of position. The smooth transition of a phase parameter indicates a diffuse interface between phases. The total free energies, interface properties, and microstructure control the phase field evolution. Open Phase Studio considers the Helmholtz free energies of each phase and uses their elastic energies to account for the pressure and stress effects on phase evolution. This software currently focuses on models of alloys, but appropriate values for silicates can be input. As a foundation, we first consider an Al-Li alloy to understand the behaviour of models. Then, we input olivine thermodynamic data via temperature-composition (T-x) phase diagrams for olivine composition and their elastic moduli to test the phase transition under different stress boundary conditions. We present our preliminary results here.
Effects of climate variability and land use on small water reservoirs in the MENA region
Authors: Aminzadeh Milad , Narayanaswamy Sankeerth , Shokri Nima
Published: March 2024

Freshwater shortages in the Middle East and North Africa (MENA) have been exacerbated with rapid population growth and changes in precipitation and drought patterns in recent decades. Agricultural production in this region relies largely on irrigation, making it vulnerable to the availability of surface and groundwater resources. Under these circumstances, small agricultural reservoirs are at the core of supporting local irrigation and livestock water demands during dry spells [1]. However, the cumulative impact of these small on-farm reservoirs on the management of limited freshwater resources in the MENA region with acute water scarcity remains unknown. We capitalize on the highly resolved satellite imagery of Sentinel 2 with 10 m resolution to identify the spatio-temporal distribution of small reservoirs (< 0.1 km2) and estimate their storage capacity in MENA. Such detailed information enables us to link the extent of reservoirs to the changes in freshwater availability and demands arising from climatic factors and agricultural activities in this region. Our preliminary results highlight correlations between the changes in cumulative area of agricultural reservoirs and variation of local precipitation and air temperature patterns. The study improves water balance and budgeting in dry regions of the world and provides insights into the impact of land cover changes on the expansion of water reservoirs supporting local irrigation demands.Reference[1] Aminzadeh, M., Lehmann, P., & Or, D. (2018). Evaporation suppression and energy balance of water reservoirs covered with self-assembling floating elements. Hydrology and Earth System Sciences, 22(7), 4015–4032. https://doi.org/10.5194/hess‐22‐4015‐2018
Hydroacoustic geophony automatic detection: an open benchmark dataset with an open model
Authors: Raumer Pierre-Yves , Bazin Sara , Royer Jean-Yves , Dorian Cazau , Vijay Ingale Vaibhav
Published: March 2024

Underwater seismic events such as earthquakes are known to produce not only seismic waves but also hydro-acoustic waves. Indeed, seismic waves arriving at the ocean bottom convert into acoustic waves in the water column. Other events, such as hot lava-seawater interactions or icequakes, also generate water-born acoustic signals. Monitoring these different signals with moored hydrophones proved to be useful and very efficient thanks to the little attenuation of acoustic waves propagating in the Sound Fixing and Ranging (SOFAR) channel. This led to the deployment of wide-range moored hydrophone networks to monitor active seafloor-spreading ridges in the world ocean. However, analyzing year-round data recordings from several stations is a cumbersome, user-dependent and most importantly time-consuming task. Despite some efforts to develop automatic detection algorithms, the community still lacks efficient and available off-the-shelf tools, as well as open datasets and benchmarks against which they could be compared objectively. To address this problem, we are glad to make publicly available three partially-annotated hydroacoustics datasets consisting of recordings from Atlantic and Indian oceans, with a total of ~60,000 hours. We propose a benchmark of models on a first task of binary classification, and an original convolutional neural network (CNN) model called TiSSNet showing promising results. To maximize the reliability of the evaluations, two datasets have been carefully and exhaustively annotated to serve as evaluation datasets. The getting started codes have also been made available on GitHub. We wish the datasets and benchmarks will be used as references upon which the state-of-the-art could be developed in a collaborative way. In the future, the best model, used as an automatic or semi-automatic detection framework, will be applied to larger datasets, and combined with multi-stations association and trilateration techniques to output nearly complete catalogs of geophonic events (source type and location, with signal characteristics).
Drivers of Common Era sea-level change in southeastern Australia: extending tide-gauge records and developing a network of high-resolution reconstructions for regional analyses.
Authors: Williams Sophie , Carvalho Rafael , Perry Prudence , Reef Ruth , Sefton Juliet
Published: March 2024

Southern Hemisphere observational records of sea-level change are rare prior to ~1950, making it difficult to close historical regional sea-level budgets and quantify individual contributions to sea level (e.g. barystatic, thermosteric). Recent work generated four microfossil-based high-resolution sea-level reconstructions from southeastern Australia, all of which indicated rapid regional rates of 20th century sea-level rise compared to the global average. However, unlike analogous work in the North Atlantic (for which there is a high-density network of high-resolution reconstructions), there remains a paucity of proxy data from the Southern Hemisphere, hindering a probabilistic estimate of regional drivers of relative sea level using a spatio-temporal model.We generate two new reconstructions using salt-marsh foraminifera from King Island, Tasmania, and Venus Bay, Victoria, to add to a growing database of Common Era sea-level reconstructions from southeastern Australia (and indeed wider Australasia). Fossil foraminifera indicate a rising palaeomarsh over the last ~150 years of ~0.15-0.25 m (average); this is interpreted as relative sea-level rise consistent with patterns observed in recent reconstructions. A chronology for the core is developed using both 14C and lead isotopes. Ongoing efforts to supplement the regional database will allow us to determine local and regional drivers of relative sea-level change in the region.
Oceanic core complexes: Serpentinite diapirs at slow ridge - transform fault intersections?
Authors: Mart Yossi
Published: March 2024

Oceanic Core Complexes (OCCs) are peridotite and serpentinite rich geological features, commonly located at the external intersections of slow-spreading mid-oceanic accreting ridges (MORs) with transform faults (TFs). The peridotites of these complexes are commonly considered to derive from the upper mantle while the serpentinites are attributed to chemical weathering that affected rock-mass during its ascent through the lithosphere. Description of cores drilled into OCCs commonly describes in detail the various peridotites but ignores the serpentinites, which are considered secondary additions. However, this presumption seems flawed due to the absence of high-pressure rocks such as eclogites, therefore it seems that the origin of the various peridotite minerals were formed concurrently with the serpentinites from pyroxenes under constrains of moderate geological pressures and temperatures, and various availabilities of H2O.The intersections between slow MORs and TFs, where most OCCs occur, are characterized by steep thermal gradients and by distinct density contrasts. The thermal gradients in the upper crust of the MOR axial rift are nearly 1300/km, due to the shallow depth of the upper mantle there. The density of the fresh basaltic lava at the MOR is ca. 2700 kg/m3, because the temperature of the fresh basalt is some 1100oC. However, the density of the older basalt that builds the older plate across the transform fault is 2900 kg/m3. It is plausible that at fast-spreading MORs the plate juxtaposed against the active spreading rift would still be warm and its density would too light to initiate the spontaneous subduction. Tectonic experiments showed that at least 200 kg/m3 density contrast between lighter and denser crustal slabs would be sufficient to initiate spontaneous subduction. Furthermore, geochemical experimentation shows that under 500oC temperatures, namely at depths of ca. 4 km under the MOR, minerals of the pyroxene group in the oceanic basalts, are likely to be altered either into peridotites under dry conditions or into serpentinites under wet constraints at such temperature. These constraints suggest that the serpentinites in OCCs are generic and not erosional features, and their light densities and plasticity could have generated the diapiric ascent of the OCCs. The density contrast between the fresh and the old basalts, juxtaposed at the ridge – transform junctions, could take place if the spreading rate of the MOR is slow and the older slab has the time required to cool and reach the density of 2900 kg/m3. Keywords: Ridge-transform intersection, oceanic core complexes, spontaneous subduction, peridotites, serpentinites, diapirs.
Modelling gravity field of irregularly shaped bodies by numerical methods
Authors: Macak Marek , Šprlák Michal , Minarechová Zuzana
Published: March 2024

Gravity field modelling of irregularly shaped bodies such as the Earth's Moon is a challenging task that can reveal both the strong and weak points of each modelling technique. In our approach we will develop a numerical approach based on the finite element method (FEM) and compare the obtained solutions with the solution by the spectral approach that relies on spherical harmonics. In this way, we aim to study whether the numerical methods such as FEM can overcome the limitations of the spherical-harmonic-based approaches, namely their divergence in the vicinity of the gravitating body. We hope that the presented developed approach could form a valuable alternative to the spherical harmonics.
Exploring the Potential of History Matching for Land Surface Model Calibration
Authors: Raoult Nina , Beylat Simon , Salter James , Hourdin Frédéric , Bastrikov Vladislav , Ottlé Catherine , Peylin Philippe
Published: March 2024

With the growing complexity of land surface models used to represent the terrestrial part of wider Earth system models, the need for sophisticated and robust parameter optimisation techniques is paramount. Quantifying parameter uncertainty is essential for both model development and more accurate projections. History matching is an emerging technique in climate science for uncertainty quantification. Using Gaussian process emulators, history matching allows us to rule out parts of parameter space that lead to model outputs being inconsistent with observations. In this presentation, we assess the power of history matching by comparing results to variational data assimilation, commonly used in land surface models for parameter estimation. Although both approaches have different setups and goals, we can extract posterior parameter distributions from both methods and test the model-data fit of ensembles sampled from these distributions. Using a twin experiment, we test whether we can recover known parameter values. Through variational data assimilation, we closely match the observations. However, the known parameter values are not always contained in the posterior parameter distribution, highlighting the equifinality of the parameter space. In contrast, while more conservative, history matching still gives a reasonably good fit and provides more information about the model structure by allowing for non-Gaussian parameter distributions. Furthermore, the true parameters are contained in the posterior distributions. We then consider history matching's ability to ingest different metrics targeting different physical parts of the model, helping to reduce parameter space further and improve model-data fit. We find the best results when history matching is used with multiple metrics; not only is the model-data fit improved, but we also gain a deeper understanding of the model and how the different parameters constrain different parts of the seasonal cycle. We conclude by discussing the potential of history matching in future studies.
The Attachment Process of Negative Connecting Leader to the Lateral Surface of Downward Positive Leader in a +CG Lightning Flash
Authors: Qi Qi , Wu Bin , Lyu Weitao , Ma Ying , Chen Lyuwen , Lyu Fanchao , Gao Yan
Published: March 2024

In the lightning attachment process, the leader connecting behavior is an interesting topic. In the attachment process of a negative cloud-to-ground lightning flash, the “Tip to the lateral surface” connection type has been widely observed, and researchers have carried out a series of studies and discussions on the characteristics and the physical mechanisms of the leader connecting behavior. However, is there also a “Tip to the lateral surface” connecting behavior in the attachment process of the positive cloud-to-ground lightning flash? In this study, using high-speed video cameras operating with framing rates of 20 and 50 kiloframes per second, we captured an attachment process during a positive cloud-to-ground flash, which demonstrates the connection of the negative connecting leader (NCL) to the lateral surface of the downward positive leader (DPL) for the first time. When the NCL was initiated, the tip of the DPL had passed the initiation position of the NCL for about 50 m. A common streamer zone (CSZ) was observed when the three-dimensional distance between the NCL tip and the lateral surface of DPL was about 30 m. It is remarkable to note that a luminous segment (space stem/leader) with a length of about 7 m was captured within the CSZ during the attachment process. The connection between the NCL tip and the lateral surface of the DPL was caused by the development of the CSZ and its inner space leader.
Rapid trans-crustal movement of arc magma under Pagan volcano, Northern Mariana
Authors: Huang Xiaohan , Yang Alexandra Yang , Sun Mingdao , Zhao Siyu , Tan Wei , Tamura Yoshihiko , Zhao Taiping
Published: March 2024

Nearly 800 million people worldwide are exposed to volcanic hazards, with two-thirds of these areas located in subduction zones. Studying the movement of arc magma in subduction zones is particularly essential for volcanic hazard prevention. In particular, rapid trans-crustal movement of arc magma from the mantle can lead to volcanic eruptions with little warning, which would pose a high risk, yet research in this area is scarce. This paper reports for the first time the rapid trans-crustal movement of arc magma in the Izu-Mariana Arc. Systematic analyses on the volatile contents of melt inclusions in primitive olivine from the Pagan arc volcano yield exceptionally high CO2 contents of up to 6000 ppm with H2O contents of 3.7 wt%, which record magma storage at near-Moho depth of ~20 km. Diffusion chronometry of Fo, Ni and Mn in the host olivine, on the other hand, reveals that the parental magma took 15-125 days to ascend from near-Moho storage before its eruption. Such a rapid ascent of high Fo olivine from Moho to eruption is rare in arcs. That is because arc magma mostly has high water contents which would lead to viscous stalling during ascent and then delay the eruption. However, magma under Pagan volcano stored at a deeper depth than other arc volcanoes with similar water content, still ascended to eruption at a high rate. High CO2 content and exsolution in Pagan magma, compared to other arc magmas, which could provide additional buoyancy or significant overpressure through continuous CO2 degassing, and then result in rapid ascent.
Water content in primary magma compositions and mantle source of chromitites in Mesoarchean Nuggihalli greenstone belt (India)
Authors: Ma Haitao , Yang Jingsui , Cai Pengjie , Jayananda Mudlappa , Lian Dongyang , Aadhiseshan Krishnasamy Ravindran
Published: March 2024

Chromitites, found in Archean greenstone belts as the oldest ultramafic rocks, offer critical insights into the early Earth's evolution. Water plays a fundamental role in aggregation and mineralization of chromite, yet the water content of parental magma of chromitite remains unclear. This study present petrologic and elemental data on chromitites from the 3.3-3.1 Ga Nuggihalli greenstone belt, Western Dharwar craton (India), and address origin of chromitites in Archean greenstone belts particularly water contents in primary magmas. Major and trace element data of chromites and clinopyroxenes from chromitites coupled with thermobarometry, and hygrometry calculation, as well as numerical modeling reveal that the chromites are high-Cr chromites (Cr# 68.1-78.6) with low TiO2 (0.19%-0.29%), Al2O3 (9.10%-13.13%), and Ga (4.24-10.37 ppm), similar to the parental melts of high-Cr podiform chromites and boninites in modern ophiolites. The clinopyroxenes are augites with high Mg# (93-95) which corresponds to equilibrated melts with the Nuggihalli chromitites having high Mg# values (79-86), resembling ancient komatiitic or picritic magmas (75-90), crystallized in a primary magma environment. Thermobarometry and hygrometry calculation suggest that the clinopyroxenes could form at temperatures of 1194-1221℃ and pressures of 0.7-5.8 kbar with high water contents (~2.4-2.6 wt.%), exceeding water contents in mid-ocean basalts (MORB) and oceanic island basalts (OIB) source. Numerical modeling of rare earth elements indicates that moderate degrees of partial melting (1%~20%) of hydrated spinel lherzolite mantle (water content: ~478-5408 ppm). The primary magmas of the 3.3-3.1 Ga Nuggihalli chromitites are characterized by enrichment of water contents (~2.4-2.6 wt.%) and high field strength elements (HFSEs, e.g., Nb and Hf), demonstrating high comparability with boninites and arc magmas. Furthermore, the rock associations including ultramafic rocks with chromitites, high-Mg basalts and sheets of gabbro-anorthosites in the Nuggihalli greenstone belt may represent the relic of oceanic lithosphere. This declares that the 3.3-3.1 Ga Nuggihalli chromitites could have formed at a forearc basin on a subduction system.
Pore space properties of solution surfaces in shallow-water carbonates
Authors: Manniello Canio , La Bruna Vincenzo , Bezerra Hilario Francisco Rego , Araùjo Renata Emily Brito , Morais Xavier Milton , Michie Emma , Faulkner Daniel , Allen Michael John , Prosser Giacomo , Agosta Fabrizio
Published: March 2024

Diagenetic and tectonic processes taking place in platform carbonates produce significant textural and mineralogical modifications through time, controlling the pore space in terms of dimension, geometry, shape, and connectivity of single pores, and influencing both total and effective porosity. Focusing on the different types of solution surfaces, this study is conducted on Lower Jurassic, Cretaceous, and Eocene, carbonates exposed at the Viggiano Mt. and Raparo Mt., southern Apennines, Italy. Microscale analyses show that the primary porosity of these rocks was occluded by pervasive blocky cements, which precipitated during burial diagenesis of the carbonates. We aim to assess the role exerted by the roughness of bed-parallel and low-angle to bedding solution surfaces, on the pore properties and permeability values of a variety of carbonate lithofacies such as mudstones, packstones, grainstones and rudstones. Specifically, we show the results of Nuclear Magnetic Resonance (NMR), gas-porosimetry and water-permeability tests conducted on plugs cored either orthogonal or parallel to bedding interfaces. All the study plugs show an amount of effective porosity lower than 5%, with mean values of ca. 3%. Excluding larger microfractures, and sporadic intrafossil and intercrystal molds, among the various types of solution surfaces we document that the rough, seismogram-type stylolites localize secondary porosity, while smooth, wave-type stylolites do not. The seimogram type stylolites, due to the non-selective carbonate’s dissolution, form a poorly connected vuggy porosity, and the NMR results the pores are subspherical to tubular (r
Numerical Investigation of Reverse Water Level Fluctuations under Non-Isothermal Conditions with a Fully Coupled Thermal-Hydro-Mechanical Model for Geothermal Heat Pump Systems
Authors: Yue Linshan , Aichi Masaatsu
Published: March 2024

In the realm of harnessing geothermal energy, groundwater heat pumps exhibit superior thermal efficiency when compared to closed-loop geothermal heat pumps. However, the outlook for progress remains less than promising. A primary obstacle stems from the improper extraction of groundwater, which can disrupt the stress field in subsurface structures and potentially trigger land subsidence. This concern is particularly pronounced in unconsolidated soils found in coastal sedimentary plains, where the additional threat of severe flooding disasters looms. Furthermore, artificial pumping processes may give rise to coupled hydraulic phenomena, exemplified by the reverse water level fluctuations. This transient anomalous changes in hydraulic head occurs in adjacent aquifers during the initial stages of pumping from a confined aquifer, induced by strain propagation. The magnitude of the hydraulic head elevation varies from a few centimeters to several tens of centimeters, posing a challenge to the accurate interpretation of groundwater monitoring data for land subsidence prevention. Geothermal heat pump systems can also induce changes in the temperature and thermal strain of geological layers. Consequently, understanding how this strain-induced hydraulic head responds to temperature fluctuations becomes a research question. In our investigation, the hydraulic and mechanical responses of a three-layer aquifer system to groundwater pumping were assessed through thermoporoelastic numerical simulations. The simulated reverse hydraulic head changes align with field observations documented in the literature. The findings of this numerical investigation indicate that when we recharged the water into the ground, the initial head decrease is likely to occur in proximity to a recharge well within an unpumped clay layer. These deformation-induced head changes eventually dissipate following the hydraulic propagation of unsteady state drawdown from the pumped aquifer into adjacent layers. In the event of reverse water level fluctuation, it is shown that temperature has no obvious influence on the hydraulic variation, both the head variation and happening time. It is also suggested that the propagation of thermally induced strain is slower than that of hydraulically induced strain and the effect appears much later.
The impact of forest canopy structure on modelled photosynthesis
Authors: Stretton Megan , Quaife Tristan , Wilkes Phil , Disney Mathias
Published: March 2024

Despite terrestrial vegetation being one of the largest carbon sinks, it’s representation within weather and climate models is simple due to computational and data constraints. Whilst the representation of many processes has been improved, the absorption of light by vegetation canopies is still described using the assumption of a plane-parallel turbid medium, which is not realistic. This approach assumes randomly distributed leaves, with no horizontal or vertical variability, and a flat canopy base. However, it is widely used as it permits the radiative transfer for vegetation to be described using a two-stream model (Sellers, 1985) that can be solved analytically.This work examines the importance of including realistic vegetation structure in photosynthesis calculations, testing the sensitivity of modelled Gross Primary Productivity (GPP) to the common turbid-media approximation by using detailed forest canopy information. We derive a methodology for calculating GPP from radiative transfer calculations from a high-resolution, computationally demanding, radiative transfer model, DART (Discrete Anisotropic Radiative Transfer). The GPP calculation  is based upon the photosynthesis scheme from the JULES (Joint UK Land Environment Simulator) land surface model. We explore the impacts of structure on GPP for six real forest canopies, from across the globe using 3D vegetation data collected using Terrestrial Lidar Scanning (TLS). The use of a 3D radiative transfer model allows us to investigate how much difference the two-stream approach introduces compared to detailed forest canopies with different levels of structure. We examine the profiles of both the absorbed radiation (fAPAR) and GPP.Across the six forest scenes used, there is generally a reduction in GPP as more structure is introduced. However, this is particularly the case in scenes where the horizontal variation of LAI is high. Additionally, in these scenes, we find that this increase in GPP is less pronounced at low sun angles. This work suggests that consideration should be taken in incorporating horizontal variability of the vegetation within weather and climate models, particularly when identifying the effects of forests on the global carbon budget.
Health Benefits of Meeting 2-degree Warming Scenario in India
Authors: Sarkar Debajit , Dey Sagnik , Purohit Pallav , Chowdhury Sourangsu
Published: March 2024

Anthropogenic emissions are responsible for deteriorated air quality and accelerated climate change in developing countries like India. The current trajectory of emissions is expected to further degrade air quality, potentially leading to increased warming levels by the end of the century, posing severe consequences for public health. In this study, we analyzed two scenarios using the GAINS-model framework - the business-as-usual (BAU), relying on existing air pollution control policies and measures, and the sustainable development scenario (SDS), integrating advanced air pollution control policies and measures, aiming to contain the global temperature increase below 2°C by 2100. We estimated the health burden attributable to ambient air pollution in BAU and SDS scenarios, segregated into regional and sectoral emissions in India for the years 2030 and 2050. Under the BAU scenario, premature mortality and disability-adjusted life-years (DALYs) are projected to increase from 0.72 million (95% CI: 0.53-0.89) and 24.8 million (15.4-30.5) in 2015 by 9.7% and 2.4% in 2030, respectively. In 2050, mortality and DALYs are projected to further increase to 0.88 million (0.75-1.01) and 26.2 million (22.8-29.6). At the sub-national level, states with a low Socio-demographic Index (SDI) are expected to possess majority (49-53%) of the health burden. However, if India follows the SDS scenario, 0.16 million (0.14-0.18) lives and 3.7 million (3.2-4.3) DALYs can be avoided in 2030. The corresponding benefits in 2050 will be 0.34 million (0.29-0.39) lives and 8.4 million (7.1-9.7) DALYs, respectively, relative to the BAU scenario. Our results reveal that states with a high SDI would experience the most significant benefits (15% and 26% for mortality & 26% and 44% for DALYs in 2030 and 2050), as compared to middle and low SDI states. The findings underscore the importance of immediate adoption of cost-effective and advanced technologies driven by sustainable development policies is imperative to mitigate air pollution and climate change simultaneously. A stronger mandate to revise the environmental standards and health policies is necessary to maximize health benefits in India. 
Impacts of rainfall variability on river discharges and suspended discharges : A Case Study in Chenyulan Watershed, Taiwan
Authors: Huang Wen-Shun , Chen Jinn-Chyi , Chien Kuo-Hua , Lia Yue-Ting , Wu Fan
Published: March 2024

In this study, the variations of rainfall, river discharges and suspended sediment discharges were analyzed in the Chenyulan watershed in Nantou County, central Taiwan. The hydrological data, such as rainfall, daily discharges and daily suspended sediment discharges, was collected based on Neimaopu hydrology station during the period from 1972 to 2020. The yearly costs of structure conservation to prevent sediment disasters and slope hazard events were implemented in the watershed between 1999 and 2020 as well. The Rating Curve Method with the formula Qs=aQb is adopted to estimate sediment discharges with the corresponding discharge events. The impact factors that caused the variation of discharges and suspended sediment discharges were also analyzed to provide the references for the influence of geological and hydrological changes on sediment yielded on slope and following suspended sediment discharges in the rivers in the watershed. The analyzed results show that the suspended sediment discharges in 1972-1989 are less than the average value in 1990-2009 at the same discharges. The suspended sediment discharges in 2010-2020 are gradually reverted to that in 1972-1989. The causes of decreasing the suspended sediment discharges in last decade are analyzed, including: 1. The variations of rainfall were gradually calmed in last decade; 2. the loose soil on slopes in the watershed caused by Chi-Chi earthquake became concreted with time; 3. the landslide and debris flow disasters obviously decreased in last decade and the soil yield from slopes has slowed down; 4. the local government involved a lot of money to build the conservation structures in upstream creeks to trap the loose soil and control the volume of sediments from flowing into rivers.
Cushion gas requirements for hydrogen storage in global underground gas storage facilities
Authors: Talukdar Mayukh , Behera Chinmaya , Heinemann Niklas , Miocic Johannes , Blum Philipp
Published: March 2024

To ensure system security and flexibility, storing excess renewable energy as hydrogen is considered an integral component of future energy systems. Cyclic underground hydrogen storage (UHS) with injection production cycles is planned to meet energy demand until new subsurface sites are prepared for storage. To avoid geomechanical risks caused by dynamic pressure fluctuations during cyclic storage, cushion gas is stored in such reservoirs. Cushion gas requirements for sites are still unknown. Therefore, in this study, we calculate the cushion gas requirement of various hydrogen storage sites using reservoir properties. Hydrogen requires less cushion gas by volume than methane. Cushion gas volume in UHS sites varies with the initial reservoir pressure, gas flow rate, well tubing size, and erosional velocity. Cushion gas requirement decreases with increasing reservoir pressure, increasing gas flow, increasing well tubing size, and decreasing erosional velocity. In the studied sites, cushion gas volume ranged from a few % (0-5%) to 99% of the total gas volume. Shallow sites cannot store much hydrogen because of the high cushion gas %. On the other hand, sites deeper than 1100 m are unsuitable owing to insufficient structural trapping and enhanced biogeochemical reactions. Considering these factors, we report the optimum cushion gas volumes for various underground storage sites worldwide.
Blue Carbon Additionality: New Insights from the Radiocarbon Content of Saltmarsh Soils and their Respired CO2
Authors: Houston Alex , Garnett Mark , Austin William
Published: March 2024

International policy frameworks recognize the net drawdown and storage of atmospheric greenhouse gases through management interventions on blue carbon ecosystems (saltmarshes, mangroves, seagrasses) as potential emissions offset strategies. However, key questions remain around the ‘additionality’ of the carbon sequestered by these ecosystems, and whether some fraction of the organic carbon (OC) that does not derive from in-situ production (allochthonous) should be included in carbon budgets. This study compares the radiocarbon (14C) contents of saltmarsh soils and CO2 evolved from aerobic laboratory incubations to show that young OC is preferentially respired over aged OC, and that the latter is also vulnerable to remineralisation under oxic conditions. The results from this study are the first to empirically show the remineralisation of aged OC from a blue carbon ecosystem. This highlights that management interventions which reduce the exposure of saltmarsh soils to oxic conditions support the inclusion of some portion of allochthonous OC in carbon budgets. Elevated temperature incubations provide preliminary evidence that the predominant source of respired OC will not change under predicted future warmer conditions. Saltmarsh typology also influences the 14C content of both the bulk soil and respired CO2, highlighting the importance of site selection for optimized blue carbon additionality. 