bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring boron isotope fractionation during interaction of silicate melts and hydrous fluids: an experimental approach concerning ore formation
Authors: Rauscher Jakob , Wunder Bernd , Wilke Max , Trumbull Robert , Jahn Sandro , Sieber Melanie J. , Michaud Julie , Pohl Florian , Scicchitano Maria Rosa , Fechtelkord Michael , Appelt Oona
Published: March 2024

The magmatic-hydrothermal transition is an important but poorly-understood process in the formation of Sn-W, Nb-Ta and Li deposits associated with evolved granites and pegmatites. Theory predicts that boron isotopes will fractionate between magma and fluid, so the magmatic-hydrothermal transition may be recorded in the borosilicate mineral tourmaline, which is widespread and common in these kinds of deposits. The key information needed to interpret the tourmaline record is the B-isotope fractionation between granitic melts and the fluids derived from them but former experimental studies on B-isotope fractionation between the relevant phases are not in agreement (e.g. Kowalski and Wunder, 2018, Maner and London, 2018).
This study fills this gap by an experimental, multivariant approach. We synthesized a glass of haplogranitic composition (Ab40Or25Qtz35) and produced variants of water content (0, 4 and 6 wt%), aluminum saturation (ASI 0.7, 1, 1.3) and boron concentration (2 and 5 wt%). For each composition we determined the coordination environment of B in the glass and the fractionation of B isotopes between the respective melt and aqueous fluid at near-solidus temperature. The first part of the study was the chemical characterization and analysis of B coordination in the glasses. The NMR analysis of 11B indicates that the coordination of 11B is dominantly trigonal in all glasses, but there is an increase of tetrahedral coordination with increasing boron concentration and water content. Fluid-melt fractionation experiments are ongoing and first results will be presented.
References:• Kowalski, P., Wunder, B. (2018). Boron isotope fractionation among vapor–liquids–solids–melts: Experiments and atomistic modeling. In: Marschall, H., Foster, G. (eds) Boron Isotopes. Advances in Isotope Geochemistry. Springer-Verlag, Berlin-Heidelberg, volume 7, pages 33–69• Maner, J. L., London, D. (2018) Fractionation of the isotopes of boron between granitic melt and aqueous solution at 700 °C and 800 °C (200 MPa), Chemical Geology, Volume 489, Pages 16-27
Impact of Errors in Buoy Measurements on Nonlinear Fourier Spectra
Authors: Lee Yu-Chen , Wahls Sander
Published: March 2024

The nonlinear Fourier transform (NFT) has been recently used to analyze the measured rogue waves in shallow water (Teutsch et al., Nat. Hazards Earth Syst. Sci., 2023). When analyzing field measurement data from the buoy, measurement errors are unavoidable due to various factors. The drag forces on the buoy can e.g. result in low-frequency measurement noise (Ashton and Johanning, Ocean Eng., 2015), while the sensors employed on the buoy are limited in bandwidth and contribute noise themselves (Yurovsky and Dulov, Ocean Eng., 2020). It is still uncertain how the noise generated during the buoy measurement influences the nonlinear Fourier spectrum computed by the NFT. In this study, we discuss the impact of measurement errors on the nonlinear Fourier spectrum of water waves. We first generate random-phase time series from typical wave spectra such as the Pierson-Moskowitz (PM) spectrum for various significant wave heights. We will then artificially incorporate measurement errors into the generated time series. The impact of the errors is studied by comparing the nonlinear Fourier transforms of the time series with and without measurement errors.
Mapping the Plastic Legacy: Geospatial Predictions of a Microplastic Inventory in a Complex Estuarine System Using Machine Learning
Authors: Enders Kristina , Lenz Robin , Fischer Franziska , Schwarzer Klaus , Seiß Guntram , Fischer Dieter , Labrenz Matthias
Published: March 2024

The persistence of microplastics (MP) in aquatic environments presents a pressing concern, with sediments serving as substantial repositories for these anthropogenic particles. Estuarine depositional systems are sensitive indicator environments for MP monitoring as they: (1) represent aquatic-terrestrial interfaces acting as a bottleneck for MP accumulation coming from land (capable of capturing riverine run-off as well as the often highly populated coastal areas), (2) comprise a confined area, favourable for sampling initiatives as compared to other systems such as long river courses or disperse inland waters. Hence, understanding MP distribution in intricate estuarine systems is essential, yet current models often falter in capturing complexities to sufficiently describe the present pollution patterns for an entire geomorphological region.We address this gap by employing machine learning techniques to predict spatial MP inventories deposited in the Schlei, Northern Germany. Notably, the complex hydrodynamic regime, influenced by narrowings and braided embayments, freshwater tributaries, wind-driven mixing, and brackish inflows, creates an interplay of fluvial and marine sedimentary processes, which poses non-trivial challenges for reliable modelling of sedimentary MP transportation. Our approach, termed NIXVEGS (Nested Iterative X-Validation-to-Ensemble-modelling through Grid Searches), leverages machine learning, integrating model selection, rigorous validation, and ensemble techniques tailored for small datasets.We estimated ~20 trillion MP particles or ~14.5 tonnes (50-5000 µm) residing in upper sediments of the Schlei proper, emphasizing the pivotal role of sediments as primary MP reservoirs. Our modelling concept is founded on the idea of applying granulometric proxies to account for the hydrodynamic regime bias in observed MP concentrations. We found that the high complexity of the geomorphology and extreme input events – both are predominant conditions in our study system – produce major spatio-temporal discontinuities in MP data which are not alleviated by a granulometric normalisation. Here we use hydrodynamic tracer simulations to derive variables which incorporate these discontinuities in empirical predictive modelling, but discuss simpler possibilities to enable modelling studies in systems for which such simulation data might not be feasible to acquire.This study provides a novel framework for geospatial prediction of MP inventories in complex aquatic systems. The integration of granulometric proxies and hydrodynamic discontinuities elucidates MP distribution patterns, offering a pathway for robust predictions and informed mitigation strategies. Our findings underscore the critical role of sediments in storing and reflecting the contemporary plastic legacy, crucial for comprehensive environmental management.
The Global Extremes Digital Twin of Destination Earth: successes and challenges
Authors: Vannière Benoît , Sandu Irina , Dueben Peter , Forbes Richard , Polichtchouk Inna , Van Niekerk Annelize , Sützl Birgit , Diamantakis Michail , Denissen Jasper , Gascon Estibaliz , Maier-Gerber Michael , Lledo Llorenç , Bastak-Duran Ivan , Tsiringakis Aristofanis , Becker Tobias , Schröttle Josef , Zaplotnik Ziga
Published: March 2024

At the end of the first phase of the Destination Earth initiative in May 2024, ECMWF will deliver a prototype of the global component of the Weather-Induced Extremes Digital Twin (or Global Extremes DT). The Global Extremes DT will monitor worldwide extreme weather events up to 5 days ahead and at an atmospheric resolution of 5 km. Furthermore, it incorporates two impact sector models: the CaMa-Flood river routing model for predicting flood risk, and a flexible aerosol scheme that monitors selected aerosol species, contributing to air quality assessment. Since August 2023, a daily forecast is performed with the prototype Global Extremes DT on the ECMWF's HPC Atos. In this presentation, we will summarise the work done during the first phase of Destination Earth and revisit some successes and challenges encountered in predicting extreme weather events.A large selection of extreme weather cases has been analysed to demonstrate the added value of the high-resolution DT over the ECMWF operational forecast. Clear improvements were found for near-surface fields in regions of complex terrain, the intensification of tropical cyclones, the magnitude of orographic precipitation and subsequent flood events. Yet, we also find that standard NWP scores are not improved readily when the horizontal resolution is increased, and specific developments had to be made to adapt the physics of the model and exploit the full benefit of high-resolution. Although we find that non-hydrostatic effects do not matter up to a resolution of 2.8 km, and thus do not justify the extra cost of a non-hydrostatic dynamical core, an exception is strong subtropical jet regimes over high orography. In that case, the orographic gravity waves are not handled correctly by the hydrostatic dynamical core. As a result, the model’s mean orography needed special filtering at small scales and the model timestep had to be reduced. The degradation of NWP scores at kilometre-scale also prompts the need to find new ways to assess the improvement of physical realism.Finally, we will give an overview of the current developments at ECMWF that will be part of future versions of the global extremes DT, such as a new prognostic TKE turbulent scheme, modified settings for atmospheric convection and a revised orographic drag parameterization.  
Assessing the chemical availability and environmental fate of fallout radionuclides in cryoconite
Authors: Clason Caroline , Davidson Harriet , Millward Geoffrey , Fisher Andrew , Taylor Alex
Published: March 2024

Glaciers are stores for contaminants, both local and further afield in origin, that are released into the environment through anthropogenic processes. Cryoconite, a heterogenous granular material commonly found on glacier surfaces, is now known to be an efficient accumulator of contaminants such as fallout radionuclides (FRNs) and potentially toxic elements, with multiple regional studies reporting notable concentrations of radioactivity in cryoconite that far exceeds that which is found in other environmental matrices. Indeed, concentrations of FRNs in cryoconite can be as much as three orders of magnitude higher than those found in nearby proglacial sediments. While we now understand that this ‘hyper-accumulation’ of FRNs is commonplace on glaciers around the world, our understanding of the extent to which release of contaminants stored in cryoconite poses an environmental downstream risk is in its infancy. To assess both the activity concentrations and chemical availability of FRNs within cryoconite, we conducted novel sequential chemical extractions twinned with gamma spectrometry for cryoconite samples from glaciers in Arctic Sweden and Iceland. Major and minor elemental composition of cryoconite was also analysed with Wavelength Dispersive X-ray Fluorescence (WD-XRF) spectrometry. The results of these experiments demonstrate that different cryoconite-bound FRNs undergo varying degrees of solubilization, with consequences for increased contaminant mobilization under higher melt scenarios. Our work identifies a clear requirement for further research in this field in order to improve understanding of downstream environmental risk from the secondary release of legacy contaminants under continued glacier retreat.
EarthCARE mission for global height-resolved cloud particle categories and vertical motion
Authors: Sato Kaori , Okamoto Hajime
Published: March 2024

Improved representation of ice-phase processes in numerical models necessitates an enhanced understanding of ice-particle microphysics/radiative properties and their respective formation conditions. The EarthCARE JAXA L2 standard/research algorithms for clouds, precipitation and vertical motions aims at providing more detailed information of cloud particle categories and associated cloud microphysics/radiative properties from ATLID-CPR-MSI synergy. In particular, measurements from CPR Doppler and ATLID are expected to enable more comprehensive exploration of the relation between different cloud particle categories and the dynamical conditions. Based on complimentary information from long-term A-train data, the cloud particle category classification methodology planned for EarthCARE is tested and a new dataset has been developed. With this dataset, the geographical dependence of the occurrence of different ice cloud particle habit category and their properties that will be further investigated in detail from EarthCARE observations are discussed. Activities related to JAXA L2 validations from EU-Japan collaboration are developing new ways of combining ground-based active sensors and detailed surface observation of snow and rain to improve the quantification of precipitation and particle type retrievals. These studies would be valuable for further assessing the physical processes associated with cloud-precipitation formation from the EarthCARE mission.
Data-driven global projection of future flooding in 18.5 million river reaches
Authors: Zhang Boen , Slater Louise , Moulds Simon , Wortmann Michel , Liu Yinxue , Yin Jiabo , Gu Xihui
Published: March 2024

Reliable flood projection is crucial for designing suitable flood protection structures and for enhancing resilience in vulnerable regions. However, projections of future flooding suffer from cascading uncertainties arising from the climate model outputs, emission scenarios, hydrological models, and the shortage of observations in data-sparse regions. To overcome these limitations, we design a new hybrid model, blending machine learning and climate model simulations, for global-scale projection of river flooding. This is achieved by training a random forest model directly on climate simulations from 20 CMIP6 models over the historical period (1985−2014), with extreme discharges observed at approximately 15,000 hydrologic stations as the target variable. The random forest model also includes static geographic predictors including land cover, climate, geomorphology, soil, human impacts, and hydrologic signatures. We make the explicit assumption that the random forest model can ‘learn’ systematic biases in the relationship between the climate simulations and flood regimes in different regions of the globe. We then apply the well-calibrated random forest model to a new vector-based, global river network in approximately 18.51 million reaches with drainage areas greater than 100 km2. Global changes in flood hazard are projected for the 21st century (2015−2100) under SSP2-4.5 and SSP5-8.5. We show that the data-driven method reproduces historical annual maximum discharges better than the physically-based hydrological models driven by bias-corrected climate simulations in the ISIMIP3b experiment. We then use the machine learning model with explainable AI to diagnose spatial biases in the climate simulations and future flood projections in different regions of the globe.
Age-associated increase in soil organic matter enhances soil microbial diversity in urban green spaces
Authors: Yang Yerang , Kang Hojeong
Published: March 2024

Urban green spaces (UGS) are increasingly recognized as a solution to mitigate urban challenges by providing essential ecosystem services, supported by soil microbiomes crucial for biogeochemical processes. Previous studies comparing microbial diversity between UGS and natural ecosystems have shown inconsistent results, potentially due to overlooking the time elapsed since UGS construction, a significant factor influencing soil properties. To investigate this, 30 UGS across Seoul, South Korea were selected based on their age, along with 7 natural ecosystem sites outside Seoul for comparison. The study focused on exploring the relationship between UGS age and changes in soil chemical and microbial properties. The findings reveal a notable correlation between the elapsed time since UGS construction and various soil characteristics, including chemical properties, microbial community structure, diversity, and functional properties. As UGS mature, these properties gradually resemble those found in natural ecosystems, which was further confirmed through global meta-analysis. This indicates that as UGS age, soil chemical properties, especially soil organic matter, increase, thereby enhancing microbial diversity and shifting functional profiles to align more closely with natural ecosystems. This insight implies that current UGS management practices positively influence soil health and ecosystem functions. This study not only enhances our understanding of soil microbial ecology in UGS but also offers valuable guidance for managing UGS to promote sustainable urban ecosystems.
The origins and fate of dissolved organic carbon in a density-stratified carbonate aquifer on a tropical coastal landscape
Authors: Brankovits David , Pohlman John , Martínez García Alejandro , Alvarez Fernando
Published: March 2024

Flooded caves within carbonate coastlines serve as important conduits for carbon transport and transformation prior to groundwater expulsion into the sea. To investigate the sources, magnitude and biogeochemical reactions regulating carbon sources within an unconfined coastal aquifer, we analyzed the concentrations and δ13C values of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) at four sites along a flow path, a 6-km shoreline-perpendicular transect of flooded coastal caves in the northeastern Yucatan Peninsula, Mexico. The study revealed significantly higher DOC concentrations after regional rainfall compared to a mid-summer drought, suggesting precipitation as a key driver of the downward DOC flux from the surface. The decomposition of organic matter in the saturated soils of mangroves and tropical forest is the source of high DOC (on average, 678 µM; δ13C-DOC = −28‰) in the shallow fresh groundwater. The regional seaward tendency of DOC in the upper aquifer to become more 13C-enriched is primarily driven by increased mixing near the coast with saline groundwater, which is lower in concentration (70 µM, on average) and more 13C-depleted (δ13C-DOC = −26‰) than the seawater DOC (158 µM; −19‰). Evidence for net DOC consumption, along with positive and negative changes in δ13C-DOC values, is consistent with microbe-mediated transformation of organic matter primarily occurring in the upper aquifer’s low salinity waters. Diminishing DOC, coinciding with 4- to 5-fold increase in DIC concentrations while δ13C-DIC becomes more positive, implies that organic matter diagenesis also enhances carbonate dissolution. These landscape-level observations reveal hydrologic and biogeochemical factors that regulate the internal functioning of a coastal aquifer ecosystem and influence the quality and quantity of carbon exported to the coastal sea, where the Mesoamerican Barrier Reef resides.
 The Last Fissural Eruptions of the Manda Hararo Magmatic Segment, Central Afar (Ethiopia), Constrained from New cosmogenic Ages
Authors: Birhane Yafet Gebrewold , Pik Raphael , Bellahsen Nicolas , Schimmelpfennig Irene , France Lydéric , Flahaut Jessica , Ayalew Dereje , Yirgu Gezahegn
Published: March 2024

The Afar depression at the northern end of the East African Rift system is presently experiencing the final stage of continental break-up and progressive onset of steady magmatic spreading. The Magmatic Rift Segments in Afar broadly analogous to those observed within the mid oceanic ridges, offer the opportunity to study both mantle and crustal processes. Investigating the crustal architecture of those magmatic segments represents a key aspect to decipher fundamental parameters that control focussing of magmatic and tectonic activity during the generation of magmatic crust. Here, we present the typical organization of a 32 km long subsegment of the Manda Hararo magmatic rift system, with fissural activities symmetrical to an apparent mid segment magmatic reservoir and establish geochronology of the last eruptive history. We combine field investigations, precise mapping of volcanological and tectonic features, cosmogenic 36Cl exposure dating and geochemical analysis of lavas to constrain the temporal frame and the dynamics of magmatic processes. Our results show that the recent historical volcanic events (~ 500 to 2000 years) are sourced from calderas and fissures representing an alternating sequence of effusive and explosive (block fields) activities related to a coherent rifting episode along a single self-consistent magmatic sub-segment. Those recent fissural flows resurfaced a large portion of the segment and emplaced on older thick pahoehoe flows with a rather long lag-time of about 75 kyr separating the two episodes. Strongly contrasted geochemical signatures are also observed between those two volcanic episodes, with more differentiated and trace elements enriched basalts for the recent one, compared to the older one which are characterized by a unusual depleted signature. These new results for the Central Afar Manda Hararo rift have important implications for: (i) the local hazards along the segments, and (ii) the volcano-tectonic organization of the segment with coexistence of contrasted melt reservoirs on the underlying transcrustal plumbing system.
Identification of Earthquakes and Anthropogenic Events in Madagascar
Authors: Razafindrakoto Hoby N.T. , Rakotoarisoa A. Tahina
Published: March 2024

Earthquake catalog is a key element in seism hazards. However, it may be contaminated by non-natural earthquake sources. Hence,This study aims to discriminate natural and non-natural earthquakes through machine learning techniques and spatio-temporal distribution of the events. First, we propose a Convolutional Neural Network based on spectrograms to perform the waveform classification. It is targeted to applications in Madagascar. The approach consists of three main steps: (1) generation of the time–frequency representation of ground-motion recordings (spectrogram); (2) training and validation of the model using spectrograms of ground shaking; (3) testing and prediction. To measure the compatibility between output predictions and given ground truth labels, we adopt the commonly used loss function and accuracy measure. Given that the spatial distribution of the seismic data in Madagascar is non-uniform, we perform two-step analyses. First, we adopt a supervised approach for 6051 known events in the central part of Madagascar. Then, we use the outcome for the second step of training and perform the prediction for non-categorized events throughout the country. The results show that our model has the potential to separate earthquakes from mining-related events. For the supervised approach, among the 20% used for testing, 97.48% and 2.52% of the events give correct and incorrect labels, respectively. These pre-trained data are subsequently used to perform predictions for unlabeled events throughout Madagascar. Our results show that the model could learn the features of the classes even for data coming from different parts of Madagascar.From the analyses of the spatio-temporal patterns of seismicity, we also found evidence of induced earthquakes associated with the heavy-oil exploration in Tsimiroro, Madagascar with an increase in the rate of earthquake occurrence in 2022.
Microplastic transport in rivers and their hyporheic zone – combining modeling and experiment
Authors: Fleckenstein Jan , Dichgans Franz , Boos Jan-Pascal , Gilfedder Ben , Frei Sven
Published: March 2024

Microplastic (MP) pollution in the aquatic environment has become a problem of growing concern due to potential adverse effects on aquatic organisms and ecosystems. While MP transport and fate in marine systems has been researched to quite some extent relatively little is known about the transport mechanisms of MP particles in terrestrial surface waters and in saturated porous media like in groundwater or the hyporheic zone (HZ).We investigated the transport and fate of small (1, 3 and 10 μm diameter) polystyrene MP particles in a rippled, sandy stream bed (D50 = 1.04 mm) using CFD simulations calibrated to a set of flume experiments. A novel detection system for fluorescent MP particles (Boos et al. 2021) was used to track and quantify particle movement in the turbulent open water and in the hyporheic sediments in the laboratory flume following a pulse injection of MP particles into the surface water compartment. A new, integrated CFD simulation scheme within the OpenFOAM suite of CFD solvers was implemented for the flume system for a seamless simulation of water flow and particle transport in the open water and in the hyporheic sediments (Dichgans et al. 2023). Additionally we simulated the transport and fate of a range of “virtual” particles in the open water for different channel geometries using a Lagrangian approach.Simulations show that 1 μm MP particles are transported through the HZ like a solute, following the typical hyporheic flow cells below the bedforms. Transport and particle progression through the HZ could be adequately described with an advection-dispersion equation. Larger 10 µm MP particles instead showed retarded transport through the HZ, while retardation increased with travel distance in the sediments. Our results indicate that advective pumping across the streambed interface can transport very small MP particles through the HZ, while larger particles are increasingly retained. Distinct flow structures in the open water are found to be decisive for the fate of MP particles in the river channel.References:Dichgans, F., Boos, J.P., Ahmadi, P., Frei, S., Fleckenstein, J.H. (2023), Integrated numerical modeling to quantify transport and fate of microplastics in the hyporheic zone, Water Research, 243, https://doi.org/10.1016/j.watres.2023.120349Boos, J.-P., Gilfedder, B. S., & Frei, S. (2021), Tracking microplastics across the streambed interface: Using laserinduced-fluorescence to quantitatively analyze microplastic transport in an experimental flume. Water Resources Research, 57, e2021WR031064.https://doi.org/10.1029/2021WR031064Boos, J.-P., Dichgans, F., Fleckenstein, J.H., Gilfedder, B. S., Frei, S. (2024) Assessing the Behavior of Microplastics in Fluvial Systems: Infiltration and Retention Dynamics in Streambed Sediments. Water Resources Research, accepted
Comparison of remote sensing ground based systems for volcanic emission monitoring
Authors: Corradini Stefano , Guerrieri Lorenzo , La Spina Alessandro , Merucci Luca , Salerno Guseppe , Brenot Hugues , Friedrich Martina , Campion Robin , Rivera Cardenas Claudia , Vargas Brancamontes Dulce Maria , Gonzalez Gonzalez , Rodríguez Iglesias Lizzette
Published: March 2024

Ground-based remote sensing systems provide safe, real-time, continuous and reliable measurements of parameters of volcanological interest and have become indispensable tools for monitoring volcanic activity and potentially mitigating its effects on the environment and local communities. Ground-based systems, where installed, offer continuous spatial and temporal coverage, providing data of high resolution and sensitivity, which are essential for validating satellite data The latter are characterised by much greater density and larger spatial coverage, and for this reason have now become irreplaceable for volcanic monitoring on a global scale.    This work presents the preliminary comparison results of simultaneous measurements from ground-based systems, consisting of different types of instruments operated by several international research groups. Among these, the most relevant systems we used were (1) a new portable and low-cost TIR system consisting of three collimated cameras, one in the visible, a panchromatic TIR in the 8-14 μm window and an identical TIR camera filtered with a bandpass centred at 8.7 μm, for the detection of SO2 emission height, columnar content, and flux, (2) two high-performance SO2 dual UV imaging systems (EnviCam3) with synchronous acquisition of images (on- and off-band wavelength channels for SO2 detection), and an integrated spectrometer (co-aligned with cameras to provide calibration of SO2 retrievals), (3) a MAX-DOAS, and (4) an IR camera continuously looking at Popocatépetl thermal anomalies.  The described ground-based systems were used for simultaneous volcanic emission monitoring measurements of Sabancaya Volcano, Perú, and Popocatépetl Volcano, Mexico, in dedicated field campaigns organized in November 2022, and February 2024 respectively, partly funded by the INGV ATTEMPT and DYNAMO projects, and the KAIROS project (SESAR 3 Joint Undertaking).The SO2 fluxes time series obtained from the different ground based systems were cross-compared with each other and with the flux retrieved by the TROPOMI instrument on board the S5p satellite.These types of comparative measurements represent a significant step forward in understanding the relationships between the various ground-based measurements carried out, their use for validating space-based measurements and, in particular, the estimation of SO2 flux using remote sensing optical methods.
Significance of hydrogen abstraction in the formation of highly oxygenated organic molecules in the OH oxidation of monoterpenes
Authors: Zhao Defeng , Shen Hongru , Luo Hao , Luc Vereecken , Kang Sungah , Iida Pullinen , Fuchs Hendrik , Hallquist Mattias , Wahner Andreas , Kiendler-Scharr Astrid , Mentel Thomas
Published: March 2024

Secondary organic aerosol (SOA), formed by oxidation of volatile organic compounds, significantly influence air quality and climate. Biogenic highly oxygenated organic molecules (HOM), particularly those formed from monoterpenes, play a key role in SOA formation and growth. As the most important daytime oxidant, hydroxyl radical (OH•) initiated HOM from monoterpenes is believed to be mainly formed via OH addition channel. However, for α-pinene and limonene, we found that the contribution of hydrogen abstraction channel by OH contribute a significantly to HOM formation. We will present our observations and theoretical calculations, showing the role of hydrogen-abstraction and alkoxy radicals for fast autoxidation leading to HOM formation. We also provide formation mechanisms of and yields of HOM, suggesting the non-negligible contribution of the hydrogen abstraction channel to ambient SOA, particularly in OH-rich areas.
Negative surface chlorophyll concentration anomalies in the Southeast Arabian Sea during 2015 and 2019 summers
Authors: Huang Huaming
Published: March 2024

Satellite observation revealed two extremely low surface chlorophyll concentration events in the southeast Arabian Sea (SEAS, 6oN-15oN, 72oE-77oE) during the summer monsoons (June to October) of 2015 and 2019. The results indicate that the physical processes leading to negative SEAS chlorophyll anomalies during the 2015 and 2019 summer monsoons were inconsistent. In the 2019 summer monsoon, the warm SSTA and low chlorophyll in the SEAS are mainly related to the weakened upwelling and deepened thermocline depth due to the combined effects of local wind anomaly and the arrival of westward-propagating downwelling coastal Kelvin wave driven by easterly anomalies near eastern Sri Lanka during extreme positive Indian ocean dipole (IOD) event. Deeper thermocline depth and stronger downward movement during the 2019 summer made it difficult to transport nutrients upward, which in turn led to reduced surface chlorophyll concentrations in the SEAS. Positive IOD-induced easterly anomaly in the southern Bay of Bengal during the 2015 summer drove downwelling coastal Kelvin wave to propagate westward deepening the thermocline in the SEAS. Due to local wind stress anomalies favored upwelling and counteracted the downward motion of the downwelling coastal Kelvin wave. The downward transport (thermocline depth anomaly) in the SEAS during the 2015 summer was only one-third of (half of) that in 2019. Meanwhile, the upper ocean layer in the SEAS experienced extreme warming (the SSTA exceeded +0.8oC) due to the development of super El Niño in 2015. This significant warming enhanced marine stratification and prevented the subsurface nutrients from reaching the surface, which is unfavorable for the chlorophyll bloom. Deeper thermocline and weaker mixing allowed chlorophyll concentrations to reach extreme negative anomalies despite weaker IOD strength in 2015 than in 2019.
 
A Framework for Signal Shredding and Signal Detection Using a Physical Avalanching Rice Pile
Authors: Duller Robert , Griffin Chloe , Straub Kyle
Published: March 2024

Tectonic, climatic, and anthropogenic forcing generate sediment flux signals that propagate across the Earth’s surface. Some of these signals get stored in strata but autogenic processes in operation at the Earth's surface can shred (i.e. degrade) and obscure many signals of environmental change prior to stratigraphic storage. Here we advance on earlier seminal work and use a physical rice pile to identify critical autogenic timescales and establish autogenic thresholds that can be used to understand of how a signal of a given period or magnitude is manifested in an efflux time series and whether or not a signal is shredded or obscured by autogenic noise. Time-permitting there will be a more general discussion on how this applies to landscapes and strata.
Interaction of tectonics and surface process during oblique rifted margin formation. Insights from 3-D forward coupled geodynamic-surface process modelling.
Authors: Theunissen Thomas , Huismans Ritske S. , Rouby Delphine , Wolf Sebastian , May Dave A.
Published: March 2024

The magma-poor passive rifted conjugate margins in the Southern Equatorial Atlantic, North Atlantic/Arctic oceans, and Northern Mozambique Channel display en-echelon extensional segments separated by long transform faults (>300 km), influenced by inherited weaknesses. Using advanced 3-D forward geodynamic modeling coupled with surface processes, we investigate the formation of oblique rifts and passive margins. Our focus is on pre-existing weaknesses parallel to the extension direction, exploring the system's sensitivity to various erodibility factors. Key findings include: (1) erodibility within a low to moderate range has limited influence on the morpho-structural evolution of the oblique continental rift, (2) pure-strike slip faults reactivating transform weaknesses result in reduced topography, (3) major catchments sink in the inner corner at the tip of each extensional segments, and (4) hinterland drainage network capture along extensional segments is absent, controlled by isostatic rebound during rift flank drainage divide migration. This study enhances our understanding of the complex interplay between inherited weaknesses, erodibility, and the evolving morphology of oblique rifted margins.
Expressing the quality of sediment in the context of river monitoring plans
Authors: Reis Anabela , Roboredo Marta
Published: March 2024

The management of river systems at the catchment scale must guarantee the quality of ecosystems, which is largely dependent on sediment quality. Sediment have a complex and dynamic role in a variety of ecosystem functions and services, and are an indicator of sources of pollution in the upstream drained areas. The need of the inclusion of sediment sampling in monitoring plans, according to the Water Framework Directive (WFD), was already been recognised, but more knowledge is necessary to define the most adequate methodologies not only related to sediment sampling and chemical analysis, but as well to the expression of the results and classification of sediment in terms of contamination levels.
Regarding the evaluation of sediment pollution by metal(oid)s, it is common to calculate contamination indices to quantify the metal enrichment in sediment. The assumptions on the basis of the calculation of different indices are similar: to compare the content of metal under consideration with a background, or reference, value for the same element (e.g. Igeo and CF), which can be normalized (e.g. EF) to a reference element considered conservative (e.g. Al, Fe, Li, Sc, Ti, and Zr), which concentration in the sample medium will practically exclusively be influenced by lithological sources. To distinguish between the human and natural contributions to metal contents in sediments is a challenge, because of the influence of natural local variability of metals on sediment composition, as well as the fluvial processes involved in its dynamics. In order to overcome a possible overestimation of metal concentration in unpolluted sediment, it is fundamental to select a proper reference metal concentration. The common use, as reference value, the mean elemental contents of upper continental crust (UCC) is valid for larger river basins, where several types of rocks outcrop, but in small-sized catchments hardly reflect the local average bedrock chemical composition.
This study considered two small sized catchments, subjected to different environmental pressures, and investigated the contents, pattern of the spatial and temporal distribution, and enrichment metals in fluvial sediments (potential environmental risk associated), by applying contamination indices frequently used in environmental studies. The results were interpreted in terms of the reference values used in the classification of the quality of the sediment.
Acknowledgments: FCT – Foundation for Science and Technology, Portugal, through the Project UIDB/00073/2020 and UIDP/00073/2020, I&D D unit Geosciences Center (CGEO).
Mapping saltwater intrusion via Electromagnetic Induction (EMI) for planning a Managed Aquifer Recharge (MAR) facility in Maltese Island
Authors: De Carlo Lorenzo , Turturro Antonietta Celeste , Caputo Maria Clementina , Sapiano Manuel , Mamo Julian Alexander , Balzan Oriana , Galea Luke , Schembri Michael
Published: March 2024

In coastal areas, saltwater intrusion causes a depletion of the resource by reducing potable and irrigation freshwater supplies and causing severe deterioration of groundwater quality.This trend is observed in Pwales Valley – Maltese Island, where the water resource management plays a crucial role for the environmental sustainability of the area, given the importance of intensive agricultural activity along this valley. In order to tackle such phenomenon, actions or adaptation measures against climate change are strongly required.  For example, Managed Aquifer Recharge (MAR) is an increasingly important water management strategy to maintain, enhance and secure stressed groundwater systems and to protect and improve water quality.For accurately plan a MAR facility, it is crucial to define a hydrogeological model of the studied area, with the use of traditional hydrogeological measurements and innovative unconventional techniques. In recent years, Electromagnetic Induction (EMI) measurements, based on subsurface electrical conductivity data, have been increasingly used for investigating the saltwater intrusion dynamics due to their high sensitivity to the salinity.In the study area of Pwales Valley, a MAR scheme is being planned and, for this aim, a hydrogeological model has been developed through an EMI survey.More than 20,000 apparent electrical conductivity (ECa) data were collected to generate a quasi 3D high-resolution model of electrical conductivity of the Pwales Valley. The results highlighted the spatial extension of the tongue-shape salt water intrusion from east to west along the valley, as well as some geological-hydrogeological peculiarities such as the thickness of the salt wedge and the irregular top surface of the bottom impermeable layer, otherwise undetectable with other techniques. This approach confirms to be a useful tool for an effective hydrogeological characterization, essential for planning mitigation and tackle climate changes actions or adaptation measures, such as a MAR plant.
“Determination of Hydric Potencial through Geoelectric and Piezometric methods in the Ichickcollcococha Wetland, Pachacoto Hydrographic Unit, Cordillera Blanca, Perú.” 
Authors: Mamani Leila Maribel , Jara W. Harrinson , Chacca Luna Velnia , Torres Juan C. , Mallqui Helder , Cosi Manuel , Quispe Cristian , Aquino Milagros
Published: March 2024

Abstracts
High-Andean bofedales are vegetated wetlands that play a crucial role in the context of climate change by facilitating the capture of carbon dioxide and regulating water. However, global warming has led to the glacial retreat of major snow-capped peaks, such as the Pastoruri Glacier, resulting in water scarcity that directly impacts these ecosystems. Hence, there is a pressing need to study them. This research aims to characterize the physical structure of the Ichickcollcococha bofedal, located in the Pachacoto Hydrographic Unit in the southern sector of the Cordillera Blanca, Peru. The objective is to determine its water storage potential during periods of high precipitation and drought. The study employs the Vertical Electrical Sounding (VES) geophysical prospecting method, corroborated by vibrating wire piezometers installed in the Ichickcollcococha bofedal. This method allows for a detailed analysis of the subsurface resistive properties, generating geo-electric profiles that detail the internal structure of the bofedal.
Three horizons have been identified: the upper layer is loosely composed of organic material (vegetation, cushioned bofedales) with high moisture content, reaching a depth of approximately 1.5 meters and average resistivity values around 431 Ohm.m. The second layer extends to a depth of 11 meters with resistivities of 67 Ohm.m, corresponding to organic materials such as peat and saturated sands. The third horizon, with estimated depths of 80 meters and resistivities around 1301 Ohm.m, corresponds to underlying limestone rock. The data obtained from the Ichickcollcococha bofedal align with characteristic values of glacial-origin peat bogs.
The findings of this study provide a comprehensive understanding of the internal characteristics of the Ichickcollcococha bofedal, highlighting its contribution to the knowledge of its internal dynamics and its implications for the water potential of high-Andean bofedales. Furthermore, the results offer valuable information for modeling and water resource management.
Keywords: Bofedal, Hydric potential, geoelectric method, VES.
The effect of Pacific climatology on the North American Ice Sheet at the Last Glacial Maximum
Authors: Dow William J. , Sherriff-Tadano Sam , Gregoire Lauren J. , Ivanovic Ruza
Published: March 2024

Surface ocean conditions and atmospheric dynamics can affect the surface mass balance (SMB) of remote ice sheets via their influence on heat and moisture transport. Here, we use the FAMOUS-ice coupled climate-ice sheet model, coupled to a slab ocean, to simulate the Last Glacial Maximum (LGM). The model was run hundreds of times to produce a large ensemble that captures a range of uncertain model inputs (parameter values). We investigate the range of simulated atmospheric circulation patterns in the 16 ‘best’ ensemble members based on constraints, such as global temperature, their relationship to sea surface conditions in the North Pacific and the interactions with the North American ice sheet. We present evidence of upper tropospheric planetary waves that facilitate communication between the tropical Pacific and extratropical Laurentide ice sheet region, yet there are clear differences in upper tropopsheric dynamics when compared to recent historical period. There is limited evidence for this tropical-extra-tropical relationship being directly responsible for regional differences in Laurentide SMB evolution.
Logging of self-potential gradients to track saline intrusion in chalk, gravel and sand aquifers around the United Kingdom
Authors: Rowan Tom , Butler Adrian , Flynn Raymond , Hamill Gerard , Donohue Shane , Jackson Matthew
Published: March 2024

Coastal aquifers, a vital drinking water (and agricultural) resource for over a billion people, are facing increasing risks of seawater contamination due to the dual challenges of population growth and climate-induced sea-level rise. With water stress expected to intensify and water use consumption growing annually, there is an urgent need for innovative methods to track saline intrusion in these aquifers.  Current monitoring techniques like observational boreholes are limited in their warning capabilities, while resistivity imaging, despite its effectiveness, is prohibitively expensive and logistically challenging, (MacAllister et al. 2016).Self-Potential (SP), naturally occurring voltages arising from ion separation in the subsurface, is a promising geophysical technique to identify and manage saline intrusion, provided its source mechanisms are well understood. There are two key sources of SP in hydrology. Electro-kinetic potentials (VEK), due to fluid flow induced by pressure gradients, and exclusion-diffusion potentials (VED), due to ion concentration gradients in the subsurface. The balance of these effects depends on a variety of variables including the physical and chemical properties of geological material in which the saline-fresh water interface is located. Spatial and temporal changes in these potentials provide  insight into the location and behaviour of the saline-fresh interface.This study introduces a novel SP profiling approach that employs both fixed and movable electrodes within a borehole, greatly enhancing the data acquired from SP measurements. Observations across various UK locations have revealed SP profiles exceeding 50mV. Coastal aquifers including those of Chalk, Gravel and Sand have been investigated. This talk presents not only gathered results but also details insights in the practical assessment of these gradients. Notably, these SP gradients are dynamic, with changes seemingly connected to the movements and proximity of the saline interface. The findings are corroborated by laboratory experiments and numerical models, showing that the dynamics of SP gradients can serve as an early indicator of saline intrusion in coastal aquifers. BibliographyMacAllister, DJ., Jackson, M. D., Butler, A. P., and Vinogradov, J. (2016), Tidal influence on self‐potential measurements, J. Geophys. Res. Solid Earth, 121, 8432– 8452