bluuebunny/crossref_metadata_2025 huggingface dataset:
Variable effects of ecosystem restoration in a eutrophic coastal lagoon: reoxygenation by increasing water exchange
Authors: van Helmond Niels A.G.M. , Zygadlowska Olga M. , Klomp Robin , Lenstra Wytze K. , Jetten Mike S.M. , Slomp Caroline P.
Published: March 2024

Increased anthropogenic activities are affecting water quality, e.g. leading to eutrophication and deoxygenation, culminating in biodiversity loss in coastal ecosystems globally. In the Southwest Delta in the Netherlands, large scale engineering to protect coastal areas against storm surges has turned several tidal inlets and estuaries into coastal lagoons and (marine) lakes. The water quality in these ecosystems has strongly deteriorated as a result of stagnation of bottom waters in combination with eutrophication. One such ecosystem, Lake Veere, showed signs of recovery after restoration of water exchange with the adjacent tidal marine Eastern Scheldt in 2004. In recent years, regular water monitoring has revealed the return of low-oxygen conditions, however, along with other signs of worsening water quality such as fish kills and jellyfish blooms. Here, we assess the role of the sediments in the (re)occurrence of low-oxygen conditions in Lake Veere. During two sampling campaigns in 2022, water column and sediment samples were collected. Geochemical analysis, including direct in-situ flux measurements with a benthic lander, revealed an increasing sedimentary oxygen demand (SOD) from the western (sea-side) part of the lake to the east, from ~10 to >100 mmol O2 m-2 d-1. This gradient in SOD opposes the observed trend in water column deoxygenation, with low-oxygen conditions predominantly prevailing in the central and western part of the lake and not in the east. This indicates that, despite restoration efforts, large parts of the lake are still highly sensitive to deoxygenation. Sediment analyses show the near-absence of iron-oxides, hence little capacity to buffer toxic hydrogen sulfide, which indeed accumulated in pore waters, reaching concentrations of up to 10 mmol L-1. In the central part of the lake, hydrogen sulfide even accumulated in the bottom waters, pointing towards its potential involvement in the observed fish kills in the region. Our results illustrate the difficulty of improving water quality through changes in water exchange alone because of strong legacy effects of eutrophication and deoxygenation in the sediment.  
A Global Assessment of Compound Humid Heatwaves-Extreme Rainfall in Major Coastal Cities
Authors: Ganguli Poulomi , Merz Bruno
Published: March 2024

Humid heatwaves, defined as extreme temperatures combined with high relative humidity, can affect large populations and result in crop damage, causing public health emergencies and threatening food security. The consequences for society are even more severe when extreme rainfall follows a humid heatwave. There is evidence of the increasing occurrence of humid heatwaves—extreme rainfall compound events in several parts of the globe. Their compound impact depends on the response time, the statistical interdependency between the two interacting causal drivers, and their severity. While the correlation between temperature and rainfall tends to be negative at daily or monthly time scales, the correlation between short-duration rainfall extremes and high temperatures is often positive at shorter time scales during the summer. A positive (negative) correlation can result in a higher (lower) risk of compound heatwave-extreme rainfall events. Across the coasts, the dependence strengths between these two variables are often elusive due to the influence of large-scale atmospheric teleconnection. On a global scale, the statistical coupling between humid heatwaves and extreme rainfall events has not been investigated across the coasts. To fill this knowledge gap, this study provides an observational assessment of the compound interactions of summer heatwave amplitude (i.e., the peak temperature of the hottest day during the heatwave episode) and extreme rainfall (described by > 90th percentile threshold of daily rainfall magnitude) across 29 major coastal cities in the tropics (23.5°N - 23.5°S), subtropics (23.5°N - 35°N and 23.5°S - 35°S) and mid-latitudes (35°N – 60°N and 35°S - 60°S). It finds a significant (P < 0.05) increase in the frequency of compound humid heatwaves-extreme rainfall events in the past few decades, with a more robust increase over the northern hemisphere compared to the southern hemisphere. The mean response times between the heatwave amplitude and the peak rainfall tend to be shorter for the southern sub-tropics than the northern hemisphere sites, indicating a swift transition between two extremes in these regions. Using a multivariate probabilistic framework, we further demonstrate that a modest to substantial increase in heatwave amplitude in summer can enhance the rainfall extremes by 80%, with the most significant increase occurring in the sub-tropics. The findings reveal a strong coupling between humid heatwaves and extreme rainfall in sub-tropical climate regimes, contrasted by a relatively weak coupling across the tropics. Understanding the interactions between humid heatwaves and extreme precipitation across coastal megacities will help decision-makers and stakeholders to adapt and mitigate these compound hazards in densely populated settlements.
Identification of low flow events by machine learning algorithms
Authors: Lebrenz Henning , Pavia Daniela , Staufer Philipp
Published: March 2024

An improved forecast of low flow events in catchment basins could be a valuable tool for the operation and decision making of dependent infrastructure (e.g. wastewater discharge, water abstraction) along corresponding rivers. Therefore, the classification of 6642 independent low-flow-events (being the Q347 as the discharge less than the 95%- exceedance quantile of the FDC) from 55 catchment basins within the Kanton Solothurn (Switzerland) was performed by five different machine learning algorithms (i.e. knn, decision tree, random forest, support vector machine, logistic regression). Herein, each low flow event was characterized by 47 static and dynamic parameters (i.e. description of catchment and event history), being supplemented by differently defined (near) non-low-flow events, leading up to a total population of approx. 18000 discharge events.The validation and verification showed different qualities of the classification accuracy for the forecast of low-flow events, being dependent on the selection of the defined event populations, the selected machine learning algorithm and the definition of classes. In general, the support vector machine and random forest may lead, with the presumption of carefully selected classes, to forecast accuracies of >90%.
A regime change within Amery Ice Shelf cavity by a reversed current in the twenty-first century
Authors: Jin Jing , Payne Antony , Bull Christopher
Published: March 2024

The Amery Ice Shelf (AmIS), the third largest ice shelf in Antarctica, has experienced a relatively low basal melting during the past decades. However, it is unclear how AmIS melting will respond to a future warming climate. Here, we use a regional ocean model forced by a low-emission scenario and a high-emission scenario to investigate AIS melting by 2100. The melt rate is projected to increase multiple times in 2100. An abrupt increase in melt rate happens in the 2060s in both scenarios. A mechanism that drives the jump of melting is investigated. A redistribution of local salinity (and then density) in front of AmIS forms a new geostrophic balance, leading to the reversal of local currents. This transforms AmIS from a cold cavity to a warm cavity, and results in a jump of ice shelf melting. This regime change draws our attention to the role of oceanic processes in the basal mass loss of Antarctic ice shelves in climate change.
Pb Isotopic Compositions of Soils and the Impact of Heavy Metal Smelters in Urbanized Industrial Settings, East Los Angeles, California, U.S.A. 
Authors: Ayuso Robert , Foley Nora , Johnston Jill , Indela Rani , Jackson John , Bickerstaff Damon
Published: March 2024

Lead isotopes of soil profiles were measured to survey possible sources of lead. Thirty-seven soil profiles (n > 150 samples) were obtained near two lead battery recycling smelters: Exide (recently shutdown) and Quemetco/Ecobat (currently in operation) affecting thousands of residential sites. Preliminary soil Pb isotopic compositions plot as a band in Pb isotope space from radiogenic values typical of rock-derived lead to lower values that likely indicate anthropogenic lead. Three overlapping soil groups were established based on Pb isotope analysis by TIMS (Thermal Ionization Mass Spectrometry). Group 1 consists mainly of soils near the Exide smelter and nearby residential sites. Group 1 has low isotopic values with moderate variations in 206Pb/207Pb ~1.167–1.176, 208Pb/207Pb ~ 2.432–2.438, 206Pb/204Pb ~18.24–18.344. Group 2 has more radiogenic values than Group 1: 206Pb/207Pb ~1.178–1.190, 208Pb/207Pb ~2.439–2.443, 206Pb/204Pb ~18.34–18.56 and consists mostly of residential soils surrounding the Exide smelter. Group 3 is more radiogenic than Groups 1 and 2: 206Pb/207Pb >~1.190, 208Pb/207Pb >~2.443, 206Pb/204Pb >~18.56. Soils near the Quemetco facility have similar variations and overlap the three groups.  About 80% of the Pb isotopes in leached soils near Exide have Pb compositions that match those of the smelters. Group 2 has up to about 67% Pb resembling the Exide smelter output and Group 3 yields up to about 18% matching Pb. Sites near Quemetco contained up to about 86% Pb isotopically similar to the Exide signature. Sites containing lead that isotopically matches soils near the Exide smelter are interpreted as contaminated by human activities. Smelter isotopic signatures are found as deep as 30 cm in the soil profiles.  Our results demonstrate the need for establishing baselines and background concentrations of lead (and other metals such as As, Cd, Zn, Sb, and Cu) and Pb isotopic compositions of soils, waters, and air before smelters and other industrial facilities are in operation (which are commonly located in disadvantaged communities, for example in East Los Angeles), and especially during property transitions. Elemental and isotopic data can be used to assess legal liability and assist local, State, and national agencies for effective cleanup and proper remediation.
Evaluating Two-Dimensional Horizontal Grids in a Deterministic Air Pollution Model: Estimating the Impact on Outputs, Inputs, and ANN-CHIMERE
Authors: Bouzghiba Houria , Ajdour Amine , Abderrahmane Mendyl , Géczi Gábor
Published: March 2024

Air pollution, especially from ozone and particulate matter, significantly contributes to environmental and health problems. Monitoring complexity and high costs have made modeling a parallel approach to surveillance. Models such as CHIMERE are essential in combining weather conditions, emissions, boundaries, and various physical processes, including transport and spatial resolution. This study introduces three methodologies to assess the influence of a two-dimensional horizontal grid in the Eulerian atmospheric transport model. It explores the impact on outputs, inputs, and model fitting. The first approach analyzes the resolution effect on CHIMERE outputs, focusing on O3. The second approach investigates various effects on inputs, including temperature (T), wind speed (WS), Planetary Boundary Layer Height (PBLH), Land Use and Land Cover (LULC), and Emissions (E). The third approach created a straightforward, strong, and precise ANN-CHIMERE adjustment model to evaluate the impact of spatial resolution in this context. The outcomes are verified through ozone measurement data collected in Agadir and Casablanca, Morocco, during various periods in 2016 and 2021.The results show that a higher horizontal grid improves the probability of good predictions. The impact of input data accuracy on high resolution can be concluded, providing insights into the limitations of CHIMERE in predicting output data. The new ANN-CHIMERE adjustment model delivers superior outcomes at high resolution, exhibiting an enhanced correlation coefficient and a significant reduction in the RMSE. In the future, the proposed approaches can be applied for spatial resolution optimization, maintaining the accuracy of the results and the computation time. It can also be adopted as an adjustment process of the inputs and outputs of deterministic air pollution models.
Climate change signals of radiative forcing and feedback unveiled from long-term trends of spectrally resolved surface longwave radiation
Authors: Huang Yi , Liu Lei , Gyakum John
Published: March 2024

Surface warming is directly associated with the surface energy balance, where downwelling longwave radiation is a critical factor influencing and reflecting surface temperature variations. Accurately identifying various forcing and feedback mechanisms is essential to making more realistic predictions about future climate change. Spectrally-resolved radiance measurements play an important role in this pursuit by leveraging the distinctive absorption features of atmospheric compositions. Only recently, the availability of comprehensive, long-term records of spectrally resolved radiation and atmospheric properties has enabled us to observe and quantify the forcing and feedback factors, such as the cloud feedback characterized by its high uncertainty.This study initiated by homogenizing the 23-year record of downwelling longwave radiance (DLR) observed by the Atmospheric Emitted Radiance Interferometer (AERI) at the Southern Great Plains site. A detailed DLR record for diverse sky conditions was obtained, enabling the determination of long-term trends in both clear-sky and all-sky scenarios. These trends reveal distinct spectral signals associated with various meteorological variables, forming the basis for further climate change signal attribution analysis.Subsequently, we develop and validate a novel spectral fingerprinting method tailored to constrain surface forcings and feedbacks from long-term DLR trends. Our analysis identifies positive CO2 and negative O3 surface forcings in both clear-sky and all-sky conditions. Moreover, we observe that changes in temperature and water vapor concentration over the 23-year period contribute to an increase in downwelling longwave radiation. Significantly, our study discovers a negative cloud feedback that offsets the increase in downwelling longwave radiation resulting from elevated CO2, water vapor, and atmospheric temperature. These attributions of radiation changes, derived from AERI observations using the fingerprinting method, are validated against the kernel method and compared with the simulations of Global Climate Models.
Beyond stream power: the dominance of landsliding on the active Taiwan orogen
Authors: Li Fang-Yu , Hsieh Meng-Long , Wu Chun-Ran , Chen Yi-Hao
Published: March 2024

Fluvial bedrock incision, which creates topographic relief and influences hillslope stability, has been considered the key process linking denudation and tectonic uplift in non-glaciated mountains. However, taking the Taiwan orogen as an example, this study argues that landslides can dominate over river incision in governing the erosion of active mountains. The Taiwan orogen, reaching 3000 – 4000 m in elevation, is prone to landsliding triggered by heavy rains or large earthquakes. It is shown in the orogen that landslides could drive catchment expansion and bedrock-river avulsion. Also, by determining the yield/caliber of bedload sediment, landslides have controlled river incision/deposition processes and, thus, the morphology of bedrock rivers (width, gradient, sinuosity, and shape of longitudinal profiles). The significant spatial/temporal diversities in landslide sequences, with various magnitudes/frequencies, then account for: (1) the occurrence of tributaries that are atypically wider or gentler than trunk rivers; (2) the wide ranges of bedrock incision rates (ranging from zero to several centimeters per year) over different time spans; (3) the contrasts in terrace sequences (and thus river evolutionary histories) among catchments; (4) the differential bedrock incision along rivers, leading to the creation of knickpoints (including waterfalls). All the observations above challenge the applicability of stream power law (assuming the drive of river incision by hydraulic power) in modelling bedrock river incision in the Taiwan orogen. We further find that the activities of landslides around the major drainage divides > 3000 m in elevation have been much lower than the activities of landslides in the mid-elevation regions (perhaps due to the lower seismicity in the high mountains). Given this and the commonness of low-relief surfaces stranded on the major drainage divides, it is unlikely that erosion of the orogen has offset the tectonic uplift. We believe that the elevation of the orogen has been increasing and it is the glacial erosion that can balance the tectonic uplift in the future.     Landslide; Fluvial bedrock incision; stream power law; low-relief surface; Taiwan orogen
Emerging river flow and hydrological drought trends in Great Britain
Authors: Chan Wilson , Tanguy Maliko , Chevuturi Amulya , Hannaford Jamie
Published: March 2024

Hydrological drought frequency and severity is projected to increase for the UK. However, there is not yet robust observational evidence for decreasing river flows and increasing hydrological drought severity. This lack of evidence may stem from short observational records, human influences on river flows and internal climate variability. As a result, river flow trends in the past and in the near-term may be different to the trend induced by long-term climate change. This lack of congruency poses significant challenges for decision-makers faced with uncertain future projections on the one hand and an apparent lack of observed changes on the other: underscoring the need for approaches that bridge this gap. Single-Model-Initial-Condition-Large Ensembles (SMILEs) provide an ideal opportunity to reconcile past observations and future projections as they isolate the effect of internal climate variability. Here, we use the 50-member CRCM5 12km SMILE to drive GR6J catchment hydrological models for 190 catchments across Great Britain. Results show that observed trends in precipitation and river flows are within the spread of the large ensemble, which includes both robust wetting and drying trends over the historical period that could have arisen from internal climate variability. We further estimate the time of emergence for each catchment, i.e. the decade at which river flow changes exceed natural climate variability. Winter river flows increase with warming and are estimated to exceed natural climate variability before the 2050s for many catchments, with implications for flood risk. Summer river flows are estimated to reduce with warming, including hotspots in southwest Britain with an early time of emergence, exacerbating existing pressures on water resources. Autumn flows for catchments in southeast England are estimated to decrease but are not estimated to exceed natural climate variability until late 21st century. Establishing water management and adaptation strategies is crucial well in advance of catchments reaching their time of emergence (i.e. before a statistically significant trend is detectable). These results highlight the potential to use SMILEs to explore plausible alternative realisations and explore storylines of low-likelihood, high-impact hydrological extremes.
Oil palm yield in Southeast Asia impacted by management and climate change
Authors: Syahid Luri Nurlaila , Luo Xiangzhong , Lee Janice Ser Huay
Published: March 2024

Oil palm is a primary commodity in the Southeast Asian region and has replaced a substantial portion of natural forests in this area, resulting in a shift in regional ecosystem and ecosystem-climate interactions. Previous site-level evidence suggested that oil palm activities (i.e., production yield) are influenced by social, biological, and climatic factors, however, it remains unclear how oil palm yield has changed across Southeast Asia and the dominant driver for the changes. In this study, we used ground survey of oil palm yield, in combination of remote sensing of near-infrared reflectance (NIRv), to examine the dynamics of oil palm yield from 2001 to 2017 in Southeast Asia, particularly in Malaysia and Indonesia. Utilizing multiple sources of open datasets, we investigated the roles of management (i.e., smallholder and industrial), biotic (i.e., stand age) and climate in influencing oil palm yield in Southeast Asia, and provide a quantification of their respective contributions to yield changes. The study advances our understanding of the historical changes in oil palm yield and their dominant factors, providing guidance to the future management of oil palm for sustainable production and ecosystem services.
Diverse modes of macropore flow—How to include them in predictive models?
Authors: Nimmo John R.
Published: March 2024

Films, rivulets, snapping rivulets, sliding drops, slugs—many flow modes besides filled-tube, Poiseuille-type flow occur in macropores. Some of these fit reasonably into Darcian formulations and the analog of laminar viscous flow in water-filled tubes. But others do not. These exceptions may be the main reason for failures to predict the speed and travel distance of preferential flow.A useful first step for an improved model of macropore flow is the classification of diverse flow modes into categories based on their intrapore boundary conditions. Within a flowing macropore, the gas-liquid and liquid-solid interfaces, with the effects of interfacial constraints such as surface tension and contact angles, determine the geometry of the flowing liquid phase and its controlling frictional influences. A classification scheme with four categories can account for the various flow modes that have been observed in lab and field experiments. This categorization helps to distinguish which flow modes are amenable to Darcian or Poiseuille-type representation and which are not. Some of the exceptions are approachable with wave or film-flow concepts as in several recently-developed models. Yet there are other flow modes that do not fit well in any of these models, and in some cases these may be the most important means of rapid and long-distance transport. Other sorts of physical processes may provide suitable analogs for these, for example free-fall concepts like initial acceleration, speed-dependent frictional forces, and terminal velocity. In any case, the diversity of macropore flow modes needs to be considered in the development of markedly improved models of preferential flow.
Novel application of artificial neural networks to derive lithofacies in the Bunter Sandstone Formation of the UK Southern North Sea
Authors: Li Zhenghong , Huuse Mads , Taylor Kevin , Ma Lin
Published: March 2024

The Bunter Sandstone Formation (BSF) in the UK sector of the Southern North Sea is thought to have a significant potential for CO2 storage, which would help the UK achieve net-zero carbon emissions by 2050. During the assessment phase, a robust lithofacies classification scheme and accurate identification enable better control for delineating the petrophysical property distribution in 3-D space, which is vital for further estimating the storage capacity and simulating CO2 migration.   In previous studies, several different lithofacies classification schemes were proposed for calculating the CO2 storage capacity of BSF traps. However, the establishment of these schemes was almost entirely dependent on well-logging data due to limited cores and corresponding thin sections. For example, the ‘cemented sandstone layers’ were identified only by low gamma-ray values with a sharp increase in density values and a decrease in acoustic values, which leaves significant uncertainty because of the lack of detailed lithological description and core calibration. For lithofacies identification based on well-logs, artificial neural networks are of great potential due to their strong non-linear mapping ability. Numerous researchers used the fully connected neural network (FCNN) to recognize lithofacies, but this method can only construct point-to-point mapping, which cannot take into account the previous information (data points in well-logs) of sequence data and results in not being fully competent in lithofacies identification.This study aims to partition the BSF reservoirs into several relatively homogeneous lithofacies based on cores, thin sections, SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction) analysis. We summarize each lithofacies characterization including grain size, porosity/permeability, 3D network structure of pore and cement determined by X-ray CT. Data pairs composed of logs and corresponding lithofacies types are selected for training neural networks. On this basis, we employ the algorithms designed for sequence data to achieve lithofacies identification, and make a comparison with the widely used FCNN method.
The South Atlantic Magmatic Province: An Integration of Early Cretaceous LIPs in the West Gondwana
Authors: Avelino de Macedo Filho Antomat , Oliveira Alisson , Janasi Valdecir , Hollanda Maria Helena
Published: March 2024

Extensive igneous activity, currently identified from NE Brazil and western Africa to the Falkland Islands and South Africa, preceded the fragmentation of the Western Gondwana supercontinent in the Early Cretaceous. The Paraná-Etendeka Magmatic Province (PEMP) is characterized by continental basaltic flows and igneous plumbing systems in SE South America and its African counterpart. In NE Brazil, dyke swarms and sill complexes compose the Equatorial Atlantic Magmatic Province (EQUAMP). A prominent feature of EQUAMP is the Rio Ceará-Mirim dyke swarm, an arcuate igneous plumbing system approximately 1,100 km in length. Aeromagnetic data suggests that the Rio Ceará-Mirim dykes stretch from the corner of South America to the northwest border of the São Francisco Craton. At this point, the dykes shift orientation to the NNW, extending towards the south, where they appear to connect with the Transminas dyke swarm (northern PEMP). The apparent continuity of dykes as a single entity would constitute a massive transcontinental swarm of about 2,300 km. A similar relationship is observed for the Riacho do Cordeiro (southern EQUAMP) and Vitória-Colatina (northern PEMP) dykes, indicating continuity across the São Francisco Craton of about 1,600 km. This study, supported by new petrological, geochemical, isotopic, and geochronological data, combined with geophysical and geodynamical analyses, demonstrates that the Transminas and Vitória-Colatina dyke swarms share the same composition and age as the Rio Ceará-Mirim and Riacho do Cordeiro dyke swarms, respectively. The set of new evidence supports a genetic connection between the PEMP and EQUAMP. Therefore, they can be collectively referred to as a single large igneous province related to the early stage of the South Atlantic rifting process in the West Gondwana realm: The South Atlantic Magmatic Province.
Improving modeled ice dynamics in Northwest Greenland with transient calibration: From multi-decadal trends to seasonal cycles
Authors: Badgeley Jessica , Seroussi Helene , Morlighem Mathieu
Published: March 2024

State-of-the-art ice sheet model simulations used in the Ice Sheet Model Intercomparison Project (ISMIP) show a mismatch with recent observations of dynamic ice sheet change. In particular, the difference between the modeled and observed cumulative mass balance trend over the last several decades calls into question the accuracy of current projections of ice sheet contribution to sea level rise. Here, we use one of these models, the Ice-sheet and Sea-level System Model, to investigate how transient calibration may improve model hindcasts of ice dynamics and impact projections. Transient calibration is a relatively new capability in ice flow models; it uses a time series of observations to invert for uncertain model parameters, such as basal friction and ice rheology. With more observational constraints than the common snapshot inversion method, transient calibration has been shown to better capture trends and to have the ability to estimate how parameters evolve through time. We apply this method to Northwest Greenland, a region undergoing rapid changes that also has high-resolution, high-accuracy data for bed topography, ice surface velocity, and ice front positions. We find that transient calibration brings hindcast simulations of cumulative mass balance to within observational error. We also find that, when the basal friction parameter is allowed to vary, transient calibration can help mimic the impacts of subglacial hydrology and reproduce observations of seasonal velocity variability. Future simulations to 2100 using the ISMIP6 protocols show that the use of transient calibration leads to greater mass loss and, in the near term out to 2050, has a greater impact on mass balance than the choice of climate forcing scenario.
Geologic, Topographic, and Seismic Characteristics of Large Landslides Triggered by 2023 Kahramanmaras Earthquakes, Türkiye
Authors: Gorum Tolga , Tanyas Hakan , Yilmaz Abdussamet , Karabacak Furkan , Wang Gonghui
Published: March 2024

The devastating Kahramanmaras earthquake sequence occurred on February 6, 2023. Two main events, Mw 7.8 and Mw 7.5, occurred 9 hours apart, affected 11 cities in Türkiye, and affected an area of ∼90,000 km2. This was the strongest historical earthquake doublet of magnitudes above 7.5 ever recorded in this region, and the consequences were catastrophic. The earthquake doublet triggered more than 3,600 landslides. Among these landslides, 35 of them have an area greater than 50,000 m2. Here, we focus on those largest coseismic landslides and show that 21 of them are pre-event landslides reactivated during the earthquake. They concentrate along a 5km-wide buffer zone around the surface rupture. Approximately 90% of these large landslides are distributed along the western section of the Eastern Taurus Mountain Belt, which is highly deformed and results in numerous overthrusts extending for 50 to 100 km. The geologic units in this part of the Taurus Mountain Belt consist of sedimentary, metamorphic, and igneous autochthonous and allochthonous units. The spatial distribution of landslides closely coincides with the topographic differences. They mostly (>82%) occurred on hillslopes where local relief varies between 500 and 700 m, and slope steepness ranges from 20° to 45°. Our preliminary analyses also revealed a relationship between the fault rupture dynamics and the distribution of large landslides. In addition to the rupture dynamics and topographic contrasts in the area, vertical lithological differences and the long-term tectonic deformations affecting autochthonous and allochthonous units have primary controls on the distribution of large landslides triggered by this earthquake doublet.
Paleoenvironmental and geomorphological changes in an ancient baldcypress swamp preserved on the Northern continental shelf in the Gulf of Mexico
Authors: Reese Andy , DeLong Kristine , Harley Grant , Garretson Katie , Garcia Andrea , Xu Kevin , Moran Kelli , Broome Kendall , Bergan Ellen
Published: March 2024

Wave action and seafloor scouring, likely from Hurricane Ivan, exposed an area of baldcypress (Taxoidum distichum) stumps, still in growth position and rooted in terrestrial soil, on the northern continental shelf of the Gulf of Mexico.  This site, known as the Underwater Forest, is located roughly 10 km off the coast of Gulf Shores, Alabama, USA, in approximately 18m of water.  Radiocarbon and optically stimulated luminescence dates from the mud/peat sections of the cores suggest a baldcypress swamp existed between approximately 70-40 ka BP (MIS 3-4) during the Würm glaciation.  Multiproxy analysis of sediments suggests significant geomorphological changes occurred to this backswamp environment overtime, which significantly impacted vegetation assemblage of the area.  Pollen evidence shows a clear transition from a baldcypress/tupelo gum (Nyssa aquatica) community to an alder (Alnus) dominated bar community.  This change suggests a transition to a braided river system, though it remains unclear whether these geomorphological changes resulted from terrestrial sources, marine transgression, or a combination of both.  The final vegetation change is to a more open, marsh environment resulting from sea-level rise.  Tree-ring analysis of the stumps suggest a synchronous death event, likely by burial, which may have also preserved the site.
Connecting the early temporal evolution of solar energetic particles to the properties of coronal shock waves
Authors: Jarry Manon , Dresing Nina , Vainio Rami , Rouillard Alexis , Plotnikov Illya , Kouloumvakos Athanasios
Published: March 2024

Solar energetic particle (SEP) events, particularly those of significant magnitude, are commonly associated with fast and wide coronal mass ejections (CMEs). These CMEs generate and drive shock waves in the solar corona, proving to be highly efficient in particle acceleration to high energies. Understanding the intricate connections between shock wave properties and SEP characteristics is crucial for advancing Space Weather forecasting.To achieve this objective, we employ a methodology to analyze a SEP event involving a coronal shock wave, observed by several spacecraft well distributed around the Sun. Initially, we reconstruct the 3D ellipsoidal shape of the expanding shock, enabling the extraction of its geometry and kinematic properties. Using magneto-hydrodynamics (MHD) cubes, we then reconstruct the magnetic connectivity of spacecrafts and retrieve the MHD properties of the shock wave at the intersections with these magnetic field lines. The temporal correlations between the shock properties and the SEPs recorded by individual spacecraft can finally be compared.Through the application of this methodology, we identify enhanced correlation coefficients between SEPs and shock parameters, such as speed, Alfvénic Mach Number, and theta_BN (the angle between the shock's normal and the magnetic field line). This work is funded by the H2020 SERPENTINE project.
­­Non-targeted VOC Quantification through the Simultaneous Coupling of an in-situ Gas Chromatograph to Electron and Chemical Ionization Time-of-Flight Mass Spectrometers
Authors: Claflin Megan , Lerner Brian , Stark Harald , Krechmer Jordan , DeCarlo Peter
Published: March 2024

Non-traditional VOC emissions, including emerging pollutants, air toxics, and volatile chemical products (VPCs) span a range of volatilities and molecular structures that impact their reactivity in the atmosphere and eventual fate. However, little is known their source apportionment, temporal behavior, and relative importance to health impacts along with ozone and SOA formation. With the need to characterize these emissions, comprehensive measurement techniques that capture the unexpected but are also highly specific to detail molecular structure and provide compound quantification are needed.The work presented in this study uses chemical ionization (CI) techniques (H3O+, NH4+, NO+, O2+) for the direct detection and quantification of VOCs considered to be hazardous air pollutants (HAPs). With our work, we show that the ionization patterns for these classes of compounds within each ionization scheme can be used to expand these methods to interpret unknown signals in complex environments. This detailed characterization was conducted by coupling in-situ gas chromatography (GC) to the CI-TOF-MS for pre-separation of the complex mixture. Our results show how the speciated data can be used to deconvolve the complexities of chemical ionization detection (including the presence of fragmentation, cluster formation, and mixed ionization schemes e.g. proton transfer, charge transfer, dehydration).To apply these methods to ambient atmospheric measurements we need to reconcile the need for both continuous isomer specific quantification and high time resolution data. To accomplish this, we simultaneously coupled the in-situ GC with both CI and electron ionization (EI) TOF-MS. Resulting in the generation of three data sets (GC-EI, GC-CI, and direct-CI data) that offer continuous GC quantification, universal detection of speciated organics (EI), speciated CI data to constrain interferences, and direct-CI data for high time resolution data. This instrument combination was deployed in Spring 2023 for a 4-week mobile laboratory campaign in a region of southeast Louisiana, US that is dense with petrochemical production and industrial activity, to quantify hazardous air pollutants to gauge exposure for the local population. The combination of the in-situ GC, EI-TOF-MS, PTR-TOF-MS was used to provide highly specific, quantitative data on VOCs considered to be air toxics in the area, while also acquiring high time resolution PTR-TOF data that allowed the characterization of different point sources and their variability over time-of-day and day-of-week.
Monitoring Spatiotemporal Seismic Velocity Changes Using Seismic Interferometry and Distributed Acoustic Sensing in Mexico City
Authors: Li Yang , Perton Mathieu , Sánchez-Sesma Francisco J. , Spica Zack
Published: March 2024

Mexico City, the most populated city in the Americas, undergoes significant seismic hazards. Conventional seismometers often suffer from limited spatial density, restricting detailed observations in urban areas. In contrast, Distributed Acoustic Sensing (DAS) can convert standard telecommunication fiber-optic cables into dense seismic arrays, providing great potential for high-resolution spatiotemporal monitoring. Therefore, we installed a DAS interrogator in Mexico City in May 2022 in a long-term fashion to collect data for observational studies in the region. The fiber crosses the city from south to north along a 29-kilometer path following the subway track. The dataset comprises 2266 channels with a 12.8-m spacing and a 200-Hz sampling rate. On Sep. 19, 2022, a Mw7.6 earthquake occurred in Michoacán, approximately 450 km away from the City. Exactly 37 years after the great 1985 Mw8.1 event. The DAS system provided high-quality, ultra-dense, yet unique data for this earthquake in particular. One of the goals of this study is to assess the earthquake-induced changes in the sedimentary basin material properties. For this endeavor, we employ seismic interferometry on the ambient noise field of DAS data and the stretching method to monitor seismic velocity variations in Mexico City. Our analysis reveals a velocity drop following the 2022 Mw7.6 earthquake in some city areas. The results indicate that DAS can effectively monitor the velocity variations in urban environments, offering valuable insights for urban hazard assessment.
The 2012 and 2023 Mw 7.6 tsunamigenic earthquakes at the Philippine trench and tsunami hazard implications
Authors: Heidarzadeh Mohammad , Gusman Aditya Riadi , Mulia Iyan E. , Suppasri Anawat
Published: March 2024

On 2nd December 2023, the eastern coasts of Philippines were struck by an M7.6 earthquake followed by a moderate tsunami measuring 0.5 m in height. The earthquake was the result of thrust faulting in the Philippine Trench (subduction zone) at the depth of 32.8 km according to the United States Geological Survey. Philippine Trench is the result of tectonic convergence between the Philippine Sea and Sunda plates. The December 2023 earthquake resulted in three deaths; however, no death or casualty was reported due to the tsunami. This event reminds another M7.6 tsunamigenic earthquake on 31st August 2012 in the outer-rise region of the Philippine Trench that occurred approximately 300 km from the 2023 epicenter causing one death (https://doi.org/10.1007/s00024-014-0790-2).From historical records, two prominent events in the region are an M 8.0 – 8.3 tsunamigenic earthquakes in 1918, and an M 7.9 earthquake in August 1976. The latter event generated a locally destructive tsunami that killed 5,000 people. It appears the largest recorded event in the region is the 1918 earthquake with a magnitude in the range of M 8.0 – 8.3. Considering the relatively short span of recorded earthquake history, the 1918 event cannot conclusively be regarded as the largest possible event from the Philippine Trench. Recent insights from global earthquakes in various subduction zones suggest that the occurrence of M9 earthquakes is feasible in any subduction zone, provided that the zone's length is sufficient to accommodate such events. Therefore, it is important to study the hazards from M9 earthquakes and potential tsunamis in the Philippine Trench and investigate the risks to infrastructure. The purpose of this research is to study the tsunamigenic potential of the Philippine Trench by modeling the 2012 and 2023 events and comparing them, modelling potential worst-case tsunamigenic earthquakes in the region and investigating their hazards and risks to infrastructure. The methodology used in this research are waveform analyses, spectral and wavelet analysis, numerical modelling, and fault tree analysis (FTA). We develop a cascading risk model based on FTA for critical infrastructure in the region.
Drivers of ocean carbon sink variability across spatial scales
Authors: McKinley Galen , Fay Amanda , Carroll Dustin , Menemenlis Dimitris
Published: March 2024

Since the preindustrial era, the ocean has removed roughly 40% of fossil CO2 from the atmosphere, and it will eventually absorb at least 80% of human CO2 emissions. While there is no doubt that the ocean is a critical player in the global carbon cycle, many uncertainties remain and the drivers and magnitude of interannual-to-decadal timescale variability remain poorly constrained. A key question is the extent to which external forcing, specifically the variability of the atmospheric pCO2 growth rate, or internal ocean variability is the dominant mechanism of variability. We use a suite of experiments from the ECCO-Darwin data-assimilative ocean biogeochemistry model to isolate and explore the impact of these two drivers. We demonstrate that at the global scale, external and internal variability equally drive ocean sink variability. However, as the spatial scale becomes more regional, internal variability becomes increasingly dominant. To diagnose the future evolution of the global-scale ocean carbon sink in response to a changing atmospheric growth rate, both skillful observation-based products and data-assimilative models will be required.   
Chemical composition and triple Sr isotopes of Gang-Kou River, Southern Taiwan
Authors: Chao Hung-Chun
Published: March 2024

    Radiogenic Sr isotope (87Sr/86Sr) is a robust tool for provenance identification in hydrology, affected mainly by chemical weathering, lithological background and climatic changes while stable Sr isotope (δ88Sr) may provide complementary information about weathering, adsorption, or carbonate precipitation. In this study, river water samples from the mainstream and the major tributary located at Gang-Kou River catchment were collected seasonally for two years. Major ions, trace elements, and Sr isotopes were measured. The results show that the major anions are bicarbonate (2.35 to 5.24 mM), chloride (0.413 to 1.11 mM), and sulfate (0.187 to 0.817 mM). The major cations are sodium (0.567 to 1.41 mM), calcium (0.720 to 1.66 mM), and magnesium (0.508 to 0.922 mM). The Sr isotopes of river water in the mainstream decrease from upper steam to down steam (from 0.71287 to 0.71174) and are higher than the major tributary. In reverse, the Sr isotopes of major tributary increase from upper steam to down steam (from 0.71066 to 0.71136). The major tributary shows lower Sr isotopes during wet season while the mainstream shows no seasonal variations. The major tributary also shows slightly higher δ88Sr than the mainstream without seasonal variation. The result of major elements with Sr isotopes indicates silicate weathering dominates the river water chemistry while the major tributary shows slightly higher portion of carbonate weathering. Besides that, river water chemistry shows higher carbonate weathering contribution in wet season than dry season. To summary, Sr isotopes are more sensitive to the source variations in water chemistry than the chemical compositions. The results of dissolved phase in Gang-Kou River catchment indicate possible implication to the province identification of the sediments at the estuary.
Moon-forming impactor as a source ofEarth’s basal mantle anomalies
Authors: Yuan Qian , Li Mingming , Desch Steven J. , Ko Byeongkwan , Deng Hongping , Garnero Edward J. , Gabriel Travis S. J. , Kegerreis Jacob A. , Miyazaki Yoshinori , Eke Vincent , Asimow Paul D.
Published: March 2024

Seismic images of Earth’s interior have revealed two continent-sized anomalies with low seismic velocities, known as the large low-velocity provinces (LLVPs), in the lowermost mantle. The LLVPs are often interpreted as intrinsically dense heterogeneities that are compositionally distinct from the surrounding mantle. Here we show that LLVPs may represent buried relics of Theia mantle material (TMM) that was preserved in proto-Earth’s mantle after the Moon-forming giant impact. Our canonical giant-impact simulations show that a fraction of Theia’s mantle could have been delivered to proto-Earth’s solid lower mantle. We find that TMM is intrinsically 2.0–3.5% denser than proto-Earth’s mantle based on models of Theia’s mantle and the observed higher FeO content of the Moon. Our mantle convection models show that dense TMM blobs with a size of tens of kilometres after the impact can later sink and accumulate into LLVP-like thermochemical piles atop Earth’s core and survive to the present day. The LLVPs may, thus, be a natural consequence of the Moon-forming giant impact. Because giant impacts are common at the end stages of planet accretion, similar mantle heterogeneities caused by impacts may also exist in the interiors of other planetary bodies.