bluuebunny/crossref_metadata_2025 huggingface dataset:
European Forest Type Map
Authors: Giannetti Francesca , Zorzi Ilaria , Linser Stefanie , Neumann Mathias , Cheval Sorin , Collalti Alessio , Vangi Elia , Grieco Elisa , Travaglini Davide , Chirici Gherardo , Barbati Anna
Published: March 2024

Forest types are key factors to consider when monitoring forests, particularly in consideration of  the increasing need to assess how climate change is affecting different forests in Europe and beyond. A comprehensive classification system is indeed essential for understanding the diverse forest ecosystems, tracking their changes over time and across various spatial and geographical scales. Moreover, it provides valuable insights on the baseline conditions and current states of forest ecosystems, aiding in decision-making for conservation and resource management. A "forest type classification scheme" aims to break down extensive forested areas, like stocked forest land, into smaller, more similar units. This breakdown helps streamline the analysis, interpretation, and communication of forest-related data. In Europe, the European Forest Types (EFT) classification system has demonstrated its effectiveness and user-friendliness in facilitating the comprehension, interpretation, and dissemination of data regarding indicators that depict the conditions and changes within European forests, as well as forest management practices. The EFT, could support a standardised reporting of several forest area related indicators. This includes assessments of biodiversity, organised into ecologically similar groups across the entire European region. However, until now, there was no EFTs map available for Europe.  To produce the map, a comprehensive analysis of relevant spatial datasets available at the European scale, essential for mapping, was first carried out.  Based on the variety of the datasets available, the JRC dataset featuring a comprehensive 39 forest tree species "relative probability of presence (RPP) maps”, was used along with eight different forest masks developed to identify environmental diversity, to accurately identify the different EFT categories. The RPP maps and the forest masks were used as inputs in a rule-based expert system algorithm to identify the 14 EFT categories and provide a thorough explanation for the classification of the EFT categories. The raster map created at a scale of 100 metres enabled the production of the first consistent EFTs maps across Europe and marked a significant advancement, providing a systematic means of classifying forest areas into EFTs, filling a critical gap in the spatial monitoring and reporting of forest indicators in the context of international frameworks. Moreover, existing EFTs maps can effectively be used as a basis for forest monitoring and support for decision-making, including forest-based adaptation and mitigation needs.This study was funded by the Horizon Europe Project OptFor-EU (Grant agreement n°101060554).
Investigating effects of different vegetation layers on soil erosion with a portable rainfall simulator
Authors: Seitz Steffen , Gall Corinna , Riveras-Muñoz Nicolás , Song Zhengshan , Scholten Thomas
Published: March 2024

Small-scale field rainfall simulators provide scientists with a tool to investigate complex interconnections between landcover and soil erosion experimentally. In particular, specific effects of vegetation such as plant structure or traits on sediment translocation are of key interest in erosion studies. A main feature of portable rainfall simulators is the formation of repeatable precipitation patterns with a kinetic energy corresponding to natural rainfall events at different locations in the field. Despite not measuring the whole process chain of water erosion, they assist to shed light on individual influences on sediment transport with an enhanced number of replications and thus adding to field measurements under natural rainfall.In this context, the Tübingen Rainfall Simulator (TRS, single-nozzle,
Adaptations of symbiotic nitrogen fixation minimize its contribution to ecosystem nitrogen cycles
Authors: Sheffer Efrat
Published: March 2024

Plant symbiosis with dinitrogen-fixing bacteria is a plant trait that affects plant fitness directly. Indirectly, symbiotic N-fixation influences the ecosystem nitrogen cycle. However, little is known about the ecology of symbiotic nitrogen fixation and specifically its feedback with the addition and recycling of soil nitrogen. Our studies examined how the conditions that influence plant performance also influence its regulation of symbiotic nitrogen fixation at the level of individual plants, and how these two, in turn, determine whether new nitrogen enters the soil, or other components of the ecosystem.Our findings indicate that a diversity of nitrogen fixation strategies have been adopted by ephemeral herbaceous legumes, while perennial drought-adapted legumes, which have to survive through a dry rainless summer, always downregulated their investment in fixation when provided with external nitrogen source (facultative strategy).  We found that stress conditions (such as plant-plant competition) also invoked strong downregulation of nitrogen fixation in response to nitrogen availability in the soil. Downregulation of symbiotic nitrogen fixation was stronger in juveniles compared to mature individuals, and in woody perennials compared to herbaceous annuals. These results highlight that regulation of N-fixation is influenced both by plant N-demand and by a tradeoff between N-fixation and other carbon-demanding processes.At the level of the ecosystem nitrogen cycle we found that, contrary to expectations, there is no added nitrogen in the surrounding of our studied N-fixing shrubs. Instead, we show that fixed nitrogen is allocated to different tissues within the plant and is lost and decomposed indirectly, primarily via grazing and fruit predation.We conclude that regulation of nitrogen fixation and nitrogen conservation, are key adaptations influencing the fitness and persistence of nitrogen-fixing plants in the community, with broader consequences on existing perceptions on how N-fixation influences the ecosystem nitrogen cycle.
Complementary approaches to characterize the jet stream dynamics in summer and link them to extreme weather in Europe
Authors: Banderier Hugo , Tuel Alexandre , Woollings Tim , Romppainen-Martius Olivia
Published: March 2024

Recent studies have highlighted the link between upper-level jet dynamics, especially the persistence of certain configurations, and extreme summer weather in Europe. The weaker and more variable nature of the jets in summer makes it difficult to apply the tools developed to study them in winter, at least not without modifications. Here, in order to further investigate this link, we present two complementary approaches to characterize the jet dynamics in summer in the North Atlantic sector.First, we apply a jet axis detection and tracking algorithm to ERA5 reanalysis data to extract individual jets and classify them in the canonical categories of polar and subtropical jets. Then, we compute a wide range of jet indices on each jet to provide easily interpretable scalar time series representing upper-tropospheric dynamics.Second, we apply the self-organizing map (SOM) clustering algorithm to the same data to create a distance-preserving, discrete, 2D phase space. The dynamics can then be described by the time series of visited SOM nodes, in which a long stay in a given node relates to a persistent state and a rapid transition between nodes that are far apart relates to a sudden dramatic shift in the configuration of upper-level flow.We first compare these two approaches to each other to assess their consistency, and then use them to relate the jet dynamics to a known driver of variability, Rossby wave breaking. Finally, we present preliminary results linking persistent jet dynamics to extreme heat events in Europe.
Quantifying the contribution of forcing and three prominent modes of variability to historical climate
Authors: Schurer Andrew , Hegerl Gabriele , Goosse Hugues , Bollasina Massimo , England Matthew , Mineter Michael , Smith Doug , Tett Simon
Published: March 2024

Climate models can produce accurate representations of the most important modes of climate variability, but they cannot be expected to follow their observed time evolution. This makes direct comparison of simulated and observed variability difficult, and creates uncertainty in estimates of forced change. Here we discuss the use of a particle filter data-assimilation technique in a global climate model, that sub-selects members among an ensemble of simulations, to follow the observed Northern Atlantic Oscillation, El Niño Southern Oscillation and Southern Annular Mode, without the use of nudging terms. We investigate the role of these three modes of climate variability, as pacemakers of climate variability since 1781, evaluating where their evolution masks or enhances forced climate trends. Since the climate model also contains external forcings, these simulations, in combination with model experiments with identical forcing but no assimilation, can be used to compare the forced response to the effect of the three modes assimilated and evaluate the extent to which these are confounded with the forced response. The assimilated model is significantly closer than the “forcing only” simulations to annual temperature and precipitation observations over many regions, in particular the tropics, the North Atlantic and Europe. We will show that the NAO variability leads to large multi-decadal trends in temperature, and sea-ice concentration, and that constraining the El Niño–Southern Oscillation reconciles simulated global cooling with that observed after volcanic eruptions.
Soil organic carbon change after 28 years of fertilisation in temperate conditions of Estonia
Authors: Kauer Karin , Astover Alar
Published: March 2024

Substantial progress has been made in estimating and mapping soil organic carbon stocks, but the quantification of carbon stock change rates still needs exploration in numerous soil and management combinations. In this research, the soil organic carbon (SOC) changes and soil organic matter (SOM) composition in the long-term experiment (established in 1989, Tartu, Estonia) with sandy loam soil were studied. The experiment involves three-field crop rotation (potato-spring wheat-spring barley) with two fertilization regimes: (1) mineral fertilisation (N rates 0, 40, 80, 120 and 160 kg ha-1) and (2) same mineral fertilisation treatments with farmyard manure amendment. During 1989–2017, every spring the soil samples were taken from the 0-20 cm soil layer, and SOC concentration was measured by dry combustion. In 2017, the size fractionation of soil samples was also performed. In 2022, the soil samples were also taken from the area surrounding the experimental site, which has not been cultivated since the experiment was established and has been as permanent grassland (GR). Soil mineral-associated organic matter (MAOM fraction;
Magmatic nanogranitoids in the Late Cretacous zircon from Slavonian Mts. (Croatia)
Authors: Schneider Petra , Balen Dražen
Published: March 2024

Micro-Raman spectroscopy was used to determine the inclusions in early-crystallised magmatic zircon from the Late Cretaceous (~82 Ma on zircon) acidic igneous rocks in the Slavonian Mts. (Mt. Papuk and Mt. Požeška Gora), located in the southwestern part of the Pannonian Basin (Croatia). The host rocks (granite and rhyolite) are predominantly peraluminous and alkali to calcic-alkali and were formed from high-temperature (up to 950 °C), ferroan and oxidised, dry A2-type of magma.The mineral inclusions detected in the zircon from granite and rhyolites are anatase, apatite, hematite, ilmenite and possibly magnetite. Although anatase is generally considered to form in low-temperature hydrothermal environments and is regarded as metastable, experimental studies in the field of materials science have shown that anatase, compared to rutile, is being stabilised in the systems under a high cooling rate.Numerous multiphase solid inclusions contain various polymorphs of feldspars (albite, K-feldspar, kokchetavite and kumdykolite) and SiO2 (quartz or cristobalite), hematite and phyllosilicates (kaolinite and muscovite). Such mineral association confirms the existence of an early granitic melt; therefore, this type of inclusion can be regarded as melt inclusions. Melt inclusions with such composition represent nanogranitoids, commonly found in peritectic garnets from high grade metamorphic rocks. Compared to the nanogranitoids of anatectic origin previously reported in partially melted rocks, here they represent primary inclusions of parental magma, i.e. magmatic nanogranitoids, that were protected from later equilibration with the melt or alteration by fluids. Furthermore, here we present the first finding of kokchetavite and kumdykolite in a magmatic zircon. This finding is a strong evidence that kumdykolite and kokchetavite do not require ultra-high pressure (UHP) to form and therefore should not be considered as exclusively UHP phases. Instead, together with anatase, these polymorphs are likely evidence of rapid uplift and consequent rapid cooling of hot oxidised magma generated in the deep (lower) crustal level. The rapid uplift was most likely aided by the weak zones in the continental crust, such as deep faults in a local back-arc extensional (half-)graben in the course of the Late Cretaceous regional geological event associated with the closure of the Neotethys Ocean in the area of the present-day Slavonian Mts.
Benchmarking model performance in complex human-water systems.
Authors: Salwey Saskia , Pianosi Francesca , Coxon Gemma , Bloomfield Hannah
Published: March 2024

Human activities must now be considered as an integral part of the water cycle. Consequently, the integration of human-water interactions into hydrological modelling is essential for the large-scale simulation of flow. However, whilst the last decade has seen substantial advancements in the guidance available for modelers on how best to benchmark and evaluate flow simulations in natural catchments, there is little discussion surrounding how these practices may differ in more complex, human-impacted catchments.Here we discuss some of the key issues in benchmarking model performance in human-impacted catchments and demonstrate these using a large-sample of reservoir-impacted catchments across Great Britain. We find that evaluation metrics designed for natural systems do not always translate to those impacted by human activity, where reservoir-impacted flow timeseries can have a substantially different distribution. In light of the new parameters and model assumptions associated with representing human activities within the natural water cycle, we suggest that the integration of uncertainty quantification and sensitivity analysis (UQ and SA) for robust model evaluation is particularly important. We discuss the need for clear accessible workflows for the application of UQ and SA in the evaluation of complex and large-scale water resource system modelling.
Beavers and flood alleviation: Human perspectives from downstream communities
Authors: Auster Roger , Barr Stewart , Brazier Richard
Published: March 2024

The activities of an animal – beavers - are increasingly recognised as a nature-based solution to hydrological extremes; dams and wetlands that beavers create attenuate flows downstream whilst delivering multiple benefits for the environment and for people. There can however also be challenges for people living alongside beavers. Q-Methodology is a technique for eliciting an understanding of human perspectives that exist within a context, enabling a rich understanding of human subjectivity within a context. We used Q-Methodology to elicit an understanding of perspectives that exist about beavers and their role in natural flood management among communities living downstream of three beaver sites in England, where Eurasian beavers (Castor fiber) are currently being reintroduced. Diverse perspectives that exhibited a range of value judgements were identified, including favourable viewpoints which valued multiple benefits beaver activities can provide, as well as less favourable viewpoints with some perceiving a reliance on beaver-led natural flood management to be less predictable and of higher risk than relying upon human-led interventions. In response to our findings, we support a catchment-based approach to beaver management so as to incorporate contextual perspectives in decision-making, and to enable dissemination of knowledge about beaver behaviours within communities. Further, we encourage future research into whether Beaver-Dam Analogues (in-stream structures that mimic beaver dams or their function) could be used as ‘starter dams’ to encourage beaver activities in optimal locations, as this may inspire confidence in beaver-led flood defence by working with the animal to develop a 'right dam in the right place' strategy.
Investigating the Potential for Using Real-Time Neutron Monitor Data as a Proxy for Estimating the Impact of Ground-Level Enhancements on Radiation Doses at Aviation Altitudes
Authors: Larsen Nicholas , Mishev Alexander
Published: March 2024

Solar eruptions can accelerate solar energetic particles (SEPs) to high energies which can, if they have sufficient energy, penetrate the Earth’s magnetic environment leading to numerous space weather hazards that can affect infrastructure and human health. Strong SEP events can be detected by ground-based neutron monitors (NMs) and registered at the Earth’s surface as ground-level enhancements (GLEs) if several NMs detect a significant increase in cosmic-ray count rates caused by arriving SEPs. The increase in the flux of high-energy particles entering the atmosphere during GLEs enhances the complex radiation environment at high altitudes which can pose a serious risk to airplane crew and passengers. As such there is a strong desire to develop nowcasting models that can quickly estimate the impact of GLEs on human health to help mitigate the threat GLEs pose. One avenue of approaching this issue is the development and application of proxies that allow for quick conservative estimates of the hazards. In this work, 21 of the 73 currently recorded GLEs have been analysed using the same verified method revealing the SEP characteristics during the events. These characteristics are used as inputs into a newly developed CRAC:DOMO radiation model to compute the radiation dose experienced at aviation altitudes. A comparison was then done with the real-time NM data during the GLE events to establish a relationship between the modelled dose and empirical NM data through a large statistical analysis. This was successful, with a very strong relationship being shown between the two variables. This result provides scientific support for using real-time NM data as a potential proxy in future nowcasting models aimed at estimating and mitigating the impacts of GLEs on humans and the aviation industry.
Agricultural Ditches are Hotspots of Greenhouse Gas Emissions Controlled by Nutrient Input
Authors: Wu Wenxin , Niu Xueqi , Li Si-liang , Yan Zhifeng
Published: March 2024

Agricultural ditches are pervasive in agricultural areas and are potential greenhouse gas (GHG) hotspots, since they directly receive abundant nutrients from neighboring farmlands. However, few studies measure GHG concentrations or fluxes in this particular waterbody, likely resulting in underestimations of GHG emissions from agricultural regions. Here we conducted a one-year field study to investigate the GHG concentrations and fluxes from typical agricultural ditch systems, which include main ditches (MD), branch ditches (BD), collector ditches (CD), and field ditches (FD), in an irrigation district located in the North China Plain. The results showed that almost all the ditches were large GHG sources. The mean fluxes were 333 μmol m-2 h-1 for CH4, 7.1 mmol m-2 h-1 for CO2, and 2.4 μmol m-2 h-1 for N2O, which were approximately 12, 5, and 2 times higher, respectively, than that in the river connecting to the ditch systems. Nutrient input was the primary driver stimulating GHG production and emissions, resulting in GHG concentrations and fluxes increasing from the river to MDs, BDs, and then CDs as the ditch systems approached farmlands and potentially received more nutrients. Despite FDs being directly connected to farmlands, their GHG concentrations and fluxes were lower due to seasonal drying and occasional drainage. The ditches covered approximately 3.3% of the 312 km2 farmland area in the study district and the total GHG emission from the ditches in this area was estimated to be 26.6 Gg CO2-eq yr-1, with 17.5 Gg CO2, 0.27 Gg CH4, and 0.006 Gg N2O emitted annually. Overall, this study demonstrated that agricultural ditches were hotspots of GHG emissions, and future GHG estimations should incorporate this ubiquitous but underrepresented waterbody.  
Effect of pore structure and CO2-oil-rock interactions on sweep efficiency of CO2 EOR in tight sandstone reservoirs
Authors: Cheng Yuting , Qu Yiqian , Cheng Xin
Published: March 2024

CO2-oil-rock interactions and complex pore structure affect the sweep efficiency (ES) and wettability, thus having a significant impact on CO2 enhanced oil recovery in tight oil reservoirs. In this study, we selected 10 rock plugs from the Yanchang Formation, Ordos Basin in China. First, casting thin sections and mercury intrusion capillary pressure were performed to investigate the microscopic pore structure characteristics of the tight rock samples. The results show that pore structure can be divided into three types (RT-I, RT-II, and RT-III) from good to poor qualities. On this basis, CO2 floodings using the Nuclear Magnetic Resonance technique were performed to investigate the influence of pore structure on the ES in large (PL) and small (PS) pore throat intervals. With the increase of displacement pressure, the oil recovery of RT-I, RT-II and RT-III are about 70.9%, 67.8% and 10.16%, respectively. The ES of PL of all samples are similar, while the ES of PS decrease subsequently for the three types. Pressure, mineral composition and the complex pore structure are attribute to the differences. On one hand, higher displacement pressure leads to lower interfacial tension and viscosity, resulting in higher oil recovery. On the other hand, CO2 is more likely to vaporize the light oil components, resulting in the asphaltene precipitation. Quartz with a smooth surface is not easy to precipitate, while most clay minerals are easier to absorb asphaltene and are likely to alter the wettability of pore surfaces. Thus, in comparison to RT-III, the ES of RT-I with a higher quartz content is higher in PS. In addition, the worse the relationship between pore structure configurations, the greater the capillary pressure, causing the different ES between RT-I and RT-II. The findings in this study shed a light on the understanding of complex mechanisms for CO2 EOR in tight oil reservoirs. 
Fluid-mineral interactions of apatite minerals — an indication of paleo-environment changes
Authors: Gong Mo , Wang Yu
Published: March 2024

There are few direct quantitative records of past climate (e.g., temperature, precipitation), so we make use of proxy—a physical, chemical, and/or biological entity that responds to climate—to indicate paleo-environment and paleo-climate. Geochemical data (such as elemental and stable isotope ratios) stored in minerals to infer environmental changes that associated with fluid activity can be used by modern techniques. Apatite is an ideal mineral for dating fluid–rock interaction and the cessation of fluid influence, because it is highly susceptible to fluid containing Ca, SO3, Na, Cl, P2O5, and PO3, causing changes of crystal chemistry and structures. Fractures in apatite can also promote fluid–mineral interaction and replacement of elements.
The Liupanshan Basin is a Mesozoic-Cenozoic faulted sedimentary basin that located at the northeastern part of the Tibetan Plateau. Many paleoclimate studies have been carried out on the northeastern margin of the Tibetan Plateau through sedimentology, like pollen, grain size, chroma, and geochemistry such as carbon and oxygens isotopes, and other indicators to discuss the environmental variation history and its driving mechanism. Thermochronological studies have also been performed to limit the uplift and exhumation history, and the AFT ages data show a wide and mixed span, from 168.7 Ma to 7.3 Ma. It is not ruled out that the change of apatite element composition caused by fluid-mineral interaction may affect the AFT ages, hence, the physical and chemical characteristics of apatite collected from the Liupanshan Basin were studied through CL imagine, BSE imaging, and EMPA compositional analysis. Under the microscope, the alteration of minerals such as feldspar and plagioclase and the filling of carbonate veins can be clearly observed, indicating fluid-rock interaction. The apatite particles from the Cretaceous strata are mostly subhedral-anhedral, with developed fractures, and the phenomena of regeneration, transformation and re-transformation can be observed. The preliminary EBSD analysis results show that the content of F element in apatite subjected to fluid and later alteration increases, and the content of Cl element is relatively low. The SO3, Na, and PO3 significantly increased for the new growth apatite and fluid-mineral interacted apatite. Clearly, it shows that the apatite fission track ages (27~8 Ma) mark the new growth or interacted ages of the Cretaceous sedimentation, also show that this area is with the acidic fluid basin, corresponding to the uplift of the Tibetan Plateau and global climate change.
Characteristics and predictive significance of spatio-temporal space images of M ≥ 4.0 seismic gaps on the southeastern margin of the Tibetan Plateau
Authors: Su Youjin , Zhao Xiaoyan
Published: March 2024

 In the present study, seismic gaps are identified as periods with no occurrence of M ≥ 4.0 earthquake over dT ≥ 400 days. After examining all records in the Sichuan-Yunnan-Tibet-Qinghai junction area on the southeastern margin of the Tibetan Plateau in 1970−2022, a total of six M ≥ 4.0 seismic gaps were identified. Spatio-temporal images of the seismic gaps had similar characteristics and demonstrated spatial overlapping and statistical significance. The quiet periods of the six seismic gaps included 419−777 days (approximately 580 days on average). The semi-major-axis and semi-minor-axis lengths were in the 880−1050 km (approximately 987 km on average) and 500−570 km (about 533 km on average) ranges, respectively. Case analysis results revealed that the images of M ≥ 4.0 seismic gaps were of high significance in predicting M ≥ 6.7 strong earthquakes in the region, and they could be used as a predictive index on a time scale of about 1-0.5 year or less.
Paleocene surface exposure ages imply an early development of hyperaridity in the Atacama Desert
Authors: Ritter Benedikt , Binnie Steven A. , Stuart Finlay M. , Fabel Derek , Albert Richard , Wennrich Volker , Dunai Tibor J.
Published: March 2024

The (hyper-) arid climate of the Atacama Desert preserves traces of ancient landforms. Clusters of cosmogenic 21Ne exposure ages of pebbles from Early Miocene sediment surfaces indicate the preservation and continuous exposure (low to no erosive surface activity) since the Late Eocene, with distinct phases of low fluvial activity and deposition during the Neogene. A reduction of significant fluvial activity since ~10 Ma, and the complete absence since ~1-2 Ma, indicate extreme hyperarid conditions.  Single exposure histories of Paleocene age, with age clusters during the Eocene and Oligocene, demonstrate remarkable landscape stability throughout the Cenozoic. Phases of fluvial activity, i.e. the end of a fluvial period and the beginning of continuous exposure to cosmic rays, coincide closely with trends and aberrations in regional and global Cenozoic climate variability.
Plasma environment of Mercury’s magnetosphere as seen by BepiColombo during its third flyby
Authors: Hadid Lina ,   MSA, MIA and MEA / MPPE teams
Published: March 2024

On June 19th 2023, BepiColombo performed its third (MFB3) gravity assist maneuvers at Mercury. During this flyby, the spacecraft approaching the planet from dusk-nightside toward dawn-dayside and traveling down to close distances ~ 235 km altitudes above the planet’s surface. Even though BepiColombo is in a so-called “stacked configuration” during cruise (meaning that most of the instruments cannot be fully operated yet), a number of instruments can still make interesting observations. Particularly, despite their limited field-of-view, the particle sensors allow us to get a hint on the plasma composition and dynamics along a unique path across the magnetosphere and very close to the planet. In this presentation, we will show an overview of the plasma environment from the Mercury Ion Analyzer (MIA) and the Mercury Electron Analyzer (MEA); moreover we will present the first ion composition observations of the Mass Spectrum Analyzer (MSA). MIA, MSA and MEA are part of the Mercury Plasma Particle Experiment (MPPE, PI: Y. Saito) consortium that is a comprehensive instrumental suite for plasma, high-energy particle and energetic neutral atom measurements onboard Mio (Saito et al. 2021). During this flyby, MSA and MIA revealed the presence of energetic (> 10 keV) and cold (< 100 eV) heavy ions inside the magnetosphere around closest approach. Moreover, we will show major features of the Mercury magnetosphere highlighting different regions: 1) plasma sheet, 2) nightside bounday-layer and 3) magnetosheath [Hadid et al., Nature Communications, under review].
A stable cadmium isotope perspective on organic carbon burial trends during the Palaeocene-Eocene Thermal Maximum
Authors: Elms Hannah , Dickson Alexander
Published: March 2024

Biogeochemical models, such as COPSE and cGENIE, have been used to predict the carbon cycle response to emissions into the atmosphere under various forcing scenarios. However, there is still significant uncertainty over model predictions of the magnitude of organic carbon burial into ocean sediments. This limits our understanding of C cycle feedbacks during periods considered to be potentially analogous to current anthropogenic induced climate change.Stable cadmium isotopes (ẟ114Cd) have potential as a palaeoproxy for organic carbon burial in marine settings, due to the fractionation of Cd during burial in association with organic carbon. Therefore, the generation and evaluation of ẟ114Cd records in organic-rich shale sections encompassing periods of climatic and/or environmental change in the geological past is likely to be a useful tool in tracking and quantifying organic carbon burial trends during such events.Here we present stable cadmium isotope records from four sections of organic-rich shales covering the Palaeocene-Eocene Thermal Maximum (PETM) occurring around 55.9 Ma, which is both the most recent and most analogous interval of rapid climate fluctuations in the geological record to modern-day climate change. We evaluate these records in terms of their organic carbon burial signals (and so carbon removal from the Earth system) during the lead-up to, onset, peak and recovery of the PETM event, as an initial assessment of the ability of stable cadmium isotopes to trace this process. Better quantification of organic carbon burial will enable the responses of the Earth System to rapid climate change to be better understood. 
The quantitative attribution of climate change to runoff increase over the Tibetan Plateau
Authors: Wang Yunfei , Ye Aizhong
Published: March 2024

Runoff from the Tibetan Plateau (TP), known as the Asian water tower, is crucial to regional hydrological processes and the availability of water for large population living downstream. Climate change, especially marked atmospheric warming and altered precipitation patterns, have significantly affected the cryospheric hydrological process in the TP, particularly runoff. However, it is still unclear to what extent precipitation and temperature contribute to runoff change on the TP and the regional variability is not well understood. In this study, a large-scale, high-resolution, and well-calibrated distributed hydrological model was employed to simulate the long-term runoff of the TP over the past six decades (1961-2019). Then, spatiotemporal characteristics of runoff were analyzed. Furthermore, the impacts of precipitation and temperature on runoff variation were quantitatively estimated. The results found that the annual runoff decreased from southeast to northwest, and has been increasing over the past six decades. Notably, precipitation is a more important contributor than temperature across the plateau, contributing 72.08 % and 27.92 % to the runoff change, respectively. Besides, the influence of precipitation and temperature on runoff varies among basins, with the Daduhe Basin and the Inner Basin being the most and least influenced by precipitation, respectively. This research analyses historical runoff changes and provides insights into the contributions of climate change to runoff on the TP, which helps understand the hydrological response to climate change in mountain regions.
Early Results of Ozone Production Rate Estimates Using Satellite Observations: Insights From Numerous NASA Atmospheric Composition Campaigns
Authors: Souri Amir , González Abad Gonzalo , Wolfe Glenn , Johnson Matthew , Duncan Bryan , Verhoelst Tijl
Published: March 2024

Questions about how regulations have shaped ozone pollution regionally cannot be answered by studying observed surface ozone concentrations alone, as we must precisely determine ozone production rates, which refer to the amount of ozone molecules photochemically produced in the atmosphere. Through an extensive suite of NASA's airborne campaigns such as DISCOVER-AQs, KORUS-AQ, INTEX-B, SENEX, and ATOMs, constraining a well-characterized chemical box model, we establish a simple but robust relationship between ozone production rates and various observable parameters; some of these factors, fortunately, are being measured or constrained by satellite observations, which has allowed us to create the first-ever maps of ozone production rates across the globe. We quantitatively and qualitatively assess this product's efficacy through independent airborne campaigns and by contrasting extreme events to a norm. We have a clear path forward to enhance this innovative product using agile machine learning algorithms for the years from 2005 to 2024, along with its well-characterized error budget.
Theory and modelling of the effects of grain sorting, compaction & cementation on porosity and permeability
Authors: Luo Miao , Glover Paul , Lorinczi Piroska
Published: March 2024

Just how much do sorting, cementation and compaction control the porosity and permeability of rocks? In this work we start with making extremely accurate porosity and permeability measurements on binary grain mixtures, arriving at good agreement between them and theoretical results. These seemingly simple experiments are difficult to carry out with the degree of precision needed to test the models. We have developed a methodology allowing porosity and permeability to be measured to within ± 4.415% and ± 4.989% (at a flow rate of 5.13 cm3/s) of each value, respectively. The newly developed theoretical framework includes both the interstitiation mixing process and several replacement processes.A major result of this work is that the theoretical models describing these two processes are independent of grain size and grain shape. The latter of these two findings infers that the models developed in this work are applicable to any shape of grain or type of packing, providing that a representative porosity of each size of grain pack is known independently, either experimentally or theoretically. Experimental validation has shown that the newly developed relationships for porosity described measurements of porosity for near-ideal binary mixtures extremely well, confirming that porosity is always reduced by binary mixing, and that the degree of reduction depends upon the size of the ratio between the two grain sizes.  Calculation of permeability from the packing model has also been carried out. Six different permeability estimation methods have been used. It was found that the most accurate representations of the experimental permeability were obtained (1) when the exact RGPZ method was used with the porosity mixing models developed in this work, and (2) when the exact RGPZ method was used with the weighted geometric mean to calculate a representative grain size. For mixtures where there is a large difference in grain sizes, permeability (k) varies little for the ranges of mixtures from 28% to 100% of small grains (about 4*k), only increasing significantly as the fraction of small grains falls below 28% to zero (to 2 orders of magnitude in k) because the small grains then only partially occupy the space between the large grains. For mixtures of grains of similar sizes, the situation is remarkably different. The variation in permeability for small grain fractions between 100% and about 28% is much amplified (2 orders of magnitude in k), while the increase in permeability as the fraction of small grains falls from about 28% to zero is similar to the other case, and perhaps slightly less pronounced (about 1.5 orders of magnitude in k). This counterintuitive behaviour is important for the interpretation of how sorting affects permeability, implying a greater spread of permeabilities for rock composed of grains with a small difference in grain size.
Turbulent heat exchange between Circumpolar Deep Water and Winter Water on the Amundsen Sea Continental Shelf, Antarctica 
Authors: Wang Xingchi , Firing Yvonne , Naveira Garabato Alberto , Fernández Castro Bieito , Spingys Carl
Published: March 2024

The intrusion of Circumpolar Deep Water (CDW) onto the Amundsen Sea continental shelf is a primary driver of basal melting and thinning of the West Antarctic ice shelves. The interaction between CDW and the overlying, near-freezing Winter Water (WW) on the continental shelf is thought to limit the heat that ultimately reaches the ice shelves. However, such interaction, and the processes underpinning it, remain little understood. In this study, we analyze over one hundred microstructure and finestructure profiles across the Amundsen Sea continental shelf. Our analysis indicates a strong correlation between microstructure turbulent kinetic energy dissipation and the finescale horizontal kinetic energy (HKE) associated with internal waves, suggesting that wave breaking is key to turbulence production in the region. Exploiting this relationship, we construct a 2-year time series of finescale HKE and turbulent dissipation from a mooring dataset acquired at the Pine Island-Thwaites West (PITW) trough. The time series reveals a distinct seasonal signal, with a range spanning one order of magnitude and diverse drivers. By combining a regional numerical model with the mooring diagnostics, we then estimate the turbulent diapycnal diffusivity and associated vertical heat flux between CDW and WW at the PITW trough. This provides insight into the heat loss experienced by CDW on its pathway toward the ice shelves.
Ambient noise tomography of Popocatépetl volcano, México
Authors: Esquivel-Mendiola Leonarda I. , Calò Marco , Iglesias Arturo , Tago Josué , Macías José Luis
Published: March 2024

Popocatépetl volcano is among Mexico’s most risky due to its proximity to populated areas. Since its reactivation in 1994, several geophysical studies have been performed to understand the eruptive history, volcanic activity, and associated hazards. Although several seismic studies were carried out using permanent and temporal seismic network records, the internal structure of Popocatépetl volcano is still unclear.In this work, we propose the first 3D velocity model of Popocatépetl volcano, describing the whole edifice inverting group velocity dispersion curves. We used data recorded at 39 broadband seismic stations installed in different epochs. We computed ambient noise cross-correlations, which were computed using two methods to increase the information for the modeling. Our results suggest the presence of a mushroom-shaped Popocatépetl’s system composed of two high shear wave velocity regions, the first one located at 5-0 km a.s.l., the second one located at 4-7 km b.s.l., and a narrow ‘pipe-like’ conduit connects both. The shallow high velocities are related to old and young volcanic structures due to mixed magmatic materials, which are affected by an intense degassing process that increases the magma viscosity and crystal content. The deepest reservoir is interpreted as a magmatic body that is confined due to the lithostatic pressure. The intermediate region is considered a narrow pipe conduit, where there is a low-velocity layer at the same depth. Moreover, our model reveals evidence of buried volcanic paleo-structures and the remains of ancient collapses generated by previous eruptions.
Temporal and spatial investigations of the isotope biogeochemistry of a coastal peatland area under sporadic flooding 
Authors: Saban Rhodelyn , Jenner Anna-Kathrina , Ehlert von Ahn Catia Milene , Schmiedinger Iris , Böttcher Michael
Published: March 2024

The interface between the terrestrial and marine environments regulates the interactions between the adjoining domains. Natural and anthropogenic alterations influence the processes and exchanges of materials. This study aims to determine the biogeochemical processes before and after anthropogenic changes in the coastal protection at the southern Baltic Sea coast proximal to a peatland (Hütelmoor, Rostock, Germany). Spatial and temporal investigations, with the use of stationary porewater lances, characterize the dynamics of biogeochemical transformation processes. Porewaters were measured for in-situ physico-chemical parameters and analyzed for dissolved organic and inorganic carbon (DOC and DIC), major ions, redox-sensitive elements and nutrients concentrations. Stable isotopes (ẟ13C-DIC and -DOC, ẟ2H- and ẟ18O-H2O, and ẟ34S- and ẟ18O-SO4, and ẟ34S-H2S) and non-stable isotopes (223Ra, 224Ra) were also measured. Results indicate high concentrations of DOC which may have originated from peat degradation and high concentrations of DIC, which may have been derived from organic matter mineralization, terrestrial and marine carbonate dissolution, and Baltic Sea-derived DIC. Minor contributions from CH4 oxidation cannot be ruled out. Diagenetic transformations are also reflected in the vertical profiles of redox-sensitive ions (such as Fe, Mn, SO4 and H2S). Sulfate, dominantly from Baltic Sea water and microbial reduction-oxidation, influences diagenesis. Water is a mixture of different brackish and freshwater sources.  Moreover, submarine groundwater discharge (SGD) was observed from 150 cmbsf and also evident in 224Ra activities. With the changes in the coastal protection status, internal transport processes of porewaters in the sediment are evidently influenced by the hydrogeodynamics along the coastline on a local to regional scale.
Transport of Biodegradable Nanoplastics Affected by Weathering and Proteins in Unsaturated Porous Media
Authors: Yu Yingxue , Flury Markus
Published: March 2024

The increasing threat from plastic pollution has promoted the widespread application of biodegradable plastic. In agriculture, biodegradable plastic, mainly in the form of biodegradable plastic mulch, has received a lot of attention due to its in-situ degradability and satisfying agronomical performances. However, biodegradable plastic mulches do not degrade instantaneously but rather fragment into micro- and nanoplastics, and these micro- and nanoplastics could reside in soil or even migrate along soil profiles. Here, we investigated the mobility of pristine and weathered polybutylene adipate co-terephthalate (PBAT) nanoplastics in sand columns under unsaturated flow conditions. We further studied the effect of proteins on the mobility of PBAT nanoplastics with both negatively charged bovine serum albumin and positively charged lysozyme. We found that (1) the pristine and the weathered PBAT nanoplastics were mobile with or without the presence of proteins; (2) the positively charged lysozyme inhibited the transport of PBAT nanoplastics; and (3) lower water saturation inhibited the transport of PBAT nanoplastics via physical straining. These results suggest that biodegradable nanoplastics generated from biodegradable plastic mulches are mobile and may transport readily along soil profiles.
Assessing windstorm hazard emerging from multiple types of storms
Authors: Fathollahzadeh Attar Nasrin , Marra Francesco , Canale Antonio
Published: March 2024

In the context of global climate change, windstorms pose significant environmental, ecological, and socioeconomic challenges. Mountainous and forested regions of Europe, including the Veneto region in northern Italy, have been devastated by unprecedented events such as the storms in July 2023 and Vaia in October 2018, raising the question whether such events may occur more frequently in the future. The probability of observing such extremes in present-day climate can be quantified using cumulative distribution functions of annual maxima wind speeds, obtained from extreme value analysis methods. Once these are derived, however, is it near to impossible to project future changes in these distributions as extreme wind speeds are caused by storms driven by diverse synoptic conditions, the characteristics and occurrence frequency of which may change differently in response to climate change.This study introduces a method to derive cumulative distribution functions of annual maximum wind speeds explicitly considering the intensity and occurrence frequency of multiple types of storms. Independent windstorms are separated and their maximum hourly wind speed is isolated. Storms are then organized into types based on their local wind direction using a clustering technique. We then use a multi-type Simplified Metastatistical Extreme Value distribution (SMEV) to estimate the cumulative distribution function of annual maximum wind speed for the location of interest. The study focuses on mountainous areas, seeking a simpler relation between typical wind directions and synoptic conditions.A thorough leave-one-out evaluation with benchmark models, including the traditional Generalized Extreme Value distribution (GEV) and a single-type SMEV, is conducted on 22 mountain stations in the Veneto region (northern Italy). We show that, overall, the proposed multi-type method provides estimates of extreme return levels that are comparable with the ones of single-type SMEV and GEV. Our results demonstrate that it is possible to derive cumulative distribution functions of annual maximum wind speeds explicitly considering storms emerging from different marginal processes. This paves the way to the use of projections of large-scale atmospheric dynamics from climate models to improve our prediction of future extreme wind speeds. Keywords: Windstorm; Extreme events; Wind direction classification; Multiple types; Simplified Metastatistical Extreme Value (SMEV); Mountainous areas.