bluuebunny/crossref_metadata_2025 huggingface dataset:
Geologic exploration activities increase methane emissions from boreal peatlands.
Authors: Korsah Percy , Strack Maria , Davidson Scott , Xu Bin
Published: March 2024

In recent years the preservation and restoration of peatlands has been pushed to the forefront of climate change mitigation plans. Unfortunately, boreal peatlands in Canada are threatened by extensive industrial exploration and extraction of natural resources. Many of these anthropogenic disturbances include linear pathways for geologic exploration of petroleum and mineral resources, also known as seismic lines. Apart from reported changes in peatland micro-topography and the lack of tree re-establishment, seismic lines crossing peatlands impact ecohydrological conditions leading to alterations in carbon (C) cycling. However, few studies have quantified the extent of these changes, resulting in a lack of reporting of these impacts in estimates of anthropogenic greenhouse gas emissions. This study took place in northern Alberta (Canada), across wooded bogs and a wooded fen. The primary objective was to evaluate the impact of seismic lines on CH4 and CO2 fluxes in the field and under laboratory conditions. CH4 fluxes and the net ecosystem exchange of CO2 (NEE) was measured over two growing seasons from 48 paired plots across the bogs and fen using the closed chamber technique, while 144 incubation jars with replicate samples were deployed in the lab. Corresponding data on environmental variables including peat temperature, vegetation cover, biomass and water table depth were recorded as well. Seismic lines crossing peatlands significantly increased CH4 emissions, almost doubling in fens (176%) and tripling in bogs (261–308%) compared to their surrounding peatland areas. This was driven by warmer and wetter conditions on the line as well as a vegetation shift to more productive species. These results are essential for accurate greenhouse gas reporting as well as restoration planning and design.
Participatory science at school: The Black Carbon educational experiment
Authors: Delville Laurence , Léon Jean-François , Macouin Mélina , Raynal Estelle
Published: March 2024

Black carbon (BC), also known as soot, is a fine particulate matter consisting of carbon particles produced from incomplete combustion of carbon-based fuels. BC contributes significantly to the air quality degradation and has various environmental impacts. BC is a short-lived climate agent and contributes to global warming.Measuring BC using citizen science involves simple but precise methods to estimate its presence in the environment. The Black Carbon EDUcational program (BC-EDU) is an initiative supported by the Caliph'air project. Calisph’Air is an outreach activity of the Centre National d’Etudes Spatiales in the frame of the CALIPSO space research program. BC-EDU actively involves middle school teachers and students. The BC-EDU serves as an educational tool, raising students' awareness of pollution issues by studying soot particles in the ambient atmosphere.BC atmospheric concentrations are measured daily using a light absorption technique on air filters thanks to a small aethalometer specifically designed for the students (manufactured by Staneo). The total BC deposit on the air filters is finally analyzed using a thermo-optical method (Sunset OC/EC analyzer).We present the campaigns carried out with 8 middle schools in 2018 and new experimentations on indoor and outdoor BC concentrations in 2024 in France. We evaluate the students and teachers engagement in such a research-led initiative and the impact of crowd-based BC monitoring for understanding BC sources and transport in and around middle schools.
Assessment of different temporal clock-network solution strategies
Authors: Chatzinikos Miltiadis , Delva Pacôme
Published: March 2024

Optical clocks are now one of the most precise measurement devices. They reach systematic uncertainties of a few 10−18, which can be resolved after a mere few hours of measurement with optical lattice clocks based on trapped neutral atoms. This constant amelioration of their accuracy and stability permitted numerous applications in the field of metrology, fundamental physics and chronometric geodesy. Specifically, geodetic applications, like the determination of gravity potential differences over large distances, become feasible at the level of 0.1 m2 s−2. In this context, optical clocks are considered as a unique tool for monitoring and understanding the daily to annual evolution of corresponding geophysical phenomena including the spatial-temporal variations of the gravity potential field.
The aim of this paper is to analyze two different ground clock-network solution strategies and asses their impact on the estimation of the Earth’s temporal gravity field variations and their precisions. The first strategy consists of two steps. In the first step, the gravity potential differences derived from a number of ground optical clock-stations are processed independently for each session. In the second step, the gravity field variations are estimated independently for each clock-station considering the precision derived from each session solution. The second one is a one-step strategy, which estimates the gravity field variations of all clock-stations and their precisions simultaneously for all sessions. The ground clock-network solutions performed applying the least-squares adjustment procedure and different datum definition methods.
In order to assess the temporal gravity field variations derived from the two strategies, we developed a simulation study that exploits the monthly gravity field solutions of the GRACE FO mission and the session solutions of the European Permanent GNSS Network (coordinate time-series along with their covariances). In addition, we simulated and applied different noise models to the measurements of the clock-network considering or not the spatial correlations existed among the stations.
Periodic climatic variations during collisional orogenesis – insights from coupled tectonic-surface-process models
Authors: Wolf Sebastian G. , Braun Jean , Huismans Ritske S.
Published: March 2024

Mountain building through continent-continent collision is typically accommodated by crustal thickening and creates topography as a consequence of isostatic compensation. Precipitation-fueled erosion, in-turn, counteracts orogen growth and provides a feedback-loop between tectonics, surface processes, and climate. Climate on Earth varies on different timescales and with variable dominant periodicity. Orbital forcings, e.g. Milankovitch cycles, change climate with periods up to in the order of 1e5 years, while internal “tectonic” forcings change climate on longer timescales in the order of (several) Myrs. The feedback between tectonics and climate-fueled erosion raises the question: How do collisional mountain belts respond to climatic variations on Earth? Here, we use numerical coupled tectonic-surface processes models to explore the influence of periodic climatic variations on collisional mountain building on Earth, specifically focusing on the evolution of sediment flux and topography. Our results from the coupled numerical models are compared to and supported by a simple analytical solution. We find that climatic forcings with a short period have a small effect on orogen height (Gain G < 0.1), that is lagging by 1/4 phase, while the effect on the sediment flux is in phase and strong (G ≈ 1). These results are independent of orogen type and expected to be observable in orogens limited in height by crustal strength or erosional efficiency. Climatic forcings with a long period result in a low gain in sediment flux (G < 0.3), that is lagging by up to 1/4 phase. The effect on topography is in phase and with a high gain of up to G ≈ 1. However, the effects of long-period forcings are not well expressed in strength-limited orogens and can primarily by observed in erosion-limited orogens. Comparing our modelling results with typical tectonic and surface processes timescales of orogens on Earth shows that variations in erosional efficiency due to orbital forcings, i.e. Milankovitch cycles, are likely detectable in the sedimentary record, while it is challenging to disentangle the autogenic dynamics of mountain building and periodic long-term climatic forcings.
Modeling particle impacts on granular media for the analysis of aeolian saltation
Authors: Mahjoub-Bonnaire Provence , Bourrier Franck , Oger Luc , Chambon Guillaume
Published: March 2024

Grain transport by saltation is involved in numerous geophysical phenomena such as wind-blown sand, snow drift, aeolian soil erosion, dust emission, etc. Particle impacts on a granular bed trigger rebound and ejections processes, which can lead in certain conditions to a steady state of solid transport. The present work is dedicated to the analysis of the impact processes at the grain scale, with the objectives of inferring robust statistical laws and better understanding granular transport, accounting for the possible role played by adhesion between the grains.The study is based on numerical simulations with the DEM (Discrete Element Method). The numerical experiments consist in throwing a spherical particle on a granular packing with controlled velocity (Froude number between 0 and 200) and impact angle (between 10° and 90°). The contact model (friction, cohesion) between the grains is varied to represent different types of granular materials (e.g., dry sand, wet sand, snow).We investigated the influence of incident parameters on the impact process, focusing on the incident particle rebound and on the number and velocities of ejected particles. For non-cohesive granular beds, the simulations were compared to laboratory experiments of impacts of spherical particles on granular packings in order to validate the model . In particular, the restitution coefficient of the incident particles and the number of ejected particles were found in good agreement with experimental results. The simulations also give access to quantities that cannot be easily measured in the experiments. Hence, we could observe an anisotropy of ejected particles velocities for grazing impact angles, which is more pronounced when the incident velocity decreases. Preliminary results concerning cohesive granular beds will also be presented, considering contact laws representative of liquid (capillary) and solid cohesion processes. Effect of cohesion on the number of ejected particles, and energy dissipation processes within the cohesive granular beds, will be discussed.
Local influences of emission source characteristics and meteorological factors on nitrate and ammonium partitioning in Korea
Authors: Seo Jihoon , Kim Jin Young , Kim Kyung Hwan , Kim Jong Bum
Published: March 2024

Particulate air pollution in Korea is influenced by both local emissions and the transportation of particles and precursors in continental outflows. Alongside local high-NOx and NH3 conditions, the inorganic-rich and hygroscopic transported particles enhance the gas-particle partitioning of inorganic precursor gases (HNO3, NH3) into particulate nitrate and ammonium, synergistically resulting in heavy haze pollution. Local source characteristics can impact concentrations of precursor gases and particle acidity, which are crucial factors in inorganic gas-particle partitioning. However, the episodic or background effects of transported particles and precursors make it challenging to clearly identify the local influences of emission source characteristics on chemical composition and concentrations. In this study, we investigated local effects on the gas-particle partitioning into nitrate and ammonium using hourly data of PM2.5 chemical compositions, NH3 concentration, and meteorological variables from three different sites in Korea: a typical urban site in Seoul, an industrial site in Ansan, and a rural site affected by industrial sources in Seosan. To isolate the effect of local characteristics from the impact of long-range transport from China, backward trajectories and wind speed were additionally utilized. Partitioning ratios of total HNO3 (HNO3 gas + particulate nitrate) and total NH3 (NH3 gas + particulate ammonium) were analytically calculated by using particle acidity and liquid water contents from the ISORROPIA II thermodynamic model. Results show that the particle acidity from the three sites is not significantly different, despite a large difference in total HNO3 and total NH3 concentrations. However, high relative humidity and liquid water content at the coastal-industrial site, Ansan, can result in a larger nitrate fraction. Local characteristics of secondary inorganic aerosols depend not only on different local source characteristics but also on different local meteorological conditions, particularly relative humidity, which affects nitrate and ammonium partitioning.
Are the foraminiferal assemblages useful proxy for detecting methane emissions in shallow water environments? the case of Scoglio d’Africa (Tuscan Archipelago, Northern Tyrrhenian Sea) ?
Authors: Di Bella Letizia , Casalbore Daniele , Conte Aida Maria , Conti Alessia , Cornacchia Irene , D’Ambrosi Andrea , Gaglianone Giovanni , Ingrassia Michela , Spatola Daniele , Pierdomenico Martina , Provenzani Claudio , Ruspandini Tania , Chiocci Francesco Latino
Published: March 2024

In this research benthic foraminiferal response to shallow water methane (CH4) emissions located in the area around Scoglio d’Africa (Tuscan Archipelago, Northern Tyrrhenian Sea were used as proxy for the individuation of) was investigated. The site is located in the southernmost part of the Elba-Pianosa Ridge, a mainly submarine, north-south elongated morpho-structural high separating the Tuscany Shelf to the east from the Corsica Basin to the west. In the study area, submarine methane emissions have been studied since the 1960s and they are linked to the combined action of two processes: biogenic (microbial process called methanogenesis) and thermogenic origin. The aim of this study is to verify the use of foraminifera as a proxy for detecting the presence of methane emissions and elaborate a microfaunal pattern distribution to apply in recent, future and fossil record. Methane (CH4) is an important greenhouse gas, with a global warming potential about 20 times as large as carbon dioxide (CO2) on a 100-year horizon. In the marine environment, coastal areas represent methane hotspots highly exceeding emissions from the open ocean. In this view, Scoglio d’Africa provides a much-promising study site for multidisciplinary marine research like carbon capture and storage, geochemistry of hydrothermal fluids and ocean acidification vs. benthic and pelagic organisms. The microfaunal analyses were carried out from sediment samples coming from 11-16 m depth are shown. The samples were collected by grab and scuba during two sampling surveys in 2021 and 2022. The preliminary results of this research highlighted a very patch distribution and variability in density and biodiversity probably linked to the irregular distribution of the venting activity on the ground floor. The complexity of the interaction of the ecological factors characterizing extreme environments such as shallow hydrothermal vents did not allow us to carry out a real pattern of biota responses in situ. However, some significant considerations can be highlighted. Firstly, a strong loss of biodiversity and collapse in faunal density are recorded due to the combined effects by the CH4 emissions and the mud flow setting. Secondarily, the rare living specimens are represented by agglutinated species like Lepidodeuterammina ochracea and Ammodiscus sp., miliolid taxa like Quinqueloculina stelligera and Siphonaperta agglutinans, and among hyaline species, Rosalinids and H. depressula resulted the more resilient taxa. Moreover, the research provides new constrain on the ecological behaviour of some foraminiferal species in response to extreme conditions due to methane release.
Plant and macrofauna communities dynamics in constructed Technosols over 10 years of experimentation
Authors: Araujo José , Pando-Bahuon Anne , Lerch Thomas
Published: March 2024

Greater progress in the circular economy is expected to enable large cities to benefit more from ecosystem services. Reusing urban wastes can help reshape the urban environment and make the ecosystem more suitable for human use. Excavated material from building sites is one of the most abundant waste resources in megacities around the world, and some of this mineral waste can be used to create substrates, known as constructed Technosols, for the development of new green spaces. However, long-term studies are needed to determine the influence of the parent materials used in Technosol formulations on the community dynamics and trajectory of these new ecosystems. In this study, we assessed the impact of organic amendment on the evolution of constructed Technosols and the diversity of plant and soil macrofauna. A large-scale experiment was set up in 2013 in the suburban region of Paris, France, using excavated mineral materials with or without green waste compost (10%, v/v). Flora and macrofauna inventories were carried out over 10 years, as well as the physico-chemical properties of both Technosols. Plant biomass was consistently higher in the Technosols amended with compost, while plant diversity converged towards the same level. Soil macrofaunal diversity was negatively affected by the organic amendment initially, but after 10 years it was similar between the two soils and the neighboring soil used as reference. Macroorganisms abundance increased linearly during the first 4 years, especially for earthworms in Technosols with compost, but after 10 years it also decreased to a lower level compared to the neighboring reference soils. This study showed that Technosols constructed with mineral waste is a promising alternative to natural topsoils for green spaces. The addition of compost promoted plant growth throughout the experiment and had no impact on the diversity of plants and soil macrofauna in the long term.
An uncertain future for anthropogenic aerosols in Africa, and their climate and health impacts
Authors: Lund Marianne T. , Amooli Joe A. , Chowdhury Sourangsu , Johansen Ane N. , Samset Bjørn H. , Westervelt Daniel M.
Published: March 2024

We explore the wide spread in projections of African mid-century anthropogenic air pollution levels, and associated health impacts, resulting from the large diversity in available future emission pathways for the region.While emissions of aerosols and their precursors have declined in some regions, first in North America and Europe, more recently in China, many low- and middle-income countries, including much of Africa, are increasing their emissions and are projected to continue to do so with future industrialization, although the evolution depends in socioeconomic and technological factors. This is likely to drive changes in climate hazards as well as deterioration of air quality, increasing risks for under-resourced, vulnerable populations. The impacts of African aerosols on regional temperature, hydroclimate, and extreme events are, however, less well studied and quantified than for other historical emission hotspots. Moreover, very limited data availability and distinct regional characteristics of sources result in high uncertainties in estimates of African emissions. This uncertainty translates into future projections, which exhibit a striking spread in magnitudes and trends. For instance, available estimates for emissions of sulfur dioxide and black carbon in 2050 differ by up to 70% and 90% between the Shared Socioeconomic Pathways (SSPs) and scenarios developed for the UN Environmental Programme’s (UNEP) Integrated Assessment of Air Pollution and Climate Change in Africa.Here we explore implications of this spread for downstream modeled quantities of relevance for climate and health impact assessments. We use emissions from 10 different pathways as input to the chemical transport model OsloCTM3 and simulate the distribution of anthropogenic aerosols across the African continent in 2050. The associated impact on premature mortality is calculated. Preliminary results show surface PM2.5 concentrations differing by up to a factor 2 between the highest and lowest scenario when averaged over the African continents, with markedly higher local spread. Sub-continental differences are substantial, pointing to the need to consider Africa in more geographical detail than often done.
Exploring Environmental Impacts on High Frequency Radar Signal Variability in Taiwan's Northern Coastal Waters
Authors: Cheng An , Chang Huan Meng , Chien Hwa , Yu Hsin Yu
Published: March 2024

    This study focuses on the spatiotemporal analysis of High Frequency Radar (HFR) signal intensity under various environmental conditions, utilizing data from four LERA MKIII systems along the northern coast of Taiwan. This investigation spans from 2023 to 2024. The radar systems are strategically positioned at different locations: Shalun station operates at 24.4 MHz with a boresight angle of 0 degrees, Beigang station at 26.77 MHz with a boresight of 345 degrees, Chaojing station at 27.75 MHz with a boresight of 0 degrees, and Zhongjiao Bay station at 31.75 MHz with a boresight of 55 degrees. The coordinates for these stations are respectively 121.24°E, 25.11°N (Shalun); 121.16°E, 25.08°N (Beigang); 121.80°E, 25.14°N (Chaojing); and 121.63°E, 25.24°N (Zhongjiao Bay). Each HFR system consists of a linear array of 16 receiving antennas and utilizes the beamforming method to process signals within a boresight angle range of ±60 degrees.    This study's methodology employs time series analysis techniques to scrutinize High Frequency Radar (HFR) data, correlating it with various environmental observations. By charting the Signal-to-Noise Ratio (SNR) of the radar signals across different range cells along the radar's boresight azimuth over time, we identify temporal and spatial trends. Notably, periodic fluctuations in the radar signal time series have been observed. These fluctuations seem intricately linked to tidal cycles, exhibiting a significant correlation with the angular disparity between tidal flow direction and the radar's boresight azimuth. Additionally, a decrease in radar signal strength coupled with an increase in noise levels was noticed under conditions of elevated winds and waves. The research aims to precisely quantify the interplay between radar signals and the collective influence of tides, waves, and wind speeds. This thorough analysis seeks to deepen our understanding of how environmental elements impact radar performance, thereby contributing to a more nuanced comprehension of coastal ocean dynamics.
Fourier-transform infrared (FTIR) spectroscopy on archaeological sediments as a tool for selecting samples for ancient DNA
Authors: Vanghi Valentina , Slon Viviane
Published: March 2024

The retrieval of ancient DNA (aDNA) from archaeological sediments represents a promising alternative approach to sampling frequently scarce skeletal remains for palaeogenetic investigations (e.g., Slon et al 2017; Gelabert et al., 2021; Vernot et al., 2021). Yet, the source of the DNA fragments within substrates, and the factors that lead to their long-term preservation, remain poorly understood. As a result, the current practice of sample selection in the field tends to be mostly haphazard, leading to a wide variability in the success of aDNA recovery from archaeological sediments.
We set out to develop an innovative strategy to field sampling of sediments, aimed to improve the speed and efficiency of screening samples for aDNA analysis, while concurrently ensuring affordability and an easy interpretation of the results. Employing a semi-portable Fourier-transform infrared (FTIR) spectroscopic instrument, we conducted a comprehensive characterization of archaeological sediments. This facilitated the examination of bioapatite spectral features, that we used as a proxy for bone particles, from which we could test predictions regarding the presence or absence of aDNA fragments.
The efficacy of this methodology was validated using sediment samples from different archaeological sites within the southern Levant, characterized by distinct contextual attributes (e.g., environmental conditions, type of site, age, etc.) and varying degrees of aDNA preservation. Preliminary results suggest that our approach could facilitate the selection of samples more likely to preserve aDNA in fieldwork settings, while hinting at the possible source of these aDNA fragments in the sediments.
Acknowledgements:
This study is funded by the John Templeton Foundation (grant #62571 to V.S.)
Bibliography
Gelabert, et al. 2021, Current biology: vol. 31,16:3564-3574.e9. doi:10.1016/j.cub.2021.06.023
Vernot, B. et al. 2021, Science vol. 372,6542:eabf1667. doi:10.1126/science.abf1667
Slon, V. et al., (2017), Science 356(6338): 605-608
Future projection of extreme precipitation and temperature indices in Central Asia using CORDEX-CORE
Authors: Rai Praveen , Bangelesa Freddy , Abel Daniel , Ziegler Katrin , Huang Jingshui , Schaffhauser Timo , Disse Markus , Paeth Heiko
Published: March 2024

Our study aims to investigate the development of extreme climate indices based on temperature and precipitation over Central Asia using multiple RCMs from CORDEX-CORE. The study area is defined by an overlapping area of the Central Asian (CAS) and the East Asian (EAS) CORDEX domains to increase the number of ensemble members from 4 to 10. This enables us to compare the biases and projections among the ensembles of the different domains as well. We focus on three-time slices of the present (1981-2005), the mid- (2031-2065), and far-future (2071-2095) using the scenario RCP8.5.For precipitation indices, an increase of consecutive dry days in EAS and a slight to moderate decrease in the northern parts of CAS during the mid-future compared to present values is observed. Consecutive wet days, very heavy precipitation events (R20mm), the maximum one-day precipitation, and very wet days (R95p) are projected to increase in most areas. All indices show a further intensification towards the end of the century over large parts of the domain. For temperature indices, the ensembles project a strong increase over the high mountain regions and southern parts for the consecutive summer days, the heat wave duration index, and the percentage of very hot days (TX90p). Accordingly, the number of consecutive frost days and the percentage of very cold days (TX10p) are projected to decrease. However, some discrepancies in the projected changes prevail among the different RCMs being part of the two CORDEX-domains and in specific landscapes like complex mountain or lake areas.
Snow depth distribution measurements using low cost LiDAR sensors
Authors: Ruttner-Jansen Pia , Glaus Julia , Voordendag Annelies , Wieser Andreas , Bühler Yves
Published: March 2024

Redistribution of snow by wind is an important factor influencing the avalanche danger. However, it is challenging to get detailed information on variations of snow depth in avalanche release areas with sufficiently high spatiotemporal resolution. We have developed a distributed measurement system containing two low cost LiDAR sensors, cameras and meteorological sensors. In autumn 2023 we have deployed this system at a first test site, in the area of a frequently released avalanche. Two stations equipped with the sensors cover an area of around 20'000 m² and provide the snow depth distribution once per hour with a spatial resolution on the cm to m-level. The (near) real time data transmission to a local server allows for an up-to-date assessment of the conditions in the slope. First analyses show the small temporal changes of average snow depth from epoch to epoch for small areas (1m²), including some local avalanche events. We will present first results obtained from the unique dataset resulting from acquisition at high spatio-temporal resolution over the entire winter season 2023/2024, focusing particularly on the snow depth variations before and after avalanche events. In the future, the newly built up snow depth database and the additionally recorded meteorological parameters will be used to model, predict and evaluate the snow depth redistribution on a slope scale level. The data collected directly within the release areas will improve the process understanding of avalanche formation and forecasting, and will thus contribute to better protection of people and infrastructure.
Timescales of diffusion-dominated radionuclide migration – an evaluation of selected existing nuclear waste repository sites and test sites 
Authors: Peche Aaron , Tran Tuong Vi , Altfelder Sven
Published: March 2024

The release and migration of radionuclides towards the biosphere from underground waste repositories may pose a threat to the environment and humans. Therefore, the understanding of transport processes of radionuclides in the subsurface is crucial in order to predict the arrival in the near-surface environment for effectively mitigating and managing associated risk. Processes controlling radionuclide transport may be advection, dispersion, diffusion, sorption and decay, among others.In the context and typical locations of existing waste repositories and test sites, diffusion-dominated transport occurs. Typically, local permeabilities and flow velocities are so small that advection and dispersion would only become significant at very large timescales. The processes of diffusion, sorption (possibly modulated by pressure and temperature) and decay may often be crucial for a) predicting the gradual release and movement of contaminants from the repository into the surrounding geological formations and b) in the geological barrier itself as part of safety analyses. Therefore, understanding of barrier-specific diffusion processes is essential for assessing long-term containment and designing effective concepts to ensure reliable isolation of radionuclides over a time period long enough for their decay to safe levels and to avoid potential environmental risks associated with the disposal of radioactive waste.In the present desktop study, we calculate diffusion-dominated transport of specific radionuclides (Tritium, Technetium, Neptunium a.o.) for various host rocks (tuff a.o.). We calculate radionuclide breakthrough curves and timescales using the 1D analytical model by Lapidus & Amundson (1952), extended for decay in Bear (1972). In order to validate transport parameters for specific radionuclides in specific rock, we analytically try to reproduce physical radionuclide diffusion experiments. Subsequently, we use the validated transport parameters to predict timescales of diffusion-dominated transport.References:Bear, J., 1972. Dynamics of Fluids in Porous Media. American Elsevier, New York.Lapidus, L., & Amundson, N. R. (1952). Mathematics of adsorption in beds. VI. The effect of longitudinal diffusion in ion exchange and chromatographic columns. The Journal of Physical Chemistry, 56(8), 984-988.
Exploring the role of functional traits in regulating the spatial and temporal variability in land surface phenology across temperate forests
Authors: Zhao Yingyi , Wang Zhihui , Yan Zhengbing , Moon Minkyu , Yang Dedi , Meng Lin , Bucher Solveig Franziska , Wang Jing , Song Guangqin , Guo Zhengfei , Su Yanjun , Wu Jin
Published: March 2024

Plant phenology, the study of recurring plant life history events’ timing, is a key indicator of global environmental change and significantly impacts ecosystem functions and services. Land surface phenology (LSP) characterizes plant phenology by monitoring seasonal plant canopy structure dynamics via satellites. Numerous studies have demonstrated that ecosystem-scale LSP variability is mainly driven by climate and environmental conditions across different ecosystems. However, significant spatial and temporal phenological variations are still observed within local landscapes where environmental conditions are relatively similar. This suggests that biotic factors may be important to regulating LSP variability, but their role in determining phenological variability has been underexplored. To address this knowledge gap, we selected four temperate forest sites with minor topographic relief to ensure the homogeneity of environmental conditions and examined how functional traits regulate intra-site spatial and temporal LSP variability. We combined plant functional traits derived from remote sensing data with multi-year Harmonized LandSat-Sentinel-2 (HLS) data to investigate the effects of functional traits on phenological variability. For spatial LSP variability, we assessed the extent to which functional traits could explain the variation in the start of season (SOS) and end of season (EOS). We found that functional traits showed a substantial explanatory power for spatial phenological variability across all the study sites, with cross-validation correlations (cv) ranging from 0.50 to 0.85. For temporal LSP variability, we used multi-year series of the two band Enhanced Vegetation Index (EVI2) to calculate the cumulative deviation of EVI2 values from their long-term means, which served as an indicator of temporal phenological variability. Functional traits also significantly contributed to the temporal variability across all sites, with cv ranging from 0.46 to 0.71. Furthermore, our results show that plant traits related to vegetation competitive ability and productivity (e.g., canopy height, plant area index, and leaf mass per area), are crucial to explaining intra-site phenological variability, but their relative contributions vary among different sites. Collectively, these results demonstrate that functional traits play a critical role in regulating intra-site spatial and temporal LSP variability, and plants employ diverse strategies to cope with the environment, which ultimately impacts various ecological processes.
The effectiveness of river bank filtration system on nitrate removal (Śrem site, Poland)
Authors: Dragon Krzysztof , Siepak Marcin , Drożdżyński Dariusz , Górski Józef
Published: March 2024

In the river bank filtration systems (RBF) the extracted water quality is strongly depending on source (river or lake) water quality. It is well known that these systems can effectively remove emerging contaminants (pharmaceuticals, personal care products or pesticides) from polluted river waters. The common river water contamination is related to nitrate which is observed at high concentrations commonly. Moreover, the nitrate concentrations in the rivers are usually very changeable seasonally. The current work presents the effectiveness of the RBF system in nitrate removal from polluted source (river) water. For this purpose, the water chemistry changes during filtration between the river and productive wells were used, while for identification of denitrification processes the isotopes of d18O and d15N dissolved in nitrate were used. The RBF site located in Śrem (Wielkopolska region, Poland) was selected for the presented research. The water samples were taken from the river and six continuously pumped wells. The water sample representing ambient groundwater was analysed as well. The wells at a close distance from the river (40-50 m) and the wells located at a greater distance from the river (70 – 95 m) were chosen for investigation. The visible differentiation of nitrate concentration was observed. The highest nitrate concentrations were observed in the river and wells located at a close distance from the river (~5 mg/l) and then the nitrate concentrations decrease (to a level of
Exploring tree-ring anatomy to improve hydroclimate reconstructions in Northern Europe
Authors: Seftigen Kristina , von Arx Georg , Björklund Jesper
Published: March 2024

The extreme European summer heat-droughts of 2003 and 2018, compounded by the threat of continued climate change, highlight the need to better understand the frequency, severity and seasonality of such events. The widths of annual tree rings currently provide the most detailed and spatially complete proxy information of European hydroclimate of the past millennium. Ring width is easy to measure and may be well correlated with hydroclimate, but is notorious for overestimating persistence/memory in climate. Using ring width to understand frequencies of droughts may therefore be inherently misleading. In recent studies, latewood density of conifers has showed great potential to improve drought reconstructions. However, wood density is measured at a resolution unable to accurately represent latewood density in very narrow rings, which are often, but not always, the drought-related rings/years most relevant to represent correctly. Hydroclimate studies could therefore be substantially improved by using high-resolution wood anatomical parameters. Anatomical parameters are not only expected to yield higher correlations with hydroclimate, but importantly, provide unbiased reconstructions of the frequency and severity of past droughts, in contrast to ring width and density.Here we explore the potential to improve reconstructions of inter- and intra-seasonal droughts and hydroclimate by using tree-ring anatomy of Scots pine growing across cool yet drought-prone habitats in Northern Europe. This is done by measuring the anatomical cell dimensions of 15 living trees from the Isle of Gotland, south-eastern Sweden. X-ray maximum latewood density (MXD) and its blue intensity counterpart (MXBI) have previously been measured, providing an optimal opportunity for testing the accuracy and potential advantages of dendroanatomical parameters as climate proxies. Preliminary results show an exceptional variability in the latewood density notably coinciding with dry and wet years, and highlight anatomical MXD and maximum radial cell wall thickness as the two most promising wood anatomical proxy parameters for past hydroclimate.
Control of buoyancy forces and thermal softening on the emplacement of low-angle thrust sheets during continental collision
Authors: Dubina Olga , Schmalholz Stefan , Podladchikov Yury
Published: March 2024

A characteristic feature of some collisional orogens, such as the Alps, are low-angle thrust sheets. The most prominent thrust sheet in the Alps is likely the Glarus nappe that has been displaced at least 30 to 40 km. The Glarus thrust has been studied for more than 150 years and these studies created much knowledge of, for example, rock deformation, strain localization, and softening mechanisms. However, the type of forces and the mechanisms that drive the tens of kilometers displacement at a low angle during continental collision remain unclear. Furthermore, the relative importance of softening mechanisms at the base of the thrust sheet is still disputed and proposed mechanisms include fluid overpressure, grain size reduction, or fluid release caused by shear heating.In this study, we investigate the formation of low-angle thrust sheets and nappes with two-dimensional thermo-mechanical numerical models. We consider a lithosphere-mantle system with a continental crust that exhibits initially a horizontal variation in crustal thickness. The lithosphere is shortened by far-field convergence velocities. For simplicity, we apply thermal softening due to shear heating as the only softening mechanism since this mechanism requires the least assumptions in our thermo-mechanical model. The applied numerical algorithm is based on a staggered finite difference discretization and a matrix-free iterative pseudo-transient solver.Preliminary numerical results indicate that buoyancy forces due to lateral crustal thickness variations can trigger the formation of sub-horizontal thrusting and a switch from a locally pure shear-dominated to a simple shear-dominated deformation. Without lateral thickness variations and associated buoyancy forces, thermal softening causes thrusting with 45-degree angles and, hence, no low-angle thrusting. We perform systematic numerical simulations and dimensional analysis to evaluate the conditions that are required to generate low-angle thrusting during lithospheric shortening.
Climatic controls on dinosaur evolution, diversity and biogeography
Authors: Dunne Emma , Schnetz Lisa , Farnsworth Alexander , Lautenschlager Stephan , Godoy Pedro , Tasimov Eren , Butler Richard , Greene Sarah
Published: March 2024

Dinosaurs were dominant members of terrestrial ecosystems throughout the Mesozoic, yet only recently are studies beginning to illuminate the key role of global climate variation in controlling dinosaur biodiversity, global distribution, and macroevolution. Our work uses statistical, biogeographic, and phylogenetic comparative approaches with comprehensive fossil occurrence data and paleoclimate data from general circulation models to quantitatively examine key hypotheses connecting patterns of dinosaur diversity and evolution with climatic conditions. We examined the impact of climate change in driving early dinosaur evolution across the end-Triassic mass extinction (ETME). Our results demonstrate that the geographic distribution of early sauropodomorphs was constrained by climate and following the ETME, the expansion of climate zones facilitated the geographic expansion of sauropodomorphs and other dinosaurs. Evolutionary model-fitting analyses provide evidence for an important evolutionary shift from cooler to warmer climatic niches during the origin of Sauropoda. This same approach is also revealing the relationship between climatic conditions and dinosaur diversity in the Jurassic to Cretaceous, with implications for our understanding of the origins of sauropod gigantism and the evolution of herbivory. Our results suggest that primary productivity was a key climatic factor in driving sauropod evolution and promoting the evolution of larger body sizes, supporting the hypothesis that gigantism was facilitated by the increasing availability of high quality vegetation. Analyses of dinosaur paleoclimatic niche space show evidence of niche partitioning between herbivorous theropods and ‘traditional’ herbivorous dinosaurs (e.g. sauropods), indicating that climatic changes may have influenced evolutionary innovations related to dinosaur diet. Further work examining the relationship between dinosaur diversity and changes in vegetation using state-of-the-art vegetation models will illuminate the key role played by environmental change in controlling dinosaur diversity and evolution throughout the Mesozoic.
Hydrogeochemical and soil CO2 efflux weekly monitoring network for the surveillance of Cumbre Vieja volcano, La Palma, Canary Islands
Authors: Arencibia Hernández Mónica , Feraco Rosella , O'Shea Siobhan , Cartaya Sttefany , Rodríguez Fátima , Melián Gladys V. , Asensio-Ramos María , Padrón Eleazar , Pérez Nemesio M. , Hernández Pedro A. , Padilla Germán D.
Published: March 2024

La Palma Island, spanning 708.32 km2, resides at the north-western edge of the Canary Archipelago and is among the youngest within this group. In the last 123,000 years, volcanic activity has been exclusive to Cumbre Vieja in the island's southern region. The last volcanic activity (Tajogaite eruption) took place at the west flank of Cumbre Vieja from 19 September to 13 December 2021. It was a fissure and powerful strombolian eruption with a magnitude VEI = 3 (Bonadonna et al., 2022). Due to the absence of visible geothermal manifestations, recent decades have witnessed a burgeoning interest in studying diffuse degassing as a vital tool for volcano monitoring. With the aim of strengthening the geochemical monitoring of Cumbre Vieja volcanic activity, we have conducted on a weekly basis from October 2017 to the present, two distinct studies for volcano monitoring. Firstly, we monitored physical-chemical parameters and the chemical/isotopic composition and dissolved gases in the groundwater of two galleries (Peña Horeb and Trasvase Oeste) and three water wells (Las Salinas, Charco Verde, and San Isidro) before, during, and after the Tajogaite Volcano eruption at Cumbre Vieja from September 19 to December 13, 2021. We observed significant temporal variations in pH, EC, ion content, pCO2, and δ13C-CO2, correlating with interactions between deep volcanic fluids and groundwater. These changes showed good temporal agreement with the eruption and seismic swarms leading up to it. Simultaneously, we established a network of 21 closed static chambers to measure soil CO2 effluxes. Before the eruption (October 2017 to December 2020), the recorded soil CO2 efflux averaged 7.30 g·m-2·d-1 across Cumbre Vieja (7.48, 7.35, and 7.11 g·m-2·d-1 in the north, east, and west, respectively). Post-eruption (March 2022 to present), it averaged 7.51 g·m-2·d-1 (8.09, 7.58, and 6.99 g·m-2·d-1). The absence of data during this crucial period impedes direct comparisons and assessment of volcanic activity using this specific monitoring tool.These methods underscore an approach to bolster volcanic surveillance on La Palma Island. Our study emphasizes the importance of monitoring the chemical and isotopic composition of groundwaters linked to active volcanic systems. Such evaluations offer critical insights into magmatic gas input within aquifers, despite limitations encountered during eruptive phases, as witnessed in the case of Cumbre Vieja in 2021.Bonadonna et al. (2022). J.  Geophys. Res: Solid Earth, 127, e2022JB025302.
Subduction Retreat in the Southernmost Beishan Block led to the final closure of the Paleo-Asian Ocean: Evidence from the Deep Seismic Reflection Profile
Authors: Xiong Xiaosong , Li Hongqiang , Chen Xuanhua , Zhou Jianbo
Published: March 2024

The Beishan Block is also known as the Beishan tectonic belt. As the southern part of the Central Asian orogenic belt (CAOB), it is a key study area to understand the successive open and closure history of the Paleo-Asian Ocean  in Paleozoic, which resulted in the largest Phanerozoic accretionary orogen on Earth, and voluminous mineralization. Four near-W-E-trending Paleozoic ophiolitic melange zones are distributed in the Beishan block, featured by the outcrop of meta-ultramafic rocks, gabbro, basalts, with some clastic rocks. Due to the different geochemistry and zircon U-Pb ages of gabbros or other rocks obtained in different ophiolitic mélange zones, the final closure location, time and subduction polarity of the Paleo-Asian Ocean are contentious, in particular in the southern Beishan block (SBB). In this paper, we reported a 140-km-long single-fold seismic section through the general analysis and processing of the data from eleven large dynamite shot records, which was acquired in the deep seismic reflection profiling in 2018. The result provides new constraints on the architecture of the lower crust and the depth and geometry of the Moho below the South Beishan. The main characteristics are: two sequences of north-dipping reflectors developed in the lower crust-to-upper mantle; a sub-parallel reflector in the middle crust at the depth of 8 s two-way travel (TWT), and several south-dipping reflectors in the upper crust in ther northernmost end of the profile. Combined with other geological, chronological and geophysical data, we proposed that the sequences of north-dipping reflectors in the lower crust penetrating to the upper mantle represent two-stages’ subduction of the Huahai ocean, which is the southernmost ocean of the  Paleo-Asian Ocean, and the subduction slab of the Huahai ocean retreated southward from late Silurian-late Devonian to late carboniferous-early Permian, and led to the final closure of the  Paleo-Asian Ocean in the Beishan area. The two-stage subduction produced Huaniushan arc and Shibanshan arc subsequently. The sub-parallel reflection in the middle crust represents the decollement between the upper and lower crust, which acted as the decoupled interface of the large-scale overthrusting in the Mesozoic.