bluuebunny/crossref_metadata_2025 huggingface dataset:
Across-crown and canopy variations of plant functional traits and spectra for deciduous broadleaf and evergreen coniferous species in a temperate forest
Authors: Lai Roxanne , Nakaji Tatsuro , Akitsu Tomoko Kawaguchi , Hyodo Fujio , Noda Hibiki , Kobayashi Hideki
Published: March 2024

Rapid and large-scale characterizations of forest canopies using remote sensing and modelling techniques are necessary, but the extent to which leaf-level traits and spectra can be upscaled to validate larger scale remote sensing data and vice versa is still not well understood. For one, spatial variations of leaf-level traits across tree crowns and canopies can bias results. While differences in extreme crown variations (e.g., shade and sun leaves) have been observed, across crown variation (i.e., sunlit leaves from top and sides of crown), which is of particular importance to increasingly higher resolution optical airborne and satellite remote sensing applications, have not been as widely documented.Here, we investigated the across-crown and canopy variations of leaf-level plant functional traits and spectral reflectances and transmittances in a temperate forest in northern Japan. Our study period spanned the growing and senescence periods from July to October 2023 as well as deciduous broadleaf and evergreen conifer tree species. For each tree, we collected and processed sunlit leaves from two different crown positions visible to overhead aircraft: the top of the tree crown (TC) and at the tree crown periphery (CP).We found differences in certain trait values (e.g., carbon (C) concentration,  d13C, leaf mass per area (LMA), chlorophyll, and total carotenoids) and spectra between TC (average height of 16.7 m above ground level) and CP (average height of 12.5 m above ground level) positions. We also show that differences between trait values and spectra between crown positions varied across tree species and over the growing and senescence periods. Overall reflectance and transmittance spectra across species showed increasing difference between TC and CP, especially in the near-infrared (NIR) region, from the growing to the senescence periods. Collectively, results suggest that crown sampling positions should be considered in the estimation of functional traits from spectral information, reflecting the dynamics of crown architecture. Particularly in spectral regions such as the NIR or short-wave infrared (SWIR), as well as during periods of senescence, where greater difference between crown positions were found.
A Comparative Analysis of Fluvial Propagation and Divide Migration in the Liqiu River Basin, Eastern Tibet
Authors: Wang Wei , Zhang Jinyu , Liu-Zeng Jing
Published: March 2024

     The assessment of rock uplift and climatic conditions through channel profiles traditionally relies on the assumption of topographic equilibrium. Nevertheless, there is a growing acknowledgment that landscapes frequently transition away from this equilibrium as a result of shifts in boundary parameters, such as base-level changes, climatic fluctuations, drainage network reconfigurations, or tectonic activities. Notably, the dynamic nature of drainage divides can introduce substantial disequilibrium into the profiles, severing the tight linkage between channel morphology and the spatiotemporal distributions of tectonic uplift, climatic conditions, or lithologic resistance. It is therefore vital to quantify the rates of river network adjustment and drainage divide migration to fully unravel the complex narratives of landscape evolution, as well as evaluate the influence of mobile divide mobility on the interpretation of river profiles in tectonically active settings.      In the context of this research, we utilized a topographic index alongside 10Be-derived catchment-wide denudation rates to explore how river channels and drainage divides of the Liqiu River in Eastern Tibet adapt to environmental and tectonic forces. Our discovery reveals a significant temporal lag, with divide migration occurring at a pace roughly tenfold slower than that of river channel adjustments. Despite the continuous movement of divides, the channels' swift morphological response broadly maintains their fidelity as indicators of regional uplift, climatic perturbations, and bedrock characteristics.
Study on the inhibitory effect of inhibitor based on the coal molecular structure analysis: A case study of Zhundong coal, Xinjiang, China
Authors: Wang Dezhi , Zeng Qiang
Published: March 2024

 The aim of this work is to use the changes in coal molecular structure to study the effect and mechanism of inhibitors, and to provide a reference for better preventing and controlling coal spontaneous combustion. In this study, Xinjiang Zhundong coal was used to construct the macromolecular structure. Three inhibitors, CaCl2, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), and 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][OTF]), were selected to be mixed with raw coal, and three different inhibitor concentrations were set for each inhibitor. The changes in the molecular structure of the coal under different inhibitor concentrations and temperature conditions were analyzed by Fourier infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis. ChemDraw and Materials Studio were used to construct a coal molecular structure model with an inhibitor concentration of 20% at 50 ℃. Results showed that the molecular formula of the ZD2-1 is C222H123O39N. The coal molecule contained a higher number of aliphatic hydrocarbon branches and a lower degree of aromatic ring condensation. When heated to 300 ℃, the proportion of adsorbed oxygen in raw coal decreased obviously, while the reduction of adsorbed oxygen was inhibited under inhibitor conditions. The change of functional groups of coal samples was obvious under 20% CaCl2 inhibitor concentration, and the dosage was less than that of 30% inhibitor concentration, revealing the optimal inhibitory effect on coal samples of Zhundong with this concentration. Both ionic liquid inhibitors have obvious effects on the hydrogen bonding content in coal macromolecules, and the effects of both inhibitors on the hydrogen bonding of coal molecules are more obvious in the range of room temperature-50°C, thus inhibiting the coal oxygen reaction. The effect on hydroxyl ether-oxygen hydrogen bonding was the most obvious among the different hydrogen bonds.
Unified Model of Forecasting Ozone
Authors: Liu Zhenze , Li Ke , Wild Oliver , Doherty Ruth , O'Connor Fiona , Turnock Steven
Published: March 2024

The chemical transport models face challenges in simulating the concentrations of surface ozone accurately in all conditions when meteorology and chemical environment are changing. The capability of capturing the principle physical and chemical processes is clearly limited. We propose a unified framework based on deep learning to provide a more accurate prediction of surface ozone. The model is tailored to individual observation sites in China, forming a specific graph that would reflect the interaction between spatial and temporal connection in physics and chemistry. This mitigates the uncertainty associated with model resolution and emissions. We show that the model achieves the State-of-the-Art (SOTA) performance in simulating MDA8 ozone among current process-based and other deep learning models. The model structure is also flexible to be applied to other places where observations are available such as Europe and North America. This work underscores great benefits that can be gained through implementing more measurement sites to enhance the density of the model graph.
GNSS unmodeled error processing based on the resilient mathematical model compensation in high-precision GNSS positioning
Authors: Zhang Zhetao , Li Bofeng
Published: March 2024

Global Navigation Satellite System (GNSS) plays an increasingly important role in all walks of life. In order to meet the demands of different users, it is crucial to establish corresponding correct mathematical models, especially in the field of precise positioning and navigation. However, due to the spatiotemporal complexity of and limited knowledge on GNSS errors, some residual errors would inevitably remain even after being corrected with differencing and linear combination, empirical model correction, and traditional parameterization. These residual observation errors are referred to as unmodeled errors. In fact, the unmodeled errors have adverse impacts on high-precision GNSS positioning. However, most existing studies mainly focus on handling the part of systematic errors that can be adequately modeled and then simply ignore the part of unmodeled errors that may actually exist. To make a breakthrough in the precision and reliability of GNSS applications currently, this study focuses on the theory and method for processing the GNSS unmodeled errors based on the mathematical model compensation, including resilient functional model adjustment and resilient stochastic model optimization. Specifically, according to the significance and properties of unmodeled errors, the unmodeled-error-ignored model, unmodeled-error-corrected model, unmodeled-error-fixed model, unmodeled-error-float model, and unmodeled-error-weighted model are proposed, where the approaches of significance testing, geometry-free/based/fixed models, hemispherical/hierarchy maps, composite stochastic model, multi-epoch partial parameterization, and inequality and equality constraints are adopted. Ultimately, an unmodeled error processing flow that can adaptively adjust as the external conditions change is proposed, then one can obtain high-precision GNSS positioning solutions.
Using IMERG precipitation patterns to index climate at the mesoscale: A basis rotation method based on climate bistability - an update
Authors: Kontsevich George , Löwemark Ludvig
Published: March 2024

As communities observe recurring regional weather patterns they will often ascribe colloquial names to them such as the Meiyu in East Asia or the Santa Ana winds of California. However, attaching quantitative characterizations to these same names often proves challenging. Classically heuristics have been developed for particular locations and climate phenomena, but their inherent subjectivity undermine the robustness of any subsequent quantitative analysis. To develop a neutral universal mesoscale metric we start by observing that the spatial distribution of rain in a given region is controlled by the interplay between the meteorological parameters (humidity, wind, pressure etc.) and the Earth’s topography. As a result, each recurring climactic phenomena exhibits a unique regional signature/distribution. Unlike at the synoptic scale, mesoscale climate patterns are largely stationary and an accumulation of two decades of high resolution satellite observations means that these patterns can now be reliably numerically extracted. The key additional observation is that at the mesoscale climate phenomena typically have either one or two non-co-occurring stationary states. This allows us to isolate patterns by a simple bifurcating of the subspace of the first two singular vectors. The end result behaves like a trivial Empirical Orthogonal Function (EOF) rotation that has a clear interpretation. It isolates the climate patterns as basis vectors and allows us to subsequently estimate the presence of the climate phenomena at arbitrary timescales. As a case study we use gridded precipitation data from NASA’s Global Precipitation Measurement (GPM) mission (compiled in to the IMERG dataset) in several regions and timescales of particular interest
Signatures of tectonic-climatic interaction during the Late Cenozoic orogenesis along the northern Chinese Tian Shan
Authors: Zhang Huiping , Zhao Xudong , Lv Honghua
Published: March 2024

The Chinese Tian Shan is one of the most actively growing orogenic ranges in Central Asia. The Late Miocene-Quaternary landscape evolution of northern Tian Shan has been significantly driven by the interaction between tectonic deformations and climate change, further modulated by the erosion of the upstream bedrocks and deposition into the downstream basins. In this study, only the accessible Kuitun River drainage basin in northern Tian Shan was considered, and detrital zircon geochronology and heavy minerals were analyzed to investigate the signature of the driving forces for Miocene sedimentation in northern Tian Shan. This study first confirmed a previously recognized tectonic uplift at ca. 7.0 Ma and further revealed that the basin sediments were mainly derived from the present glacier-covered ridge-crest regions during 3.3–2.5 Ma. It is suggested Late-Pliocene to Early Pleistocene sedimentation was likely a response to the onset of the northern hemispheric glaciation. Although complicated, this study highlights that the tectonic-climatic interaction during the Late Cenozoic orogenesis can be discriminated in the northern Chinese Tian Shan.
Effect of high intensity soil and water conservation engineering measures on soil erosion and sediment transport
Authors: Huang Yanzhang , Gao Guangyao , Wang Yue
Published: March 2024

The middle reaches of the Yellow River (MYR) cover a significant portion of the Loess Plateau, rendering it among the most heavily impacted regions by soil erosion globally. Consequently, the MYR are characterized by high-intensity soil and water conservation measures, such as terracing and silt check dams, which exert a profound impact on soil erosion and sediment transport in this region. However, there is currently no accurate and clear assessment of sediment interception and sediment reduction contributions for large-scale and complex cascading silt check dams. This study enhances the Revised Universal Soil Loss Equation (RUSLE) model by coupling the processes of soil erosion, slope sediment production, and channel sediment transport. The study evaluates the slope erosion and sediment production through the combination of RUSLE and the Sediment Connectivity Index (IC). Additionally, it calculates the sediment interception and sediment output in the channel based on silt check dams sediment interception efficiency. Accurate classification of complex cascading silt check dams is crucial for assessing their sediment reduction contributions. The research employs a flow-based method for precise dam classification and incorporates the latest terracing distribution data to accurately assess the sediment reduction contributions of high-intensity engineering measures in the MYR. The research findings indicate: (1) The average annual soil erosion rate in the MYR from 1981 to 2017 is 13.32±31.94 t ha-1 yr-1, with moderate to severe soil erosion covering 15.1% of the area. (2) Over the past 40 years, there has been an overall decreasing trend in soil erosion in the MYR, with a significant reduction covering 8.65% of the area. Significant decreases in soil erosion began to appear after 2000, with an average annual soil erosion rate reduction of 0.34 t ha-1 yr-1. (3) Based on the cascading situation of silt check dams, the 2187 large silt check dams in the MYR are classified into 6 categories. Taking the initial siltation year as an example, for basins controlled by silt check dams, the sediment output rate without silt check dams is 3.444 t ha-1 yr-1, while with silt check dams, the sediment output rate is 0.468 t ha-1 yr-1, achieving a sediment reduction contribution of 86.4%. The upcoming tasks include: (1) investigating the interannual fluctuations in sediment reduction attributed to silt dams and validating the model; (2) formulating diverse scenario assumptions to evaluate the sediment reduction contributions from engineering measures and vegetation restoration. This study seeks to precisely evaluate the impact of high-intensity soil and water conservation measures on mitigating soil erosion and sediment transport in the MYR, offering insights for regional soil and water conservation practices and sustainable management.
Conductive textile electrodes for time-efficient ERT surveys performed in coarse-blocky mountain environments
Authors: Pavoni Mirko , Boaga Jacopo , Bast Alexander , Lichtenegger Matthias , Buckel Johannes
Published: March 2024

Electrical resistivity tomography (ERT) is one of the most accurate geophysical techniques to distinguish between frozen and unfrozen ground in permafrost areas. Performing the measurements, however, requires considerable logistics and time efforts. This is mainly due to the fact that optimal galvanic contact between the electrodes and the ground surface is necessary to collect reliable ERT datasets. Therefore, the traditional steel-spike electrodes must be steadily coupled between the boulders and wet with salt water on coarse blocky surfaces. To further decrease the contact resistances, sponges soaked in salt water can be inserted between the spike and the surface of rocks. Nevertheless, this traditional coupling system is particularly time-consuming, making it challenging to collect several ERT survey lines in a single workday in mountain environments. Recently developed conductive textile electrodes were applied to facilitate the deployment of ERT arrays in rock glacier environments. Instead of hammering the steel spikes, the conductive textile electrodes can be easily pushed between the boulders and wet with less water (compared to the sponges). Consequently, this new electrode approach decreases the time needed to prepare an ERT array. In this work, we evaluate the performance of the textile electrodes by comparing these with the traditional electrode approach, considering common investigation lines. This comparative test has been carried out in three test sites, which present different lithologies, surface characteristics and using different electrode spacing. The collected datasets were statistically analysed with robust regression analysis and Wilcoxon rank-sum test to examine the accuracy and significant differences between the two electrode systems regarding contact resistances, injected electrical current, measured apparent resistivities, reciprocal error, and inverted resistivity values. The obtained results demonstrate that conductive textile electrodes are suitable to collect reliable ERT datasets and, consequently, applying this approach in future ERT measurements performed in high mountain environments with coarse blocky surfaces (e.g. rockfall deposits, blocky slopes, or rock glaciers) would allow to acquire more survey lines (e.g. realisation of pseudo-3D geometries) extending the characterisation of the subsurface.
Palaeomagnetic dating of the Grotta Romanelli (Apuglia, Italy) upper sedimentary filling: Insights on the Late Pleistocene-Holocene palaeoenvironment and human settings in the Mediterranean
Authors: Tema Evdokia , Lanci Luca , Pieruccini Pierluigi , Mazzini Ilaria , Sardella Raffaele
Published: March 2024

Situated along the Adriatic coast of southern Apulia (Italy), Grotta Romanelli (40.02o N, 18.43o E) is a natural coastal cave considered as a key site for understanding the Middle Pleistocene-Holocene geomorphological, palaeoenvironmental and stratigraphic evolution of the Mediterranean area. Its sedimentary fillings, extremely rich in archaeological and palaeontological findings have been long investigated for their stratigraphical and palaeontological aspects while efforts, mainly based on radiocarbon and pollen analyses, have been focused on better understanding their chronological framework. In this study, we propose a new age model based on the palaeomagnetic record of the uppermost Stratigraphical Unit IUS5 of Grotta Romanelli, also known as Terre Brune. Stepwise alternating field demagnetization provided well-defined directions, which were compared with the reference geomagnetic field curves calculated from the SHA.DIF.14k global geomagnetic field model directly at the cave’s geographic coordinates. A continuous age model was determined taking into consideration the principle of stratigraphic superposition. A selection of reliable, previously published, radiocarbon ages from animal teeth, bones and charcoal was also used for comparison. The proposed age-depth model covers the 14ka-8ka BP period, offering new insights on the chronology of the sedimentation and frequentation of the cave before its complete infilling. This chronological frame enables new considerations on the palaeoenvironmental evolution and climate changes that took place during the transition from the Late Pleistocene to the Holocene, and offers new insights on the dating of the Grotta Romanelli fossil remains, human rests and archaeological artifacts, including lithic tools and rock art.
The interplay of Atmospheric Rivers and topography on snowmelt induced landslides in Northern Anatolian Mountains (Türkiye)
Authors: Aslan Harun , Gorum Tolga , Bozkurt Deniz , Sen Omer Lutfi , Ezber Yasemin , Akbas Abdullah , Fidan Seckin
Published: March 2024

Landslides triggered by snowmelt, as one of the main hydrometeorological triggering factors, and their interaction with Atmospheric Rivers (ARs—long and narrow horizontal water vapor transport characterized by high water vapor content and strong low-level winds) and topographic conditions are not adequately elucidated. During the February–April 2022 period, extreme snowfalls in the Northern Anatolian Mountains, followed by a rapid snowmelt event, triggered more than 300 landslides. Accordingly, based on local and national news sources as well as public institution reports, an inventory was created by mapping 330 landslide events that occurred as a result of rapid snowmelt during this period. This landslide inventory compiled for the Northern Anatolia Region, one of the most susceptible regions in Europe, as well as Türkiye in terms of landslide events, provides a unique opportunity to understand the process dynamics underlying snowmelt-induced landslides. Revealing the combined and/or individual roles of meteorological weather events such as sudden temperature rises, heat waves, rain-on-snow events, and/or the foehn effect, associated with ARs or synoptic-scale weather events, in triggering these landslides is essential for better understanding possible such events in the near-future and to taking effective measures to mitigate socio-economic losses.The spatio-temporal distribution of snowmelt, air temperature, and snow-water equivalent (SWE) variables at daily and monthly scales for the February to April 2022 period according to long-term climatology (1993–2022) as well as landslide events triggered by ARs were analyzed. Additionally, the impacts of altitude and slope steepness on the spatio-temporal distribution of landslide events were revealed. Over the study area during February–April 2022, both monthly SWE and snowmelt values had positive anomalies, while air temperature values showed positive anomalies only for February and April. The analysis of landslide events triggered by ARs based on a 5-day window for AR passages showed that ARs as a triggering factor were responsible for 62% of total landslide events. On the other hand, as time progressed during the period February–April 2022, an increase in the altitude and slope steepness values at which landslide events occurred gradually increased. In addition to a gradual escalation of landslide occurrences to higher altitudes with time, we observed that landslides are limited to around 800 m, which further suggested that this may be caused either by limited soil thickness cover above a certain altitude or by the air temperature below the thawing degree.
Research on Space Weather Chain Model Based on Large and Small Model Co-evolution
Authors: Chen Zhou
Published: March 2024

Research on Space Weather Chain Model Based on Large and Small Model Co-evolution
 
Zhou Chen1,2,3 ,Jing-Song Wang3, Meng Zhou1,2, Haimeng Li1,2, Rongxin Tang1,2, Xiaohua Deng1,2
 

Institute of Space Science and Technology, Nanchang University, Nanchang, Peopleʼs Republic of China;
Information Engineering School, Nanchang University, Nanchang, Peopleʼs Republic of China
Key Laboratory of Space Weather, National Center for Space Weather, Meteorological Administration, Beijing, Peopleʼs Republic of China

 
Corresponding author: chenzhou760@foxmail.com
 
For space physics, a complete space weather event typically follows a general pattern of formation and development from the surface of the Sun, propagation and evolution in interstellar space, and finally having impacts and effects in the magnetosphere, ionosphere, and upper atmosphere of near Earth space, known as the causal chain of space weather. Therefore, when conducting ionospheric and thermosphere forecasting research, it is necessary to consider the state of the sun as the source in order to improve predictions. Especially under extreme conditions (such as during geomagnetic storms), the prediction of key solar parameters is the most important prerequisite for predicting the thermosphere and ionosphere. In order to improve the prediction level of extreme space weather events, multi-modal deep learning technology was adopted and physical constraints were added to address the physical relationships in time, space, and causal driving of solar, ionospheric, and thermosphere observation data in space physics. Global ionospheric TEC prediction, global ionospheric four-dimensional electron density prediction, orbital thermosphere atmospheric density prediction, and global thermosphere atmospheric density prediction were carried out, respectively, And research on solar flare prediction has been conducted, and a chain forecasting method combining the sun, ionosphere, and thermosphere has been preliminarily implemented.
Nitrogen Cycling and Root Dynamics in an Agroforestry System
Authors: Ephrath Jhonathan , Ilani Talli , Silberbush Moshe , Berliner Pedro
Published: March 2024

Primary productivity in arid zones is limited by the lack of water and soil nutrients. Conveying and storing flood water in plots surrounded by embankments allows agricultural activity in areas where there is generally insufficient rainfall to sustain agricultural production. The efficient exploitation of the stored water was achieved by intercropping trees with an annual crop and pruning the former before planting the intercrop. This approach minimized competition for water and solar radiation. However, in order to ensure the long-term viability of such a system nutrients have to be added to the soil in order to compensate for the uptake of the intercrop, Nitrogen being the main element. The composted leaves of a leguminous shrub-like tree incorporated into the soil could satisfy the nitrogen demand of the intercrop. We tested this approach in a simulated runoff agroforestry system with fast-growing acacia (A. saligna) trees as the woody component and maize (Zea mays L.) as intercrop for two consecutive seasons. Ten treatments were applied (radical pruning before intercrop planting, compost application and planting of the intercrop as factors) and  the below- and above-ground effects and interactions examined. Pruning the trees canopies changed the trees’ root spatial and temporal distribution, allowing the annual crop to develop between the trees. Addition of compost significantly increased intercrop yield irrespective of the presence of the woody component while the presence of the intercrop did not affect the productivity of the trees. The highest productivity was obtained for the pruned trees, intercrop and added compost treatment.  A significant increase in the presence of tree roots was observed for the deeper parts of the soil profile for the pruned trees, intercrop and added compost treatment.  The addition of composted leaves from the leguminous woody component to the intercrop resulted in a very high water use efficiency of the water stored in the soil.
Till formation and subglacial deformation in a stratigraphic complex Late Pleistocene sequence (Einödgraben / Aurach, Kitzbühel Alps, Austria)
Authors: Reitner Jürgen M. , Menzies John
Published: March 2024

Knowledge of subglacial conditions is of great relevance in understanding glacier dynamics. A combination of micro- and macrosedimentological analysis of diamictons and deformation structures can form the basis for the reconstruction of past subglacial conditions. We present the results of such a study on subglacial tills, within an Alpine environment, at Einödgraben in the Kitzbühel Alps (Tyrol/Austria). The Late Pleistocene succession there (MIS 5d-MIS 2) shows great diversity in facies from wood-bearing alluvial to glaciolacustrine to subglacial deposits. Two glaciogenic diamictons (tills) within the sequence were analysed at the microscale and are correlated to the Last Glacial Maximum (LGM; Würmian Pleniglacial) and the early Lateglacial phase of ice decay. The first deformation phase of pre-LGM deposits occurred most likely in a subglacial setting close to the advancing glacier margin and resulted in diapir-like glaciotectonic macro-structures, which are unique for an inneralpine area. Subglacial erosion over these structures occurred and later pre-LGM emplaced deposits underwent deformation and partial homogenisation immediately beneath the glacier base leading to diamictons, indicative of subglacial deformable bed conditions. The tills of the LGM and the Würmian Lateglacial show a range of microfacies and deformation structures evidence of close and rapid changes in till rheology and stress field dynamic in the subglacial environment. Our study demonstrates the need for a reinvestigation of deposits occurring in the proximity of past active ice interfaces. The paleoglaciological evidence assembled from the detailed and spatially close research on the microsedimentology of till at Einödgraben reflects our increasing comprehension and understanding of till microsedimentology in Alpine environments. An awareness is also shown of the need for much further research on the glacial depositional mechanics in mountainous terrains that are different from those in the immense lowland plains of the extensive paleo-ice sheets of North America and Northern Europe.
Seasonal floodplain dynamics control Fe-rich colloid characteristics
Authors: Engel Maya , Noel Vincent , Pierce Samuel , Babey Tristan , Kovarik Libor , Kukkadapu Ravi , Zhao Qian , Chu Rosalie , Boye Kristin , Bargar John
Published: March 2024

High concentrations of Fe-rich colloids have been detected in the anoxic zones of our Slate River floodplain field site (CO, USA) since 2018. We speculated that the composition and abundance of the colloids is controlled by the seasonal dynamics and spatial heterogeneities of the subsurface. Therefore, our goals were to 1) decipher the structure and chemical composition of Fe-rich colloids, 2) identify mechanisms of colloid transformation and 3) understand their biogeochemical function.TEM analysis revealed nano-spheres and nano-assemblages that consist mainly of Fe, O, Si, and C, with lower contributions from Al, S and Ca. Based on this elemental distribution, we hypothesized that the colloids are composed of Fe minerals that are associated with organic matter and Si. This was further confirmed through Mössbauer spectroscopy and Fe-EXAFS that indicated the colloids consist ferrihydrite associated with organic matter and Si. NanoSIMS imaging detected co-localities of Fe, S, Si, and O, as well as C and N, which demonstrate once more that these are ferrihydrite-based colloids that are embedded in an organic matter-Si matrix. These findings are intriguing as they demonstrate high abundance of ferrihydrite-based colloids in anoxic depths of our field site. The stability of the colloids is likely attributed to the coating of organic matter and Si that serves as a protective layer against the reducing conditions. Nevertheless, our data also showed that colloids collected during snowmelt (Spring 2021) contained a higher proportion of Fe(II) than colloids collected during baseflow conditions (Summer 2021). XPS analysis measured higher atomic percentages of C and Si compared to Fe and O in baseflow versus snowmelt colloids, indicating a decrease in the organic-Si protective layer under baseflow conditions, allowing for Fe(II) oxidation and an increase in Fe(III)/ferrihydrite content. The fact that there is an occurrence of S species only in the more reduced snowmelt colloids illustrates the dynamic and delicate composition of these environmental colloids during seasonal changes in hydrology and porewater chemistry.We are also in the process of interpreting our seasonal data that will shed light on the controls over the seasonal dynamics of the colloids. We have already linked Fe(II) colloid abundance to lower vertical porewater velocities and higher organic matter levels, and are working on additional analyses including data acquired from FT-ICR-MS analysis of the organic composition of the colloids.
Human impact on grain size variations of river gravel bars in the western Himalaya: Insights from a UAV survey
Authors: Patel Narendra K. , Schlunegger Fritz , Mair David , Pati Pitambar , Prado Ariel Henrique Do
Published: March 2024

Downstream variation in bed material size was investigated over a stretch of the Yamuna River in the western Himalayan region in India. Data on grain size distribution along rivers are critical for understanding river systems and material transport. Flow regulation caused by dam construction can alter sediment transport mechanisms, generating morphological changes. Using an uncrewed aerial vehicle (UAV), we investigated precise grain size variation along the Yamuna River and its tributaries in the Siwalik region, from Lakhwar Dam to Hathni Kund Barrage. All photos were collected via UAV survey.On these datasets, grain size variation was observed across dams. The upper Yamuna River's bed-load sediments are becoming finer-grained downstream. Since the dam barrier and low flow energy force large particles to remain above the dam, smaller particles are found downstream of the dam. During the survey, evidence of mining in several locations along the river suggests the influence of anthropogenic activity in the regions. Accordingly, this study sheds light on the potential consequences of dam construction on material transportation. We observed that dams work as a barrier for coarse grain particles, which may have an impact on the dam in the near future. Field evidence and preliminary processed data indicate that the size of the gravel bar along the river course has been modified by many human interventions (hydroelectric dams, barrages, mining).
Offshore freshened groundwater identified in southern Sicily (Italy) by applying well logs petrophysical interpretation. 
Authors: Chiacchieri Damiano , Lipparini Lorenzo , Micallef Aaron , Quiroga Elizabeth
Published: March 2024

The work focused on the Oligo-Miocene Ragusa Formation, a known regional shallow aquifer in the Hyblean Plateau in southern Sicily, made of medium to high porosity carbonates deposited in the ramp environment, also investigated in the adjacent offshore by deep well drilling.The main objective was to investigate if and how this known shallow onshore aquifer extend in the coastal area and possibly offshore.A detailed methodology was defined for the quantitative use of geophysical logs from about five deep Oil & Gas wells to characterize groundwater in the Ragusa Formation in terms of pressure, piezometry and salinity distribution, as it follows:A first step was the digitization of the full suite of logs required for the application of petrophysical workflow for each well analysed, for a total of about 25 km of digitized logs, such as SP (Spontaneous Potential), GR (Gamma Ray), DT (Sonic log) and Resistivity logs.
At the same time a synthetic lithological log for each selected well was built, to support the understanding of lithological influence of electrical logs.
A customised petrophysical workflow to calculate porosity and salinity (concentration of salts in TDS) was applied, considering: lithotypes, BHT (borehole temperatures), porosity (derived to DT – sonic log), pore fluid resistivity.
A comparison of TDS results with salinity data from DST and composite logs was performed.
A detailed well correlation and comparison between onshore shallow water wells and deep Oil&Gas wells, both onshore and offshore, was carried out.
By applying this petrophysical approach, it was possible to identify and quantified key indications of the presence of fresh groundwater in the Ragusa Formation carbonates both onshore and offshore in southern Sicily (Italy). Indeed, has been demonstrated that the onshore outcropping aquifer appear likely connected with the deep offshore aquifer due to positive indications in the same geological formation 10 km offshore from the coastline.
On the decadal linkage of seagrass growth in southern Taiwan with the Pacific Meridional Mode
Authors: Hsu Liang-Yu , Tseng Wan-Ling , Hsu Pei-Chun , Chen Kuan-Yu , Wang Shih-Yu , Lin Hsing‐Juh
Published: March 2024

While decadal predictability is one of the key information demands on marine management and conservation endeavors, the lack of long-term observed records and complex climate variability challenges understanding it. Seagrass beds are not only important blue carbon sinks but also crucial habitats and feeding grounds for diverse marine organisms. This study uses in-situ data from 2001 to 2021 to investigate the primary decadal environmental control, the Pacific Meridional Mode, on seagrass growth in southern Taiwan. Two primary seagrass metrics, aboveground biomass and cover, were examined against various environmental and meteorological variables. Our initial findings reveal a significant correlation between PMM and seagrass growth. Aboveground biomass exhibits a robust negative correlation with PMM, while cover displays a weaker yet positive association. Further examination of regional climate dynamics unveils notable shifts in surface solar radiation, temperature, and rainfall concerning seagrass. Specifically, increased aboveground biomass coincides with reduced solar radiation, lower temperatures, and enhanced rainfall in southern Taiwan, resembling a negative PMM-like pattern. This pattern underscores the sensitivity of aboveground biomass to large-scale climatic fluctuations across the Pacific basin. Conversely, seagrass cover demonstrates opposing patterns compared to aboveground biomass but with less statistical significance. This suggests that cover growth is influenced by a broader array of factors, resulting in a more nonlinear response. In essence, our research underscores the vital role of PMM and regional climate conditions in shaping tropical seagrass growth, offering further insights for marine conservation efforts.
Spatial distribution and health risk assessment of heavy metals pollution in soil within Agricultural and industrial areas in the Eastern Province, Saudi Arabia
Authors: Yassin Mohamed , Mundher Yaseen Zaher , Tawabini Bassam , Abba Sani , Muzzamil Hussain Shah Syed , Halder Bijay , Aljundi Isam
Published: March 2024

This study aimed to explore the level of heavy metal contamination in the soil of agricultural and industrial areas in the Eastern Province of Saudi Arabia. It adopted a novel approach integrating multiple disciplines including sampling, laboratory analysis, spatial analysis, and risk evaluation. The research focused on pinpointing levels of contamination, identifying their sources, and evaluating associated ecological and human health hazards. Due to its varied agricultural and industrial activities, the Eastern Province faced potential environmental challenges linked to heavy metal pollution. This study tackled the essential task of understanding the spatial spread and associated risks of heavy metals in soil, offering insights critical for effective environmental management and policymaking. Over 60 soil samples were gathered from different industrial and agricultural sites. Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES) was employed for the analysis of various heavy metals in these samples. The soil samples underwent evaluation for heavy metal presence, with their pollution levels assessed through indicators such as the heavy metal pollution index (HPI), heavy metal evaluation index (HEI), modified heavy metal index (MHMI), and degree of contamination (Cdeg). Experimental findings revealed average concentrations of heavy metals in mg/Kg for As, Ba, Hg, Pb, Ni, V, Cd, Cr, Cu, and Zn are 1.21, 110.62, 0.08, 6.34, 8.95, 9.98, 1.18, 31.79, 6.76, and 23.44 respectively. A general trend emerged in the concentration levels, with the highest averages observed in samples from industrial areas, followed by agricultural sites. Particularly notable were barium concentrations in the industrial area, peaking at 1966.5 mg/kg, and copper levels, with a maximum of 95.75 mg/kg in the same area, occasionally surpassing the permissible limits. This methodology provided crucial insights for enhancing water environment management and protection, addressing the urgent need for effective environmental governance and policy development. The findings from this project are not only relevant to the Eastern Province but also applicable to other regions experiencing similar soil contamination challenges.
Effect of volcanic activity on organic matter accumulation: Insights from the lower Aptian shales in the eastern Tethys
Authors: Nie Ying , Fu Xiugen
Published: March 2024

Volcanic activity is generally accompanied by the widespread deposition of organic matter (OM)-rich sedimentary rocks throughout Earth’s history. However, the inherent connection between OM accumulation in deposits and volcanism remains controversial. In this study, we presented high-resolution organic and inorganic geochemical data of the lower Aptian shales in southern Tibet of eastern Tethys to reveal how volcanic activity affected OM accumulation. Enrichment factors of Mo and U as well as Th/U ratio indicated that the studied shales were deposited under oxic-to-suboxic bottom water conditions. Bioproductivity-related Ba/Al reflected a high biotic productivity during deposition. Multiple geochemical proxies revealed that volcanic material occurred within the lower Aptian deposits and volcanism was prevalent in this time. A significant positive correlation between OM content and bioproductivity proxy, combined with the weak or moderate negative correlations among OM content and redox, sedimentation rate and detrital input indicators, demonstrated that OM accumulation was primarily governed by the surficial bioproductivity level. Significantly, the good coupling of volcanic proxies with OM content and biotic productivity suggested that volcanic activity released abundant nutrient elements (e.g., N and P) into the ocean to stimulate the improvement of bioproductivity in surficial water column and then controlled OM accumulation during sedimentary period. This study underscores that volcanic activity plays a constructive function in OM accumulation by enhancing the bioproductivity during the lower Aptian shale deposition.
Functionality-based evaluation of three crop models with different key process simulation approaches across maize–soybean cropping systems in Nebraska, USA 
Authors: Michael Yaron , Egorov Fedor , Helman David
Published: March 2024

Using numerical crop models that simulate fundamental plant-related processes is the most efficient way to get insights into crop responses to future potential climate-weather-environmental conditions. This is because numerical crop models can be easily manipulated while focusing on single or multiple factors. Based on functions (empirical relationships) and equations (physical representation of the processes) derived from experimental observations, such models are our most advanced attempts to predict crop “behavior” under future conditions. The current standard practice is to run as many crop models as possible and then use an ensemble of these model outputs to predict an “averaged” change in yield production and crop quality metrics in the future. However, even though tens of different crop models are often being used in the ensemble, the differences among the models can be reduced to very few core functionality processes being simulated differently in such models. Functionality-based model evaluation involves evaluating the model's ability to simulate the underlying processes that determine crop yield rather than just comparing the model output to observed data. This approach can help identify the sources of model discrepancies and improve the accuracy of crop yield projections.Here, we used three crop models with different functionality-based approaches (DSSAT, WOFOST, and Gcros) to assess biophysical parameters, including leaf area index, aboveground biomass, and grain yield, in a maize–soybean cropping system in Nebraska, USA. We calibrated the models using field data from the US-Ne Mead site, acquired through the AmeriFlux net, as well as soil information derived from the POLARIS soil properties dataset (30 m spatial resolution). We run the models with the 4km GRIDMET weather dataset for maize and soybean across Nebraska to examine the conditions (meteorological, climatic, and other static factors) that drive the change in the results of the different crop models. We aimed to select the most suitable model for best representing the impacts of future climate and environmental changes on these crops in the area per local conditions. We present essential discrepancies among the models and attribute such differences to the functionality-based representation of key processes in the models.
Investigating the Causes of Interannual Variation in Solar Radiation Reflection at the Top of the Atmosphere over the Tibetan Plateau
Authors: Jian Bida , Li Jiming
Published: March 2024

 In the context of global warming, the radiation balance in the Tibetan Plateau region is closely linked to changes in the cryosphere, such as glacier retreat, reduced snow cover, and degradation of permafrost. The abnormal changes in radiation balance further impact the East Asian circulation and global climate change. In this study, based on 23 years (2000-2022) of data from the Clouds and the Earth's Radiant Energy System (CERES) for atmospheric and surface radiation fluxes, the temporal and spatial characteristics of solar radiation reflection at the top of the atmosphere (TOA) over the Tibetan Plateau (TP) and its components, including cloud, atmospheric, and surface components, were analyzed. The results showed that the average TOA solar radiation reflection over the TP was 128.5 W m-2, with cloud component contributing approximately 60.3 %, clear-sky atmospheric component contributing approximately 18.4 %, and surface component contributing approximately 21.3%. From 2000 to 2015, there was a significant decreasing trend in TOA solar radiation reflection over the TP, with a Sen's slope of -1.59 W m-2 10a-1. The interannual variability intensity (i.e., standard deviation of anomalies) was approximately 1.44 during this period. However, from 2016 to 2022, the interannual variability intensity increased to 3.62. The changes in interannual variability of TP solar radiation reflection were closely related to the changes in cloud, atmospheric, and surface parameters. Further analysis is needed to understand the reasons for the changes in radiation balance over the TP. This study plans to explore the impacts and contributions of various atmospheric circulation factors on the interannual changes in TP solar radiation reflection and its components using reanalysis meteorological data and synthesis analysis, aiming to reveal the possible mechanisms behind the abrupt change in interannual variability intensity around 2015.