bluuebunny/crossref_metadata_2025 huggingface dataset:
Bimodality in river bed state suggests critical transitions at high flow
Authors: van de Vijsel Roeland C. , de Lange Sjoukje I. , Torfs Paul J.J.F. , Hoitink A.J.F. (Ton)
Published: March 2024

River bedforms affect bed roughness and, with that, fluvial hydraulics. With increasing flow velocity, subaqueous bedforms grow from flat beds to ripples to dunes, before diminishing again to an upper stage plane bed. Previous studies report an increase in the standard deviation of bedform height with increasing transport stage (a measure of flow strength), and rapid switches in time between contrasting bed configurations. Not much attention has been given to this phenomenon despite its importance in, for example, flood prediction. This study reanalyzes experimental data from earlier experiments. We show that there are statistically strong indications that the increase in standard deviation is due to the emergence of bimodal distributions in river dune height for transport stages larger than 18. This is consistent with our understanding of the physics, as time series of observed dune heights exhibit flickering between low and high dunes, suggesting critical transitions between two alternative morphological states. We hypothesize that local sediment outbursts drive temporary shifts from suspended- to bed load conditions, causing dunes to form transiently before returning to an upper stage plane bed. Flickering behavior of dunes at high transport stages implies that one single snapshot is not enough to capture the state of a system, with far-reaching implications for field measurements and experimental designs. The possibility of alternative dune states also calls for a reconsideration of classical equilibrium relations. This study implies a presence of tipping points in geomorphology and calls for further research to understand and quantify flickering behavior in sediment beds at high transport stages.
Contribution of ozonation forming the particulate nitrosodi-methylamine (NDMA) in the ambient air 
Authors: Choi Na Rae , Kim Yong Pyo , Lee Ji Yi , Kim Eunhye , Kim Soontae , Shin Hye Jung
Published: March 2024

Nitrosamines, organic compounds featuring the nitroso functional group (N-NO), are found in both gas and particle phases in the ambient air, known for their carcinogenic properties. The International Agency for Research on Cancer (IARC) has classified most nitrosamines as likely carcinogenic to humans. Given their carcinogenic nature, it is crucial to manage ambient concentrations of nitrosamines. Nevertheless, the concentrations of nitrosamines in Seoul, South Korea, surpass the recommended level of 10 ng/m3 set by the Norwegian Institute of Public Health (NIPH).In the previous study, the contributions of primary emissions and atmospheric reactions were investigated using field measurement data from Seoul, Korea, along with a kinetic box. It was estimated that there was a mixed contribution of the atmospheric reaction and primary emission. In addition, the model estimation result showed that nitrosamine formation was enhanced by nitrosation under higher concentrations of NOx in Seoul. However, there was a large discrepancy between the measured and estimated concentrations of particulate nitrosamines in Seoul. Therefore, further identification of the hidden reaction forming nitrosamines was necessary.This study aimed to identify whether ozonation could be an unknown reaction forming particulate nitrosodi-methylamine (NDMA) to reduce the discrepancy between the measured and estimated concentration of NDMA in the previous study. Ozonation of dimethylamine (DMA) can form dimethylhydrazine (UDMH), subsequently, UDMH reaction with O3 and O2 can produce NDMA in the ambient air. In order to quantify the contribution of ozonation, the ozonation mechanism was added to the kinetic box model developed in the previous study. The model simulation results showed that (1) the ozonation contributed to the ambient concentration of NDMA (7.9 ± 3.8% (winter); 1.9 ± 3.0% (spring); 10.0 ± 0.77% (summer); 3.6 ± 7.3% (autumn)), (2) the relatively higher O3/NOx ratio in summer (1.63 ± 0.69; 0.64 ± 0.52 (winter); 1.14 ± 0.92 (spring); 0.52 ± 0.54 (autumn)) could enhance ozonation, and (3) relatively lower pH in summer (2.2 ± 0.4; 5.3 ± 1.2 (winter); 3.9 ± 1.2 (spring); 3.9 ± 0.7 (autumn)) could hinder nitrosation compared to that in other seasons.
A novel modeling approaches to understand the fate and transport of microplastics in aquatic environment
Authors: Chaturvedi Sadashiv , Min Liu , Kumar Amit , Wenfan Zeng
Published: March 2024

The pervasive presence of microplastics (MPs) in natural waters presents a global threat to aquatic ecosystems and human well-being. While field monitoring is extensive, the focus has primarily been on characterizing MPs types, occurrences, and distributions, with limited attention has been made on modeling, because of the unavailability of datasets, inadequacy of the methodologies, and site-specific studies. This gap prompted to build the advocating of hybrid models that integrate hydrodynamics with process-based for categorization, transportation, and transformation, and further know the potential risks of ecological, climatic and human health so that associated risks could be mitigated. Additionally, standardizing data calibration and validation is essential to enhance the comparability of modeling results with field investigations, critical for informed decision-making in addressing the global challenge of MPs pollution. Thus, addressing this gap in understanding microplastic activities, dynamics, and their interactions within aquatic environments is pivotal in the global scientific fraternity. A new numerical framework, CaMPSim-3D, integrates a Lagrangian particle-tracking model (PTM) with a Eulerian-based hydrodynamic system (TELEMAC) is applied to simulate microplastics' fate and transport. This innovative model considers various advection schemes, revealing significant differences in predictions, with the Third Order Total Variation Diminishing (TVD3) Runge-Kutta method showing promise by providing accurate results at lower computational costs.
Global energy consumption for desalination and wastewater treatment
Authors: Magni Michele , Jones Edward R. , Bierkens Marc F. P. , van Vliet Michelle T. H.
Published: March 2024

An estimated 2 billion people across the globe lack access to a safe source of drinking water, while 3.6 billion people are not connected to safely managed sanitation. Expansion of technologies for drinking water and wastewater treatment is key to tackling global challenges in water supply and sanitation. Unconventional water resources, such as desalination and wastewater reuse, are also increasingly being adopted to alleviate water scarcity.Modelling the current energy use of these technologies is essential to improve our understanding of the interdependencies between the water and energy sectors, and to prevent conflicts between mitigation of anthropogenic climate change, energy security and alleviation of global water scarcity. However, most research on energy-for-water has been conducted at local to regional scales, with inter-comparisons limited to a few cities or countries worldwide. Previous studies have also typically lacked spatial or temporal distribution, limiting their application in larger-scale assessments.The aim of this research is to estimate global energy consumption for desalination and wastewater treatment at 5 arcmin resolution. Preliminary model results show that desalination required 0.74 – 1.04 EJ in 2015 to produce 29.8 km3 of freshwater, while 0.30 – 0.79 EJ were consumed in the same year to treat 186.4 km3 of wastewater. Large uncertainties in energy consumption for wastewater treatment are mostly caused by lack of data on advanced purification. The gridded output of our model may enable spatial representation of these processes in Integrated Assessment Models and Energy Supply Models, and the evaluation of future energy demands towards global clean water provision. Future work aims to shine light on global hotspots of energy consumption for clean water supply and the effects of unconventional water resources on the water-energy nexus.
Short and long-term multiphase reactive transport processes during a pilot test of air injection into a sandstone gas storage facility
Authors: De Windt Laurent , Sin Irina , Banc Camille , Petit Anélia , Dequidt David
Published: March 2024

This study is based on unique field data on a 3-year pilot test during which air containing 8 mol% O2(g) was injected as a cushion gas into a natural gas reservoir, a carbonate-cemented sandstone aquifer located in the Paris Basin (France) [1]. The oxygen was fully depleted several months after injection completion, meanwhile CO2(g) was detected around 2–6 mol%; the pH decreased from 8 to 6, while reducing conditions shifted to mildly oxidizing ones with increasing concentration of sulfates in equilibrium with gypsum. After the test completion, the long-term evolution of the aquifer was assessed by a 15-year survey. The pH gradually returned to its near initial state and sulfates were reduced by 2 to 3 times. Data on the release of trace metals (Ba, Cu, Pb, Zn) during and after the test were also available.Multiphase reactive transport models were developed on these field data using the HYTEC reactive transport code in 2D-reservoir configurations [1]. At the short-term scale, modeling focused on the gas-water-rock reactive sequence during the air injection: 1/ depletion of the injected O2(g) due to pyrite oxidation, 2/ leading to acidity production and dissolved sulfates, 3/ acidity buffering by calcite dissolution, 4/ followed by gypsum precipitation and CO2(g) exsolution. At the long-term scale, the modeling tackled with the progressive return to the baseline chemistry of the deep aquifer that was 1/ mostly driven by transport processes and 2/ to a lesser extent, slow water/rock chemical interactions.These field-based models developed at short and long-term could be used as a workflow for other gas storage facilities, e.g. biomethane, compressed air, and CO2.[1] Sin, I., De Windt, L., Banc, C., Goblet, P., Dequidt, D. (2023). Assessment of the oxygen reactivity in a gas storage facility by multiphase reactive transport modeling of field data for air injection into a sandstone reservoir in the Paris Basin, France. Science of The Total Environment 869, 161657.
Wet calc-alkaline magmatic fractionation in the middle-upper crustal sections of continental arc: Insights from Neoproterozoic Nanba intrusive complex, western Yangtze Block, South China
Authors: Zhu Yu , Lai Shao-cong
Published: March 2024

Elucidating petrological and geochemical characteristics of continental arc crustal fragments can provide unique insights into the magmatic evolutional path and physicochemical conditions (e.g. P-T-H2O) in continental magmatic arcs. This contribution provides a comprehensive dataset of petrology, mineralogy, geochronology, and geochemistry for Neoproterozoic Nanba intrusive complex in the western Yangtze Block, which stands for the well-exposed arc middle-upper crustal sections of Neoproterozoic continental magmatic arc, in order to evaluate their magmatic source and fractionation process. The Neoproterozoic Nanba intrusive complex, composed of cumulate gabbros, hornblende gabbros, gabbro-diorites, diorites, granodiorites, K-feldspar granites, and monzogranites, were emplaced at ca. 796–790 Ma. The different lithologies from the Nanba intrusive complex display relatively homogeneous Sr-Nd-Hf isotopes, indicating a cogenetic evolutional process. The predominantly depleted isotopic characteristics, together with high values of Ba, Rb/Y, and Ba/La, demonstrate that these rocks mainly originated from subduction fluids-metasomatized mantle source. Petrological and geochemical characteristics as well as hornblende thermobarometer collectively support that the ca. 796–790 Ma Nanba intrusive complex, following the calc-alkaline trend, was dominated by wet cogenetic fractionation of hornblende accompanied by plagioclase and accessory minerals under middle-upper crustal levels (2.4–4.7 kbar). The cumulate gabbros stand for accumulation residues of hornblende + plagioclase + Fe-Ti oxides from fractionated basaltic melts. The high-SiO2 K-feldspar granites and monzogranites display complementary trace elements, which represent residual silicic cumulates and extracted interstitial liquids in the shallower crystal mush reservoir, respectively. In combination with previous studies, we propose that the middle-upper crustal sections of Neoproterozoic continental arc in the western Yangtze Block underwent hornblende-dominated fractionation followed by significant crystal-liquids separation for the genesis of high-SiO2 melts in shallower crustal level. The cogenetic evolution plays a significant role into moulding petrological and geochemical diversities of Neoproterozoic igneous rocks and differentiation process of continental arc crust in the western Yangtze Block.
The control of Indonesian Throughflow and sea level changes on the paleoclimatic variability along the northwest Australian margin over the last~800 kyr: Insights from clay mineral, grain size and radiogenic isotope records at IODP Site U1483
Authors: Sarim Muhammad , Xu Jian
Published: March 2024

Mid-Late Quaternary sediments collected from high sedimentation Site U1483 of the International Ocean Discovery Program (IODP), located off the Scott Plateau of the northwest Australian margin were analyzed for clay mineral assemblages, radiogenic isotope, and siliciclastic grain size records, in order to reconstruct sediments provenance, ocean currents behavior and variability of Australian summer monsoon over the last ~800 kyr. Clay mineral fractions are mainly dominated by smectite, followed by moderate kaolinite and illite, and minor chlorite. Our provenance model suggests the Victoria and Ord Rivers of the Kimberley region as the primary sedimentary sources for Site U1483 over the past ~800 kyr. The Strontium-Neodymium-Lead (Sr-Nd-Pb) isotope values (87Sr/86Sr: 0.730-0.720, ƐNd: -8.22 to -10.73 and 206Pb/204Pb: 19.25 to 18.95) at Site U1483 are consistent with the isotope composition of northwest Australian sediments and indicate only a minor sediments contribution from the Timor region by ITF.
Time-series variation in the clay mineral and grain size records indicate strong glacial-interglacial cyclicity, with small grain size, high smectite, and low kaolinite and illite during glacials, while interglacials are marked by a relative increase in kaolinite and illite, mean grain size, and decrease in smectite. (Kaolinite+illite+chlorite)/smectite and kaolinite/smectite ratios coupled with clay/silt ratio were adopted to indicate variability in the intensity of the ITF and Australian monsoon. High values of kaolinite/smectite and (kaolinite+illite+chlorite)/smectite ratios during the interglacials indicate a wet summer monsoon with high river discharge and a strong ITF. In contrast, during glacials, the low values of kaolinite/smectite and (kaolinite+illite+chlorite)/smectite imply a dry summer monsoon and a weak ITF. In addition, our proxy records display a variation shift around 450 ka which coincides with the timing of the Mid Brunhes Event (MBE) and marks the transition into extreme glacials-interglacials. The proxy records spectral analysis display concentration of power on 100-kyr, 41-kyr, and 23-kyr bands, implying that both high-latitude ice sheet and the precession-driven low-latitude processes influenced clay mineral sedimentation along the northwest Australian margin.
Generation of the charnockite by residua entrainment in water-deficient melts: insights from minerals composition and H2O-in-zircon
Authors: yang Hang , Yao Jinlong
Published: March 2024

Charnockite is an orthopyroxene-bearing felsic rock and an important constituent of the deep crust, thus, it holds significant importance in uncovering crustal growth and differentiation mechanisms. However, its generation and preservation remain debated. By focusing on mineral records, we here aim to provide a more detailed understanding of these issues. The Gaozhou charnockite in the Yunkai terrane of South China was chosen for extensive mineralogical studies and thermodynamic modeling. The Gaozhou charnockite contains granulitic enclaves, and mineral assemblages within charnockite can be divided into three phases, with the peak phase mainly composed of orthopyroxene, and minor biotite. Meanwhile, the charnockite and enclaves show comparable compositions of biotite and orthopyroxene. Embayed textures and high TiO2 content in biotite grains suggest high-temperature anatexis. On the other hand, the orthopyroxenes with inclusions and high Al2O3 content indicate peritectic origin. Moreover, reaction intergrowths of biotite with orthopyroxene grains have also been observed, suggesting that these grains were generated by the consumption of biotite. The Gaozhou charnockite has much lower zircon water content (135 ppm, median) as compared to that of the contemporary Opx-free granites (202-643 ppm, medians) in the Yunkai terrane, indicating dry primary parental melts. In addition, phase equilibria modeling constraints peak anatexis conditions at 860-870 ℃/6.2-7.0 kbar. Peritectic orthopyroxenes must have been generated by the incongruent melting of biotite under high-temperature granulitic facies in the lower crust. Subsequently, these grains were entrained and migrated by low water content melts to the upper crust. Therefore, overall observations favor a model of selective entrainment of source materials at a low magma water environment for the generation of the Gaozhou charnockite.
How Does Mei-yu Respond to Climate Change?
Authors: Sun Bo
Published: March 2024

Mei-yu is an important weather phenomenon in the middle-lower Yangtze River valley (YRV) region. For instance, in 2020, extreme precipitation events frequently occurred in the YRV region during the Mei-yu period, which caused flood and resulted in over 200 deaths/missing persons and over 170 billion CNY of direct economic losses. Whereas in 2022, persistent high temperature and drought events occurred in the YRV region, which greatly affected the agriculture, hydropower, and human health in the YRV region. These extreme events during the Mei-yu period have brought severe challenges to the government for combating climate change.This study investigates the changes in the characteristics of Mei-yu under global warming and the potential reasons based on observation and reanalysis data during 1961–2022. It is found that the number of days without rainfall (NDWOR), intensity of rainfall event, and frequency and intensity of extreme precipitation events (EPE) in the YRV region have increased significantly during the Mei-yu period (June 15–July 10) over past decades. These trends indicate that the weather during the Mei-yu period is becoming more unstable and extreme under global warming. Particularly, the increasing trends in intensity of rainfall events and EPE (NDWOR) account for a relatively large (small) portion of the variability of corresponding variables, suggesting that the increased rainfall intensity is a key feature in the response of Mei-yu to climate change.The increasing trend of NDWOR during Mei-yu is attributed to decreased relative humidity. According to the Clausius-Clapeyron equation, the saturation specific humidity (qs) would dramatically increase as the global warming continues, at an increasing rate of approximately 7% per℃ rise in temperature. As qs increases more dramatically than q under global warming, the RH is decreased, which may lead to more days without rainfall during the Mei-yu period.The increased intensity of rainfall event, and frequency and intensity of EPE may be correspond to the thermodynamic and dynamic effects in the YRV region during the Mei-yu period. Through analyzing the regional rainfall events in the relatively cold period of 1961–1980 and in the relatively warm period of 2001–2022, it is found that the transient southerly water vapor transport, water vapor convergence and enhanced convection in the troposphere associated with the regional rainfall events in the YRV region during the relatively warm period are notably larger than that during relatively cold period during the Mei-yu period.Furthermore, the response of Mei-yu to 2℃ of global warming with respect to pre-industrial climate is analyzed using CMIP6 models. The results suggest that the NDWOR, intensity of rainfall events, and frequency of EPE will increase in the YRV region during the Mei-yu period under the 2℃ warming scenario, which imply a more challenging climate risk management in the future.
Imbalance in lake variability but not embodying driving factors on the Qinghai-Tibetan Plateau calls on heterogeneous lake management
Authors: Leng Xuejing , Fu Bojie , Feng Xiaoming
Published: March 2024

Comprehensive regional remote analysis tends to neglect lakes in exorheic basins on the Qinghai-Tibetan Plateau (QTP), and a concurrent lack of discussions on whether there exist imbalanced explanations for the driving forces of both internal and external lakes is also present. We integrate multisourced lake datasets, high-resolution information, and available altimetry datasets to establish multiple mathematical models to meta-simulate lake volume changes, extend current lake variation datasets, and quantify the imbalance of variations and factors driving the water mass budget. The results showed that the primary cause of lake variations in QTP is net precipitation (57.75 ± 31.46%), followed by glacier runoff (33.53 ± 31.42%), and permafrost (8.34 ± 7.87%). Even though glacier runoff is currently considered as a weak factor of lake variation, heterogeneous results call for remaining attention in glacier-induced lake basins. Imbalance embodying in lake variability but not in contributions of driving factors, which calls for special lake management ways in different watersheds.
Characteristics and mechanisms of the severe compound cold-wet event in southern China during February 2022
Authors: Li Huixin , Sun Bo
Published: March 2024

A severe compound cold-wet event occurred in southern China (hereafter referred to as CWESC) in February 2022, leading to enormous socioeconomic losses. In this study, we proposed a new index to denote the severity of the compound cold-wet event. Based on the multivariate survival method, the CWESC in February 2022 is identified as the severest event during the past six decades. Our results indicate that the CWESC in 2022 is jointly regulated by the La Niña-like SST condition in the tropical Pacific and the warm SST anomalies in the North Atlantic, and a teleconnection in the Northern Hemisphere during winter (hereafter referred to as TNHW) plays the key role. The TNHW pattern originates from the tropical Pacific, and it splits into two routes over the North Atlantic. The northern branch of TNHW propagates via the Arctic and Siberia, causing intensified near-surface northerly wind and partially inducing an anomalous anticyclone over the western North Pacific (WNP). The southern branch of TNHW propagates via the Mediterranean and western Asia, inducing a deepened India–Burma trough and partially inducing the anomalous anticyclone over WNP. The intensified near-surface northerly wind causes enhanced cold advection over southern China, while the deepened India–Burma trough and the anomalous anticyclone over WNP cause increased southerly warm and moist air flow towards southern China, resulting in the CWESC in 2022. Moreover, four groups of numerical experiments forced by tropical Pacific, North Pacific, and North Atlantic SST anomalies are conducted based on the Community Atmosphere Model version 5. The results confirm the important roles of the La Niña-like condition and the warm SST anomalies in the North Atlantic in causing the CWESC in 2022.
 
Aerosol Chemical Composition and Sources over East Africa’s Background Atmosphere
Authors: Kirago Leonard , Gustafsson Örjan , Gaita Samuel , Haslett Sophie , DeWitt H. Langley , Gasore Jimmy , Potter Katherine E. , Prinn Ronald G. , Rupakheti Maheswar , Ndikubwiwamana Jean D. , Safari Bonfils , Andersson August
Published: March 2024

Aerosol emissions from sub-Saharan Africa are perceived to influence the regional climate, impact precipitation patterns, and impair human respiratory health. However, the magnitudes of these perturbations are ill-constrained, largely due to limited ground-based observations and uncertainties in emissions from different sources. Of particular concern are black carbon, a climate-warming agent and a more toxic component of atmospheric aerosols. To investigate the fine participate chemical composition and sources, we collected filter samples from the Rwanda climate observatory - a strategically located regional background site at the summit of Mt. Mugogo. The filter samples were analyzed for carbonaceous aerosols and water-soluble inorganic species. In addition, multi-year high-temporal resolution BC data was retrieved from an AE33 Aethalometer. Overall, we find a strong seasonal cycle for all investigated chemical species, where the maxima coincide with large-scale upwind savanna fires. The Aethalometer BC data show notable inter-annual variability with no clear long-term trend. For source apportionment, mass ratios and highly precise isotopic techniques unambiguously show highly elevated biomass burning contributions, up to 93 ± 3%, with a clear and strong savanna burning imprint. The study further provide improved relative emission factors of key aerosol components in savanna-fires-influenced background atmosphere. Taken together, this study provides quantitative source constraints on Eastern Africa aerosol emissions, with implications for parameterization of satellite fire and bottom-up emission inventories as well as regional climate and chemical transport modelling.
Geospatial assessment of treeline shifting in response to climate change in Langtang National Park, Central Nepal
Authors: Bhatta Sijar , Wasti Samiksha
Published: March 2024

The Himalayan region nurtures diverse treeline species, yet its delicate ecosystem is highly susceptible to even minor climate variations, prompting inevitable shifts in forest distribution and recruitment patterns. We used geospatial data from remote sensing in GIS and field observation to estimate the treeline position & rate of treeline shifting in Langtang National Park (LNP) of Central Nepal. The methodology encompassed regression analysis to quantitatively assess inter-variable relationships, while Pearson correlation analysis was undertaken to evaluate the correlation between treeline positions and climatic variables. A Mann-Kendall trend test was used to determine the significance of trends in time series datasets. A significant increasing trend of mean treeline was marked with an average treeline shifting rate of 37.23 m/decade. NDVI increased by 0.003 unit/yr, and the area of forest increased by 12506 ha/yr. Trend analysis showed that the annual average minimum temperature increased significantly by 0.045˚C/yr while annual average maximum temperature and the annual rainfall decreased significantly by 0.022˚C/yr and 1.584 mm/yr respectively. A significant positive correlation of treeline with winter (Feb), pre-monsoon (Apr) and monsoon (Aug, Sept) minimum temperature and pre-monsoon (Mar), monsoon (Jun, Sept) and post-monsoon (Nov), maximum temperature was observed indicating that the treeline in LNP is more sensitive to temperature than precipitation.
Keywords: Climate Change, Normalized Difference Vegetation Index (NDVI), Treeline, Himalaya, GIS and RS
Rayleigh-wave Ambient Noise Investigation for the OHANA Experiment in the NE Pacific
Authors: Laske Gabi , Atkisson Grace , Talavera Soza Sujania , Collins John , Blackman Donna
Published: March 2024

The OHANA experiment comprises a 15-month deployment of 25 broadband ocean bottom seismometers (OBSs) in the northeast Pacific Ocean, about halfway between Hawaii and the North American west coast. The primary objective of this project is to explore the crust, lithosphere and asthenosphere in a 600~km wide region west of the Moonless Mountains, covering mainly 40-to-50 Myr old Pacific lithosphere. A fundamental question to be addressed is whether this particular area has the signature of a typical oceanic lithosphere that has a normal plate cooling history. Alternatively, we seek evidence for a previously proposed reheating process, e.g. resulting from small-scale shallow-mantle convection. The new data enhance seismic imaging in a regional as well as in a global context. Regionally, short-period ambient noise and long-period earthquake-derived Rayleigh wave dispersion provide the centerpiece for imaging the crust and upper mantle. In  a top-down approach,we start with the assembly and analysis of ambient-noise cross-correlation functions between 5 and 25 s. We present an initial assessment of high signal-to-noise quality cross-correlation functions. We derive path-averaged dispersion curves for the fundamental mode and present tomographic images from initial inversions. Furthermore, our cross-correlation functions contain prominent waveforms from overtones that can help improve resolution as a function of depth.
Unusal equilibrium behavior of forest ecosystems in the Loess Plateau
Authors: Chen Ning , Ma Li , Yang Liping
Published: March 2024

Ecosystems may exhibit various equilibrium behaviors (e.g., linear and threshold), which will dramatically affect how we understand and regulate ecosystem dynamics under different environmental conditions, thus reshaping ecosystems’ sustainable development. Studying equilibrium behaviors is particularly crucial for the Loess Plateau because hundreds of billions of Chinese Yuan have been paid to alter ecosystem structure and thereby to reduce soil erosion. Resultant increasing vegetation, however, exhausts soil water, which heavily threatens the sustainability of ecosystem function and services therein. It has been a widespread and long-lasting controversy over whether and where to afforest. However, one of the most fascinating equilibrium behaviors of alternative stable states, which permits more than one states under the similar conditions, has largely ignored in the framework. By integrating remote sensing products, a minimal model, and environmental data, this study explored alternative tree-cover states and its effects on functions and services of forest ecosystems in the Loess Plateau. The equilibrium behavior along annual precipitation gradient appeared to a threshold-type (uni-stability) combined with a fold bifurcation. That is, tree cover showed a threshold-type uni-stability when annual precipitation was lower than 400 mm, beyond which alternative stable states of high tree cover (forest, >35% tree cover), and medium tree cover (open woodland, 7%~35% tree cover) co-existed. Increasing spatial heterogeneity, and especially vegetation-precipitation positive feedback would advance the thresholds of transitions between alternative states towards to higher annual precipitation. Furthermore, regime shift from forest to open woodland states increased carbon stock, while reduced water yield, i.e., carbon and water formed a trade-off. This unusual balancing behavior not only enriches our understanding theoretically but also substantially benefit afforestation planning in the Loess Plateau practically, thereby promote forest ecosystem functions and services of forest ecosystems.
Impact of deforestation on global monsoon precipitation   
Authors: Liang Yue , Xu Xiyan , Jia Gensuo
Published: March 2024

The global monsoon system represents the dominant variation in the climate with profound regional and global impacts, influencing the livelihood of billions of people. However, how large-scale deforestation induced changes in water cycle and energy balance may modify global monsoon systems are not well understood. In this study, we investigate the biophysical effect of deforestation on global monsoon precipitation and circulation based on multiple earth system models in the Land Use Model Intercomparison Project (LUMIP). The results show that large-scale deforestation induces global monsoon precipitation and circulation intensity weakening. A 20 million km2 of global tree cover loss leads to annual precipitation reduction of about 15.0 mm per year (mm yr-1) and 26.2 mm yr-1of Multi-Model Ensemble (MME) in global monsoon and land monsoon domain. The precipitation is reduced by 16.8 mm in the Northern Hemisphere summer monsoon (NHSM) regions from May to September with weakened circulation intensity. Deforestation induces temperature asymmetry between the northern hemisphere and the southern hemisphere, and hemispheric thermal contrast is thus decreased. As a result, the north-to-south meridional pressure gradient weakens, leading to the NHSM circulation and precipitation intensity decrease. Deforestation-induced hemispheric temperature asymmetry also increases the northward cross-equatorial atmosphere heat transport that drives southward shift of Intertropical Convergence Zone, which suppresses the NHSM precipitation. The drying monsoon region in response to deforestation is fairly consistent among the models implying the adverse effects of large-scale deforestation beyond the region of land use change.
Assessing the future solar resources over India at 1.5°C and 2°C warming worlds
Authors: Ghosh Sushovan , Ganguly Dilip , Dey Sagnik
Published: March 2024

India aspires to increase its reliance on renewable energy sources to fulfil its climate commitments. Among renewables, Solar Photovoltaic (SPV) energy has grown rapidly around the world, including in India. However, little is known about how solar dimming and global warming may affect solar power over the region in the future. The production of SPV energy is influenced by meteorological parameters, highlighting the concerns related to grid stability, intermittency, and reliability caused by weather-induced variability.  Under the Paris Agreement, all the nations agree to restrict the global warming to “well below” 2°C above pre-industrial levels and, if possible, “pursue” efforts to limit warming at 1.5°C. Therefore, it is imperative to understand future climate change and their spatial heterogeneity at 1.5°C and 2°C warming for developing  strategies for renewables. This research examines the distribution and variability of India's solar resources by utilising state-of-art global climate models from Coupled Model Intercomparison Project phase 6 (CMIP6) and CMIP6 - NASA Earth eXchange Global Daily Downscaled Projections (NEX-GDDP). The analysis of global mean temperature changes reveals that the 2030s and 2040s will be the decade when majority CMIP6 models reach 1.5°C and 2°C warming under SSP2-4.5 (intermediate emission pathways) and SSP5-8.5 (high emission) scenarios respectively with respect to  pre-industrial period (1850–1900).We find that under the intermediate (high) emission scenarios, the annual mean surface solar radiation over the Indian landmass will decrease by -8±3 Wm-2 (-5±2 Wm-2) relative to the baseline period (1985-2014) at 1.5°C global warming. An additional 0.5°C of warming (at a global warming level of 2°C) results in a comparatively smaller decline in surface solar irradiance with respect to baseline under both scenarios. At 1.5°C and 2.0°C global warming, most regions are anticipated to experience an increase in surface irradiance under the SSP5-8.5 scenario, as compared to SSP2-4.5. The magnitude and direction of change of aerosols, clouds and associated meteorological parameters needs to be explored further. This research will contribute to crucial planning and decision-making processes concerning India and other nations with similar interests.
Early Diagenesis In Carbonate Sediments
Authors: Sheng KaiQi
Published: March 2024

Extensive lacustrine carbonate-rich shale intervals including upper fourth member (Es4s shale) and lower third member (Es3x shale) of the Paleogene Shahejie Formation have been deposited in the Boxing Sag, Dongying depression, Bohai Bay Basin, East China. These two representative shale members are considered to be good exploration prospects in the study area. In order to clarify the diagenetic process and exploration significance of sparry calcite in lacustrine calcareous shales, we take calcareous shale in Es4s to Es3x members in Boxing Sag as the research object, By means of thin section identification method, EDS line scan, Scanning Electron Microscopy, Fluid Inclusion Analysis, carbon and oxygen isotope and other methods, sparry calcite is classified, and then the genesis and diagenetic fluid of various types of sparry calcite are studied, so as to clarify the formation mechanism of sparry calcite, and finally discuss the influence of sparry calcite on reservoir. Finally, the influence of sparry calcite on the development of reservoir pores was discussed. The results show that the types of sparry calcite in the study area include granular calcite, porphyritic calcite and fibrous calcite, which are mainly caused by biological oxidation and thermal evolution of organic matter. Biogenic calcite has the characteristics of rich Mg and δ13C, and the organic matter makes the crystal more enriched with Fe and deficient δ13C. The formation of three kinds of sparry calcite has different effects on pore development, which is probably beneficial to improve reservoir physical properties.
Crustal Structure and Magmatism of the Southern Kyushu-Palau Ridge
Authors: Zhang Jie , Li Jiabiao , Ding Weiwei , Ruan Aiguo , Wei Xiaodong , Tan Pingchuan
Published: March 2024

The Kyushu–Palau Ridge (KPR) is the result of the subduction of the Pacific Plate, separated from the proto-Izu–Bonin–Mariana arc by the back-arc spreading, showing variations in arc structures. The volcanism related to the subducted slab at the remnant arc stops before the initial back-arc spreading. However, the KPR accretion did not stop right when the back-arc spreading started. The internal structure not only reveals the arc characteristics but also contains crisis information about how the arc formed. The less revealed velocity structure in the southern KPR might hinder an understanding. Herein we studied the crustal magmatism at the southern KPR based on the detailed velocity structure. Results show that the KPR’s crust to the west is 6.0–7.6-km-thick with one summit at the basement and a flat Moho boundary; to the east, the crust has a thickness of 7.0–11.0 km, and three summits are observed at the basement sharing one depressed Moho boundary. These structural diversities indicate the presence of two independent seamounts (west and east), with different periods of magmatism. By calculating the duration of volcanism, we hypothesized that the formation of the western seamount of the KPR requireed a magmatism duration of ~4 Myr and one stable volcanic source. In contrast, the eastern seamount needed two volcanic sources and a total magma loading time of ~10 Myr with ~19-Myr period gap in magmatism. By analyzing the KPR evolution, we conclude that multiple volcanic sources and episodic magmatism caused the diversities in arc structures at the KPR; the initiation of back-arc spreading at ~26 Ma might have inhibited the magmatism related to the subduction; however, the back-arc-related partial remelting of the lower island arc would have led to a new magma source and reconstructed the preexisting island arc, thus leaving multiple conduits inside it.
Estimating fracture characteristics and hydraulic conductivity from slug tests in epikarst of southwest China
Authors: Liu Xiuqiang
Published: March 2024

In the epikarst zone of carbonate areas, numerous fractures have different sizes, shapes, and filling materials. Determining the fractures' horizontal hydraulic conductivity (Kh) simply using slug tests is challenging due to variable flow states (e.g., steady and unsteady). In this study, we characterized fracture features of apertures and soil fillings in terms of 260 fractures of 25 borehole logs at five sites in a karst area of southwest China. The Bouwer and Rice (B & R) solution and a numerical model were used to determine Kh based on the best fitting of observed water head in 105 slug tests. The results comparatively show that Kh from the B & R solution is significantly underestimated. For numerical modeling, the non-linear flow expressed by the Dupuit and Forchheimer equation can improve the water head fitting when the Reynolds number (Re) > 17.27. The optimized Kh ranges 0.014 – 2673 m/d. The mean value of Kh is about 100 times the median value, suggesting that epikarst flow might be controlled by a limited number of larger fractures. Expectedly, Kh exponentially increases with d, but three is a turning point for the fracture aperture d around 10 mm, Kh abruptly decreases due to soil filling. The hydraulic permeability in the naturally full-filling fractures resembles the soil matrix. In contrast, the partial-filling fractures can create preferential pathway with a high Kh around the soil-rock interfaces, allowing preferential flow in fractures. These results fundamentally improve our understanding of water infiltration, retention, and availability for plant uses. 
Long-term Aerosol Monitoring at the Western Arabian Peninsula and Red Sea Coast
Authors: Shevchenko Illia , Stenchikov Georgiy , Engelbrecht Johann
Published: March 2024

The Arabian Peninsula is one of the World’s largest dust source regions. It is also affected by natural and anthropogenic pollution of African, Asian, and European origin. As the Arabian Peninsula is highly under-sampled, we have since 2012 established and maintained aerosol monitoring sites at King Abdullah University of Science and Technology (KAUST), as well as in the North-Western part of the Arabian Peninsula, and the Red Sea coast. The sites incorporate the following instrumentation. Two CIMEL sun photometers operational since 2012 as a part of the NASA Aerosol Robotic NETwork (AERONET), providing aerosol optical depth (AOD) and aerosol parameters, reporting data to the NASA Goddard website (http://aeronet.gsfc.nasa.gov/cgi-bin/type_piece_of_map_opera_v2_new). The AOD distribution over the Red Sea is measured during KAUST Red Sea cruises using a hand-held sun photometer (Microtops II). The data are reported to the NASA Maritime Network (http://aeronet.gsfc.nasa.gov/new_web/maritime_aerosol_network.html). Vertical Distribution of aerosols is sampled using the Micro Pulse Lidar (MPL) operating as a part of the NASA MPLNET (http://kimura.gsfc.nasa.gov/site--‐page?site=Kaust). We measure aerosol deposition rates on a monthly basis using passive samplers in different several locations (KAUST, 2015-2023; Al Wajh Lagoon, 2021-2022; DUBA & Tabuk,2022 -2023) and conducted a mineralogical analysis of deposited aerosols by X-ray diffractometry (XRD) and measured particle size distributions using Mastersizer3000.Our objective in this study is to conduct an in-depth analysis of the combined effects of natural and anthropogenic pollution on air quality, climate, and application of renewable energy across the Arabian Peninsula, providing a scientific foundation for model calibration in this region. Here we report on the data sets collected in 2012- 2023:KAUST campus site: Six dust deposition samplers, AERONET, MPL
Al Wajh Lagoon site: Nine dust deposition samplers
Duba site: Two dust deposition samplers
Tabuk site: Two dust deposition samplers
In our group’s research at KAUST, these data sets, in combination with the available satellite observations, were integrated into the meteorology-chemistry-aerosol model, WRF-Chem, to quantify the aerosol environmental impacts and support environmental decision-making in the region.
A Unified Framework for Forward and Inverse Modeling of Ice Sheet Flow using Physics Informed Neural Networks
Authors: Cheng Gong , Morlighem Mathieu , Francis Sade
Published: March 2024

Predicting the future contribution of the ice sheets to sea level presents several challenges due to the lack of observations of critical boundary conditions, such as basal sliding. Traditional numerical models often rely on data assimilation methods to determine spatially variable friction coefficients by solving an inverse problem, given an empirical friction law. However, these approaches are not versatile, as they demand sometimes extensive code development efforts when integrating new physics into the model. Furthermore, the requirement for comprehensive data alignment on the computational grid hampers their adaptability, especially in handling sparse data effectively. To tackle these challenges, we propose a transformative approach utilizing Physics-Informed Neural Networks (PINNs) to seamlessly integrate observational data and underlying physical laws into a unified loss function, facilitating the solution of both forward and inverse problems within the same framework. We illustrate the versatility of PINNs by applying the framework to two-dimensional problems on Helheim Glacier in southeast Greenland. By systematically concealing one component within the system, we showcase the ability of PINNs to accurately predict and reconstruct hidden information, emphasizing their adaptability to handle scenarios marked by missing or incomplete datasets. Furthermore, we extend the application to address a challenging mixed inversion problem. We show how PINNs are capable of inferring the basal friction coefficient while simultaneously filling gaps in sparsely observed ice thickness. This mixed inversion problem represents a class of scenarios beyond the reach of conventional numerical methods. Our unified framework offers a promising avenue to enhance the predictive capabilities of ice sheet models, reducing uncertainties and advancing our understanding of intricate ice dynamics.
Copper nanoparticles: Insecticidal action, resistance management  and effect on  endosymbiont abundance in olive fruit fly Bactrocera oleae 
Authors: Malandrakis Anastasios , Varikou Kyriaki , Kavroulakis Νektarios , Nikolakakis Antonis , Dervisi Irene , Reppa Chrysavgi , Papadakis Stefanos , Holeva Maria , Chrysikopoulos Constantinos
Published: March 2024

The effectiveness of copper containing nanoparticles (Cu/CuO-NPs) against insecticide-resistant olive fruit flies (Bactrocera oleae) and their impact on the insect’s reproductive and endosymbiotic parameters were evaluated. The insecticidal activity of both nano and bulk copper [Cu(OH)2] was comparable or greater than that of the reference insecticide deltamethrin at recommended doses as revealed by feeding experiments. A significant synergistic effect between Cu-NPs or CuO-NPs and deltamethrin was observed in terms of adult mortality. Furthermore, the deltamethrin + Cu-NPs combination decreased the total number of offspring as compared with the untreated control. The above combination also significantly decreased the mean number of stings, pupae, female and total number offspring of the surviving female, compared to deltamethrin applied alone. The abundance of the Candidatus Erwinia dacicola- a B. oleae larvae bacterial gut endosymbiont- was adversely affected by bulk and nanosized copper. Concluding, Cu-NPs have a great potential to control insecticide-resistant B. oleae populations by reducing adult and larval survival and fecundity, and provide the means for reducing the environmental footprint of pesticides by minimizing their required doses.This study was co-financed by the European Regional Development Fund of the European Union and Greek national funds through the Rural Development Program (RDP/ΠΑΑ) 2014 – 2020, under the call "Cooperation for environmental projects, environmental practices and actions for climate change“ (project code: Μ16SΥΝ2-00354).