bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a UAV-borne cavity-enhanced albedometer for in-situ measurements of the vertical profiles of aerosol optical properties
Authors: Zhao Weixiong , Zhou Jiacheng , Fang Bo , Wang Shuo , Zhang Weijun , Chen Weidong
Published: March 2024

Vertical profiles of aerosol light scattering (bscat), absorption (babs), as well as the single scattering albedo (SSA, ω), play an important role in the effects of aerosols on climate, air quality, and local photochemistry. However, direct measurement of the vertical profiles of these optical parameters remains challenging. Although some aircraft observations have been carried out, there is still large uncertainty.In this presentation, we will report the development of an unmanned-aerial-vehicle (UAV)-borne cavity-enhanced aerosol single scattering albedometer (CEA-albedometer) operating at λ = 532 nm for simultaneous in-situ measurements of the vertical distributions of bext, bscat, babs, and ω. The achieved detection precisions in laboratory were 0.38, 0.21, and 0.43 Mm-1 for bext, bscat, and babs, respectively, for a 1 s data acquisition time.The UAV used here was a petrol-powered hexacopter with a flight height of up to 1.5 km and a speed of up to 20 m/s. The maximum take-off weight of the UAV was ~ 150 kg, and about 30 kg of equipment can be carried. The full load flight endurance time was about 80 minutes depending on the temperature and wind. It was controlled by a GPS module with a precision of 0.1 m in the horizontal direction and 0.05 m in the vertical direction.The concept of using UAVs for atmospheric research began in the 1990s. Nowadays, it has developed rapidly, and various instruments have demonstrated impressive performance. The UAV flight platform reported here demonstrated good performance and will become a valuable and powerful tool for atmospheric boundary layer research.
Global convergence in the response of terrestrial gross primary production to atmospheric vapour pressure deficit
Authors: Huang Chao , Huang Jingfeng , Xiao Jingfeng , Li Xing , Chen Fusheng
Published: March 2024

  With climate warming, atmospheric vapor pressure deficit (VPD) shows an increasing trend, which may restrict plant growth. However, there is still uncertainty regarding the response mechanisms of plant transpiration and photosynthesis to VPD, soil moisture, and their interactions. This uncertainty leads to significant discrepancies among different Earth system models when simulating the impact of atmospheric drought on terrestrial ecosystem productivity, and it constitutes a crucial source of uncertainty in predicting the global carbon balance of land ecosystems in the future. In this study, through analyzing field measurements, satellite-derived data, and Earth system model (ESM) simulations, we reveal a similar threshold response pattern of GPP to VPD for most ecosystem types, where GPP initially increases and then decreases with increasing VPD. When VPD exceeds these thresholds, increased soil moisture loss and atmospheric drought stress lead to reduced stomatal conductance and lowered light saturation point in plant leaves, decreasing terrestrial ecosystems' productivity. Existing Earth system models emphasize the influence of CO2 fertilization on land ecosystem productivity and predict a continuous increase in global terrestrial GPP throughout the 21st century. However, these models also indicate a significant reduction in GPP of low-latitude land ecosystems when VPD exceeds the threshold. This finding highlights the impact of climate warming on VPD and implies potential limitations on future land ecosystem productivity due to increased atmospheric water demand. This study suggests incorporating the interactions among VPD, soil moisture, and canopy conductance into Earth system models to enhance the predictive capacity for the response of land ecosystems to climate change.
On the Formation and Maintenance of the Interannual Variability of the North Atlantic Oscillation
Authors: Yang Yang , Liang X. San , He Wei-Bang
Published: March 2024

Motivated by the observation that the interannual variability of the North Atlantic Oscillation (NAO) is associated with the ensemble emergence of individual NAO events occurring on the intraseasonal time scale, one naturally wonders how the intraseasonal processes cause the interannual variability, and what the dynamics are underlying the multiscale interaction. Using a novel time-dependent and spatially localized multiscale energetics formalism, this study investigates the dynamical sources for the NAO events with different phases and interannual regimes. For the positive-phase events (NAO+), the intraseasonal-scale kinetic energy (K1) over the North Atlantic sector is significantly enhanced for NAO+ occurring in the negative NAO winter regime (NW), compared to those in the positive winter regime (PW). It is caused by the enhanced inverse cascading from synoptic transients and reduced energy dispersion during the life cycle of NAO+ in NW. For the negative-phase events (NAO−), K1 is significantly larger during the early and decay stages of NAO− in NW than that in PW, whereas the reverse occurs in the peak stage. Inverse cascading and baroclinic energy conversion are primary drivers in the formation of the excessive K1 during the early stage of NAO− in NW, whereas only the latter contributes to the larger K1 during the decay stage of NAO− in NW compared to that in PW. The barotropic transfer from the mean flow, inverse cascading and baroclinic energy conversion are all responsible for the strengthened K1 in the peak stage of NAO− in PW.
Global plastic export by rivers: large differences in trends between microplastics and macroplastics 
Authors: Puranik Suhas , Micella Ilaria , Strokal Maryna
Published: March 2024

Plastic pollution in aquatic ecosystems has become a major concern due to the adverse consequences it poses to marine and human health. Rivers are a major source of inputs of plastic waste into seas. Modelling studies in the past have estimated plastic fluxes into seas for microplastics or macroplastics. However, sources of both macro- and microplastic exports by rivers to coastal waters and their past and future trends have hardly been addressed simultaneously in a spatially explicit way (e.g., sub-basins). This includes both point sources (sewage) for microplastics from car tyre wears, personal care products, household dust and laundry as well as diffuse sources (mismanaged solid waste) for macroplastics and their fragmentation to microplastics. This study aimed to analyse the past (2010-2020) and future (2020-2100) river export of macro- and microplastics using the MARINA-Plastics model using a scenario with the rapid urbanization and high economic development under high global warming in the existing MARINA-Plastics (Model to Assess River Inputs of pollutaNts to seAs for Plastics). The model results show that estimated that globally, the annual river export of macroplastics is modelled to decrease by only 7% whereas the river export of microplastics is modelled to increase by 144% between 2010 and 2020. The large increase for microplastics is associated with increasing trends in urbanization over the period of 2010-2020. In the future, globally, the annual river exports of macroplastics are projected to increase by 118% and microplastics are projected to decrease by 8% in 2100. The sub-basins of the Atlantic, Indian and Pacific Oceans will account for more than 85% of the total river export of plastics in the future. The large increase for macroplastics is related due to poor management of waste and poor collection rates. The hotspots for macroplastic pollution in coastal waters are modelled to shift from Europe and North America to Africa and Asia in the future. Our insights could inform the design of plastic reduction policies at the international level and support the achievement of Sustainable Development Goal 14 (clean marine waters).All authors acknowledge the support of the Water Systems and Global Change Group of Wageningen University. I. Micella is supported by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 956623 (InventWater).
Long-range transport of Saharan dust to East Asia and their regional impacts
Authors: Liu Qiantao , Huang Zhongwei , Hu Zhiyuan , Bi Jianrong , Shi Jinsen , Zhou Tian , Dong Qingqing
Published: March 2024

Saharan dust accounts for about 50-60% of the total global dust and can affect regional climate, environment and ecosystems through direct and indirect effects. However, the long-range transport of Saharan dust to East Asia and the further specific effects on its weather and climate are still poorly understood. Using the satellite observations combined with the model simulations, the multiple reanalysis data and HYSPLIT trajectory analysis, we systematically study the long-range transport of Saharan dust to East Asia and further study the impact of Saharan dust on the direct radiative forcing, clouds and precipitation in East Asia. A quarter (24.3 ± 6.2%) of dust cases in East Asia were originated from the Sahara Desert. The long-range transported Saharan dust is usually located in the upper troposphere of East Asia. The total annual average amount of Saharan dust transported over East Asia is 33.05 ± 9.78 Tg/year. Saharan dust can be transported eastward throughout the year and contributes about 35.8% of the dust to the upper troposphere in northern China in spring, which is almost equivalent to the amount of dust lifted from the East Asian dust source. Furthermore, in terms of regional impact, Saharan dust has a cooling effect on the surface and the top of the atmosphere, and a heating effect on the atmosphere. During a rainfall event, Saharan dust reduces the cloud supercooled water path over the Taklimakan Desert by 13.3 g/m2 in 3 h, converting supercooled water clouds into ice clouds and increasing the cloud ice-water path. As a result, a large amount of dust that acts as ice nuclei induces rainfall in the hinterland of the Taklimakan Desert as high as 6.32 mm. This study provides a new perspective on the important role of Saharan dust over East Asia, contributes to a better understanding of its long-range transport properties over East Asia and the sources of dust aloft in East Asia, and elucidates the impact of long-range transported dust on regional direct radiative forcing, clouds, and precipitation to better assess the impact of dust on climate and environment.
Multi‐year variations of submicron aerosol composition and sources in Ireland
Authors: Lei Lu , Fossum Kirsten , Lin Chunshui , Ceburnis Darius , Afzal Aqeel , Spohn Teresa , Chevassus Emmanuel , O'Dowd Colin , Ovadnevaite Jurgita
Published: March 2024

The air quality in Ireland was once significantly deteriorated by air pollutants emitted from domestic coal combustion activities in the 1980s. Thanks to the smoky coal ban which was put into force in 1990, the air pollution in Ireland has been improved gradually and surely. However, extreme air pollutions with the mass concentration of submicron aerosols (PM1) exceeding 300 μg m-3 were still observed sporadically during cold months, which were mainly related to domestic solid fuel combustion, and the disproportionate impacts from so-called “low-carbon” and “carbon-neutral” solid fuels (e.g., peat and wood). Moreover, due to the increasing wood stove advertisements and significant fuel price increase caused by Ukrainian-Russian war, the emissions from local solid fuel combustion activities could greatly impair the air quality in Ireland in the future. Since the situation is changing year to year, it’s very critical to conduct continuous field aerosol measurements and have a deeper insight into the medium/long-term variations for more targeted and effective regulations in the future. In this study, based on the parallel real-time measurements of submicron aerosol species at three representative sites over Ireland, the multi-year variations of aerosol chemical composition and source emissions have been analyzed.The air quality in Dublin has been improved gradually since 2016, with the annual average mass concentration of PM1 decreased from 8.0 μg m-3 in 2016 to 4.1 μg m-3  in 2022, and the total number of days when PM1 concentration exceeds the WHO recommendation value (15 μg m-3) has decreased to 11 days in 2022. Specifically, the extreme air pollutions have been reduced significantly, e.g., the maximum hourly PM1 concentration has decreased to 77 μg m-3 in 2022 compared to 317 μg m-3 in 2016.  The high PM1 concentrations in Dublin were more related to local emissions, especially domestic solid fuel burning, characterized by large contributions from primary organic aerosols. While long-range transport also plays an important role with high fractions of inorganics especially Nitrate (NO3). The chemical composition of PM1 in Dublin was similar over the years, i.e., dominated by Organics (Org) and then followed by NO3 or sulfate (SO4). However, it’s worrisome to find that the mass concentration of SO4 has been increasing since 2021 and showed higher contribution to PM1 especially during cold months, indicating that the sharply increasing fuel prices recently may have led to a change in fuel usage, possibly with more coal and solid fuel combustion in households. This could indicate severe air pollution episodes that need further and more effective regulations in the near future to ensure good enough air quality.   
X-informatics at the center of scientific discovery: Detecting biosignatures, predicting mineral occurrences, and characterizing planetary kinds. 
Authors: Prabhu Anirudh , Morrison Shaunna , Hazen Robert , Wong Michael L. , Hystad Grethe , Cleaves II Henderson J. , Eleish Ahmed , Cody George , Gatne Vasundhara , Chavez Jose P , Ma Xiaogang , Fox Peter ,   Mineral Informatics Team
Published: March 2024

Data Science and Informatics methods have been at the center of many recent scientific discoveries and have opened up new frontiers in many areas of scientific inquiry. In this talk, I will take you through some of the most recent and exciting discoveries we've made and how informatics methods planned a central role in these discoveries. First, we will look at our work on data-driven biosignature detection, specifically how we combine pyrolysis-gas chromatography-mass spectrometry and machine learning to build an agnostic molecular biosignature detection model. Next, we will talk about how we used association analysis to predict the locations of as-yet-unknown mineral deposits on Earth and potentially Mars. These advances hold the potential to unlock new avenues of economic growth and sustainable development.Finally, we will set our sights on exoplanets—celestial bodies orbiting distant stars. The discovery of thousands of exoplanets in recent years has fueled the quest to understand their formation, composition, and potential habitability. We develop informatics approaches to better understand, classify and predict the occurrence of exoplanets by embracing the complexity and multidimensionality of exoplanets and their host stars.
Identifying opportunities and barriers for skillful sub-seasonal prediction of East Asian summer monsoon precipitation
Authors: Liu Fei
Published: March 2024

Accurate sub-seasonal (2-8 weeks) prediction of monsoon precipitation is crucial for mitigating flood and heatwave disasters caused by intra-seasonal variability (ISV). However, current state-of-the-art sub-seasonal-to-seasonal (S2S) models have limited forecast skills beyond one week when predicting ISV events. Here, we find, regardless of models, that the prediction skills for ISV events depend on the propagation stability of events’ preceding signals. This allows us to identify opportunities and barriers (OBs) within S2S models, understanding what the models can and cannot achieve in ISV event prediction. Focusing on the complex East Asian summer monsoon (EASM), we discover that stable propagation of Eurasian and tropical atmospheric wave trains towards East Asia serves as an opportunity, providing skillful prediction up to 13 days ahead. However, the Tibetan Plateau barrier highlights the limitation of EASM predictability. Identifying these OBs will help us gain confidence in making accurate sub-seasonal prediction.
Properties of the bed of Thwaites Glacier, West Antarctica, estimated from vibroseismic surveys (2022-23 and 2023-24)
Authors: Eisen Olaf , Zeising Ole , Hofstede Coen , Laubach Hannes , Koch Florian , Anandakrishnan Sridhar , Brisbourne Alex ,   GHOST team
Published: March 2024

In the Antarctic field seasons 2022/23 and 2023/24 the GHOST team (Geophysical Habitat of Subglacial Thwaites: https://thwaitesglacier.org/projects/ghost) as part of the International Thwaites Glacier Collaboration (ITGC), collected several hundred kilometers of multi-fold seismic reflection profile of Thwaites Glacier. The data cover the center flow line (first season) and across flow profiles (second season), starting 60 km upstream from the grounding line. The seismic profiling set-up consisted of a seismic vibrator source and 60 geophones on a 1.5 km long cable, all towed by a tracked vehicle. The combination of surface seismic source and towed geophone array allows for rapid and high quality data acquisition. The seismic signal penetrates approximately 200 meters into the bed with deeper structures imaged in places. The along-flow profile revealed a repeating of bedforms alternating between relatively flat and smooth regions a few km long, and regions of more pronounced topography of 10s to 100s of meter high bumps. In addition we imaged what we interpret as sediment filled basins.  Comparison with high-resolution ground-based swath radar allows the identification of geomorphological bedforms, such as megascale glacial lineations, sediment-filled basins and troughs, which can then be directly identified in the seismograms. We present a first preliminary evaluation of the subglacial characteristics and discuss the potential relevance of the subglacial boundary condition for ice flow dynamics.
Tomographic evidence on multistage plate subduction in Northeast Asia: Implications for lithospheric deformation and intraplate volcanism
Authors: Wang Zhi , Liu Lijun , Fu Yi , Zhao Liang
Published: March 2024

Since the Early Mesozoic, extensive Cretaceous intraplate volcanism, cratonic lithospheric thinning, and widespread crustal deformation have been documented in Northeast (NE) Asia. Global plate reconstruction models and paleo-magnetic data suggest a highly complex subduction system under NE Asia since the early Mesozoic, with proposed Mesozoic models including continuous subduction of the Izanagi plate and possible subduction of intra-oceanic arcs and early Cenozoic subduction of an active spreading ridge. Although subduction is a critical factor impacting continental deformation, the interactions between deep dynamic processes and surface tectonic responses remain debated. Based on a systematic investigation of seismic tomography, plate reconstruction, and igneous rock data, we present a new model of continental co-deformation with a multistage subduction history involving the Proto-ocean, Izanagi, and Pacific plates in Northeast Asia. The high-resolution mantle seismic structures were ascertained using a novel global tomographic inversion based on adaptive inversion mesh refinement and regional velocity perturbation constraints from 298,725 hand-picked and > 16 million arrival times of multiple P-wave phases (e.g., P, pP (pwP), PP, PcP, Pdiff, PKP, PKiKP) which were recorded by the 4,107 temporary and permanent stations in Northeast Asia. The unprecedented data reveal new integrative views on the geometry and behavior of mantle high-velocity anomalies associated with a sequence of oceanic lithosphere subduction events. The extensive compilation of dated volcanic samples provides strong constraints on past subduction events. Positions of remanent slabs derived from a multistage subduction history were reconstructed using the ages of initial subduction and slab sinking rates, where the geographical distribution of remnant slabs observed in our tomographic model helps to define the plate reconstruction history since the Early Mesozoic. The inferred multi-plate subduction configuration with slab advance, rollback, stagnation, break-off, and foundering, together with implied slab dehydration, should have resulted in various degrees of fluid-rock interactions among the slabs, the asthenosphere, and the continental lithosphere. We argued that fluid intrusions and mantle flow have played crucial roles in episodic intraplate volcanism and craton lithosphere thinning in different subduction stages. The Early Cretaceous intraplate volcanism, the ancient cratonic lithospheric thinning, and the crustal deformation have been caused mainly by a successive effect of the Proto oceanic plate and Izanagi slab subduction, but less by the Pacific plate subduction. These findings provide a systematical framework for understanding the co-evolution of the continental lithosphere with deep mantle dynamics in NE Asia and also serve as an excellent illustration of how the Earth's interior works.
Deep Atlantic Multidecadal Variability
Authors: Yang Jiajun , Li Jianping , An Qirong
Published: March 2024

Investigating deep‐sea temperature variability is essential for understanding deep‐sea variability and its profound impacts on climate. The first mode in the Atlantic is referred to as Deep Atlantic Multidecadal Variability (DAMV), characterized by a north‐south dipole pattern in the mid‐high latitudes with a quasi‐period of 20‐50 years. The DAMV and Atlantic Multidecadal Variability, despite a statistical discrepancy, may be different responses to ocean heat transport (OHT) driven by the Atlantic Meridional Overturning Circulation (AMOC) at distinct depths separately. The relationship between the DAMV and the AMOC is established, indicating the AMOC is likely to transport surface heat downwards by deep convection and contribute to such dipole pattern in the deep Atlantic. Furthermore, meridional OHT proves the AMOC can explain the DAMV variation as a dynamic driver. These results reinforce the importance of deep‐sea studies concerning the Atlantic climate system.
The Interplay between Land Use Changes and Hydrological Processes in the Upper Offin Basin of Ghana
Authors: Tilahun Seifu , Anane Gyebi Afia Sarpong , Adusei-Gyamfi Junias , Amponsah Andoh Kwaku , Atampugre Gerald , Cofie Olufunke
Published: March 2024

The transformation of the food system is intricately linked to the effective management of land and water resources, particularly in regions where diverse land uses compete for limited space. The upper Offin sub-basin serves as a prime example of this complexity, where agricultural, mining, and agroforestry practices fight for arable land, influencing the local food system and changes in hydrological processes. This study aims to comprehend the flow paths, the status of water resources, and land use changes in the agroforestry-dominated landscape of the upper Offin basin in Ghana. To assess historical land use patterns, Landsat images were utilized, alongside trend analyses of past hydro-climatic variables and a Thornthwaite-based water balance incorporating inputs from remote sensing and secondary data spanning from 1981 to 2022. Furthermore, the study instrumented an upland Mankran watershed in the upper Offin, where citizen scientists measured basic hydrological variables in three landscape positions—such as daily rainfall, streamflow rates, and groundwater levels—and water quality parameters (nitrate, phosphate, and mercury) from June to October 2023. The analysis revealed that annual and monthly rainfall exhibited minimal changes over the study period (1981–2022). Forest areas experienced a general decrease, while croplands and built-up areas increased between 2008 and 2021, impacting water balance components. Actual evapotranspiration (AET) based on the water balance model and WaPOR data demonstrated a decreasing trend, while streamflow at the basin outlet increased from 1986 to 2012. The runoff coefficient and the hydrological simulation based Thornthwaite-based water balance demonstrated that subsurface flow dominated the runoff processes, constituting approximately 20% of the average annual rainfall. This is also supported by the nitrate concentrations only peaked in rivers in June, while agricultural wells exhibited consistently high concentrations throughout the rainy period, suggesting leaching through subsurface flow. Phosphate concentrations increased in streams as the rainy period progressed, mirroring well concentrations, and mercury concentrations were low in surface water but four times higher in groundwater, indicating further the subsurface flow dominance. This study provides crucial insights for informed decision-making regarding the hydrological processes amid changing landscapes for sustainable agriculture and biodiversity preservation in the region. The emphasis on subsurface flow dominance underscores its significance in potential transport mechanisms for water quality within the landscape. Landscape management interventions must consider the role of subsurface flow to safeguard environmental resources, enhance water quality, and protect human health.
Managing the trade-off between agricultural productivity and groundwater protection in Switzerland – a model-approach based on long-term lysimeter data
Authors: Holzkämper Annelie
Published: March 2024

Nitrate pollution of groundwater is still an issue of concern at many drinking water wells located in the Swiss lowlands, where agricultural areas are the main pollution source. Extensification measures (e.g. conversion of arable land to extensive grassland, reduction of vegetable/potato areas in favor of cereals) are generally considered to be effective to reduce nitrate leaching to groundwater. However, these measures are also associated with large losses in agricultural productivity and can thus only be implemented on small focused areas within contribution zones of drinking water wells. It is hypothesized here that the trade-offs between agricultural production and groundwater protection can better be managed if more nuanced mitigation strategies are implemented at a broader scale. Such strategies would target at an improved synchrony between plant nitrogen demands and soil nutrient availabilities (e.g. by inclusion of cover crops and optimizing crop rotations, through reduced soil management and demand-driven fertilization practices). Since evaluating the effects of such strategies is anything but trivial given the high complexity of the process interactions and the strong influence of climatic variability, it is the aim of this work to train a mechanistic field scale model that simulates soil water and nutrient dynamics at a field scale in response to soil, climate and management drivers (DAISY model). The calibration builds on an extensive dataset from the lysimeter station Zurich Reckenholz including detailed data since 2009 on nitrate leaching, seepage water generation, soil moisture, water tension, soil temperature, and crop yields for a series of different experiments including non-inversion tillage, cover cropping as well as different fertilization types and amounts. The calibration strategy and selected calibration/validation results will be presented and discussed in context with implications for model applications.
Links between large volcanic eruptions, basal mantle structures and mantle plumes
Authors: Cucchiaro Annalise , Flament Nicolas , Arnould Maëlis , Cressie Noel
Published: March 2024

As part of mantle convection, mantle plumes rise from the deep Earth, leading to volcanic eruptions during which large volumes of mafic magma are emplaced at Earth’s surface over a few million years. In 1971, Jason Morgan showed that seamount chains could be used to calculate the absolute motion of tectonic plates above fixed mantle plumes. This ground-breaking work notably led to the study of the relationship between Earth’s deep interior and its surface. Mantle plumes have been critical to constrain absolute plate motions in Earth’s recent geological past, with the development of both fixed-hotspot and moving-hotspot plate-motion models. Recent studies also revealed a statistical link between large volcanic eruptions and basal mantle structures in space and time, suggesting that large volcanic eruptions, mantle plumes, and hot basal structures are intrinsically connected. In these studies, mantle plumes were considered as the implicit process connecting volcanic eruptions at the surface to hot basal mantle structures. Geodynamic models suggest that mantle plumes are generated by two large antipodal hot basal mantle structures, up to ~1,200 km thick, and shaped by subducted oceanic crust through time. Here, we systematically compare three volcanic-eruption databases, four global tomographic models, and six reconstructions of past global mantle flow, to investigate the spatio-temporal links between volcanic eruptions, hot basal mantle structures, and modelled mantle plumes from 300 million years ago to the present day. We find that large volcanic eruptions are spatially closer to fixed and moving hot basal mantle structures than to modelled mantle plumes, because mantle plumes cover an area that is five orders of magnitude smaller than the area covered by hot basal mantle structures. The strength of the spatial-statistical relationships is largest between volcanic eruptions and modelled mantle plumes and, overall, it is larger between volcanic eruptions and moving basal mantle structures than between volcanic eruptions and fixed basal mantle structures.  This suggests that large volcanic eruptions are preferentially associated with mantle plumes generated from the interior of mobile basal mantle structures, which is in sharp contrast to previous studies that suggested mantle plumes are generated from the edges of fixed basal mantle structures.
Isotopic Analysis of Dissolved CO2 and CH4 in a Coastal Permafrost Zone
Authors: Traylor Shawnee , Youngs Sarah , Pohlman John W. , Kessler John D. , Manganini Kevin , Pardis William , Michel Anna P. M. , Nicholson David P.
Published: March 2024

The steady rise in global temperature is likely to perturb the cycling and transfer of carbon in the coastal Arctic. Given the high carbon content of Arctic soils, this region may become an increasingly important source of methane (CH4) and carbon dioxide (CO2) in response to permafrost loss in coming decades. We present targeted observations along a lake to bay system during the spring thaw around Cambridge Bay, in the coastal Canadian high Arctic. In this system, greenhouse gases produced in the freshwater environment are transported to the bay, where they may undergo further transport, transformation, or ventilation to the atmosphere. As warming alters the timing and dynamics of the ice retreat, carbon sources may shift and the magnitude of outgassing may change. We investigate the sources and pathways of the dissolved CO2 and CH4 via radio- and stable carbon isotope analyses, and conduct a spatial survey using a sensor suite containing a dissolved gas extractor, greenhouse gas analyzer, conductivity-temperature-depth probe, and oxygen optode. Across the transect, observed CH4 ranged from 1-5900 ppm, with δ13C values ranging from -70 to -47‰ (mean: -61.1±10.5‰); CO2 ranged from 100-3350 ppm, with δ13C values of -12 to +38‰ (mean: 6.1±13.1‰). Isotopic depletion of 13C correlated with lower CH4, while enrichment consistent with a primary productivity signal was seen in lower CO2 concentrations. Isotopic signatures additionally clustered with habitat type, revealing spatial variability in the processes controlling the production and transformation of CH4. Radiocarbon dating of the dissolved gases indicated predominantly modern carbon sources at all locations, with the high-CH4 melt ponds containing the youngest carbon (mean age of CH4: 148±16 years; mean age of CO2: 252±16 years). This work aims to enhance our understanding of interannual variability in the carbon cycle dynamics at this site, and to assess the system’s response to a changing climate.
From Fields to Faucets: Modelling the Dynamics of Rural-Urban Water Transfers
Authors: Marston Landon , Amaya Maria , Lin Chung-Yi
Published: March 2024

Growing societal water demands and decreasing water supplies are straining water available for ecosystems and communities in many basins. Increasingly, the only viable option to meet growing urban water demands is to reallocate water from rural agricultural water uses when water supplies have already been fully allocated and it is no longer possible to develop new water supplies. Despite the growing importance of rural-to-urban water transfers, the implications of these transfers on rural prosperity and inequalities are poorly understood. Here, we couple an agent-based model (ABM) with an input-output model to capture the behavior of individual irrigators and how their water transfer decisions propagate through the broader rural economy and shape social dynamics. In this presentation, we will detail our unique modeling framework and share initial results testing multiple hypotheses evaluating how rural-urban water transfers are shaped by social, hydrologic, regulatory, and economic context. This research brings new insights that can be used to evaluate the direct and indirect socioeconomic impacts of water transfers and it can help shape policy to minimize potential negative externalities associated with water transfers.
Significant reduction of potential exposure to extreme marine heatwaves by achieving carbon neutrality
Authors: Oh Seok-Geun , Son Seok-Woo , Jeong Sujong , Cho Yang-Ki
Published: March 2024

Marine heatwave (MHW), a prolonged period of anomalously warm seawater, has a catastrophic repercussion on marine ecosystems. With global warming, MHWs have become increasingly frequent, intense, and prolonged. To avoid irreversible damages from such extreme events, net-zero human-caused carbon emissions by 2050s, called carbon neutrality, were proposed. Here, we evaluate the impact of carbon neutrality on MHWs in the late 21st century using multi-model projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6) Shared Socioeconomic Pathway (SSP)1-1.9 and SSP3-7.0 scenarios. It is found that if the current “regional rivalry” over carbon emissions policy continues into this century (i.e., SSP3-7.0), the MHWs in the late 21st century will become stronger over 1°C and longer lasting over 365 days than historical ones, especially in the western boundary current and equatorial current regions. Approximately 68% of the global ocean will be exposed to permanent MHWs, regionally 93% in the Indian Ocean, 76% in the Pacific Ocean, 68% in the Atlantic Ocean, 65% in the Coastal Ocean, and 48% in the Southern Ocean. Such extreme MHWs can be significantly reduced by achieving carbon neutrality (i.e., SSP1-1.9). In particular, the proportion of exposure to permanent MHWs can be reduced to as low as 0.02 to 0.07%, depending on the region. This result underscores the critical importance of ongoing efforts to achieve net-zero carbon emissions to reduce the potential ecological risks induced by extreme MHW exposure.
Seafloor Cold Seeps as Crucial Mediators of Arsenic Enrichment in Deep Sea
Authors: Li Jiwei , Dong Xiyang , Peng Xiaotong
Published: March 2024

Seafloor cold seepage systems are environments known for their high levels of arsenic, a prevalent and toxic metalloid in nature. However, the biogeochemical mechanisms of arsenic enrichment remain poorly understood. In this study, sediment cores recovered from the active, inactive, and reference areas of the Hama cold seep in the South China Sea were examined using geochemical and metagenomic analyses. Geochemical data revealed evident enrichment of total arsenic, sulfide-bound arsenic, and organic arsenic in the seep site sediments compared to the reference area. Metagenomic analyses identified genes involved in arsenic oxidation (aoxA and arxA) primarily present in the upper zone, while arsenic reduction genes (arrA) were predominantly detected in the deeper zone of the sediment cores in the active area. Moreover, 25 metagenome-Assembled Genomes possessing arsenic reduction genes were affiliated with the Desulfobacterota, possibly syntrophic partners of the Anaerobic Methane Oxidizing Archaea. Furthermore, a strong linear correlation was observed between the dissolved arsenic and DIC (R2=0.64, p
Salinity Change and Its Implications for Ocean Stratification in the Tropical Pacific under Global Warming
Authors: hai zhi
Published: March 2024

The climatological mean and trend of salinity change evidently due to the acceleration of hydrological cycle under global warming. However, no systematic research has been focused on the decadal and long-term changes of salinity and their contributions to ocean stratification during 1940-2019. In this study, the nonlinear trend of salinity is firstly exacted using the ensemble empirical mode decomposition method, and the corresponding long-term trends and their impacts on stratification in the tropical Pacific are analyzed emphatically. The results confirm that the sea surface water becomes fresher in the tropical western Pacific and southern Pacific convergence zone, while saltier in the southeastern Pacific under global warming. Moreover, the salinity changes are regional- and time-dependent, which the salinity trends in different regions of the tropical Pacific show differences at different periods responding to SST trend. As results, under the combined effects of temperature and salinity, the sea surface density reduces significantly in the tropical Pacific, with the largest reduction centered in the warm pool, while the subsurface density in the tropical western Pacific increases. These opposite changes enhance the contrast for the density between the surface and the subsurface water, leading to more stable ocean stratification. Then, the mixed layer becomes shallower near the equatorial dateline and deeper in the warm pool, mainly due to salinity variations. Salinity and temperature contribute differently to the variations of barrier layer thickness in different regions, where the changes of salinity (temperature) correspond to the thickening of barrier layer located at 160°E east (west). It is suggested that the salinity variations in the Pacific affect the ocean thermodynamic processes under global warming, which then modulate the climate variability.
Application of Sedimentary Forward Simulation in the Kezilesu Group of the Kedong Structural Belt
Authors: Zhang Yiming , Zhang Liqiang
Published: March 2024

 In view of the problem that the Cretaceous favorable sedimentary facies belt in Kedong structural belt in the southwest depression of the Tarim Basin is not clear, in order to reduce the uncertainty of the research on the spatial and temporal distribution of source sink sedimentary systems in low drilling density areas, the applicability of sedimentary forward modeling in the Tarim Basin is explored. Based on existing geochemical data, statistical analysis of trace elements and rare earth elements is conducted to explore the ancient sedimentary environment during the sedimentation process of the Cretaceous Kizilsu Group, which is a prerequisite for conducting sedimentary forward modeling. By comprehensively utilizing drilling, seismic and other data, combined with previous research results, DionisosFlow sedimentary forward simulation software is applied to clarify the development characteristics of sedimentary systems. The results show that based on different element abundances, ratios, and sedimentary markers, the study of ancient sedimentary environments shows that the ancient climate is mainly characterized by semi humid, semi dry, and dry hot climate conditions; During the sedimentation period of the Kizilsu Group, the overall water depth was relatively shallow, and the ancient redox environment was a shallow underwater oxidation environment. The favorable paleoenvironmental conditions and abundant material sources provide favorable conditions for the development of shallow water delta sedimentary systems. The Kizilsu Group mainly develops braided river delta sediments in the northern gentle slope zone, with front edge sediments as the main type. The southern steep slope zone develops alluvial fans and fan delta sedimentary systems, and the central part develops shoreline shallow lake facies sediments. The western Kunlun Mountains in the south are the main source of material supply, while the Maigaiti ancient uplift in the north is the secondary source of material supply. The ancient uplift during the sedimentation period of the Kizilsu Group has a blocking effect on the delta that flows into the lake, dividing the southern fan delta and lake sedimentary system from the northern braided river delta and lake sedimentary system.
Development of a Multi-physics Multi-ensemble Subseasonal Prediction System and its Real-time Performance during Contrasting Indian monsoons
Authors: Joseph Susmitha , Dey Avijit , Mandal Raju , Kalshetti Mahesh , Phani Ravuri , Waje Shubham , Sahai Atul
Published: March 2024

Subseasonal predictions with a time scale of 2-4 weeks, which fills the gap between the weather and seasonal forecasts, are limited by the uncertainties arising from the initial conditions as well as the model physics. Therefore, to develop an efficient subseasonal prediction system, both these uncertainties need to be addressed. With this background, a multi-physics multi-ensemble approach has been adopted to develop a competent second-generation subseasonal prediction system at the Indian Institute of Tropical Meteorology (IITM), Pune, India. The first-generation prediction system developed at IITM is run operationally at the India Meteorological Department and has useful skills for up to two weeks.A combination of physics perturbations and initial condition perturbations with a total of 18 ensemble members is present in the system. This system has been experimentally run since May 2022. The hindcast runs during 2003-2018 are also made on-the-fly. The initial results indicate a considerable improvement in the forecast skill compared to its predecessor and have reasonable deterministic prediction skill for up to three weeks. The system could provide skilful prediction of the subseasonal variations during the two contrasting monsoon seasons 2022 (above normal) and 2023 (below normal) 2-3 weeks in advance.
Molecular transformation of organic nitrogen in Antarctic penguin guano-affected soil
Authors: Wu Libin , Sheng Ming , Liu Xiaodong , Fu Pingqing
Published: March 2024

Organic nitrogen (ON) is an important participant in the Earth’s N cycle. Previous studies have shown that penguin feces add an abundance of nutrients including N to the soil, significantly changing the eco-environment in ice-free areas in Antarctica. To explore the molecular transformation of ON in penguin guano-affected soil, we collected guano-free weathered soil, modern guano-affected soil from penguin colonies, ancient guano-affected soil from abandoned penguin colonies, and penguin feces from the Ross Sea region, Antarctica, and Fourier transform ion cyclotron mass spectrometry (FT-ICR MS) was used to investigate the chemical composition of water-extractable ON. By comparing the molecular compositions of ON among different samples, we found that the number of ON compounds (>4,000) in weathered soil is minimal, while carboxylic-rich alicyclic-like molecules (CRAM-like) are dominant. Penguin feces adds ON into the soil with > 10,000 CHON, CHONS and CHN compounds, including CRAM-like, lipid-like, aliphatic/ peptide-like molecules and amines in the guano-affected soil. After the input of penguin feces, macromolecules continue to degrade, and other ON compounds tend to be oxidized into relatively stable CRAM-like molecules, this is an important transformation process of ON in guano-affected soils. We conclude the roles of various forms of ON in the N cycle are complex and diverse. Combined with previous studies, ON eventually turns into inorganic N and is lost from the soil. The lost N ultimately returns to the ocean and the food web, thus completing the N cycle. Our study preliminarily reveals the molecular transformation of ON in penguin guano-affected soil and is important for understanding the N cycle in Antarctica.
Effects of aridification on soil total carbon pools in China's drylands
Authors: Ren Zhuobing , Li Changjia , Fu Bojie , Wang Shuai , Stringer Lindsay C.
Published: March 2024

Drylands are important carbon pools and are highly vulnerable to climate change, particularly in the context of increasing aridity. However, there has been limited research on the effects of aridification on soil total carbon including soil organic carbon and soil inorganic carbon, which hinders comprehensive understanding and projection of soil carbon dynamics in drylands. To determine the response of soil total carbon to aridification, and to understand how aridification drives soil total carbon variation along the aridity gradient through different ecosystem attributes, we measured soil organic carbon, inorganic carbon and total carbon across a ~4000 km aridity gradient in the drylands of northern China. Distribution patterns of organic carbon, inorganic carbon, and total carbon at different sites along the aridity gradient were analyzed. Results showed that soil organic carbon and inorganic carbon had a complementary relationship, that is, an increase in soil inorganic carbon positively compensated for the decrease in organic carbon in semiarid to hyperarid regions. Soil total carbon exhibited a nonlinear change with increasing aridity, and the effect of aridity on total carbon shifted from negative to positive at an aridity level of 0.71. In less arid regions, aridification leads to a decrease in total carbon, mainly through a decrease in organic carbon, whereas in more arid regions, aridification promotes an increase in inorganic carbon and thus an increase in total carbon. Our study highlights the importance of soil inorganic carbon to total carbon and the different effects of aridity on soil carbon pools in drylands. Soil total carbon needs to be considered when developing measures to conserve the terrestrial carbon sink.