Search Results (448)

This study evaluated the seasonal variability of soil–atmosphere greenhouse gas (GHG) fluxes—carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O)—across a land-use gradient in the Andean–Amazon transition zone of Colombia. The gradient included five land-use types incorporating at least one innovative climate-smart practice—improved pasture (IP), cacao agroforestry system (CaAS), copoazu agroforestry system (CoAS), secondary forest with agroforestry enrichment (SFAE), and moriche palm swamp ecosystem (MPSE)—alongside the dominant regional land uses, old-growth forest (OF) and degraded pasture (DP). Soil GHG fluxes varied markedly among land-use types and between seasons. CO₂ fluxes were consistently higher during the dry season, whereas CH₄ and N₂O fluxes peaked in the rainy season. Agroecological and restoration systems exhibited substantially lower CO₂ emissions (7.34–9.74 Mg CO₂-C ha⁻¹ yr⁻¹) compared with DP (18.85 Mg CO₂-C ha⁻¹ yr⁻¹) during the rainy season, and lower N₂O fluxes (0.21–1.04 Mg CO₂-C ha⁻¹ yr⁻¹) during the dry season. In contrast, the MPSE presented high CH₄ emissions in the rainy season (300.45 kg CH₄-C ha⁻¹ yr⁻¹). Across all land uses, CO₂ was the dominant contributor to the total GWP (>95% of emissions). The highest global warming potential (GWP) occurred in DP, whereas CaAS, CoAS and MPSE exhibited the lowest values. Soil temperature, pH, exchangeable acidity, texture, and bulk density play a decisive role in regulating GHG fluxes, whereas climatic factors, such as air temperature and relative humidity, influence fluxes indirectly by modulating soil conditions. These findings underscore the role of diversified agroforestry and restoration systems in mitigating GHG emissions and the need to integrate soil and climate drivers into regional climate models. Full article

Quantifying deep soil (10–100 cm) and non-growing-season soil respiration (SR) is crucial for refining carbon (C) cycle models, yet the regulatory mechanisms governing these processes remain unclear. The novelty of this study lies in its focus on deep soils and non-growing seasons to elucidate how soil properties regulate SR under these special conditions. We conducted an on-site field experiment in the Caragana korshinskii plantation, measuring SR at soil depths of 0–10 cm, 10–50 cm, and 50–100 cm during the non-growing season and growing. The results suggested that the annual cumulative soil CO₂ fluxes reached 510.1 (0–10 cm), 131.5 (10–50 cm), and 45.3 g CO₂·m⁻² (50–100 cm). These emissions during the non-growing season accounted for 33%, 31%, and 32%, respectively. The soil physical properties (temperature, moisture, bulk density) explained the greatest variation in SR during growing and non-growing periods, followed by the biological properties (α-diversity, root biomass) and chemical properties (soil organic C, ammonium nitrogen, total C/nitrogen ratio). Depth-specific analysis demonstrated that soil physical properties explained the most SR variance at three depths with independent contributions of 78.9% (0–10 cm), 89.7% (10–50 cm), and 76.9% (50–100 cm). These values exceeded the independent contributions of chemical properties (70.3%, 70.9%, 60.0%) and biological properties (54.9%, 45.1%, 41.6%) at the corresponding depths. Overall, deep soil and non-growing season SR represent important C emission sources; excluding them may therefore substantially overestimate net C sequestration potential. Full article

Saline–alkali soils in arid regions are increasingly recognized as critical yet underrepresented components of the global carbon cycle. However, their CO₂ flux dynamics under warming remain poorly understood. In this study, we conducted controlled growth-chamber experiments using typical saline–alkali soils from the Taklamakan Desert, where temperature, soil moisture, and atmospheric CO₂ concentrations were systematically manipulated. We quantified how warming reshaped moisture–temperature interactions regulating soil CO₂ fluxes. The results revealed a pronounced diurnal variation pattern, characterized by daytime CO₂ release and nighttime uptake. Temperature was identified as the dominant driver (R² > 0.93, p < 0.001), whereas soil moisture primarily modulated flux intensity; at 0.8 cm³ cm⁻³, fluxes declined by up to 61% compared with the baseline. Warming enhanced the temperature–moisture synergy (−43%, p < 0.01) and simultaneously reduced baseline fluxes (−56%, p < 0.01). These shifts fundamentally altered the regulation of CO₂ flux dynamics. Our findings highlight the necessity of integrating salt dynamics and carbonate equilibria into multiphase reactive transport models to improve regional carbon sink assessments. Ultimately, this study refines estimates of the contribution of saline–alkali soils to the global “missing carbon sink” (~1.7 Pg C a⁻¹) and emphasizes their overlooked role in the Earth’s carbon budget under a warming climate. Full article

The use of cover crops is one of the most effective practices for maintaining, or even improving, the carbon balance of agricultural soils, while offering various ecosystem benefits. However, replacing bare soil with cover crops can increase transpiration and potentially reduce the water available for subsequent cash crops. The study takes place in southwestern France where it is essential to strike a balance between carbon storage and water availability, and where agroecological practices are encouraged and water resources are limited and expected to diminish with climate change. In this study, estimates of cover crop biomass production, as well as of the components of the water and carbon cycles, are carried out using a hybrid approach, AgriCarbon-EO, combining modeling, remote sensing, and assimilation, with quantification of target variables and their uncertainties at decametric resolution. The SAFYE-CO₂ agrometeorological model used in AgriCarbon-EO is calibrated to represent cover crops development, and simulated variables are compared with CO₂ fluxes and evapotranspiration measured by eddy covariance (for NEE, R² = 0.57, RMSE = 0.97 gC·m⁻²; for ETR, R² = 0.42, RMSE = 0.87 mm), as well as to an extensive above-ground biomass dataset (R² = 0.71, RMSE = 93.3 g·m⁻²). Knowing the local performance of the approach, a large-scale, decametric-resolution modeling exercise was carried out to simulate winter cover crops in southwestern France, over five contrasting fallow periods. The significant variability in cover crop phenology and above-ground biomass was characterized, and estimates of the amount of humified carbon added to the soil by cover crops were quantified at the pixel level. With amounts ranging from 40 to 130 gC·m⁻² for most of the considered pixels, these new SOC values show clear trends as a function of cumulative evapotranspiration. However, the impact of cover crops on soil water content appears to be minimal due to spring precipitation. Full article

We investigated the CO₂ emissions in a mofette gas pool located in Covasna, Romania. Using a custom-built remote multi-sensor device, we monitored the gas concentrations, temperature, and pressure for seven months. The measurements showed both diurnal cycles and short-term bursts of CO₂ emissions along with instances of erratic yield anomalies. We employed the convection–diffusion equation to estimate gas flow rates without altering the natural state of the mofette. Additionally, we developed a model that uses the measured pressure and temperature to predict the CO₂ outflow yield. The model’s overall predictions approximate well the observed CO₂ flux. However, the subtle mismatches between these two suggest that subsurface geological processes, which require further investigation, may also influence the gas flow. This research provides insights into the dynamics of focused CO₂ emissions, with potential applications in environmental monitoring and therapeutic practices. Full article

The production and transport of dissolved inorganic carbon (DIC) is central to weathering reactions and the global carbon cycle. We investigated the spatiotemporal variability and export of inorganic carbon species along the rapidly weathering Langtang–Narayani river system in the central Nepal Himalaya. Over the course of one year, surface water samples were collected from sixteen stations spanning a wide range of elevations. DIC concentrations generally declined with increasing elevation, except in mid-mountain sites influenced by hot springs. Bicarbonate (HCO₃⁻) was identified as the dominant inorganic carbon species, contributing approximately 85% to the total DIC and with a similar dominant export rate of bicarbonate to total DIC export rate, followed by carbon dioxide (CO₂) and carbonate (CO₃²⁻). The river water exhibited a strong altitudinal gradient in carbonate chemistry, with CO₂ supersaturation in the lowlands and undersaturation at higher elevations. Metamorphic activities in the lower mid-mountain sites significantly influenced CO₂ concentrations and inorganic carbon dynamics. The partial pressure of CO₂ (pCO₂) varied widely (56 to 33,869 μatm), reflecting distinct geochemical and seasonal controls. The estimated DIC export rates were 93.66, 37.81, and 12.59 tons km⁻² yr⁻¹ from the Narayani River in the lowlands, the Trisuli River in the mid-mountains, and the Langtang River in the high Himalaya region, respectively. These findings highlight the critical role of elevation, seasonality, and geological processes in regulating carbon dynamics in Himalayan river systems, providing new insights into their contribution to regional carbon fluxes. A comprehensive array of significant univariate and multivariate predictive models is presented here, offering versatile applications, including the interpretation of full and partial derivatives explaining inorganic carbon dynamics within the Himalayan basin. Full article

Background: Hypoxia-induced glycolysis represents a hallmark of colorectal cancer (CRC) progression and contributes significantly to therapeutic resistance. Curcumol, a natural sesquiterpenoid derived from Curcumae Rhizoma, has demonstrated promising anti-tumor properties. However, its impact on metabolic reprogramming under hypoxic conditions remains largely undefined. Objective: The objective of this study was to elucidate the potential of Curcumol in inhibiting glycolytic reprogramming and impede CRC progression via regulation of the VHL/HIF-1α signaling pathway. Methods: CRC cells and orthotopic mouse models were treated with Curcumol under chemically induced hypoxic conditions. Metabolic alterations were evaluated using Seahorse extracellular flux analysis, Western blot analysis, quantitative real-time PCR (qRT-PCR), immunohistochemistry (IHC) and co-immunoprecipitation (Co-IP). Functional validation of glycolysis and epithelial–mesenchymal transition (EMT) phenotypes was conducted through in vitro and in vivo assays. Results: Curcumol inhibited HIF-1α-mediated metabolic reprogramming by upregulating VHL expression, thereby promoting HIF-1α degradation. This effect led to the downregulation of key glycolytic genes (HK2, LDHA, and GLUT1), decreased glycolytic flux, and lactate production, ultimately suppressing CRC cell proliferation and invasion. The anti-tumor efficacy of Curcumol was validated in both in vitro and in vivo models. Moreover, Curcumol effectively reversed the hypoxia-induced epithelial–mesenchymal transition (EMT) phenotype, suggesting that its metabolic regulatory effects may contribute to reduced metastatic potential. Conclusions: Curcumol suppresses glycolysis and CRC progression by activating the VHL/HIF-1α signaling axis. These findings underscore the potential of Curcumol as a natural metabolic regulator capable of reversing tumor metabolic reprogramming, offering a promising therapeutic strategy for CRC treatment. Full article

The Super-long Gravity Heat Pipe (SLGHP) is an efficient geothermal energy utilization technology that can transmit thermal energy by fully utilizing natural temperature differences without external energy input. This study focuses on the high-altitude geothermal environment of Mount Meager, Canada, and employs numerical simulations and dynamic thermal analysis to systematically investigate the thermal transport performance of the SLGHP system under both steady-state and dynamic operating conditions. The study also examines the impact of various structural parameters on the system’s performance. Three-dimensional CFD simulations were conducted to analyze the effects of pipe diameter, length, filling ratio, working fluid selection, and pipe material on the heat transfer efficiency and heat flux distribution of the SLGHP. The results indicate that working fluids such as CO₂ and NH₃ significantly enhance the heat flux density, while increasing pipe diameter may reduce the amount of liquid retained in the condenser section, thereby affecting condensate return and thermal stability. Furthermore, dynamic thermal analysis using a three-node RC network model simulated the effects of diurnal temperature fluctuations and variations in the convective heat transfer coefficient in the condenser section on system thermal stability. The results show that the condenser heat flux can reach a peak of 5246 W/m² during the day, while maintaining a range of 2200–2600 W/m² at night, with the system exhibiting good thermal responsiveness and no significant lag or flow interruption. In addition, based on the thermal output of the SLGHP system and the integration with the Organic Rankine Cycle (ORC) system, the power generation potential analysis indicates that the system, with 100 heat pipes, can provide stable power generation of 50–60 kW. In contrast to previous SLGHP studies focused on generalized modeling, this work introduces a site-specific CFD–RC framework, quantifies structural sensitivity via heat flux indices, and bridges numerical performance with economic feasibility, offering actionable insights for high-altitude deployment. This system has promising practical applications, particularly for providing stable renewable power in remote and cold regions. Future research will focus on field experiments and system optimization to further improve system efficiency and economic viability. Full article

The biological performance and carbon dioxide (CO₂) flux of the novel and emerging concept of a membrane carbonated microalgal biofilm photobioreactor (MC-MBPBR) for wastewater treatment were investigated using mathematical modelling in conjunction with the finite-difference method. A set of differential equations was established to model the performance of an MC-MBPBR. The impacts of CO₂ partial pressure, wastewater characteristics, and biofilm thickness on the concentration profiles and fluxes of CO₂ and nutrients (N and P) to the biofilm of the MC-MBPBR were systematically studied. The modelling results showed profound impacts of these parameters on process efficiency (CO₂ transfer and N and P removals) and the existence of an optimal biofilm thickness for maximum CO₂, N, and P fluxes into the biofilm. Penetration of CO₂ through the biofilm into the bulk water phase might occur under certain conditions. An increase in gaseous CO₂ and increased influent N and P concentrations led to higher CO₂, N, and P fluxes. The optimal biofilm thickness varied with the change in wastewater characteristics and gaseous CO₂ concentration. The modelling results were in relatively good agreement with experimental results from the literature. The proposed mathematical models can be used as a powerful tool to optimize the design and operation of the novel MC-MBPBR for wastewater treatment and microalgae cultivation. Full article

Tropical and subtropical forests account for approximately one-third of global terrestrial gross primary productivity (GPP), and the diurnal patterns of GPP strongly regulate the land–atmosphere CO₂ interactions and feedback to the climate. Combined with ground eddy-covariance (EC) flux towers, geostationary satellites offer significant advantages for continuously monitoring these diurnal variations in the “breathing of biosphere”. Here we utilized half-hourly optical signals from the Himawari-8 Advanced Himawari Imager (H8/AHI) geostationary satellite and tower-based EC flux data to investigate the diurnal variations in subtropical forest GPP and its drivers. Results showed that three machine learning models well estimated the diurnal patterns of subtropical forest GPP, with the determination coefficient (R²) ranging from 0.71 to 0.76. Photosynthetically active radiation (PAR) is the primary driver of the diurnal cycle of GPP, modulated by temperature, soil water content, and vapor pressure deficit. Moreover, the effect magnitude of PAR on GPP varies across three timescales. This study provides robust technical support for diurnal forest GPP estimations and the possibility for large-scale estimations of diurnal GPP over tropics in the future. Full article

Quantifying air emissions from livestock pastures remains challenging due to spatial variability and temporal fluctuations in emissions due to weather conditions. In this study we used a small unmanned aerial vehicle (sUAV) equipped with real-time sensors and an air sample collection system to directly measure carbon dioxide (CO₂), methane (CH₄), ammonia (NH₃), nitrous oxide (N₂O), nitrogen dioxide (NO₂), hydrogen sulfide (H₂S), total volatile organic compound (VOC), and particulate matter (PM₁, PM_2.5, PM₁₀) emissions across two dairy pastures, two beef pastures, and one sheep pasture in Wisconsin. Emission rates were calculated using the Lagrangian mass balance model and validated against ground-level dynamic flux chamber (DFC) measurements. UAV-based CO₂ concentrations showed a strong correlation with DFC measurements (R² = 0.86, RMSE = 21.5 ppm, MBE = +9.7 ppm). Dairy 1 yielded the highest emissions for most compounds, with average emission rates of 0.50 ± 0.28 g m⁻² day⁻¹ head⁻¹ for CO₂, 8.48 ± 2.75 mg m⁻² day⁻¹ head⁻¹ for CH₄, and 0.20 ± 0.60 mg m⁻² day⁻¹ head⁻¹ for NH₃. The sheep pasture, on the other hand, had the lowest CH₄ and NH₃ emission rates, averaging 0.35 ± 0.22 mg m⁻² day⁻¹ head⁻¹ and 0.02 ± 0.05 mg m⁻² day⁻¹ head⁻¹, respectively. Rainfall events (≥ 5 mm within five days of sampling) significantly elevated N₂O emissions (0.56 ± 0.40 vs. 0.13 ± 0.17 mg m⁻² day⁻¹ head⁻¹). Particulate matter emissions were significantly affected by forage density. PM_2.5 emission rates reached 1.25 × 10⁻⁴ g m⁻² day⁻¹ head⁻¹ under low vegetative cover. It was concluded that emissions were affected by both animal species and the environmental conditions. The findings of this study provide a foundation for further development of emission inventories for pasture-based livestock production systems. Full article

The liver orchestrates metabolic homeostasis through dynamic post-translational modifications. β-hydroxybutyrylation (Kbhb), a ketone body-driven modification, regulates epigenetics and metabolism in humans and mice but remains unexplored in livestock. Here, we characterize the porcine hepatic β-hydroxybutyrylome using high-resolution mass spectrometry, identifying 4982 Kbhb sites on 2122 proteins—the largest dataset to date. β-hydroxybutyrylation predominantly targets non-histone proteins (99.68%), with enrichment in fatty acid β-oxidation, TCA cycle, and oxidative phosphorylation pathways. Subcellular localization revealed cytoplasmic (38.1%), mitochondrial (18.1%), and nuclear (15.3%) dominance, reflecting BHB-CoA synthesis sites. Motif analysis identified conserved leucine, phenylalanine, and valine residues at modified lysines, suggesting enzyme-substrate specificity. β-hydroxybutyrate treatment elevated global Kbhb levels, increasing TCA intermediates (e.g., α-ketoglutarate, +9.56-fold) while reducing acetyl-CoA, indicating enhanced mitochondrial flux. Cross-species comparisons showed tissue-specific Kbhb distribution (nuclear in human cells vs. mitochondrial in mice), highlighting metabolic adaptations. This study establishes pigs as a model for Kbhb research, linking it to energy regulation and providing insights into metabolic reprogramming. Full article

Static chambers combined with isotopic (δ¹³C and δ¹⁸O) and flux (CO₂ and CH₄) measurements were applied, to explore the effects of mosses and long-term nitrogen (N) addition at two levels (22.5 and 45 kg N ha⁻¹ yr⁻¹) on δ¹³C and δ¹⁸O values of respired CO₂ across three autumn seasons under a temperate forest (northeastern China) and their relationships with CO₂ and CH₄ fluxes and with soil properties. Mosses generally depleted δ¹³C and enriched δ¹⁸O in respired CO₂, likely by altering soil microenvironments or/and substrate use. The effect of N addition on the δ¹³C and δ¹⁸O values of respired CO₂ varied with years, and its interaction with mosses had no effects on the isotopic values. The removal of mosses decreased CO₂ fluxes and the addition of N at a high dose increased CH₄ fluxes. The δ¹³C and δ¹⁸O values of respired CO₂ decreased at soil moisture levels below and above an optimum, and the moisture-dependent effect became more pronounced for the δ¹⁸O than for the δ¹³C. The results of structural equation modeling showed that 70% of the variability of δ¹³C values of respired CO_2. was accounted for by the N addition, mosses, soil moisture, and CH₄ and CO₂ fluxes, while only 22% of the variability of δ¹⁸O values of respired CO₂ was explained by these factors. The results highlight that moss–soil interaction drives the isotopic shifts, which is modulated by N availability. Soil moisture regulates the δ¹⁸O values of respired CO₂, but its drivers remain poorly understood. Future work should target processes influencing the δ¹⁸O shifts of respired CO₂ and deep soil property interactions. Full article

Desert steppe ecosystems, characterized by water limitation and high sensitivity to global climate change and anthropogenic disturbance drivers, experience profound alterations in carbon (C) cycling processes driven by the multiplicative interactions among grassland grazing, altered precipitation regimes, and elevated atmospheric nitrogen deposition. However, how historical grazing legacies modulate ecosystem responses to concurrent changes in nitrogen deposition and precipitation regimes remains poorly resolved. To address this, we conducted a field experiment manipulating water and nitrogen addition across grazing intensities (no grazing, light grazing, moderate grazing, heavy grazing) in a Stipa breviflora desert steppe. Over three consecutive growing seasons (2015–2017), we continuously monitored net ecosystem CO₂ exchange (NEE), ecosystem respiration (ER), and gross ecosystem production (GEP) to quantify ecosystem CO₂ fluxes under these interacting global change drivers. Results revealed that water and nitrogen addition did not alter seasonal CO₂ flux dynamics across grazing intensities. Light grazing enhanced ecosystem C sink capacity, whereas heavy grazing reduced NEE and GEP, diminishing C sink strength. Water addition significantly increased CO₂ fluxes, strongly correlated with soil moisture. Nitrogen addition exerted a weak C source effect in a water-deficient year but enhanced the C sink in a water-rich year. Nitrogen plus water addition significantly boosted C sink potential, though this effect diminished along the grazing pressure gradient. Our findings demonstrate that the impacts of climate change on soil C fluxes in desert steppes are mediated by historical grazing intensity. Future manipulative experiments should explicitly incorporate grazing legacy effects, and integrate this factor into C models to generate reliable predictions of grassland C dynamics under global change scenarios. Full article

Temperate grasslands are highly sensitive to climate change and play a crucial role in terrestrial carbon cycling. In the context of global warming, heterotrophic respiration (Rh) has intensified, contributing significantly to atmospheric CO₂ emissions. However, seasonal patterns of Rh, particularly differences between the growing season (GS) and non-growing season (non-GS), remain poorly quantified. This study used daily eddy covariance data from multiple flux towers combined with MODIS GPP and NPP products to estimate Rh across temperate grasslands from 2002 to 2021. We examined interannual variations in GS and non-GS Rh contributions and assessed their relationships with key hydrothermal variables. The results showed that mean Rh during GS and non-GS was 527 ± 357 and 341 ± 180 g C m⁻² yr⁻¹, respectively, accounting for 57.8 ± 14.6% and 42.2 ± 14.6% of the annual Rh. Moreover, GS Rh exhibited a declining trend, while non-GS Rh increased over time, indicating a gradual convergence in their seasonal contributions. This pattern was primarily driven by increasing drought stress in GS and warmer, moderately moist conditions in non-GS that favored microbial activity. Our findings underscore the necessity of distinguishing seasonal Rh dynamics when investigating global carbon cycle dynamics. Future earth system models should place greater emphasis on seasonal differences in soil respiration processes by explicitly incorporating the influence of soil moisture on the decomposition rate of soil organic carbon, in order to improve the accuracy of carbon release risk assessments under global change scenarios. Full article