Dry Carbon Research Articles

Carbonization of Refuse-Derived Fuel Pellets with Biomass Incorporation to Solid Fuel Production

In this work, dry carbonization (DC) and hydrothermal carbonization (HTC) of refuse-derived fuel (RDF) pellets were conducted to evaluate the physical, chemical, and fuel properties of the produced chars. In the dry carbonization tests, biomass sawdust was incorporated in different proportions on the samples to minimize agglomeration caused by the melting of the plastic fraction. The experiments were carried out in a temperature of 400 °C (DC) and 250–300 °C (HTC), in a residence time of 30 min. The respective chars and hydrochars were characterized according to their mass yield, apparent density, proximate, elemental, and mineral composition, chlorine content, high heating value, thermogravimetric profile, and surface functional groups. The results showed that the dry carbonization of RDF pellets with biomass incorporation, followed by a washing step, resulted in the production of chars with improved properties such as higher fixed carbon and higher heating value (HHV) (25–26 MJ/kg) and lower ash and chlorine content. Additionally, the HTC experiments demonstrated that hydrochars showed improved properties without the need for biomass addition and washing, however, with no significant difference in the HHV (20–21 MJ/kg). Therefore, DC of RDF pellets with 10% biomass incorporation seems to be a promising option to overcome the constraints of RDF utilization as an alternative fuel.

Phase Behavior and Rational Development Mode of a Fractured Gas Condensate Reservoir with High Pressure and Temperature: A Case Study of the Bozi 3 Block

The Bozi 3 reservoir is an ultra-deep condensate reservoir (−7800 m) with a high temperature (138.24 °C) and high pressure (104.78 MPa), leading to complex phase behaviors. Few PVT studies could be referred in the literature to meet such high temperature and pressure conditions. Furthermore, it is questionable regarding the applicability of existing condensate production techniques to such a high temperature and pressure reservoir. This study first characterized the phase behavior via PVT experiments and EOS tuning. The operating conditions were then optimized through reservoir numerical simulation. Results showed that: (1) the critical condensate temperature and pressure of Bozi 3 condensate gas were 326.24 °C and 43.83 MPa, respectively; (2) four gases (methane, recycled dry gas, carbon dioxide, and nitrogen) were analyzed, and methane was identified as the optimal injection gas; (3) gas injection started when the production began to fall and achieved higher recovery than gas injection started when the pressure fell below the dew-point pressure; (4) simultaneous injection of methane at both the upper and lower parts of the reservoir can effectively produce condensate oil over the entire block. This scheme achieved 8690.43 m3 more oil production and 2.75% higher recovery factor in comparison with depletion production.

A preliminary report of integrating sheep farming in combination with adopting biogas technology in organic rice farming systems in upland areas in Indonesia

This study aims to understand the preliminary results of integrating sheep farming in combination with adopting biogas technology in organic rice farming (ORF) systems in upland areas. The research was conducted in upland areas in Grabag Subdistrict Magelang Regency, Central Java Province (UPL1) and Kertasari Subdistrict, Tasikmalaya Regency, West Java Province (UPL2), Indonesia. At each upland area, a demo plot with a 17 m3 digester has been established, and 120 sheep were introduced. A combination of sheep and beef cattle manure was used as a biogas substrate. The soil sample of one and three-year conversion of ORF was collected, and macro and micro minerals were analyzed. The biogas quality was analyzed, including dry matter (DM), nitrogen (N), carbon (C) and nitrogen-ammonia (N-NH3). The greenhouse (GHG) emissions, including methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O), were measured. The results indicated that C-organic content at three-year conversions of ORF in UPL1 was much lower (P<0.05) than the one-year conversion. The average CH4, CO2, and N2O contents in UPL1 were 661, 477.3, and 0.16 mg/m2/day, respectively. The average CH4, CO2, and N2O contents in UPL2 were 3328, 3038 and 2.42 mg/m2/day, respectively. In UPL1, the proportion of CH4 was 52.5 %, CO2 was 47.4 %, and N2O was 0.01 % while the proportion of CH4 was 57.9 %, CO2 was 42.0 %, and N2O was 0.01 % in UPL2. To conclude, integrating sheep farming in combination with adopting biogas technology in the ORF system improves manure management and provides organic fertilizer, which subsequently reduces the use of artificial fertilizer and avoids GHG emissions.v

Increased rainfall frequency enhances dry seasonal soil mineral-associated organic carbon in a subtropical forest

Climate models predict longer and more severe droughts, and alterations in the frequency and intensity of rainfall events. However, how changing precipitation patterns affect soil organic carbon (SOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) remains unclear. Here, we conducted a three-year rainfall manipulation experiment with ambient rainfall as the control, removal of half the total rainfall amount with unaltered frequency (DRA), and increased rainfall frequency with the total amounts unchanged (IRF) in a subtropical forest. The results showed that the rainfall treatments did not change SOC content or fractions during the wet season. In the dry season, DRA significantly increased topsoil POC but did not change SOC or MAOC. IRF significantly increased POC and MAOC levels. The increased MAOC was associated with the newly formed binary complexes of Fe3+, Al3+, and Ca2+, and the adsorption/precipitation of reduced short-range-ordered Fe oxides, likely derived from the enhanced reductive dissolution in the IRF treatment. Our results suggest that changes in rainfall frequency affect organo-mineral interactions more profoundly relative to the rainfall amount and that these effects are season-dependent. Therefore, moisture-sensitive geochemical processes play an essential role in SOC stabilization in subtropical forests.

The Effectiveness of Dry Carbon Dioxide Baths in Menopausal Syndrome: a Randomized Clinical Study

INTRODUCTION. Climacteric syndrome is characterized by significant disorders in the nervous, musculoskeletal, urinary and cardiovascular systems in women of the perimenopausal and postmenopausal periods. The main reason is a sharp decrease in estrogen levels. Menopausal hormone therapy is often used for treatment, but due to contraindications and complications, it does not always completely solve the problem. This has sparked interest in alternative treatments such as dry carbon dioxide baths. AIM. To study the effectiveness of using dry carbon dioxide baths in women with menopausal syndrome and evaluate their impact on the neurovegetative, metabolic and psycho-emotional state of these patients. MATERIALS AND METHODS. A prospective randomized study was conducted involving 70 patients with moderate climacteric syndrome aged from 48 to 60 years. Using a simple randomization method, the women were divided into 2 groups: 35 patients of the main group received 10 procedures of dry carbon dioxide baths with a CO2 concentration of 15–20 %, temperature 28–32 °C, lasting 15–20 minutes, 35 patients of the control group did not receive any treatment. To assess the effectiveness of treatment, a modified Kupperman-Uvarova menopausal index, an assessment of the effect of “hot flashes” on daily life on the HFRDIS scale, as well as daily blood pressure monitoring (SMAD) were used. RESULTS AND DISCUSSION. After treatment, patients in the main group observed a significantly significant (p 0.05) improvement in the patients’ condition in the form of a decrease in integral indicators of the modified menopausal index and an assessment of the impact of hot flashes on daily activity on the HFRDIS scale by 28.2 and 43.1 %, respectively, as well as in the form of a decrease in average daily systolic blood pressure by 13.7 %. CONCLUSION. The use of dry carbon dioxide baths is recommended for use in women with moderate climacteric syndrome, since this method significantly improves the quality of life of patients and is an effective non-drug that can reduce the drug load on the body of a woman suffering from neurovegetative disorders.

Integrating Deficit Irrigation Strategies and Soil-Management Systems in Almond Orchards for Resilient Agriculture

This work was conducted over three-year monitoring seasons of three almond cultivars (Guara, Marta, and Lauranne) subjected to deficit irrigation in combination with cover crops in a Mediterranean semiarid area (SW, Spain). Four water–soil treatments were evaluated based on the conjunction of two irrigation strategies: fully irrigated (FI), covering 100% of the ETC, and regulated deficit irrigation (RDI), with two soil-management systems: bare soil (BS) and cover crop based on a mixture of vetch (Vicia sativa L.) and oat (Avena sativa L.) (CC). Throughout the study period in trees, the yield, the stem water potential (Ψstem), leaf nutrient content (N, P, K, Ca, Mg, Na, Fe, Zn, Mn, and Cu) in soils, organic carbon, microbial biomass, fluoresceine diacetate, and enzymatic activities (dehydrogenase, protease, β-glucosidase, and alkaline phosphatase) were determined. In addition, the dry matter and carbon fixation by plant covers were evaluated. For Guara and Lauranne, yield reductions (22 and 26%, respectively) were found for water-stressed (RDI-CC) plots with respect to non-stressed combination (FI-CC) plots, contrasting with cv. Marta, without a significant impact on productivity in all combinations. That is, the RDI (~3.000 m3 ha−1) strategy enabled acceptable productivity, offering promising possibilities for cultivation performance under water-scarcity scenarios. Important differences in Ψstem could be observed and ascribed to irrigation strategies, especially for Guara and Lauranne, but without significant effects due to the soil-management systems applied. No differences were observed in the tree nutritional status due to the presence or absence of CC; however, its presence increased the fixation of atmospheric carbon, which was not the case under BS conditions. Additionally, CC significantly fostered the microbial processes and enzymatic activities, particularly in upper soil layers (0–10 cm) and with plenty of water supply in FI-CC plots and to a lesser extent in RDI-CC plots, which could encourage prominent aspects for soil quality and health restoration. Thus, the cover crop is congruent with RDI to facilitate soil functionality and water savings in a changing climate, contributing to resilient farming systems in the Mediterranean environment.

Simulation of a Hazardous Chemical Cascading Accident Using the Graph Neural Network

In the storage of hazardous chemicals, due to space limitations, various hazardous chemicals are usually mixed stored when their chemical properties do not conflict. In a fire or other accidents during storage, the emergency response includes two key steps: first, using fire extinguishers like dry powder and carbon dioxide to extinguish the burning hazardous chemicals. In addition, hazardous chemicals around the accident site are often watered to cool down to prevent the spread of the fire. But both the water and extinguishers may react chemically with hazardous chemicals at the accident site, potentially triggering secondary accidents. However, the existing research about hazardous chemical domino accidents only focuses on the pre-rescue stage and ignores the simulation of rescue-induced accidents that occur after rescue. Aiming at the problem, a quantitative representation algorithm for the spatial correlation of hazardous chemicals is first proposed to enhance the understanding of their spatial relationships. Subsequently, a graph neural network is introduced to simulate the evolution process of hazardous chemical cascade accidents. By aggregating the physical and chemical characteristics, the initial accident information of nodes, and bi-temporal node status information, deep learning models have gained the ability to accurately predict node states, thereby improving the intelligent simulation of hazardous chemical accidents. The experimental results validated the effectiveness of the method.

Stress–strain hysteresis during hydrostatic loading of porous rocks

A micro-mechanical model is proposed to predict the stress–strain hysteresis during the cyclic hydrostatic loading of fluid-saturated rocks under drained or undrained conditions. A spherical pore is surrounded by a multi-cracked shell where local deviatoric stress develops despite the remote hydrostatic loading. The effective properties of the material composing the shell are constructed assuming an isotropic distribution of cracks with no interaction, and the overall properties thanks to the spherical assemblage approach. The fluid pressure in drained and undrained conditions is assumed to be uniform throughout the assemblage. A new analytical solution is proposed, assuming all cracks are closed and slipping either forwardly or reversely. It is shown with numerical simulations for drained conditions that this assumption is indeed respected for sufficiently small values of the crack friction angle. However, for reasonable values, the closed cracks during the unloading phase could slip in either direction: reversely close to the pore and still forwardly away from the pore. Moreover, at critical radii, the slip could occur in either direction depending on the crack orientation. A similar micro-structural response is observed for undrained conditions, although the remote confining stress required to close the cracks is much larger. The model’s predictions compare favourably with recent experimental data on dry sandstones and carbonates, which were presented in a study on the influence of strain amplitude on the transition between static and dynamic properties. The crack density and matrix elasticity modulus are sufficient fitting parameters to accurately predict the hysteresis loops, especially for porosity levels above 10%.

Remediation of Arsenic and Heavy Metals and Soil Stabilization by Waste Chitosan based Biochar

Objectives : This study aims to evaluate the feasibility of converting waste chitosan adsorbents, laden with microalgae, into biochar for application as a stabilizing agent to remediate heavy metal-contaminated soil and improve soil quality.Methods : Waste chitosan adsorbents were converted into biochar through two processes: dry thermal carbonization at 400°C to produce pyrochar and hydrothermal carbonization at 200°C to produce hydrochar. The elemental compositions, surface functional groups, morphologies of the biochars were evaluated by elemental analyzer, FT-IR spectrometer, and SEM analysis. The arsenic and heavy metal adsorption characteristics of the produced biochars were assessed. Additionally, the produced biochars were applied as stabilizing agents to arsenic and heavy metal-contaminated soil with varying mixing ratios of 2, 5 and 10 wt%. After a one-week soil stabilization experiment, soil properties and TCLP(Toxicity Characteristic Leaching Procedure) leaching tests were conducted.Results and Discussion : The pyrochar produced from waste chitosan exhibited a porous structure with high pH (pH 10) and minimal surface functional groups. The hydrochar consisted of spherical particles with functional groups such as hydroxyl and amine groups on the surface, exhibiting a slightly acidic pH of 5.8. Pyrochar has a higher adsorption capacity for cationic heavy metals compared to hydrochar due to its porous structure and high pH. On the other hand, when applied to soil, hydrochar demonstrated superior stabilization efficiency for arsenic and heavy metals. This is attributed to the diverse surface functional groups containing oxygen on the hydrochar. The stabilization efficiency was influenced by the biochar mixing ratio, with a 5% hydrochar application resulting in 10-64% stabilization efficiency for all elements.Conclusion : This study confirmed that biochar produced from waste chitosan effectively stabilizes arsenic and heavy metals in soils. Additionally, the quantity of biochar used can impact its effectiveness in stabilization.

Mechanochemical carbonation of recycled concrete fines: Towards a high-efficiency recycling and CO2 sequestration

The relative slow carbonation efficiency for conventional wet and dry carbonation of recycled concrete fines (RCF) limits its resource industrial utilization. In this study, an innovative mechanochemical carbonation (MC) method was developed. The carbonation kinetics, phase assemblage and microstructure evolution of RCF during the MC process were extensively examined. The results exhibited a substantial enhancement in the carbonation efficiency and CO2 utilization rate, as evidenced by achieving a notable carbonation degree within 10 min. This accomplishment surpassed what could be achieved even after a prolonged 2 h period of wet carbonation, and the CO2 uptake capacity and utilization rate achieved via MC reached >0.3 g-CO2/g-RCF and 80 %, respectively. The superior performance of MC was ascribed to the influence of mechanochemical effects. These effects contributed to the refinement in the geometrical characteristics of RCF, exfoliation of the passivating layers, and facilitation of CO2 dissolution, which favored the structural disintegration of RCF and carbonation progress. Another distinctive aspect of MC treatment was the production of a greater proportion of metastable CC characterized by reduced crystalline size, which was attributed to modifications in the carbonation environment and the structural alterations induced by mechanochemical effects. Moreover, the precipitation of silica gels commenced at approximately 4 min in the MC process, a notably earlier onset when compared with wet carbonation; additionally, a greater abundance of silica gels was observed in the current MC procedure, resulting from the higher carbonation degree caused by mechanochemical effects. The encouraging conclusions in the present work validated the feasibility of producing carbonated RCF more efficiently and paved the way for future industrial practice.

Calcium looping-enhanced biomass gasification for methanol production: Integrating methane dry reforming and carbon utilization

Developing integrated CO2 capture and utilization (ICCU) is an attractive strategy that aims to reduce CO2 emissions while realizing the potential benefits of CO2. This paper investigates the techno-environmental-economic performance of biomass gasification to methanol (BtM) based on calcium looping (CaL) coupled with dry reforming of methane (DRM) and CaL coupled with reverse Boudouard reaction (RB). The results indicate that BtM systems based on CaL-DRM (BtM:CaL-DRM) and CaL-RB (BtM:CaL-RB) achieve CO2 capture and utilization, and enable efficient methanol synthesis. Compared to BtM:CaL-DRM, BtM:CaL-RB demonstrates higher exergy efficiency and lower global warming potential (GWP). The exergy efficiency of BtM:CaL-RB reaches 71.60 %. In terms of economic viability, BtM:CaL-DRM demonstrates more promising economic feasibility. The BtM systems reaches breakeven when the methanol selling price ranges from 440.8 $/ton to 529 $/ton. This study provides valuable insights into exploring novel ICCU systems.

Underwater carbonation of alkali-activated slag pastes

Carbonation of alkali-activated slag (AAS) materials has been primarily concerned in atmospheres with gaseous CO2. This study, by contrast, highlights that AAS pastes would also be carbonated under tap water immersion. Calcite is the main CO2-bear phase in both sodium hydroxide- and sodium silicate-activated AAS pastes, and the paste pre-cured for a longer curing period shows more severe carbonation. Additionally, calcium carbonate can densify the deteriorated microstructure of sodium hydroxide-activated paste caused by long-term leaching. The indentation modulus of pastes subjected to tap water immersion is higher than those under deionized water immersion. The uptake of CO32- by hydrotalcite (Ht) and gels is also detected, resulting in the formation of Ht-CO3 and decalcification of gels. Due to the synergistic effect of leaching and carbonation, a characteristic layered distribution of pastes close to the exposure front is observed, comprising the carbonated layer, transitional (carbonated + leached) layer, and leached layer, progressing from the outermost to the inner regions. Eventually, the kinetics of underwater carbonation, as well as the discrepancy between dry and underwater carbonation, is revealed.

Thermophysical Characterization of Materials for Energy-Efficient Double Diaphragm Preforming

The Double Diaphragm Preforming (DDPF) process uses vacuum pressure and heat to pre-shape dry carbon fabric reinforcements between flexible diaphragms in liquid composite molding (LCM). Accurate modeling of heat transfer within DDPF requires knowledge of the thermophysical properties of the constituent materials under processing conditions. This study investigates the thermal conductivity of silicone diaphragms and carbon fabrics with embedded thermoplastic binder webs, utilizing transient plane source (TPS) and modified transient plane source (MTPS) methods, respectively. Additionally, the specific heat of silicone, carbon fibers (both chopped and powdered), and binder were measured using differential scanning calorimetry (DSC). Mixed samples comprising chopped fibers with 1.8 wt% binder and powdered fibers with 3.6 wt% binder was also analyzed with DSC. This study also examined the influence of reheating cycles on the specific heat of carbon fiber—3.6 wt% binder samples—and the effect of compaction and vacuum on the thermal conductivity of carbon fabrics with an embedded binder. While silicone exhibited linear-specific heat behavior, the thermoplastic binder showed non-linearity due to phase change. The combined carbon fiber-binder samples demonstrated slight non-linear specific heat variations depending on reheating cycles. The thermal conductivity of the fabric preforms decreased with the addition of thermoplastic binder and under vacuum-compaction conditions. The established temperature-dependent specific heat relationships and thermal conductivity provide valuable data for optimizing DDPF preforming parameters and enhancing energy efficiency in composite manufacturing.

Mitigation of ammonia and methane emissions with manure amendments during storage of cattle slurry.

This study aimed at assessing the efficacy of manure amendments in abating ammonia (NH3) and methane (CH4) emissions during storage. Two experiments were carried out. Experiment 1 was conducted using 20 L of slurry for 98 days. Treatments were: aluminium sulphate (alum), lactogypsum, zeolite, actiglene, ammonium thiosulphate, biochar, dairy processing waste, Digest-IT and control (without amendment). Experiment 2 was conducted using 660 L of slurry in underground storage tanks for 77 days. Treatments were: sulphuric acid, gypsum, biochar and control (without amendment). NH3 measurements for experiment 1 and experiment 2 were conducted using the photoacoustic gas monitor and dynamic chamber techniques, respectively. CH4 was measured using the static chamber technique in both experiments. The effect of amendments on slurry composition was determined at the end of the experiments. Experiment 1 showed a significant reduction in NH3 emissions in the alum (82%), lactogypsum (46%) and zeolite (32%) treatments relative to the control (100.3% total ammoniacal nitrogen (TAN)). CH4 was reduced significantly in the alum (87%), ammonium thiosulphate (64%) and lactogypsum (67%) relative to the control (291.9 g m-2). Experiment 2 showed a significant reduction (32%) in NH3 emissions in the sulphuric acid relative to the control (4.4% TAN). CH4 was reduced significantly in the sulphuric acid (46%), gypsum (39%) and biochar (15%) treatments relative to the control (291.9 g m-2). In general, amendments altered slurry composition such as dry matter, volatile solids, carbon and nitrogen contents at the end of storage. Lactogypsum, alum and sulphuric acid were effective in abating both NH3 and CH4 emissions and can contribute to improving air quality.

Restoring a dry tropical forest through assisted natural regeneration: enhancing tree diversity, structure, and carbon stock

Deforestation is a key factor in global climate change, severely impacting ecosystem services. Effective implementation of reducing emissions from deforestation and forest degradation (REDD+) initiatives is essential for mitigating this change. Reforestation is a sustainable way to mitigate deforestation effects. We studied the impact of assisted natural regeneration (ANR) on restoring dry forest land, increasing biodiversity, structure, and carbon stock. Reforestation units were established at a multiple row planting system in a dry tropic region. We selected 63 plots, each 20 m × 20 m, categorized into multiple row–mixed plantation (MRMP) and multiple row–unmixed plantation (MRUP). We measured tree height and diameter at breast height (DBH) and evaluated biodiversity indices, including the Shannon–Weiner Index (SWI), species richness, evenness, and Important Value Index (IVI). Carbon stock was estimated using allometric equations. We identified 931 individual trees representing 27 species, 24 genera, and 14 families. MRMP showed significantly higher biodiversity, species richness, and evenness than MRUP. Terminalia arjuna was the most dominant species (IVI=124.45), followed by Khaya senegalensis (53.84). Survival rates exceeded 90 % for T. arjuna, K. senegalensis, Madhuca longifolia, and Pongamia pinnata (p<0.001). No significant differences were observed in tree DBH, tree height, tree density, basal area, and carbon stock among the plantation categories. The species Albizia saman exhibited a high diameter increment rate (4.07 ± 1.55 cm/year), followed by K. senegalensis (3.83 ± 0.43 cm/year). A mean value of 5.63 ± 1.13 MgC/ha of carbon stock was stored, while 20.66 ± 4.13 Mg/ha of atmospheric CO2 was sequestered. The results highlight that promoting mixed tree species in multiple rows to enhance biodiversity and optimize carbon regulation. This technique should be popularized to restore the dry forest landscape across the region.

Alternative Cover Crops and Soil Management Practices Modified the Macronutrients, Enzymes Activities, and Soil Microbial Diversity of Rainfed Olive Orchards (cv. Chetoui) under Mediterranean Conditions in Tunisia

In Tunisia, the olive is the most cultivated fruit crop in the northern region, where annual rainfall exceeds 400 mm. This olive-growing area is characterized by a wide coverage of marginal soil with a high slope gradient. Therefore, the inclusion of cover crops in olive orchards is a sustainable solution to enhance ecosystem productivity, improve soil fertility, and increase oil yields. This study aimed to investigate the short-term (two cropping seasons in 2021 and 2022) effects of different seeded cover crops and soil management practices on soil characteristics, as well as soil health by measuring soil enzyme activities and microbial diversity. Six cover crop types consisting of wheat, vetch, oat, fenugreek, a vetch–oat mixture, and spontaneous vegetation were tested in association with rainfed olive trees (cv. Chetoui) in the north of Tunisia and compared to a control (which was tilled periodically three times per year without intercropping). During the first cropping season, cover crops were cut as animal feed, and only residues were incorporated into the soil. However, during the second year, all cover crop biomass was incorporated into the soil. The results indicated that the dry biomass production and carbon uptake were significantly higher in grass species (wheat and oat). All of the cover crops, including the spontaneous vegetation, significantly increased soil organic matter (SOM) and macronutrient levels, mainly, available phosphorus. On the other hand, the highest level of soil nitrogen was found in the fenugreek cover crop. The soil enzyme activities in the cover crops of wheat, oat, and the vetch–oat mix were higher than those in the control. Together with the increase in soil organic matter (SOM), this demonstrates a significant improvement in soil health with cover crops. Furthermore, this study proves that the utilization of carbon sources was dominated by amides, amines, and amino acids in the fenugreek plot, while it was dominated by polymers and carboxylic acids in the case of the wheat and oat. Overall, this study demonstrates that seeding cover crops is a sustainable management practice not only to integrate livestock but also to improve soil health in semiarid olive orchards.

Cone and fruit impacts on understory flammability depend on traits and forest floor coverage

BackgroundUnderstory flammability is affected by abscised plant tissue. Extensive research has shown how interspecific differences in leaf litter traits affect flammability; however, leaves represent only one component of the litter layer. Cones and fruit are also common constituents of the forest floor, yet surprisingly little is known about how flammability is affected by their presence. In this study, we ask how flammability is affected by cones and fruit trait differences, coverage differences, and varying species and coverage combinations. To address these questions, we compared cone and fruit morphological and chemical traits among longleaf pine, loblolly pine, shortleaf pine, sweetgum, post oak, and water oak. We also used burn trials to compare fire behavior of single and mixed-species treatments at three coverage levels (10% of plot area (low), 30% (medium), and 50% (high)) integrated within a common mixed-litter layer under field conditions in central Alabama, USA.ResultsLike other plant tissues, cone/fruit dry matter, carbon, and lignin content promote fuel consumption and flame height, while nitrogen suppresses flammability. Single-species treatments produced distinct patterns in fire behavior, with longleaf pine cones consistently showing higher percent fuel consumption, flame height, and maximum smoldering temperature than sweetgum capsular heads. Mixed-species treatment results were less consistent; however, at high coverage, a representative upland three-way mixture (longleaf pine + sweetgum + post oak) showed significantly greater fuel consumption and flame height relative to a bottomland three-way mixture (loblolly pine + sweetgum + water oak) at high coverage. Medium cone/fruit coverage maximized flammability in most single and multi-species treatments and produced non-additive fuel consumption in mixtures containing longleaf pine and sweetgum.ConclusionOur results confirm that individual species’ cone and fruit flammability often parallels that of litter. Fire behavior in mixture is generally driven by the most flammable constituent species, but this result changes with cone and fruit coverage. Collectively, these results indicate that cones/fruit identity and coverage play an important role in understory flammability and should be integrated into fire behavior modeling efforts in monocultures and mixtures.

Enhancing the efficacy of biochar derived from crop residues on rice (Oryza sativa L.) dry matter, yield accumulation and soil organic carbon in Central Vietnam

Biochar from crop residues plays an important role in reclamation of degraded rice soil due to imbalance fertilizer application and soil carbon sequestration. The objective of this study aimed to evaluate the best type and rate of biochar application for rice dry matter and soil organic carbon improvement. Therefore, pot experiments were carried out in two seasons of spring and summer 2023 at the University of Agriculture and Forestry, Hue University. Twelve treatments including 2 types of biochar (rice husk and peanut shell) and 6 application rates (0, 1, 2, 3, 4, 5%) were used and arranged in a randomized block design with three replications. Research results showed that the shoot dry matter was higher 9.5 – 27.0% (spring season) and 19.1 – 26.9% (summer season) at a rate of 5% application in both types of biochar than control. Rice husk biochar application had higher shoot dry matter than peanut shell biochar application in the same application rate from 0.30 – 0.46 g/plant in both seasons. Similarly, organic carbon was found the highest content (2.15 - 2.21%) when the application of biochar from crop residues at a rate of 5%. Biochar from crop residues is considered as a good amendment for increasing crop dry matter and soil organic carbon.

Patterns and driving factors of functional traits of desert species with different elevational distributions in the Tibetan Plateau and adjacent areas

Variations in functional traits serve as measures of plants’ ability to adapt to environment. Exploring the patterns of functional traits of desert plants along elevational gradients is helpful to understand the responses and adaptation strategies of species to changing environments. However, it is unknown whether the relationship between functional traits and elevation is affected by differences in the species’ elevational distributions (elevation preference and species’ range). Importantly, most researches have concerned with differences in mean trait values and ignored intraspecific trait variation. Here, we measured functional traits of desert plants along a wide elevational gradient in the Tibetan Plateau and adjacent areas and explored functional trait patterns over elevation in species with different elevational distributions. We decomposed trait variation and further investigated characterizations of intraspecific variation. Ultimately, the main drivers of trait variation were identified using redundancy analysis. We found that species’ elevational distributions significantly influenced the relationship of functional traits such as plant height, leaf dry matter content, leaf thickness, leaf nitrogen and carbon content with elevation. Species with a lower elevational preference showed greater trait variation than species with a higher elevational preference, suggesting that species that prefer high elevation are more conservative facing environmental changes. We provide evidence that interspecific trait variation in leaf thickness and leaf carbon content decreased with increasing species’ range, indicating that increased variations in resistance traits within species make greater responsiveness to environmental changes, enabling species a wider range. Elevation, temperature and precipitation were the main drivers of trait variation in species with a low elevational preference, while the effect of precipitation on trait variation in species with a high elevational preference was not significant. This study sheds new insights on how plants with different elevational distributions regulate their ecological strategies to cope with changing environments.

An All-Atom Force Field for Dry and Water-Lubricated Carbon Tribological Interfaces

An All-Atom Force Field for Dry and Water-Lubricated Carbon Tribological Interfaces