Carbon Content Research Articles

Ni doped carbon-based composites derived from waste cigarette polypropylene filter rod with electromagnetic wave absorption performance

Abstract Polypropylene is widely used in the plastics industry, especially in the tobacco industry, served as cigarette filters to reduce tar and harm. However, it’s difficult to degrade these polypropylene plastics and suitable methods for recycling and reuse is urgent. This research proposes an efficient method for the reuse of polypropylene cigarette filters by mixing waste polypropylene filters with nickel source in different proportions, followed by a facile calcination treatment to prepare nickel-modified carbon-based composite materials with excellent microwave absorption properties. Morphology and magnetic properties of as-prepared samples were analyzed via XRD, SEM, and VSM, exhibiting an increase in carbon content with raising nickel content. Nickel ion anchored on polypropylene fiber may facilitate better fixation of carbon chains during the polypropylene decomposition process. Among the as-prepared samples, CN2 exhibited superior microwave absorption performance, with an optimal absorption peak of -26.76 dB at 7.97 GHz when matched with a given thickness of 4.3 mm, and an effective absorption bandwidth of 3.64 GHz (8.04 GHz to 11.68 GHz) with a matching thickness of 3.5 mm, covering the X band. Therefore, the as-prepared microwave absorbers provides a feasible solution for the recycling and reuse of polypropylene filters, aligning with the tobacco industry requirements for green and sustainable development.

Decade-long effects of integrated farming systems on soil aggregation and carbon dynamics in sub-tropical Eastern Indo-Gangetic plains

Integrated farming system (IFS) aims to diversify the agricultural landscapes by incorporating different components to meet the multifarious needs of the burgeoning population. The present study was undertaken to understand the impact of different cropping systems on soil organic carbon (SOC) stock, aggregate distribution, and aggregate associated organic carbon (AAOC) in 2-IFS models of varying sizes (0.4 and 0.8 ha) established during 2008–2009. After 10 years of the study, the fodder system registered the greatest TOC and carbon stocks across IFS models, with surface soil (0–15 cm) accumulating 17 and 13% higher TOC and C stock, respectively, in 0.4 and 0.8 ha models. In 0–15 cm, macroaggregates (Ma) represented the highest proportion (75–76%) in both models. Among cropping systems, the fodder system recorded the highest large macroaggregates in both IFS models. Within 0–30 cm depth, small macroaggregates are mostly found in the perennial system (fodder, guava+turmeric, and lemon intercropping system), indicating the potential to improve the aggregate stability over the seasonal (shorter duration) system. In general, micro aggregate (Mi) fraction was pre-dominant in sub-surface soil (17.35%). The maximum AAOC was found in Ma compared to Mi fractions, with approximately 67 and 63% of total carbon associated with Ma in 0.4 and 0.8 ha IFS models, respectively. Interestingly, the 0.8 ha IFS model had higher TOC (~11%) and carbon stock (~12%) than the 0.4 ha model, but AAOC did not show a similar result, indicating the influence of cropping systems on AAOC. The study indicated that the fodder-based production system had better performance in terms of soil physical health and increased aggregate stability and content of soil carbon. This is indicative of the advantages of perennial-based systems over seasonal- or annual-based cropping systems for soil sustainability in Eastern Indo-Gangetic Plains.

Use of a Glaciogene Marine Clay (Ilulissat, Greenland) in a Pilot Production of Red Bricks

Uplifted occurrences of fine-grained glaciogene marine sediments are found throughout the northern hemisphere. These sediments could be used to produce local construction materials, to rely less on imported construction materials from southern regions. In this study, a representative occurrence from Ilulissat, West Greenland, was investigated as a potential resource for local brick production. The study comprised three parts: (1) raw material characterization based on grain size distribution, major element chemistry, including total carbon, sulfur, and chloride concentrations, mineralogy, morphology, and Atterberg limits; (2) the production of test bricks at a Danish brickwork; and (3) testing of the bricks based on total shrinkage, water absorption, hygroscopic adsorption, open porosity, bulk density, compression strength, and mineralogy. The bricks produced proved to have excellent compression strength, low open porosity, and low water absorption. The shrinkage could be reduced by adding 10% chamotte to the marine sediment. Based on the investigated properties, this indicates that this type of clay is highly suitable as a resource for bricks.

A generalized adsorption model of CO2-CH4 in shale based on the improved Langmuir model

CO2 enhanced shale gas recovery (CO2-ESGR), as one of the most promising carbon capture, utilization and storage (CCUS) technologies, can both improve the shale gas production for clean energy supply and mitigate greenhouse gas emissions for the goal of carbon neutrality. The adsorption characteristics of CO2 and CH4 in shale play a key role in the reserve assessment of shale gas and the implementation of CO2-ESGR. The problem of accurate prediction of the adsorption and competitive adsorption characteristics of CO2 and CH4 in shale is still one of the main challenges for CO2-ESGR. To bridge the gap, this work developed a generalized prediction model for the adsorption properties of CH4, CO2, and their mixed gas in shale by improving the Langmuir model, covering a large range of temperature, pressure, and total organic carbon content (TOC). The mathematical models for the key parameters of the Langmuir model, the saturated adsorption capacity Q0 and Langmuir pressure PL, were built for the single-component gas based on their functional relationship with temperature and TOC, and for the mixed gas based on their relationship with Q0 and PL of the single-component gas and CO2 content. Then an improved Langmuir model for the adsorption properties of CO2-CH4 in shale was established. The accuracy of the improved model was verified with a relative deviation below 5 % in a large range of temperature (303–363 K), pressure (0–15 MPa) and TOC (1.06 %-3.83 %) by comparing the calculated adsorption with the experimental data. This generalized adsorption model not only ensures the prediction accuracy of CO2-CH4 adsorption characteristics in shale but also expands its application convenience in a large range of temperatures, pressures and TOC, providing a certain theoretical basis for CO2-ESGR technology.

Envirotyping helps in better understanding the root cause of success and limitations of rainfed production systems

The current diagnostic agronomy study of the Bankura region of West Bengal, India, examined the variations in crop yields through a socio-ecological analysis of multiple production system components. Envirotyping for root cause analysis was employed to delve into the variables that affect the performance of rainfed production systems. Mother Earth, man, machine, management, and materials (5Ms concept) were the five indicators under which the variables were grouped. Findings demonstrated the fragility of the region’s soils due to its undulating terrain, unpredictable rainfall patterns, and frequent drought scenarios. The LULC’s NDVI showed that the agricultural area is about 60% and 43% of the total geographical area in the Hirbandh and Ranibandh blocks, respectively. Soils are acidic and diagnosed with deficiency of both macro and micronutrients (phosphorous, sulfur, and boron) having poor water holding capacity (35 to 55 mm for a 50 cm soil depth). The sand and soil organic carbon contents ranged between 43.04%–82.32% and 0.17%–1.01%, respectively with a low bacterial population. These factors are the root cause for low cropping intensity (106%) and low paddy productivity (3,021 kg/ha). Overall, the study contributes to designing and scaling-up of sustainable landscape management practices that could ensure higher cropping intensity and system productivity in similar agro-ecologies with limited evidence.

Coniferous Biomass for Energy Valorization: A Thermo-Chemical Properties Analysis

Forest biomass energy, when utilized responsibly, presents a carbon-neutral and viable alternative to fossil fuels for energy storage. This research investigates the energy potential of various coniferous species, focusing on their complex chemical compositions and suitability for energy production. Key characteristics such as moisture content, volatile matter, ash content, and fixed carbon were analyzed, along with elemental composition (including nitrogen, carbon, oxygen, and hydrogen) and both gross and net heating values across different species. The proximate analysis revealed significant interspecies variations. For example, Pseudotsuga menziesii and Chamaecyparis lawsoniana exhibited the lowest moisture contents. Elemental analyses showed a broad range of values, with Larix decidua having the lowest nitrogen content and Sequoiadendron giganteum the highest carbon content. Gross and net heating values also varied considerably, with Podocarpus macrophyllus showing the lowest values and Pinus strobus the highest. Principal component analysis (PCA) was employed to identify underlying patterns, revealing correlations between the analyzed variables and the energy potential of the species. Additionally, PCA combined with cluster analysis allowed for the identification of coherent groups of species with similar characteristics. Overall, these findings highlight the diverse energy valorization potential inherent in coniferous species, underscoring the importance of considering specific chemical compositions for efficient energy production. The insights provided here are valuable for selecting coniferous species for energy valorization, emphasizing the need to consider both chemical composition and calorific potential.

Characterization of Carbide Precipitation in Low-Carbon Martensitic Steels Using an Ultrawide Field-of-View 3D Atom Probe.

It is important to understand the carbide distribution around high-energy sites such as dislocations and grain boundaries in martensitic steels as they have a major influence on the alloy performance. The aim of this study is to characterize fine ε carbides precipitated in low-carbon lath martensitic steel using the ultrawide field-of-view (FoV) CAMECA Invizo 6000 atom probe. We demonstrate the advantages of the wide FoV and determine the optimum conditions for analysis, by comparing the results such as the background noise and the C++/C+ charge state ratio (CSR) between voltage-pulsed and laser-pulsed modes. Increasing the laser pulse energy decreased the background noise and the CSR, where 70 pJ laser pulse energy produced a comparable mass-to-charge ratio spectrum to that recorded in voltage-pulsed mode, with the bulk compositions of C, Si, and Mn closest to that measured using voltage-pulsed mode. Increasing laser pulse energies to above 300 pJ decreased the bulk carbon content, with a more diffuse distribution of carbon around the carbides. This paper outlines some of the important experimental considerations when performing quantitative study of carbide precipitation in low-carbon martensitic steels using the Invizo 6000, considerations that can also be applied to other ferrous and non-ferrous alloy systems.

Effect of Integrated Nutrient Management (INM) on Soil Physico-chemical Properties in Wheat (Triticum aestivum L.) Intercrop under Beul (Grewia optiva Drummond.) Based Agroforestry System and Open Condition

The raising human health hazards due to excessive use of chemical fertilizers and pesticides in India leads cancer patients. To overcome such problems there is need of Integrated Nutrient Management (INM) in our major crop wheat and further to improve soil fertility under agroforestry system. Therefore, the present investigation was carried out to study the impact of INM on the physical and chemical properties of soil when wheat intercropped under Beul (Grewia optiva) based agroforestry system in the mid-hill region of Himachal Pradesh at Dr. Y. S. Parmar University of Horticulture and Forestry, Nauni, Solan, HP (India). INM practices were applied to evaluate their effectiveness in enhancing soil fertility, crop yield, and overall soil health. The experimental setup included various treatment combinations of organic and inorganic fertilizers viz., T1: RDF, T2: FYM, T3: Vermicompost, T4: Goat manure, T5: 50% RDF+50% FYM, T6: 50% RDF+50% VC, T7: 50% RDF+50% GM, and T8: Control to determine their synergistic effects on the soil and cereal crop. These treatments were randomly assigned to plots under two planting conditions: S1 (under Beul based agroforestry system) and S2 (open condition), with three replications each, following in a factorial randomized block design (RBD). The key physical parameters such as bulk density (g/cm3), particle density (g/cm3), porosity (%), and soil moisture (%) were measured along with chemical properties of soil including soil pH, EC (dS/m1), organic carbon content (%), and nutrient availability of N, P and K in kg per hectare. The soil data of two consecutive years and pooled data were analyzed in R Statistical Software. The results demonstrated that INM significantly improved both the physical and chemical soil properties in agroforestry system as compared to control treatment i.e. open condition. The use of 100 % FYM found to be best treatment during the course of study among various treatments of INM for soil porosity, soil moisture, soil pH, available N, P and K. The soil structure and nutrient availability were increased in second year as compared to first year which will lead to improve the growth and yield of wheat crop. The study underscores the importance of adopting INM practices in agroforestry system to achieve sustainable agriculture as well as chemical free agriculture in hilly regions of Himachal Pradesh which will be helpful for human health. Thus, the use 100% FYM fertilizer is recommended for farmers in hilly area of Himachal Pradesh for sustainable agriculture and natural farming. The findings provide valuable insights for farmers and policymakers aiming to optimize crop production and maintain soil health in similar agro-ecological zones.

The Effect of Pro- and Eukaryotic Inductors on the Synthesis and Antimicrobial Activity of Acinetobacter calcoaceticus IMV B-7241 Surfactants

By now, the mixed cultivation ("co-cultivation") of antimicrobial compound producers with other microorganisms or the introduction of biological inductors in different physiological states (live and inactivated cells, as well as the corresponding supernatants) into the culture medium is a simple, cheap, and effective way to increase the synthesis of practically important microbial metabolites and regulate their biological activity. In most studies, researchers use bacterial strains of various species as inductors, however, in recent years, there have been an increasing number of publications reporting the use of eukaryotic inductors, in response to which there's observed an increase in the synthesis of antimicrobial compounds by the bacterial producers. In addition, the effectiveness of biological inductors depends on the conditions of their cultivation and physiological state. Aim. To study the effect of the methods of preparation and physiological state of biological inductors (gram-negative bacteria Enterobacter cloacae C-8 and yeast Saccharomyces cerevisiae BTM-1) on the activity of biosynthetic enzymes and antimicrobial activity of Acinetobacter calcoaceticus IMV B-7241 surfactants. Methods. Purified glycerol and crude glycerol in equimolar carbon concentration were used as a substrate for cultivation of A. calcoaceticus IMV B-7241. The microbial inductors were grown on both agar and liquid media with glucose as a carbon source. Live or inactivated cells of S. cerevisiae BTM-1 or E. cloacae C-8, as well as the corresponding supernatant, were added to the medium in an amount of 2.5–10 % (v/v). The extracellular surfactants were obtained from the supernatant of the culture liquid by extraction with a mixture of chloroform and methanol (2:1). The antimicrobial activity of surfactants against bacterial (Bacillus subtilis BT-2, Escherichia coli IEM-1, Staphylococcus aureus BMS-1, Pseudomonas sp. MI-2) and yeast (Candida albicans D-6 and Candida tropicalis PE-2) test cultures was determined by the indicator of the minimum inhibitory concentration. The activity of enzymes for the biosynthesis of surface-active glyco- (phosphoenolpyruvate carboxylase, phosphoenolpyruvate synthetase, phosphoenolpyruvate carboxykinase, trehalose phosphate synthase) and aminolipids (NADP+-dependent glutamate dehydrogenase) was analyzed in cell-free extracts obtained after sonication of cells. Results. The introduction into the culture medium of A. calcoaceticus of IMV B-7241 with glycerol of various purification degrees, both pro- and eukaryotic inductors in different physiological states was accompanied by the synthesis of surfactants, the antimicrobial activity of which against the test cultures was higher by one to two orders of magnitude compared to preparations obtained without inductors. It was found that E. cloacae C-8 cells grown in liquid medium were slightly more effective as inductors than those grown in agar medium: the minimum inhibitory concentrations against bacterial and yeast cultures of surfactants synthesised in their presence were 1–6 and 2.5–8 μg/mL, respectively. When live S. cerevisiae BTM-1 or E. cloacae C-8 cells were used as inductors, the production of microbial surfactants with higher antimicrobial activity than those synthesized in the presence of inactivated cells or supernatants was observed: the minimum inhibitory concentrations against the test cultures were in the range of 0.85–16, 2–20 and 1.5–22 μg/mL, respectively. The higher antimicrobial activity of surfactants synthesized in the presence of a pro- or eukaryotic inductor in the medium with purified glycerol may be caused by an increase of aminolipids in their composition, as evidenced by a 1.6–2.1-fold increase in NADP+-dependent glutamate dehydrogenase activity in A. calcoaceticus IMV B-7241 cells compared to the values of cultivation without inductors. The same level of activity of this enzyme during the cultivation of the IMV B-7241 strain in the medium with crude glycerol in the presence of inductors and without them may indicate the synthesis under such conditions of other, than aminolipids, metabolites with antimicrobial activity. Conclusions. As a result of this study, it was established that the antimicrobial activity of A. calcoaceticus IMV B-7241 surfactants can be increased by introducing pro- and eukaryotic inductors in the form of live or inactivated cells, as well as the corresponding supernatants into the medium with glycerol of different degrees of purification.

Photosynthetic and Carbon Sequestering Ability of Safflower Leucea and Accumulation of Organic Carbon in Sod-Podzolic Soil

According to the content of photosynthesis pigments, the most active period of photosynthetically active radiation absorption by the leaves of Leucea safflower during the growing season was revealed. From the moment of full regrowth to flowering, the amount of chlorophylls a and b in the leaves was 6.2–8.5 mg/g of dry weight, carotene – 3–4 times less. During photosynthesis, the carbon content in the leaves of Leucea safflower practically did not change and amounted to 39.5–42.5%. The mass fraction of the main product of photosynthesis, sugars, increased from the regrowth phase to seed formation from 4.0 to 11.8%. During the period of active growth, the nitrogen content in the leaves of the leucea was 1.3–1.6, phosphorus – 1.1–1.6, potassium – 4.4–5.1%. After harvesting the safflower leucea of the 14th year of life, a high amount of сrop and root residues (CRR) was determined in the sod-podzolic soil – 13.7–17.3 t/ha. The amount of carbon absorbed during photosynthesis was 6.8–11.5 t C/ha (24.3–41.3 t CO2/ha), depending on the experiment variant, for natural phytocenosis this indicator was equal to 2.4 t C/ha (or 8.6 t CO2/ha) during the growing season. The organic carbon content under the safflower leucea of the 14th year of life in the 0–20 cm soil layer increased relative to the initial level by 3.6% in the version without fertilizers, by 15.1% in the N60P60K60 variant, and in the 20–40 cm layer by 8.8–42.6%, respectively. Relative to the virgin analogue, the carbon content in the 0–20 cm layer was 15.2–28.0 higher, in the 20–40 cm layer – 25.0–64.4%, depending on the experiment variant, which indicated the deposition of carbon in the form of humic substances due to its storage in deeper soil layers.

Effect of precursor particle size on the microstructure and Na storage performance of semi-coke derived carbon

The microstructure of carbon-based materials exerts a decisive influence on their Na storage performance. Furthermore, its evolution process may be influenced by the size of precursor particles during the pyrolysis preparation process. In this work, semi-coke has been used as the precursor, and its particle size (median particle sizes of 3, 7, 11, 15, and 19 μm) is investigated for its impact on the microstructure and Na storage performance of the resulting carbon materials (SDC-X, X = 3, 7, 11, 15, or 19). As the size of semi-coke increases from 3 μm to 19 μm, the highly-disordered carbon content of SDC-X decreases from 41.27 % to 30.94 %, while the content of pseudo-graphitic carbon associated with plateau capacity remains nearly constant. When SDC-X are employed as anodes for sodium-ion batteries, the initial coulombic efficiency (ICE) rose from 77.4 % to 82.3 % with the increase of size, primarily due to the increase in the ICE of slope region. However, despite SDC-19 having the highest ICE, its reversible capacity, rate, and cycle performance are inferior compared with the others due to its higher order degree and larger particle size. Therefore, carbon-based materials used as anodes for SIBs require a trade-off between particle size and the electrochemical performance.

Serendipita indica: A Promising Biostimulant for Improving Growth, Nutrient Uptake, and Sugar Accumulation in Camellia oleifera

Serendipita indica is a very promising root-associated endophytic fungus that is widely used on various plants; however, whether it affects the growth and physiological activity of an oilseed crop (Camellia oleifera) under field conditions remains unclear. In this study, we analyzed the effects of S. indica inoculation on root colonization rate, growth rate, photosynthetic parameters, mineral element concentrations and related gene expression, and sugar concentrations and expression of their transporter genes in four-year-old C. oleifera trees in the field. The results showed that the root colonization rate of C. oleifera increased from 3.37% to 9.42% following being inoculated with S. indica. Inoculation with S. indica significantly increased the plant height (46.81%), net photosynthetic rate (69.16%), nitrogen balance index (14.44%), chlorophyll index (21.08%), leaf K (7.4%), leaf Ca (13.52%), root P (17.75%), root K (12.80%), soil NH4+-N (17.78%), available K (26.66%), Olsen-P (184.30%), easily extractable glomalin-related soil protein (39.26%), and soil organic carbon (16.25%) concentrations compared to the uninoculated treatment. Inoculation with S. indica also significantly up-regulated the expression of CoHKT1;1 and CoCAX1;2 in the leaves and roots and CoPht1;1, CoPht1;2, and CoPht1;3 in the leaves. Plants inoculated with S. indica also presented significantly higher leaf glucose, fructose, and sucrose concentrations, accompanied by up-regulated expression of CoSWEET2a, CoSWEET7, CoSWEET9b, CoSWEET17a, and CoSWEET17b. These results suggest that S. indica has significant potential as a biostimulant for enhancing the growth and nutritional profile of C. oleifera, thereby contributing to sustainable oilseed production.

Carbon and Nitrogen Stocks in Soil under Native Pastures in the Pantanal Wetland Biome, Brazil

The Pantanal has a high diversity of native pastures that provide food for many wild and domestic animals. Pantanal cattle raising is practiced in an extensive grazing-based system that varies according to the flood levels in the area. This study aimed to evaluate the fractions of soil organic matter in areas of native pastures under different uses and to quantify C and N stocks in sandy soils of the Pantanal. Soil samples from three native pastures differentiated by the predominance of Hymenachne amplexicaulis, Axonopus purpusii, and Mesosetum chaseae under different land use systems (continuous grazing and no grazing for five years) were collected and used to quantify the contents of carbon, nitrogen, and humic fractions. The dynamics of SOM are modified in grazed areas of the Pantanal, with influence on C and N, including their stocks. Native pastures of Axonopus purpusii and Hymenachne amplexicaulis showed an increase in organic matter after five years without grazing, while Mesosetum chaseae showed lower soil density and nitrogen levels. The highest C stock was observed in ungrazed areas of H. amplexicaulis (127.41 Mg ha−1 in the 0–40 cm layer). The dynamics of nitrogen in Pantanal pastures are influenced by the type of vegetation and land management, with higher nitrogen content in the surface layer (0–10 cm) and an increasing C/N ratio with soil depth, indicating lower nitrogen availability.

Changes in Soil Aggregate Carbon Components and Responses to Plant Input during Vegetation Restoration in the Loess Plateau, China

Vegetation restoration is an effective measure to cope with global climate change and promote soil carbon sequestration. However, during vegetation restoration, the turnover and properties of carbon within various aggregates change. The effects of plant source carbon input on surface soil and subsurface soil may be different. Thus, the characteristics of carbon components in aggregates are affected. Therefore, the research object of this study is the Robinia pseudoacacia forest located in 16–47a of the Loess Plateau, and compared with farmland. The change characteristics of organic carbon functional groups in 0–20 cm, 20–40 cm, and 40–60 cm soil layers were analyzed by Fourier near infrared spectroscopy, and the relationship between the chemical structure of organic carbon and the content of organic carbon components in soil aggregates was clarified, and the mechanism affecting the distribution of organic carbon components in soil aggregates was revealed in the process of vegetation restoration. The results show the following: (1) The stability of surface aggregates is sensitive, while that of deep aggregates is weak. Vegetation restoration increased the surface soil organic carbon content by 1.97~3.78 g·kg−1. (2) After vegetation restoration, the relative contents of polysaccharide functional groups in >0.25 mm aggregates were significantly reduced, while the relative contents of aromatic and aliphatic functional groups of organic carbon were significantly increased. The opposite is true for aggregates smaller than 0.25 mm. (3) With the increase in soil depth, the effect of litter on organic carbon gradually decreased, while the effect of root input on the accumulation of inert carbon in deep soil was more lasting.

Utilization of Diversified Cover Crops as Green Manure-Enhanced Soil Organic Carbon, Nutrient Transformation, Microbial Activity, and Maize Growth

Studying green manure in several returning methods to enhance soil fertility and crop benefits is a strong foundation for cropland nutrient management. However, how different types of green manures and their variable doses affect the efficacy of applied manures, either buried or mulched, remain overlooked. The objective of this study was to optimize green manure management to enhance soil fertility and maize biomass using five types of green manures (white mustard, forest rye, fiddleneck, sufflower, and pea) in two different doses (low, 5 g per pot, and high, 10 g per pot), which were either buried or mulched before and after maize sowing. Results revealed that total carbon content increased due to green manure treatments, representing a 10% increase over control, particularly through buried w. mustard (10% increase before maize cultivation) and mulched safflower and pea (12% and 11% increase after maize cultivation over control). Dry maize aboveground biomass yields also improved across all variants, with buried mustard yielding 18.4 g·plant−1 (compared to 8.6 g·plant−1 in the control), mulched mustard yielding 16.4 g·plant−1, and buried pea yielding 17.8 g·plant−1. Green mulching generally acidified the soil (pH 5.71 compared to 6.21 in the control), except for buried fiddleneck (pH 6.39 after maize cultivation) at a high dose of manures. Carbon-mineralizing enzyme activities (dehydrogenase and β-glucosidase) were significantly increased by green manures, with buried fiddleneck showing a 22.6% and 20.6% increase over the control, and mulched fiddleneck showing a 24.5% and 22.4% increase under high doses. The study suggests that partially decomposed and mineralized mulched biomass may induce a negative priming effect on carbon-mineralizing enzymes due to a decrease in the C/N ratio of the soil. It emphasizes that the nutrient content and stoichiometry of green manures, alongside soil characteristics such as the C/N ratio, are critical factors for sustainable soil management and carbon sequestration. These findings underscore the need for careful selection and management of green manures to optimize soil health and carbon-storage outcomes.

The evolution of structural characteristics and redox properties of humin during the composting of sludge and corn straw.

Humins (HMs), the insoluble faction of humic substances (HSs), play a pivotal role in the bioremediation of pollutants by acting as electron shuttles that modulate the interactions between microorganisms and pollutants. This crucial function is intricately linked to their structural composition and electron transfer capabilities. However, the dynamics of the electron transfer capacity (ETC) of HM extracted during the composting process and its determinants have yet to be fully elucidated. This study undertakes a comprehensive analysis of the ETC of HM derived from composting, employing electrochemical techniques alongside spectroscopic methods and elemental analysis to explore the influencing factors, including the electron accepting capacity (EAC), electron donating capacity (EDC), and electron reversible rate (ERR). Our findings reveal substantial variations in the EAC and EDC of HM throughout the composting process, with EAC values ranging from 133.03-220.98 μmol e- gC-1 and EDC values from 111.17-229.33 μmol e- gC-1. Notably, the composting process enhances the ERR and EDC of HM while diminishing their EAC. This shift is accompanied by an augmented presence of aromatic structures, polar functional groups, quinones, and nitrogen - and sulfur-containing moieties, thereby boosting the HM's EDC. Conversely, the reduction in EAC is associated with a decline in lignin carbon content and the abundance of oxygen-containing moieties, as well as the diminishment of visible fulvic-like and protein-like substances within HM. Importantly, humic-like substances and nitrogen-containing moieties within HM demonstrated the capacity for repeated electron transfer, underscoring their significance in the context of environmental remediation.

The Effect of C-Organic Sediment and Litter Carbon Estimation on Fertility and Site Health in Lampung Mangrove Center

Subsurface carbon storage reflects the fertility of mangrove sites. Site fertility has implications for site health. The aims of this study, among others, are to determine the content of C-organic sediments, determine the litter carbon content, and understand the effect of C-organic and litter carbon on on-site health (soil pH and CEC). The stages of research, among others, are sediment and litter sampling on the observation plot, analysis of sediment and litter samples in the laboratory, calculation of litter carbon by dry weight, and fertility analysis of site health using multiple linear regression analysis with a significant threshold of 95%. Based on the results of the study, the highest C-organic content was observed in cluster plot 3 (CL3); the highest increase in litter carbon was at CL2, and there was a significant effect between site fertility (C-organic) and site health (pH). The pH and carbon play a role in the mobility of compounds that form organic materials. Factors influencing on-site carbon health conditions include waste production, organic material, temperature, tree species, pollution, and climate. Sediment conditions affect sigh in organic matter and the health of the site. The results of this research can illustrate the fertility and health conditions of sites inmangrove forests, so regulations can be formulated to prevent damage to mangroves.

Green Synthesis of Hexagonal-like ZnO Nanoparticles Modified with Phytochemicals of Clove (Syzygium aromaticum) and Thymus capitatus Extracts: Enhanced Antibacterial, Antifungal, and Antioxidant Activities

The green synthesis of ZnO NPs is becoming increasingly valued for its cost-effectiveness and environmental benefits. This study successfully synthesized hexagonal ZnO NPs using a combination of clove (Syzygium aromaticum) and Thymus capitatus extracts. The use of both extracts significantly improved the antibacterial and antioxidant properties of the ZnO NPs. By optimizing synthesis conditions, including ZnCl2 and extract concentrations, hexagonal wurtzite ZnO NPs were produced at room temperature with only drying at 80 °C without high-temperature annealing. The synthesized ZnO NPs exhibited a hexagonal morphology with an average particle size of 160 nm and a crystallite size of 30 nm. Energy-dispersive X-ray spectroscopy (SEM-EDX) confirmed the elemental composition of the ZnO NPs, showing a high carbon content (63.9 wt.%), reflecting the presence of phytochemicals from the extracts coated the ZnO NPs surface. The UV–Vis spectrum revealed an absorption peak at 370 nm and a bandgap energy of 2.8 eV due to lattice defects caused by organic impurities. The ZnO NPs demonstrated exceptional antioxidant activity, with a DPPH radical scavenging rate of 95.2%. They also exhibited strong antibacterial activity against both Gram-positive and Gram-negative bacteria, with inhibition zones of 25 mm against Bacillus subtilis, 26 mm against Escherichia coli, 24 mm against Salmonella typhimurium, 22 mm against Klebsiella pneumoniae, 21 mm against Staphylococcus aureus, 20 mm against Staphylococcus hominis, and 18 mm against Bacillus subtilis at 200 ppm. Furthermore, significant antifungal activity was observed against Candida albicans, with an inhibition zone of 35 mm at the same concentration. These findings underscore the effectiveness of using combined plant extracts for producing ZnO NPs with controlled morphology and enhanced biological properties, highlighting their potential for various biomedical applications.

Large grazers suppress a foundational plant and reduce soil carbon concentration in eastern US saltmarshes

Abstract Large grazers modify vegetated ecosystems and are increasingly viewed as keystone species in trophic rewilding schemes. Yet, as their ecosystem influences are context‐dependent, a crucial challenge is identifying where grazers sustain, versus undermine, important ecosystem properties and their resilience. Previous work in diverse European saltmarshes found that, despite changing plant and invertebrate community structure, grazers do not suppress below‐ground properties, including soil organic carbon (SOC). We hypothesised that, in contrast, eastern US saltmarshes would be sensitive to large grazers as extensive areas are dominated by a single grass, Spartina alterniflora. We predicted that grazers would reduce above‐ and below‐ground Spartina biomass, suppress invertebrate densities, shift soil texture and ultimately reduce SOC concentration. We tested our hypotheses using a replicated 51‐month large grazer (horse) exclusion experiment in Georgia, coupled with observations of 14 long‐term grazed sites, spanning ~1000 km of the eastern US coast. Grazer exclusion quickly led to increased Spartina height, cover and flowering, and increased snail density. Changes in vegetation structure were reflected in modified soil texture (reduced sand, increased clay) and elevated root biomass, yet we found no response of SOC. Large grazer exclusion also reduced drought‐associated vegetation die‐off. We also observed vegetation shifts in sites along the eastern US seaboard where grazing has occurred for hundreds of years. Unlike in the exclusion experiment, long‐term grazing was associated with reduced SOC. A structural equation model implicated grazing by revealing reduced stem height as a key driver of reduced soil organic carbon. Synthesis: These results illustrate the context dependency of large grazer impacts on ecosystem properties in coastal wetlands. In contrast to well‐studied European marshes, eastern US marshes are dominated and structured by a single foundational grass species resulting in vegetation and soil properties being more sensitive to grazing. Coastal systems characterised by a single foundation species might be inherently vulnerable to large grazers and lack resilience in the face of other disturbances, underlining that frameworks to explain and predict large grazer impacts must account for geographic variation in ecosystem structure.

Bark Thickness of Forest-forming Species: Modeling and Comparative Analysis

The need to assess the carbon-depositing capacity of a stand, an individual tree and its components is constantly emphasized in the world literature, since mitigation of the effects of climate change has become the highest priority. Since the carbon concentration differs in different tree species and in different components of the tree, including in the stem wood and bark, it is necessary to develop species-specific mathematical models for estimating the proportion of bark in trunks to improve the accuracy of knowledge about the carbon balance of forests. The relationship of bark thickness with both age and diameter of the tree trunk is known, but with respect to its regional variability, the data are contradictory. According to the actual data from 1100 model trees of five forest-forming species, allometric models of a mixed type have been developed. They include as independent variables the age and diameter of the trunk, as well as a binary variable characterising the influence of the growing area itself on the bark thickness of Scots pine, silver birch and Siberian larch, as well as the difference in the thickness of the bark between Siberian spruce and Siberian fir in case of joint growth in mature stands of the taiga zone. At a statistically significant level, it was found that the bark thickness of Scots pine and silver birch trees in the steppe zone is significantly greater compared to the taiga zone, and the bark thickness of Siberian larch trees in the forest-tundra is significantly greater compared to the steppe zone. The bark thickness of Siberian spruce trees is significantly less than that of Siberian fir trees. The ranking of species by bark thickness is included in the paper.