Search Results (1,170)

Global wetlands play a significant role as “blue carbon sinks”. Despite their relatively small coverage, they have enormous potential for carbon capture and sequestration, and also serve as an important natural source of atmospheric carbon dioxide (CO₂) and methane (CH₄). Wetland ecosystems are characterized by complex microbial interactions that mediate carbon (C) cycling processes, and also directly influence the dynamic changes of CO₂ and CH₄, underscoring the crucial role of microorganisms in these systems. Understanding the ecological significance of these gases and their response mechanisms to environmental changes is vital for mitigating the greenhouse effect and conserving ecosystems. This paper reviewed the major environmental challenges facing wetlands globally, such as salinization, over-fertilization, heavy metal input, and microplastic pollution, all influenced by human activities. Additionally, it examined their impact on microbial interactions that mediate the carbon cycle and related greenhouse gas emissions. This review highlighted the crucial role of microorganisms in these cycles and provided a microbial ecological perspective and theoretical foundation for promoting sustainable development and reducing greenhouse gas emissions in wetland areas. Full article

The influence of forest type on soil aggregates distribution, stability, and the contribution of aggregate-associated carbon (C) to bulk soil organic carbon (SOC) remains poorly understood. This may be crucial for the accumulation and persistence of SOC in subtropical ecosystems. In this study, we examined soil aggregate distribution and stability at two depths (0–15 and 15–30 cm) in 10-, 20-, and 30-year-old Cryptomeria japonica (Japanese cedar) and Chimonobambusa quadrangularis (square bamboo) plantations. We further assessed the contribution of carbon (C) associated with distinct aggregate fractions to bulk SOC. Across all stand ages and soil depths, macroaggregates accounted for 19–56% of total soil aggregates in Japanese cedar plantations, whereas their proportion was 30–337% higher in square bamboo plantations. In contrast, fine aggregates constituted 3–67% of total aggregates in Japanese cedar plantations, but were 29–94% lower in square bamboo plantations than in Japanese cedar plantations. Compared with Japanese cedar plantations, aggregate mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 17–88% and 35–152%, respectively, in square bamboo plantations. In Japanese cedar soils, C and nitrogen (N) were primarily concentrated in coarse macroaggregates and fine macroaggregates, whereas in square bamboo plantations, C and N were mainly associated with coarse macroaggregates only. Both aggregate-associated soil C and N varied significantly with aggregate size and forest type, and Japanese cedar soils exhibited higher aggregate C/N ratios, particularly in older stands. Bulk SOC was positively correlated with macroaggregate-associated C in both forest types and with the silt and clay fractions in Japanese cedar plantations. MWD increased with higher macroaggregate C content and declined as the proportion of C in smaller aggregate fractions increased. These findings indicate that forest type plays a critical role in regulating soil aggregation and SOC stabilization pathways, with square bamboo plantations enhancing C sequestration by promoting macroaggregate formation and stability. Full article

Biochar obtained from digestate is a promising material in the context of digestate management. However, it is important to note that the properties of the resulting material are largely dependent on the parameters of the pyrolysis process, with temperature being a particularly significant factor. The objective of this study was to evaluate the impacts of the digestate pyrolysis temperature on the chemical structure, thermal stability, and thermal decomposition characteristics of biochar produced at temperatures of 400, 500, 600, and 800 °C in an inert nitrogen atmosphere. Material characterization was performed using a range of analytical techniques, including elemental analysis, FTIR spectroscopy, thermogravimetric analysis (TGA/DTG), and coupled TGA–FTIR analysis, in order to identify volatile products released during the heating process. The results demonstrated that elevating the pyrolysis temperature results in progressive carbonization and aromatization of the carbon structure. Concurrently, functional groups containing oxygen and hydrogen were eliminated, as evidenced by declines in the H/C and O/C atomic ratios. FTIR analysis confirmed the disappearance of aliphatic and hydroxyl bands, as well as the dominance of aromatic structures and mineral components in biochar subjected to high-temperature treatment. The TGA results demonstrated an enhancement in thermal stability with increasing pyrolysis temperature. Concurrently, the TGA–FTIR analysis revealed a substantial decline in the emission of volatile decomposition products from biochar obtained at temperatures ≥600 °C. Overall, the pyrolysis temperature of digestate determines the utilization potential of the resulting biochar; in particular, low-temperature biochar can be used as a soil amendment and methane fermentation stimulant, while high-temperature biochar can be used for contaminant immobilization in soil and long-term carbon sequestration. Full article

API Classes of cement are susceptible to three major problems: carbonation, decalcification, and increased porosity of cement sheaths in CO₂-rich environments. These degradation pathways in American petroleum institute (API) Class/ordinary Portland cement (OPC) systems are well documented in laboratory and field observations for CO₂-rich wellbore service. In contrast, while geopolymer/alkali-activated binders have been increasingly studied as alternatives, the evidence remains distributed across different precursor chemistries, exposure conditions, and test protocols, and a consolidated, mechanism-based synthesis specific to CO₂ sequestration wells is still limited. Accordingly, this article presents a critical, narrative (non-systematic) review that synthesizes published laboratory and field studies on geopolymer/alkali-activated binders for CO₂ sequestration wells, with emphasis on permeability, strength retention, and microstructural stability under CO₂-rich exposure. The main outcome of this review is a mechanism-based synthesis that links CO₂–binder reaction pathways (gel chemistry/phase evolution) to pore-network and transport changes, and consolidates quantitative performance benchmarks (permeability and strength retention) relative to API Class G/OPC, while defining the key validation gaps for qualification (HPHT, cyclic/tensile integrity, mixed fluids, and long-term monitoring). Laboratory tests have already demonstrated that geopolymer samples have ultralow permeability and preserve 90% of their strength after being treated with supercritical CO₂ concentrations, while OPC loses its strength and produces macropores causing substantial growth of cement sheath porosity. Microstructural studies have shown that geopolymers do not contain portlandite but only N–A–S–H/C–A–S–H gels with low Ca content in concentrations high enough to create N–A–S–H/C–A–S–H gels, but do not suffer from multi-zone carbonation, as occurs for OPC concrete. Key challenges being tackled include slurry rheology, setting control and variability of precursors by designed admixture use and new performance specifications for higher-quality geopolymers. On the whole, geopolymers emerge as a sustainable and reliable alternative to traditional well cementing techniques for their sustainability well integrity. Full article

Forest fertilization is commonly used to enhance tree growth and carbon (C) sequestration, especially in nutrient-poor boreal forests. However, it also poses several environmental risks, including shifting ground vegetation community composition and a reduction in species diversity. This study evaluated how ground vegetation species composition responded to forest fertilization with ammonium nitrate and wood ash across forest stands with varying dominant tree species, age groups, and site types. Ground vegetation assessment was performed during the one to three years following fertilizer application. We conducted detrended correspondence analysis (DCA) to examine compositional differences in ground vegetation between control and fertilized plots and to identify ecological factors underlying dataset variation. Ordination was based on species percentage cover data, with soil chemical parameters and stand inventory metrics providing environmental context for interpreting the results. Additionally, permutational multivariate analysis of variance (PERMANOVA) was conducted to evaluate whether vegetation composition differed across the experimental design factors. Forest site type and stand developmental stage were the primary drivers of understory composition, with fertilization effects being statistically significant but ecologically modest (0.9–14.2% of variation explained by fertilization in PERMANOVAs). Wood ash treatments showed greater compositional divergence from controls than ammonium nitrate alone. Fertilization effects varied with stand age, with significant responses in middle-aged and pre-mature Norway spruce stands but not in young stands. Despite modest compositional changes, fertilization achieved substantial productivity gains (volume increment increases of 20–60% compared to controls depending on species and site conditions), suggesting that moderate fertilization for timber production can be implemented without dramatic changes to ground vegetation. These results reflect short-term responses (1–3 years after fertilization) and should therefore be interpreted as early ecological effects rather than long-term ecosystem changes. Full article

Mollisols represent foundational agricultural soils in which high organic carbon (C) and active microbiomes sustain fertility and mediate global C cycling. However, decades of intensive cultivation have depleted soil organic C (SOC) and degraded soil structure and function. Enhancing C sequestration in agricultural Mollisols through the incorporation of organic residue, such as crop residues, organic waste, and spent mushroom substrates has become an urgent scientific and management priority. This review integrates advances from the past decade, combining stable isotope probing, multi-omics analyses, and ultrahigh-resolution molecular characterization to elucidate how microorganisms mediate C sequestration during organic residue return and decomposition. We propose a four-dimensional conceptual framework, “substrate–microenvironment–metabolic pathway–residue stabilization,” that links microbial metabolism with long-term C persistence in Mollisols. We further highlight that organic residue inputs promote CO₂ sequestration via fermentation–autotrophy coupling, nitrifying autotrophy, and microbial mixotrophy. Major C sequestration pathways operate synergistically across redox microenvironments, forming stratified metabolic networks that sustain continuous C cycling. The chemical composition and decomposition kinetics of organic residue governs substrate and energy fluxes for microbial C sequestration, while soil redox status, and nutrient coupling (Carbon–Nitrogen–Phosphorus–Sulfur) collectively direct C flow toward stabilization. Microbial necromass and extracellular polymers achieve long-term C storage through mineral adsorption and microaggregate formation. Finally, we summarize recent methodological advances for tracing microbial CO₂ sequestration in agricultural Mollisols and identify key research needs on residue formation, C use efficiency, and aggregate-mineral protection mechanisms. This synthesis establishes a mechanistic foundation for biologically regulated C management and offers guidance for sustainable cropland restoration. Full article

The transformation pathways of organic carbon (OC) fractions and their interrelationship with microbial activity during natural composting (NC) and vermicomposting (VC) remain poorly understood across pig manure (PM)/straw pellets (SP) ratios. Therefore, the objective of this study was to elucidate the regulatory mechanisms of substrate mixing ratios on carbon fraction transformation and microbial functional networks during these processes. To achieve this, five PM/SP ratios [100:0 (T1), 75:25 (T2), 50:50 (T3), 25:75 (T4), and 0:100 (T5)] were composted with or without earthworms, revealing the T2 (75:25) ratio had most efficient composting performance within 60 days due to the suitable initial C/N ratio (31.65 ± 0.99). Consequently, the T2 treatment reached the highest organic degradation, including TOC reduction (58.6%), TN accumulation (63.9%), and C/N decline (74.8%) in the VC. Vermicomposting markedly stimulated functional microbial groups—nitrogen-fixing, phosphate-solubilizing, and potassium-solubilizing bacteria—thereby enhancing nutrient (N, P, K) bioavailability. The prominence of the optimal C/N ratio across multiple hydrolytic and oxidative enzymes in the VC-T2 further proved that this ratio provided an optimal nutrient and structural balance for both earthworms and microbial consortia. Strong correlations between bacterial abundance and enzyme activities (r ≥ 0.98), lignin and dissolved OC (r ≈ −0.81), and particulate organic carbon and mineral-associated carbon (r > 0.9) highlighted microbially mediated carbon stabilization through enzymatic mineralization, aggregation, and redistribution of carbon from active pools toward mineral-associated OC. This work identifies the critical PM-SP ratio for waste valorization and mechanistically links earthworm–bacteria interactions to carbon sequestration pathways. Full article

While organic amendments are extensively applied to increase soil organic carbon (SOC), the mechanisms by which they restructure soil food web energetics to regulate microbial necromass formation and carbon sequestration remain unclear. We conducted a 105-day incubation experiment to investigate how three organic amendments (straw, biochar, liquid organic fertilizer), differing in C:N ratio and pH, and applied at three rates, affect nematode food web energetics and carbon sequestration in black soils of Northeast China. Results showed that amendment properties and application rates jointly shaped nematode energetic structure, differentially regulating total energy flux (E_t) and flow uniformity (U). Straw (moderate C:N, near-neutral pH) strongly increased both E_t (up to 587% above control) and U (peak at 1.68) by fostering fungivore-dominated energy channels. Despite its high C:N ratio, biochar’s alkaline pH favored bacterial-dominated channels, improving flow uniformity (U up to 1.61) without increasing E_t. Liquid fertilizer (low C:N, high pH) produced rate-dependent outcomes: the low rate increased E_t by 210% above control via enhanced bacterial channels, whereas the high rate suppressed E_t but elevated U by reducing energy allocated to plant parasites. Critically, energy flow uniformity correlated positively with fungal necromass carbon, which drove SOC accumulation, whereas total flux was strongly linked to bacterial necromass carbon, suppressing SOC. All amendments finally enhanced omnivore-predator energy flux, boosting top-down regulation and uniform energy distribution. However, mineral fertilizer truncated the food web and suppressed flow uniformity, failing to increase SOC. Therefore, organic amendments enhance SOC by restructuring nematode-mediated energy flow by reinforcing fungal-dominated channels and/or increasing flow uniformity, thereby promoting fungal necromass accumulation and providing a mechanistic basis for targeted management of degraded black soils. Full article

Soil salinization, as a key constraint to global agricultural sustainable development, has threatened over one billion hectares of farmland, posing severe challenges to staple crop production. Therefore, this review summarizes important advances in the molecular mechanisms of salt–alkali tolerance from the model plant Arabidopsis thaliana to staple crops (rice, maize, and wheat) and compares the commonalities and differences in physiological structure and molecular regulatory networks among these species. Studies have shown that plants respond to saline–alkali stress mainly through conserved mechanisms, including salt overly sensitive (SOS) signaling pathway-mediated ion homeostasis, accumulation of osmoprotectants, reactive oxygen species (ROS) scavenging, and coordination of multiple hormone signals. However, different species have evolved unique adaptive strategies: Arabidopsis has revealed core regulatory pathways, but its simple root system limits direct application in crops; rice employs root barriers and a stem node “ion filter” to precisely regulate Na⁺ transport; maize utilizes the C4 photosynthetic pathway along with efficient osmotic adjustment and tissue compartmentalization to enhance tolerance; and wheat achieves ion detoxification through TaHKT allele variation and vacuolar sequestration. Looking forward, future breeding for salt–alkali tolerance should adopt a “crop-centric” approach, focusing on the mining and molecular design of superior alleles, combined with gene editing and multi-trait integration, to provide a theoretical basis and strategic support for developing high-yield and stable crop varieties adapted to saline–alkali lands. Full article

Tallgrass prairie ecosystems in North America sustain globally important plant and animal biodiversity while providing ecosystem services, including biomass production, forage for livestock, and carbon sequestration. Land use change has left less than 1% of North American prairies intact, and opportunities are needed for their restoration. There has been increasing interest in the establishment of prairies on degraded former minelands, where significant challenges exist in reestablishing historic vegetation communities. We examined how the productivity and diversity of mineland prairies were influenced by varying restoration treatments that had been applied nearly a decade previously. We utilized an existing prairie research plot network established using seed mixes containing from one to seven different species and differing fertilization and tillage treatments. We calibrated a non-destructive method to assess prairie biomass and used it to assess the productivity and diversity across 312 research plots. The results showed that, with the exception of C4 grasses, few originally seeded species were present. Significant differences in species richness existed as a function of the interacting effects of seed mix type and fertilization treatment. Unfertilized plots generally had a higher species richness, particularly where larger numbers of species were included in the mixes. Prairie biomass was significantly greater in seed mixes containing big bluestem (Andropogon gerardii) and was also significantly related to Shannon diversity. Our results suggest that the establishment of (Andropogon gerardii) is fundamental to maximizing the diversity and productivity of mineland prairies, especially in the absence of follow-up management. The results also suggest that caution should be exercised when considering the use of fertilizer, as this may reduce the diversity of native species by favoring competitive non-native species such as some C3 grasses. Full article

Soil organic matter (SOM) molecular composition governs its stability and ecological functions in forest ecosystems. Nevertheless, how land-use changes (LUCs) regulate the SOM molecular composition remains poorly understood, particularly the underlying mechanisms mediated by soil properties. This study investigated the effects of LUCs on SOM molecular composition in a subtropical coastal region and examined the driving roles of soil nutrient availability and enzyme activities. The research was conducted in Huanghai National Forest Park, Jiangsu Province, China, focusing on four land-use types converted from historical wheat cropland (W, as control): monoculture plantations of Ginkgo biloba (G) and Metasequoia glyptostroboides (M), a ginkgo–metasequoia mixed forest (GM), and a ginkgo–wheat agroforestry system (GW). Soil samples were collected from 0 to 20 cm and 20–40 cm layers and analyzed for SOM molecular compositions using solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy. Soil chemical properties and enzyme activity activities were also determined, with redundancy analysis (RDA) and correlation analysis applied to identify key influencing factors. Results demonstrated that LUCs significantly altered SOM molecular composition. The GW system exhibited the highest proportion of labile O-alkyl carbon (42.65%), while the M plantation accumulated greatest levels of stable aromatic carbon (up to 49.25%). During the initial decades following afforestation, soil nutrient availability and enzyme activities were confirmed as pivotal drivers of SOM molecular variation. Specifically, available potassium (AK), ammonium nitrogen (AN), and the carbon/phosphorus (C/P) ratio were significantly correlated with specific SOM components (p < 0.05). The elevated O-alkyl carbon proportion in GW was closely associated with its higher invertase activity. Notably, vertical differentiation in SOM stability was observed across land-use types, with the agroforestry system achieving the highest carbon pool management index in surface soil but showing a weakened capacity for subsoil C stabilization. RDA further confirmed that AK and AN were dominant factors shaping SOM molecular composition. In conclusion, LUCs modulate SOM chemical composition and stability primarily through altering soil nutrient availability and associated enzyme activities. Agroforestry system facilitates labile C accumulation in surface soil, whereas monoculture plantations are more conducive to stable C sequestration, especially in subsoil layers. These findings provide novel mechanistic insights into SOM dynamics following LUCs and offer a theoretical basis for formulating tailored management strategies to enhance C sequestration efficiency in subtropical coastal ecosystems. Full article

Background: This study investigated the hypolipidemic and hepatoprotective effects of refined soybean oil supplemented with an Ocimum basilicum L. extract, characterized by HPLC and found to be rich in caftaric, caffeic, chicoric, and rosmarinic acids. Methods: After a 12-week model of diet-induced hyperlipidemia, we examined the plasma levels of TC, TG, Glucose, HDL-C, and LDL-C and the LDL-C/HDL-C ratio using enzymatic kits. The Plasma Hepatic and Biliary Marker Analysis was analysed following standardized hospital protocols with quality-controlled instrumentation. Results: The supplementation with Basil-Enriched Oil (BEO) resulted in a notable redistribution of lipids, significantly reducing the plasma total cholesterol (−75%), triglycerides (−96%), and glucose (−22%), while enhancing their hepatic sequestration. This was accompanied by a marked improvement in the LDL-C/HDL-C ratio and a reduction in hepatic oxidative stress (measured by MDA). Importantly, BEO preserved liver structure and prevented steatosis, despite inducing an increase in adaptive hepatomegaly. Conclusions: The results reveal a dual mechanism whereby the antioxidant properties of BEO collaborate with reprogrammed lipid metabolism, promoting safe hepatic storage rather than harmful circulating levels. These findings strongly advocate for the extract’s potential as a nutraceutical for addressing hyperlipidemia and related metabolic disorders by targeting both oxidative stress and lipid imbalance. Further research is required to confirm these effects in clinical settings and to confirm its long-term efficacy. Full article

The global carbon cycle has become increasingly unbalanced over the past century as anthropogenic fluxes into the atmosphere far exceed the sequestration capacity of land and ocean systems. Data from 2025 show estimated annual anthropogenic emissions of ≈11.2 gigatonnes of carbon (GtC), while only ≈5.6 GtC are sequestered by land and ocean sinks mainly provided by photosynthetic CO₂ fixation. The resulting surplus of carbon emissions has led to a doubling of atmospheric CO₂ concentrations above pre-industrial values to ≈430 ppm, which is a major driver of increasingly erratic climatic phenomena. Recent data indicate that fossil fuel use will continue rising up to and beyond 2050, largely negating the drive to cut CO₂ emissions as recommended by the IPCC and other reputable transnational bodies. Hence, there is an urgent need to reduce atmospheric CO₂ levels via carbon sequestration. This review focuses on the proven capacity of biological mechanisms to sequester CO₂ at a global scale with an annual capacity in the range of gigatonnes of carbon. New measures such as re- and a-forestation, plus improved and more sustainable management of tropical tree crops, can further increase the carbon sequestration potential of these plants. By implementing these and other nature-based solutions, the highly productive tropical vegetation belt could contribute an additional 1–2 Gt of carbon sequestration via natural forests and perennial tree crops. In order to expedite this process, we examine the use of new modalities of transparent carbon trading systems that include selected tropical crops. As highlighted at COP30 in Brazil and elsewhere, this would enable tropical countries to derive benefit for costs incurred in land management changes such as reforestation, regenerative farming, and intercropping to benefit smallholders and other rural communities. In particular, carbon finance is emerging as a critical driver, with appropriately regulated and transparent carbon credit schemes offering fungible monetary compensation for climate-positive land management. Full article

The sustainable management and valorisation of agricultural and agro-industrial residues are essential to reduce environmental impacts, enhance resource efficiency, and support circular economy strategies. In Mediterranean regions, large quantities of residual biomass are annually produced from olive and citrus supply chains, representing promising feedstocks for biochar production. In this study, biochar was obtained at 600 °C in a fixed-bed reactor under a N₂ atmosphere from four representative feedstocks: olive pruning (OPr), citrus pruning (CPr), olive pomace (OPo), and citrus peel (CPe). The resulting biochar was characterized in terms of physico-chemical, energetic, and structural properties, including proximate and ultimate analyses, fuel properties, cation exchange capacity (CEC), pH, elemental ratios (O/C, H/C, N/C), thermal stability, bulk density, metal content, and surface morphology (SEM), in order to assess parameters relevant to environmental potential applications. The results highlighted clear feedstock-dependent differences. OPoB and CPeB exhibited the highest thermal stability (0.56–0.66), indicating a strong potential for long-term carbon sequestration. CPeB showed the highest CEC (47.2 cmol kg⁻¹). From an application-oriented perspective, this high CEC suggests that, when applied to soil at typical amendment rates (2–5 wt%), CPeB could potentially increase soil CEC by approximately 10–30%, thereby improving nutrient retention and cation availability. Energy yields were highest for citrus-derived biochar (42.0–47.5%), while OPoB exhibited the lowest solid yield due to its higher volatile content. SEM analysis revealed marked structural differences, with OPrB retaining an ordered lignocellulosic porous structure, whereas OPoB and CPeB displayed highly irregular morphologies, favorable for surface reactivity. Overall, this study demonstrates that olive and citrus residues are suitable feedstocks for producing biochar with differentiated properties, and that a rapid screening methodology can support feedstock selection and biochar design for targeted energy, soil amendment, and carbon management applications. Full article

There are 266 nature parks in Türkiye, including Aşıkpaşa Nature Park, covering a total area of approximately 109,023 ha; however, information regarding soil organic carbon stocks (SOCS), soil nitrogen stocks (NS), and nutrient stoichiometry in these protected forests remains limited. This study evaluates the influence of tree species, altitude, aspect, and soil depth on nutrient stocks and stoichiometry using a 3 × 2 × 3 × 3 factorial experimental design. The findings indicate that mixed stands (Black Pine + Cedar) significantly optimize nutrient storage, reaching peak N (3.531 ± 0.115 t ha⁻¹) and P (0.948 ± 0.016 t ha⁻¹) stocks. SOC and N stocks reached 66.34 ± 1.86 t ha⁻¹ and 4.032 ± 0.123 t ha⁻¹, respectively, along the altitudinal gradient. Soil pH exhibited a steady rise with altitude (from 7.86 to 8.15), contrary to typical leaching patterns, while bulk density varied depending on Altitude × Aspect × Depth interactions. Stoichiometric analyses revealed that Cedar stands maintain higher C:K ratios (3.457 ± 0.258), reflecting superior nutrient use efficiency. Furthermore, sunny aspects prioritized nitrogen mineralization (N:P ratio: 4.540), whereas shaded aspects facilitated phosphorus retention. These results prove that soil fertility and carbon sequestration are modulated by complex topographic–biotic interactions, suggesting that preserving mixed forest structures is of vital importance for ecological sustainability and forest resilience. Full article