Search Results (385)

Madinah, Saudi Arabia, is a hot-desert pilgrimage city receiving millions of religious visitors annually, yet its fine particulate matter (PM_2.5) has not been chemically characterized. The city whose population is periodically influx by millions of religious visitors, generating concentrated increases in vehicular activity while simultaneously exposing a large transient population to ambient air pollution. Despite this, its fine particulate matter (PM_2.5) has not been chemically characterized. Twenty-four-hour PM_2.5 samples were collected at five urban sites between December 2014 and February 2016 and analyzed for black carbon, water-soluble inorganic ions, and trace elements; sources were resolved by enrichment factors and positive matrix factorization (PMF), and screening-level inhalation risks estimated for eight PM_2.5-bound metals. Site means ranged from 37.7 ± 20.5 µg m⁻³ at Uhad to 103 ± 50.7 µg m⁻³ at Al-Awali, exceeding the World Health Organization 24-h guideline of 15 µg m⁻³ at all sites in every season. Observed site–cycle means ranged from 37.7 ± 20.5 µg m⁻³ at Uhad to 103 ± 50.7 µg m⁻³ at Al-Awali, with concentrations exceeding the World Health Organization 24-h guideline of 15 µg m⁻³ across the monitored site–cycle datasets. Reconstructed mass was dominated by organic matter (53–80.5%) and crustal material (15–53%). Sulfate was the dominant water-soluble ion, but secondary inorganic aerosols contributed only 1–22% of mass, resembling rapidly urbanizing arid cities rather than Asian or European megacities. PMF resolved five sources: crustal dust, industrial mixed dust, oil combustion, vehicular emissions, and secondary aerosols. Hazard quotients remained below unity and cumulative carcinogenic risks below 10⁻⁶, principally from chromium and nickel. Because these measurements precede the Vision 2030 urban-transformation program, they establish a chemically resolved reference state for evaluating future air-quality change in Madinah. Full article

Background/Objectives: This study examined the effect of three different cultural media—coconut coir, peat moss, and deep-water culture—on the metabolomic profiles of two tomato cultivars, Heinz and Roma. Tomato fruit quality is influenced by intricate interactions between the genotype and root-zone environment; nevertheless, little is known about how substrate-based systems compare metabolically to deep-water hydroponics. Methods: Fruit samples from both cultivars grown under controlled greenhouse conditions were analyzed using proton nuclear magnetic resonance (¹H-NMR) spectroscopy to identify treatment-dependent biochemical changes. Polar metabolites were extracted using a methanol–water solvent solution and examined using a 600 MHz NMR spectrometer. Spectral datasets were processed and analyzed with multivariate statistical tools such as Principal Component Analysis (PCA), Partial Least Squares Discriminant Analysis (PLS-DA), and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA). Results: Distinct clustering patterns were observed, indicating both cultivar-specific and cultivation-system-dependent metabolic differentiation. The PCA model displayed excellent explanatory and predictive capacity, while supervised OPLS-DA improved group discrimination, demonstrating that both genotype and growing medium significantly influenced the chemical composition of the fruit. Soluble sugars (glucose, fructose, and sucrose), sugar alcohols, organic acids such as citric and malic acids, and a variety of amino acids involved in nitrogen metabolism and stress reactions were among the key distinguishing factors. Carbohydrate-related spectral areas (3.0–5.5 ppm) were highly associated with treatment separation, indicating that the cultivation system had a significant impact on carbon allocation and energy metabolism. Conclusions: Fruits grown in deep water culture have distinct metabolic fingerprints from those grown on coconut coir and peat moss, implying that root-zone oxygen availability and nutrient dynamics may influence primary and secondary metabolism. Full article

Assessing the soil quality of coastal reclamation areas is fundamental to alleviating land resource scarcity in coastal cities and ensuring food security. However, it remains unclear how to evaluate soil quality in reclaimed areas and identify factors driving its variation. In this study, paddy soils from four typical reclaimed coastal areas in China (Yueqing, YQ; Longgang, LG; Rui’an, RA; Longwan, LW) were investigated to construct a minimum data set via principal component analysis and to calculate soil quality indices (SQIs). YQ had higher contents of soil organic carbon (SOC: 22.82 g kg⁻¹), total nitrogen (TN: 0.14 g kg⁻¹), total water-soluble salts (TWS: 3.09 g kg⁻¹), cation exchange capacity (CEC: 21.77 cmol(+) kg⁻¹), and available Fe (44.23 mg kg⁻¹), Mn (36.63 mg kg⁻¹), Cu (30.31 mg kg⁻¹), and Zn (8.79 mg kg⁻¹) than the other sites. RA exhibited significantly higher activities of β-glucosidase (BG: 32.79 nmol g⁻¹ h⁻¹), xylanase (XYL: 5.88 nmol g⁻¹ h⁻¹), N-acetyl-β-D-glucosaminidase (NAG: 18.00 nmol g⁻¹ h⁻¹), leucine aminopeptidase (LAP: 27.01 nmol g⁻¹ h⁻¹), and acid phosphatase (PHOS: 54.50 nmol g⁻¹ h⁻¹) than the other sites (p < 0.05). LW had the greatest bacterial and fungal abundances, whereas LW displayed the highest fungal diversity. RA showed the highest SQI (SQIw: 0.49; SQIa: 0.48), followed by LW (SQIw: 0.47; SQIa: 0.47), LG (SQIw: 0.43; SQIa: 0.41), and YQ (SQIw: 0.38; SQIa: 0.41). Random forest analysis indicated that soil enzyme activities (XYL, NAG, BG, CB, PHOS), nutrients (TN, SOC, AN), fungal abundance and diversity, and TWS were key SQI predictors (Welch ANOVA p = 0.016), with XYL being the strongest predictor (p < 0.05). Collectively, soil quality in coastal reclamation areas is co-regulated by microbial metabolic activity, nutrients, and salinity, with soil enzyme activity serving as an important indicator for its assessment, thereby deepening the understanding of soil quality dynamics within these areas and enabling their sustainable management. However, the microbial mechanisms underlying these patterns across broader environmental gradients remain to be explored. Full article

Green tea quality is largely determined by the metabolite profile of fresh leaves. However, the time-of-day-dependent dynamics of these metabolites remain largely unknown in Xinyang Maojian (XYMJ), a premium Chinese green tea. In this study, we performed the first integrative transcriptomic and metabolomic analysis of Camellia sinensis cv. Xinyang 10 shoots (one bud and one leaf) sampled at 7:00, 13:00, and 18:00 under field conditions with light intensities of 19.2, 113, and 5.4 klx, respectively. We identified 525 differentially accumulated metabolites and 19,767 differentially expressed genes exhibiting distinct time-of-day-dependent patterns. Physiological measurements confirmed significant fluctuations in starch, soluble sugars, chlorophyll, relative water content, and polyphenols throughout the daytime. A key finding was a daytime carbon allocation trade-off: primary metabolism (starch biosynthesis, glycolysis, TCA cycle) peaked at 13:00, whereas secondary metabolism (flavonoids, theaflavins, phenolic acids, anthocyanins) dominated at 18:00, supported by strong negative correlations between primary and secondary metabolic modules. Chlorophyll and oligomeric catechins peaked at 7:00; theaflavins at 13:00; and starch, soluble sugars, theanine, and organic acids at 18:00. Light-responsive transcription factors (bZIP, NF-Y, HD-Zip, SPL, ARF, MADS) and other regulators (MYB, AP2/ERF, WRKY, NAC, GRAS, bHLH) exhibited time-specific expression, sequentially modulating flavonoid, caffeine, and theanine biosynthesis, along with specific gene modules including SS3/SS4 (starch synthesis), BAM3 (starch degradation), FBA1 (carbon fixation), CYP72A219 (terpenoid metabolism), and L7A (theaflavin biosynthesis). Evening-harvested leaves accumulated higher levels of theanine (umami) and soluble sugars (sweetness), whereas morning leaves were enriched in astringent catechins and flavonols. This multi-omics dissection of time-of-day-dependent metabolism in XYMJ tea provides a scientific basis for time-of-day harvesting strategies and graded processing of tea products. Full article

To investigate the effects of interplanting Morchella (morel mushrooms) between rows of apple trees on orchard soil properties and apple tree performance, a field experiment was conducted using a cultivation system combining small-arch tunnels with plastic film covering. The Morchella was interplanted in a five-year-old apple orchard, with plots without Morchella cultivation serving as the control. Measurements included Morchella yield and quality, apple fruit quality, and leaf photosynthetic performance. Additionally, soil physicochemical properties and enzyme activities were analyzed across the 0–40 cm soil layer at different depths. The results demonstrated that: (1) Intercropping Morchella in apple interrows proved to be agronomically feasible, yielding a fresh mushroom production of 1333.74 g/m². Moreover, this cultivation system significantly enhanced the nutritional quality of the harvested morels, as evidenced by marked increases in crude fiber, total sugars, reducing sugars, and free amino acid contents. (2) In the 0–20 cm soil layer, the Morchella cultivated plots exhibited significantly higher natural water content compared to the control. The measured values for soil pH, alkali-hydrolyzable nitrogen, organic carbon, catalase activity, and sucrase activity were 5.46, 6.73 mg/kg, 38.30 g/kg, 411.86 μ mol/h/g, and 9.89 mg/d/g, respectively, all significantly greater than those in the control (p < 0.05). In the 20–40 cm layer, however, soil available potassium and organic carbon contents were 418.37 mg/kg and 28.45 g/kg, respectively, both significantly lower than the control (p < 0.05). Across both treatments, the values of soil pH, alkali -hydrolyzable nitrogen, organic carbon, available phosphorus, available potassium, and the activities of urease, amylase, catalase, and sucrase generally decreased with increasing soil depth. Notably, in the non-cultivated control plots, the contents of alkali-hydrolyzable nitrogen and organic carbon increased with depth. (3) Interplanting Morchella improved apple fruit quality to a certain extent, significantly increasing individual fruit fresh weight, fruit shape index, and the contents of reducing sugars, total sugars, and soluble solids. (4) Interplanting Morchella also enhanced the photosynthetic rate of apple trees to some degree, significantly increasing transpiration rate, intercellular CO₂ concentration, and stomatal conductance. Collectively, interplanting Morchella in apple orchards can produce a reasonably high yield of high-quality mushrooms, increase individual apple fruit fresh weight, improve the physicochemical properties of the 0–20 cm soil layer, and enhance the photosynthetic performance of the apple trees. These combined benefits demonstrate clear practical potential and support the promotion and application of this intercropping system in orchard production. Full article

Green undersown crops (GUCs) are increasingly promoted as a sustainable management strategy to improve soil quality and ecosystem services in Mediterranean orchards, particularly in the calcareous, low-organic-matter soils typical of Eastern Spain. In this context, soil quality is understood as the soil’s overall functional capacity, integrating physical structure, chemical balance, and biological activity, whereas soil fertility refers specifically to the soil’s ability to supply nutrients to plants; soil quality therefore encompasses a broader set of ecosystem functions beyond nutrient provision. However, their effects on the calcareous, low-organic-matter soils typical of Eastern Spain remain insufficiently quantified. This study evaluates the effects of seeded undersown (grasses, legumes, and flower mixtures), spontaneous vegetation, and herbicide-managed bare soil on topsoil (0–15 cm) physicochemical and biological indicators in 54 plots across three irrigated persimmon orchard sites (Granja, Cargol, and Alginet) over 18 months of treatment in the València region (Eastern Spain). Seasonal sampling was conducted at the START (early winter) and END (late spring) of the experiment period. Soil measurements at both sampling times included soil organic matter (SOM), nitrogen (N), C/N ratio, pH, electrical conductivity (EC), soil respiration rate (RR), collembolan abundance, mite abundance, and the QBS-ar index of soil arthropods. Legumes increased SOM by +1.12%, grasses by +0.22%, whereas flower mixtures (−0.44%) and spontaneous vegetation (−1.36%) showed SOM reductions associated with rapid biomass turnover. RR increased under all GUCs (+0.06 to +0.16 g CO₂ m⁻² h⁻¹), and QBS-ar improved markedly under grasses (+26.6) and spontaneous vegetation (+36.7). EC decreased across all treatments (−16 to −84 µS cm⁻¹). These results were analysed using principal component analysis (PCA). Four PCA components explained 74% of the total variance, revealing functional gradients driven by SOM, N, EC, RR and mesofauna. After 18 months, microbial biomass carbon (MBC) increased by +45–60% under legumes, water-soluble organic carbon (WSOC) by +30–50% under legumes and flower mixtures, and the enzyme activities (EA) by +20–40% under all GUCs. Herbicide-managed soils showed reduced biological activity and detectable residues of glyphosate and oxyfluorfen. PCA and linear discriminant analysis (LDA) were used to identify functional gradients and treatment separation. GUCs significantly increased SOM, MBC, EA, and mesofauna abundance compared with herbicide treatments, which showed reduced biological activity and detectable residues of glyphosate and oxyfluorfen. Legumes and flower mixtures produced the strongest improvements in biological functioning due to higher MBC, WSOC, EA and RR. PCA and LDA confirmed clear separation between GUCs and herbicide-managed soils based on multivariate differences in SOM, N, EC, RR, MBC, WSOC and mesofauna indicators. Overall, GUCs modulated soil chemistry and biodiversity and enhanced soil functioning and biological quality, supporting their adoption as a sustainable management strategy in Mediterranean orchards. Legume-based covers are recommended for rapid biological activation, whereas grass-based covers favour longer-term SOM stabilisation. These findings highlight their role as key tools for improving soil resilience in Mediterranean persimmon orchards. Full article

Rapid accumulation of soil lanthanum (La), cerium (Ce), and fluorine (F) caused by bastnasite mining development has increasingly become a concern worldwide in the past decades. However, the effects of the different chemical forms of these elements on the composition and diversity of soil dominant, moderate, and rare microorganisms are unclear. In this study, Planctomycetota was changed from dominant to moderate, caused by exchangeable and carbonate-bound forms of La and Ce. Both organic bound La (La_ORG) and water-soluble F (F_WS) were the crucial factors driving variations in the relative abundance of Patescibacteria and Bacteroidota from moderate to dominant, while the fungal phylum Chytridiomycota was changed from moderate to dominant, promoted by F_WS. La_ORG, the ferrum-manganese bound form of Ce, and F_WS displayed a negative correlation with the three rare bacterial phyla, i.e., Abditibacteriota, GAL15, and Deinococcota respectively. F_WS caused the disappearance of the rare fungal phylum Monoblepharomycota and the appearance of the rare bacterial phylum Fibrobacterota. Organic bound forms of both Ce and F showed a negative correlation with the bacterial Sobs and fungal Phylogenetic diversity indices, respectively. To summarize, the different chemical forms of La, Ce, and F showed varied effects on the composition and diversity of soil microbial communities. Full article

Underwater concrete infrastructure is gradually damaged by water scouring, chloride ingress, freeze–thaw cycles, and fatigue loading, so reliable in situ repair materials are increasingly needed. Conventional cement-based repair materials are often unsuitable for underwater use because they disperse in water, bond weakly to wet substrates, and show limited durability. Polymer-modified cementitious materials can reduce these problems by combining cement compatibility with polymer film formation and interfacial strengthening. Water-soluble polymers mainly improve fresh-state cohesion and anti-washout performance through adsorption, bridging, and flocculation regulation. In comparison, polymer emulsions and latexes are more effective after hardening, improving bonding, crack resistance, and durability through polymer films and organic–inorganic networks. For self-leveling underwater repair, the flow spread should reach at least 130 mm. For vertical repair with a 20 mm layer, a yield stress of about 360 Pa is needed to prevent sagging. Therefore, performance should not be judged by strength alone, but by constructability, interfacial water films, and pore connectivity. Future studies should consider responsive polymers, multi-component modification, standardized tests, and low-carbon binders. Full article

Carbon sequestration is considered one of the key factors for sustainable development. The marshes of Aniva Bay (Sakhalin Island) are ecosystems currently undergoing intense natural carbon accumulation (450–930 g∙C∙m⁻²∙year⁻¹) 2–4 times higher than the average speed for similar ecosystems, making this area highly promising for the implementation of “carbon farms.” Carbon sequestration could be accelerated by installing structures on mudflats that capture suspended organic matter from tidal waters. A model experiment was conducted to assess the suitability and biocompatibility of logging waste from coniferous species (Picea ajanensis, Larix leptolepis, Abies sachalinensis) for such structures by simulating their immersion in seawater. The content of phenols and tannins in the resulting water extracts was determined, and the composition of water-soluble substances was analyzed by GC-MS. Extract toxicity was investigated using the halophilic test organism Artemia salina. The experiments revealed the release of tannins in concentrations of up to 14 mg/L, which is nearly 1.5 times the maximum permissible concentration (MPC) and could potentially negatively impact the coastal ecosystem. Furthermore, the concentration of tannins leached from L. leptolepis bark exceeded the MPC by a factor of 5.5. A critical finding is the presence of highly toxic compounds in wood waste, for which targeted analysis is absent in state regulatory documents for hazard assessment. Specifically, immersion of A. sachalinensis wood led to the leaching of juvabione into saltwater at concentrations causing 100% mortality in Artemia salina. Based on the results, the most promising species for the terraformation of mudflats is the use of P. ajanensis logging waste. Full article

Reactive oxygen species (ROS) are critical drivers of redox-associated biogeochemical processes within the rhizosphere, yet the mechanisms of their generation under contaminant stress remain poorly understood. A 24-day pot cultivation experiment with four treatments (control, naphthalene, phenanthrene, and anthracene) was conducted to investigate how polycyclic aromatic hydrocarbons (PAHs) alter the production of three kinds of ROS (e.g., O₂^•−, H₂O₂, and ^•OH) in the maize rhizosphere. PAHs promoted the production of rhizosphere ROS, and the promotion effects were compound-dependent, following the order of anthracene > phenanthrene ~ naphthalene. The increases in O₂^•− content were 55.6%, 14.3%, and 17.9% under anthracene, phenanthrene, and naphthalene treatments. The H₂O₂ content was enhanced by 58.6% under anthracene treatment, 10.4% under phenanthrene treatment, and 15.4% under naphthalene treatment. The ^•OH concentrations increased by 62.5%, 21.1%, and 0.5% under anthracene, phenanthrene, and naphthalene exposure, respectively. Importantly, the variations in rhizosphere ROS’ content simultaneously fluctuated with stem length, photosynthetic rates, root exudates, dissolved organic carbon (DOC), water-soluble phenols, and enzymes activities induced by PAHs stress. Statistical analysis suggested PAH stress enhanced maize biomass (particularly stem growth), thereby improving photosynthetic efficiency and thus stimulating root exudate release. Root exudates could promote water-soluble phenol and DOC release and enhance microorganism reproduction, thereby mediating abiotic ROS’ production via electron transfer and biotic ROS’ production via extracellular release. These findings clarify the response of rhizosphere ROS to PAHs stress, providing valuable insights for rhizosphere-ROS-mediated remediation of soil pollutants. Full article

Although the health risks associated with the use of biomass fuels have received widespread attention, there has been insufficient detailed research conducted on the toxic effects and toxicity generation mechanisms of PM_2.5 produced by the use of different sources of solid organic fuels. In this study, the synchronized L4-stage Caenorhabditis elegans (C. elegans) were exposed to the suspensions of the PM_2.5 samples collected from incomplete combustion products of rice straw, wheat straw, peanut straw, rapeseed straw and the branch of poplar and paulownia. Body length, the number of fertilized eggs, accumulation of lipofuscin, and levels of reactive oxygen species (ROSs) were measured to characterize developmental toxicity, reproductive toxicity, intestinal damage, and oxidative stress. The types and mass proportions of organic carbon (OC), elemental carbon (EC), water-soluble inorganic ions, and polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 were determined. The results show that PM_2.5 generated from the combustion of the straw of oilseed crops such as peanuts and rapeseed has the most severe toxic effects on C. elegans. The toxicological mechanism was mainly mediated by severe oxidative stress and excessive generation of ROSs. The chemical characteristics of PM_2.5 have strong source-specificity, and its toxic effects are closely related to the high content of lipid-soluble PAHs in PM_2.5 from oilseed crop sources. Full article

The oxidative potential (OP) of atmospheric particulate matter serves as an effective indicator for assessing the health risks posed by reactive oxygen species (ROS). Existing studies have mainly focused on conventional particulate matter including PM_2.5, whereas systematic investigations into the OP of road dust in coal–resource–based cities are still limited. Taking Huainan City, China as the study area, this paper explored the characteristics and influencing factors of OP in water–soluble fractions of road dust from different functional zones. The results indicated that the OP of water-soluble fractions in road dust from Huainan City was 0.162 ± 0.079 pmol/min/μg, with the value in the coal mining zone being significantly lower than that in the commercial and industrial zones. The average concentration of water–soluble organic carbon (WSOC) was 67.3 ± 59.4 mg/kg, with lower levels observed in the coal mining and power plant zones. WSOC was primarily dominated by fulvic acid–like (C1) and tryptophan–like (C2) components. C1 prevailed in coal mining, power plant, and other functional zones, whereas C2 was dominant in commercial, park and residential zones. Overall, the WSOC showed a mixed-source signature dominated by endogenous sources and characterized by a low degree of humification. The total concentration of water–soluble heavy metals in road dust was 43.46 mg/kg, dominated by Fe, Sr, Cu, Ba, and Mn, with relatively lower concentrations observed in the industrial and coal mining zones. The influencing factors of OP exhibited differentiation among functional zones: in industrial zones, it was regulated by As, Mn, TC (total carbon), WSOC and its fluorescent components, while in non-industrial zones, it was closely associated with Co, TC, and WSOC. These findings indicate that road dust toxicity and its key chemical drivers in coal mining and power plant zones of coal resource–based cities exhibit distinctive characteristics. This study provides a scientific basis for the precise management of road dust pollution and the prevention of associated health risks. Full article

Chlorinated paraffins (CPs) are recognized as a novel class of persistent organic pollutants (POPs) and are categorized into short- (SCCPs, C_10–13), medium- (MCCPs, C1_4–17), and long- (LCCPs, C_≥18) chain CPs considering the carbon-chain length. Among them, SCCPs possess lower molecular weights, higher vapor pressures, and greater water solubilities compared to their longer-chain counterparts (MCCPs and LCCPs), which promote their environmental release. Consequently, SCCPs were designated as POPs of concern under the Stockholm Convention in 2017. This review concludes the recent research progress of SCCPs in China from 2015 to present, and we present a comprehensive overview of SCCP concentrations, encompassing diverse environmental matrices and human tissues, for example, air, water, soil, sediments, biota, food, human placenta, breast milk, blood, and organs (fat, kidney, liver, brain, bone, etc.). Whereafter, we summarize the development of SCCPs determination methods, benefiting from quantifying relative carbon-chain length and chlorine content of SCCPs correctly. Moreover, toxicity, toxicokinetics, and adverse health effects of SCCPs in humans from China are concluded and discussed. Meanwhile, we review the existing control and treatment technologies for SCCPs. Lastly, we describe some noteworthy and prospective issues that are worthy of further study. In the future, the relevant studies are still necessary to keep up with consecutive monitoring and evaluation of SCCP levels and relative potential health impacts in China. Full article

Carbon dots (CDs) have been widely employed in diverse fields by virtue of their excellent water solubility, low toxicity, high fluorescence stability, and favorable biocompatibility. Nevertheless, traditional preparation methods for CDs generally suffer from drawbacks that run counter to the concept of green chemistry. This review comprehensively summarizes the green synthesis technologies, machine learning (ML)-assisted synthesis strategies, and diversified application fields of fluorescent CDs. Specifically, it discusses the characteristics of synthetic organic molecular/polymeric materials and natural sources (e.g., plants and fruit peels, etc.) and elaborates on the top-down and bottom-up green synthesis methods, analyzing their advantages. It also focuses on ML’s core role in precisely regulating CD emission wavelengths, enhancing and predicting fluorescence quantum yields to optimize synthesis processes. Additionally, this review highlights the representative biological applications of CDs, including biosensing and biomedicine (e.g., bioimaging, drug delivery, and photodynamic therapy), while briefly covering their applications in other fields. Finally, the review points out current challenges in green synthesis, ML-assisted applications and industrial translation, and puts forward future research directions, aiming to promote the greenization, intellectualization and large-scale development of CDs. Full article

Prolonged cultivation of cereal-based cropping systems in the Indo-Gangetic Plain has contributed to soil degradation, groundwater depletion, and declining soil organic carbon levels, highlighting the urgent need for climate-resilient, sustainable crop diversification strategies that enhance soil carbon sequestration and improve overall soil health. A 6-year field experiment assessed 10 cropping systems (CSs) using a randomized complete block design with four replications, focusing on their effects on soil carbon stocks and sequestration at two soil depths (0–15 cm and 15–30 cm). It was inferred from the results that there is a significant variation in soil carbon stocks, with maize–peas–spring groundnut (CS6) having the highest surface carbon stock (13.0 Mg ha⁻¹) and baby corn–potato–okra (CS10) having the highest sub-surface carbon stock (11.9 Mg ha⁻¹). Carbon sequestration peaked in CS6 at 5.06 Mg ha⁻¹ at 0–15 cm, and its sequestration rate was the highest (0.84 Mg ha⁻¹ yr⁻¹). Total organic carbon (TOC) ranged from 0.63% in Rice–Wheat (CS1) to 0.73% in CS6, with similarly high values in other diversified systems. Very labile carbon (VLC) was highest in basmati rice, late-sown wheat, and cowpea (CS3) and CS6, demonstrating the benefits of legume-based systems. At depths of 15–30 cm, trends were consistent but lower. Water-soluble carbon (WSC) and hot water-soluble carbon (HWSC) showed significant differences across systems, with CS3 recording the highest values. The findings indicate that cropping systems incorporating legume diversification and green manuring enhance carbon stocks, sequestration rates, and soil carbon stability, demonstrating that crop diversification is an effective means of increasing soil carbon storage, promoting soil health, and supporting sustainable agricultural production in Northwestern India. Full article