Organic Content Research Articles

Influence of mandatory waste classification on environmental and economic impacts of residual waste treatment in Xiamen, China.

Mandatory waste classification has been widely considered as an effective solution for reducing the production and treatment amount of municipal solid waste. However, there is limited evidence regarding whether and how waste classification can affect the composition of residual waste (RW) and its environmental economic impacts. Here, an accounting method recommended by the Intergovernmental Panel on Climate Change, field surveys and cost-benefit analysis was utilized to investigate the changes in RW composition, environmental impacts and economic benefits under the waste classification policies implementation in Xiamen, China. This study found that: (1) The implementation of waste classification policies led to a significant increase in recyclable content from 17% to 51% and a decrease in organic content from 56% to 32%. (2) Waste classification effectively reduces greenhouse gas emissions from landfilling and incineration by an additional 0.34 tCO2-eq t-1 RW. (3) The introduction of mechanical recycling achieves a saving of 0.47 tCO2-eq t-1 RW at 40% recycling efficiency, a 4.5-fold increase compared to business as usual (BAU). (4) The operational benefits (900 yuan t-1 RW) from the recyclables sorting system offset the total expenses of investment, operation and waste disposal. The study successfully demonstrated that RW source-classified management can optimize the structure of waste composition, reduce environmental emissions and offer detailed guidance for the development of solid waste management systems in other cities in China.

Transmenopausal changes in cortical bone quality

Bone's resistance to fracture depends on its amount and quality, the latter including its structural and material/compositional properties. Bone material properties are dependent on bone turnover rates, which are significantly elevated immediately following menopause. Previously published data reported that following menopause, the amount of organic matrix synthesized at actively forming surfaces is significantly decreased, while glycosaminoglycan content was also modulated at resorbing surfaces, in the cancellous compartment.In the present study, we used Raman microspectroscopic analysis of paired iliac crest biopsies obtained before and shortly after menopause (1 year after cessation of menses) in healthy females to investigate changes in material/compositional properties due to menopause, in the cortical compartment. Specifically, the mineral/matrix ratio, the relative proteoglycan content, the mineral maturity/crystallinity, and the relative pyridinoline collagen cross-link content were determined at actively forming intracortical surfaces (osteons) as a function of tissue age, as well as in interstitial bone.Results indicated that it is the freshly synthesized organic matrix content that significantly declines following menopause, in agreement with what was previously reported for the cancellous compartment. This decline was not evident in the freshly deposited mineral content. None of the compositional/quality properties were altered following menopause either. Finally, no differences in any of the monitored parameters were evident in cortical interstitial bone.

Exploring How Antibody Format Drives Clearance from the Brain.

Monoclonal antibodies (mAbs) have high binding specificity and affinity, making them attractive for treating brain diseases. However, their effectiveness is limited by poor blood-brain barrier (BBB) penetration and rapid central nervous system (CNS) clearance. Our group identified blood-brain barrier modulator (BBBM) peptides that improved mAb penetration across the BBB into the brain. In this study, we investigated the pharmacokinetics of a mAb delivered to the brain using BBBMs after intravenous (IV) administration and explored the impact of antibody format (size, neonatal Fc receptor (FcRn) binding, hyaluronic acid binding) on brain clearance following direct injection into the central nervous system (CNS) via intracerebroventricular (ICV) injection. IRDye800CW-labeled antibodies were administered into C57BL/6 mice via ICV or IV injection, and organ concentrations were measured after various time points. When a mAb was coadministered with a BBBM peptide, the permeation of mAb across the BBB was increased compared to mAb alone at early time points; however, the mAb was cleared within 2 h from the brain. ICV experiments revealed that an antibody Fab fragment had a higher brain exposure than a mAb, and that a Fab fused to a hyaluronic acid binding domain (Fab-VG1) showed remarkable improvement in brain exposure. These findings suggest that BBBMs and antibody format optimization may be promising strategies for enhancing brain retention of therapeutic antibodies.

Pre-harvest application of sodium nitroprusside enhances storage root quality in red beet cultivated under normal and drought conditions.

The role of nitric oxide (NO) in plant stress tolerance, as well as in increasing post-harvest quality, has been extensively demonstrated in several fruits and vegetable crops; however, the effects of its pre-harvest application on post-harvest quality are still poorly documented. Therefore, the pre-harvest application of NO in red beet (Beta vulgaris subsp. vulgaris) plants cultivated under well-watered and drought conditions was evaluated to assess whether it improves the post-harvest quality of their storage roots. Red beet plants cultivated under well-watered (80% of water holding capacity) or drought condition (15% of water holding capacity) were sprayed weekly with water (control) or 100 μmol L-1 sodium nitroprusside (SNP), an NO donor. Sixty-six days after sowing, red beet roots were harvested, and root yield, total sugar yield, reducing sugars, non-reducing sugars, proteins, lipids, root ashes, root moisture, soluble solids, titratable acidity, pH, vitamin C, total phenolics, total betalains, betacyanins, betaxanthins and antioxidant capacity were determined. While drought led to a reduction in root yield, sugars, lipids and titratable acidity, it increased phenolic compounds, betalains and the antioxidant capacity of beets. SNP reversed the negative effects of drought on sugar, lipid and organic acid contents and increased antioxidant capacity independent of stress. Pre-harvest SNP treatment reversed drought-induced yield reductions in beets, while boosting bioactive compounds and antioxidant capacity. It also enhanced vitamin C content independently, indicating its dual role in stress mitigation and beet quality improvement. Future research should explore other crops and stress conditions. © 2024 Society of Chemical Industry.

Online Raman spectroscopy for quantitative detection and characterization of aerosolized soot

Ex-situ Raman spectroscopy is a well-established method for the structural characterization of soot but necessitates a sampling step before analysis is made. This work studied the potential to perform Raman spectroscopic measurements of soot directly in the combustion exhaust gases, i.e., online Raman measurements. Two types of soot were produced from a Mini-CAST soot generator, one immature with high organic content and one mature with low organic content. Also, two different measurement configurations were used, a 90-degree and a backscattering configuration, as well as different polarization combinations of the laser radiation and the detected photons. Spectrally resolved Raman signals were successfully recorded and analyzed for the two soot types showing differences between the characteristic D and G peaks as well as the photoluminescence signal. Additionally, the Raman cross section was determined for both soot types and found to be higher for the immature soot. It was also found that a horizontally polarized laser excitation and a 90-degree collection angle had the best potential to reduce the interference from ambient gases. This study can be seen as a first step towards remote sensing of soot.

Porosity and Organic Content in the Tuscaloosa Marine Shale: Insights from Focused Ion Beam-Scanning Electron Microscopy Characterization

Porosity and Organic Content in the Tuscaloosa Marine Shale: Insights from Focused Ion Beam-Scanning Electron Microscopy Characterization

Fulvic acid application increases rice seedlings performance under low phosphorus stress

BackgroundFulvic acid enhances plant growth and interacts synergistically with phosphate fertilizer to alleviate the agricultural production problem of low phosphorus fertilizer utilization efficiency. However, the underlying mechanism of its action remains poorly understood. In this study, we investigated the impact of fulvic acid application with varying concentrations (0, 40, 60, 80 and 120 mg/L) on rice performance in plants grown in a hydroponic system subjected to low phosphorus stress. The rice growth phenotypes, biomass, root morphology, phosphorus uptake, and the impact of fulvic acid on the rhizosphere environment of rice, were assessed.ResultsThe findings showed that adding appropriate concentrations of exogenous fulvic acid could promote the growth performance of rice under low phosphorus stress. Particularly at T1 (40 mg/L) and T2 (60 mg/L) over the control effectively increased rice biomass by 25.42% and 24.56%, respectively. Fulvic acid treatments stimulated root morphogenesis, up-regulated phosphate transporter genes, and facilitated phosphorus absorption and accumulation. Especially T1 (20.52%), T2 (18.10%) and T3 (20.48%) treatments significantly increased phosphorus uptake in rice, thereby alleviating low phosphorus stress. Additionally, fulvic acid elevated organic acids concentration in roots and up-regulated plasma membrane H+-ATPase genes, promoting organic acids secretion. This metabolic alteration can also alleviate low phosphorus stress in rice.ConclusionsThe effect of exogenous fulvic acid on physiological indicators is concentration-dependent under low phosphorus stress, enhances rice performance and reduces reliance on phosphorus fertilizer. This provides new insights to shed light on the mechanism of alleviating low phosphorus stress in rice through fulvic acid application, an eco-friendly tool.

Optimization of biological nitrogen removal in full-scale municipal WWTPs using activated sludge model simulation

The study evaluated the most efficient biological nitrogen removal (BNR) process in four full-scale municipal wastewater treatment plants (WWTPs) by using BioWin, a simulation software based on the activated sludge model (ASM). A series of experiments were conducted to determine the kinetic and stoichiometric parameters for the ASM. Results indicated that autotrophic maximum specific growth rates in the studied WWTPs were generally higher compared to previous findings, likely due to their low COD/N ratios, emphasizing the importance of local parameterization. Continuous water quality monitoring in each plant was employed to validate the model. Dynamic simulation results indicated that the error remained within an acceptable range, with a mean relative error of less than 20%, confirming the reliability of ASM parameters derived from batch experiments. Subsequently, various operational scenarios were analyzed to determine the optimal BNR process for each plant, considering influent flow rate, internal recycling, and methanol addition. Simulation outcomes suggested that O/A (oxic/anoxic) operation is preferable for plants with low organic content (COD = 60–110 mg/L), considering both operational costs and total nitrogen removal rate. Conversely, A/O (anoxic/oxic) operation might be advantageous for plants with higher influent organic matter (COD = 200 mg/L).

Biosorption of Cd(II), Co(II), and Cu(II) onto Microalgae under Acidic and Neutral Conditions

The biosorption of Cd, Co, and Cu onto three microalgae species (Chlorella vulgaris, Scenedesmus sp., and Spirulina platensis) was compared to determine the microalgae’s capability for heavy metal adsorption in acidic and neutral environments. The Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models were used to characterize the adsorption of the heavy metals onto microalgae. The maximum adsorption capacity (qmax) determined using the Langmuir and D-R model showed results in the order of Cu > Co > Cd in both acidic and neutral conditions. A shift from acidic to neutral conditions increased the microalgae’s adsorption affinity for heavy metals, as determined using the Freundlich parameter (KF). The adsorption affinity of the biomass for Cd and Co was in the order S. platensis > C. vulgaris > Scenedesmus sp. while that of Cu was in the order C. vulgaris > Scenedesmus sp. > S. platensis. In addition, it was found that the adsorption of Cd and Co enhanced the production of Dissolved Organic Content (DOC) as a byproduct of biosorption, whereas the adsorption of Cu appeared to suppress the generation of DOC. The mean adsorption energy (E) values computed by the D-R model were less than 8 (kJ/mol), indicating that physisorption was the primary force of sorption in both acidic and neutral settings. The findings of this study suggest that microalgae may be used as a low-cost adsorbent for metal removal from industrial effluent.

ATR-FTIR spectroscopy imaging of bone repair in mandibular laser-osteotomy.

The aim of this study was to verify the effectiveness of attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy in the characterization of bone repair in mandibular osteotomy using erbium, chromium-doped yttrium, scandium, gallium and garnet (Er,Cr:YSGG) laser and multilaminate drill on each side. Two mandible bone fragments were removed from 30 rabbits, and the process of bone repair was studied immediately, 3, 7, 15, 21, and 28 days after the surgery. The histological analysis allowed detecting differences in the early stages of tissue repair after bone cutting performed with the Er,Cr:YSGG laser or multilaminate drill. The ATR-FTIR spectroscopy technique was sensitive to changes in the organic content of bone tissue repair process.

Crude oil removal from water: Influence of organic phase composition and mineral content

AbstractThe effect of organic and inorganic compounds, commonly present in the mineralogy of crude oil and/or added in the washing processes of extracted crude, on the removal efficiency of emulsified oils present in waste washing waters was investigated by means of flocculation. Approximately 90% of the emulsified oil could be removed using an anionic flocculant, providing a residual turbidity below 100 NTU. The yield depended on the nature of the organic and inorganic components present. The higher the chain length of the main organic component, the greater the flocculant concentration required to remove the oil. Several components had an effect of emulsification (e.g., octane, decane), some of which rendered de‐oiling process completely ineffective (e.g., naphthenic acids). Aliphatics were the most difficult to eliminate, requiring flocculant levels in the 200–300 ppm range. This is in contrast to 75–100 ppm levels which were required to remove bi‐ and poly‐cyclic aromatics. Heavy oils were more difficult to remove than light oils. There was a strong effect of the pH of the aqueous phase. The optimum was pH = 2.0. Virtually all inorganic compounds reduced the efficiency of removing oil from water when spiked at 1%. The only exception was sodium carbonate which acted as a de‐emulsifier. Monovalent salts have a minor effect on de‐oiling, with efficiencies remaining at 80%. Divalent chlorides reduced the de‐oiling efficiency to 70% while sulphates had a more severe influence. The de‐oiling efficiency was lowered substantially with the addition of clays, zinc, cadmium, ferric oxide, calcium carbonate, and dibenyhlthiophene.

Investigation on itraconazole solubility in aqueous solutions based on models, solvent effect, thermodynamic analysis and quantum chemical calculations

The mole-fraction solubility of itraconazole in four aqueous blends of ethanol/isopropanol/DMSO/methanol within the temperature range of 283.15 to 323.15 K was experimentally obtained using the isothermal shake-flask method. Under the identical temperature and ethanol/isopropanol/DMSO/methanol composition, itraconazole solubility in DMSO+water is much higher than that in ethanol/isopropanol/methanol + water. At the same temperature, the solubility increases monotonically with organic solvent concentration. X-ray power diffraction analysis demonstrated that over the course of the investigations, there was no crystal transition or solvate formation. The modified van’t Hoff-Jouyban-Acree and Jouyban-Acree models adequately related the solubility to solvent composition and temperature, with relative average deviations (RADs) not exceeding 7.65 %. Furthermore, the extended Hildebrand solubility approach was utilized to quantitatively characterize the solubility behavior at 298.15 K for the mixtures of ethanol/isopropanol/DMSO/methanol plus water. In both instances, the RADs were maintained below 4.12 %. The solubility parameter and dipolarity-polarizability of solutions have a major impact on the solubility fluctuation, as indicated by the analysis of the linear solvation energy relationship. The preferential solvation of itraconazole at 298.15 K was examined using the efficient approach of inverse Kirkwood-Buff integrals. The preferred solvation parameters showed positive values in blends within rich and moderate ethanol/isopropanol/DMSO/methanol composition regions. This suggests that the organic solvents preferentially solvated itraconazole. When itraconazole dissolved in the blends, thermodynamic analysis of the entropy-enthalpy compensation and dissolution parameters revealed both an endothermic and an enthalpy-driven mechanism. Furthermore, the microscopic electrostatic characteristics of basicity and acidity were effectively demonstrated by means of the electrostatic potential of molecular surface. The −C=O and −N=groups of the itraconazole molecule, which link the five-membered ring, are the primary targets of the electrophilic attack. An independent gradient model based on Hirshfeld partition analysis was used to demonstrate the weak interactions between itraconazole and solvents.

Stratified structure of membrane clogs observed in full scale cross-flow tubular ultrafiltration (UF) system: Fouling characterization and a proposed two-stage formation mechanism

Membrane fouling remains a significant challenge in wastewater treatment, hindering both efficiency and lifespan. This study reports a distinct phenomenon of stratified membrane clogging observed in a full-scale cross-flow tubular ultrafiltration (UF) system treating sludge anaerobic digestion (AD) reject water. The distinct stratified structure, comprising inner and outer layers within the cake layer, has not been previously described. This research involved characterizing the filtration performance, analyzing membrane clog composition, and proposing a two-stage formation mechanism for the stratified clogs. It was revealed that higher inorganic and lower organic content in the outer layer compared to the inner layer. Acid and alkali treatments demonstrated the effectiveness of combined cleaning strategies. A mathematical model was developed to determine the critical conditions for stratified clog formation, influenced by membrane flux and cross-flow velocity (CFV). It is proposed that outer layer forms through long-term selective deposition, while the inner layer results from short-term dewatering within limited tubular space. High CFV (>2.5 m/s) prevents inner layer formation. Critical conditions for stratification occur at a flux of 18 L/m2/h with a CFV of 0.1 m/s or 65 L/m2/h with a CFV of 0.35 m/s. This study contributes a novel understanding of stratified membrane clogging, proposing a two-stage formation mechanism and identifying critical conditions, which provides insights for effective fouling control strategies and maintenance of operational efficiency for membrane systems.

Optimization Co-Culture of Monascus purpureus and Saccharomyces cerevisiae on Selenium-Enriched Lentinus edodes for Increased Monacolin K Production.

Selenium-enriched Lentinus edodes (SL) is a kind of edible fungi rich in organic selenium and nutrients. Monascus purpureus with high monacolin K (MK) production and Saccharomyces cerevisiae were selected as the fermentation strains. A single-factor experiment and response surface methodology were conducted to optimize the production conditions for MK with higher contents from selenium-enriched Lentinus edodes fermentation (SLF). Furthermore, we investigated the nutritional components, antioxidant capacities, and volatile organic compounds (VOCs) of SLF. The MK content in the fermentation was 2.42 mg/g under optimal fermentation conditions. The organic selenium content of SLF was 7.22 mg/kg, accounting for 98% of the total selenium content. Moreover, the contents of total sugars, proteins, amino acids, reducing sugars, crude fiber, fat, and ash in SLF were increased by 9%, 23%, 23%, 94%, 38%, 44%, and 25%, respectively. The antioxidant test results demonstrated that 1.0 mg/mL of SLF exhibited scavenging capacities of 40%, 70%, and 79% for DPPH, ABTS, and hydroxyl radicals, respectively. Using gas chromatography-ion mobility spectrometry technology, 34 unique VOCs were identified in SLF, with esters, alcohols, and ketones being the main components of its aroma. This study showed that fungal fermentation provides a theoretical reference for enhancing the nutritional value of SL.

Assessing Antioxidant Properties, Phenolic Compound Profiles, Organic Acids, and Sugars in Conventional Apple Cultivars (Malus domestica): A Chemometric Approach.

This study analyzed the phenolic compounds, organic acids, sugars, and antioxidant activity in different conventional apple cultivars (Malus domestica) from the Serbian market. Polyphenol profiles, sugars, and organic acid contents were analyzed by HPLC, and antioxidant activity was examined by DPPH and FRAP. Notable findings included variations in phenolic compound presence, with certain compounds detected only in specific cultivars. 'Red Jonaprince' exhibited the highest arbutin (0.86 mg/kg FW) and quercetin-3-rhamnoside content (22.90 mg/kg FW), while 'Idared' stood out for its gallic acid content (0.22 mg/kg FW) and 'Granny Smith' for its catechin levels (21.19 mg/kg FW). Additionally, malic acid dominated among organic acids, with 'Granny Smith' showing the highest content (6958.48 mg/kg FW). Fructose was the predominant sugar across all cultivars. Chemometric analysis revealed distinct groupings based on phenolic and organic acid profiles, with 'Granny Smith' and 'Golden Delicious' exhibiting unique characteristics. Artificial neural network modeling effectively predicted antioxidant activity based on the input parameters. Global sensitivity analysis highlighted the significant influence of certain phenolic compounds and organic acids on antioxidant activity.

Study on the treatment of oil production wastewater by corona discharge coupling Fenton reagent

As the main by-product of oil production, oil production wastewater has the characteristics of high organic content and poor biodegradability, which makes the low temperature plasma wastewater treatment technology get new development. The Ground electrode atomization negative corona discharge（GEANCD） technology increases the discharge current on the basis of traditional corona discharge, but the uneven atomization of liquid is a key challenge at present, which will have a great impact on the degradation of wastewater pollutants. In this study, the GEANCD reactor was redesigned and a self-developed spiral wire hole electrode (SWHE) was used to replace the conventional wire electrode (WE). The discharge characteristics of the reactor under the two electrode structures were investigated and the optimal discharge parameters were determined. Under the optimum discharge parameters, the treatment effect of the two electrode structures with or without coupling Fenton reagent on oil production wastewater was also compared. The experimental results show that under the optimal discharge parameters of flow rate of 25 mL/min, plate electrode distance of 50 mm and discharge voltage of 14 kV, the reactor equipped with SWHE has higher discharge current, and the treatment effect of oil production wastewater is better when coupled with Fenton reagent.

Role of phytoplankton composition on exudation of dissolved organic carbon in the Bay of Bengal

Phytoplankton in the marine environment exudates part of the primary production as dissolved organic carbon (DOC) into the surrounding waters. The rate of exudation of DOC is depended on the hydrographic condition, nutrient availability, phytoplankton composition, and their size structure. To examine this, samples were collected from the coastal and offshore regions where different hydrographic conditions exists in the Bay of Bengal. The coastal waters were relatively low saline, rich in inorganic nutrients, high phytoplankton biomass (Chl-a) and primary production in the coastal compared to offshore regions. The photic zone integrated Chl-a displayed insignificant difference between coastal and offshore regions whereas higher photic zone integrated primary production was observed in the former than latter region. Dominance of microplankton was observed in the coastal waters associating with high inorganic nitrogen concentrations, in contrast, picoplankton dominated in the offshore region associating with low inorganic nitrogen but high organic nitrogen concentrations. Due to high surface-to-volume ratio of picoplankton, ∼45% of the primary production exudated as DOC in the offshore compared to the coastal region (∼12%) due to dominance of microplankton. The sum of primary production and DOC exudation, called total primary production, was almost equal in the coastal and offshore regions. The mean phytoplankton biomass normalized primary production (pB) in the Bay of Bengal was low (17 ± 8 mgC mgChl-a−1 d−1) compared to Arabian Sea (37 ± 5 mgC mgChl-a−1 d−1). In contrast pB estimated based on total primary production is close (30 ± 16 mgC mgChla−1 d−1) to that of the Arabian Sea (37 ± 5 mgC mgChl-a−1 d−1) suggesting that the Bay of Bengal is equally productive compared to that of Arabian Sea than hitherto hypothesized due to strong stratification and less nutrients input in the former basin. The low sinking carbon flux observed below the photic zone is attributed to the release of primary production as DOC. The released DOC from the phytoplankton may support heterotrophic activity as evidenced by the existence of strong net heterotrophy in the Bay of Bengal. This may lead to the time lag between primary and export productions. None of these processes were incorporated into the numerical models resulting in inaccurate simulations of carbon cycling in the northern Indian Ocean. Modifications in the models by incorporating these processes may improve model simulations for a better understanding the modifications in biogeochemical processes due to climate change in the Bay of Bengal.

Improved bioenergy recovery and desalination efficiency using innovative configuration of an upflow triple enclosed cuboid compartments -photosynthesis microbial desalination cell: Experimental and modeling study

Performance of an innovative configuration of enclosed cuboid compartments-photosynthesis microbial desalination cell (EC-PMDC) for synchronous sewage treatment, desalination of seawater, and renewable energy recovery. Bioanode and biocathode were inoculated with jumbled bacterial species and mixed microalgae, respectively. The results demonstrated that maximum removal efficiency of organic content as chemical oxygen demand (COD) from the sewage was up to 99 %, whereby the total dissolved solids (TDS) removal efficiency from seawater was 91 %, accompanied with maximum power generation of 975 mW/m3. Kinetic study of bacterial growth in the EC-PMDC demonstrated excellent agreement between experimental data and those predicted by Blackman, Monod, Moser, and Teissier models with coefficients of determination (R2) equal to 0.98, 0.97, 0.96, and 0.97, respectively. Significant harmonization was obtained between the experimental results of voltage, current density, and power density with those predicted by the adopted electrochemical model. For comparison purposes, a conventionally designed photosynthesis microbial desalination cell (SC-PMDC) consisted of triple sequential cuboid compartments was setup. It was fed with similar influents as for the EC-PMDC. Maximum efficiencies of COD and TDS removals were 99 % and 81 %, respectively accompanied with power recovery of 420 mW/m3 were observed in the SC- PMDC indicating the superiority of EC-PMDC design.

Public Willingness to Pay for Farmland Eco-Compensation and Allocation to Farmers: An Empirical Study from Northeast China

Farmland eco-compensation, as a typical payment for ecosystem services scheme, aims to address trade-offs between environmental and developmental objectives. As indispensable eco-compensation supporters, the public’s willingness to pay (WTP) for farmland eco-compensation and the allocation to farmers directly affect ecological safety and sustainable development for farmland. Therefore, this study links the public’s WTP for the farmland eco-compensation to the financial subsidies received by farmers and presents a theoretical framework and research approach that connects stakeholders, applying improved choice experiments for empirical study in the black soil region of northeastern China. The results showed that the public has a positive WTP for the farmland eco-compensation program that improves the area, soil thickness, and organic content expeditiously. The public’s WTP allocation for eco-compensation varies considerably, with the share allocated to farmers in their WTP averaging 46.96%, showing a benchmark for compensation standards. The results revealed the influential relationship between the socioeconomic characteristics of the public with WTP allocation and the preferences for farmland eco-compensation, such as the positive correlation between age with WTP allocation and females’ greater preference for eco-compensation. These findings can provide new perspectives and approaches to exploring sustainable pathways for farmland eco-compensation.

Variations in water use efficiency and carbon and nitrogen concentrations in red heart Chinese fir.

Temperature can significantly (P < 0.05) affect plant growth by modifying water use strategies, which are determined by intrinsic water use efficiency (WUEi). Red Heart Chinese Fir (Cunninghamia lanceolata) is one of the most important ecological and economic plantation species in China. However, the C. lanceolata water use strategy in response to increased temperatures and uneven temporal distribution of precipitation during the growing season is rarely reported. In a 7-year-old C. lanceolata plantation, differences in WUEi and C and N concentrations in different organs were analysed by anova, and the δ13C stable isotope, C, and N concentrations in stems determined at different tree heights. Stepwise regression and variance inflation factor were used to remove autocorrelated factors, and structural equation modelling was then used to explore relationships between WUEi and climate and biological factors. WUEi differed significantly between leaf and branch at different standardized precipitation evapotranspiration indices (SPEI). WUEi and N concentration decreased with age. The highest WUEi in branches and leaves were 92.7 and 88.4 μmol·mol-1 in 2020 (SPEI = 0.00), respectively. δ13C increased with relative tree height but N concentration and C/N ratio were not affected. Air temperatures has increased in between 2014 and 2020. WUEi and N concentration decreased with increasing branch and leaf age, but C concentration increased. SPEI significantly positively affected WUEi (P < 0.05), and WUEi was significantly negatively related to C concentration, which is consistent with the trade-off between C and water.