Rich Carbon Source Research Articles

Green synthesis of nano silver-modified date syrup 3D graphene for adsorptive removal of heavy metals from wastewater and its antibacterial efficiency

Abstract Many researchers are focusing on the eco-friendly and cost-effective green synthesis of materials for removing heavy metals from wastewater using materials made from natural sources. In this research, date syrup was used as a rich carbon source while potassium chloride particles were used as a substrate. Green synthesized silver nanoparticles modified the graphene foam to enhance its heavy metal removal and antibacterial efficiency. The morphology and structure of the graphene foam were examined using scanning electron microscopy and Raman spectroscopy. The Brunauer-Emmett-Teller method examines textural features such as surface area, pore volume and diameter. The study focused on evaluating the efficiency of removing heavy metals including cadmium, lead, zinc, and chromium from water. The results indicated that the date syrup graphene foam has high heavy metal removal efficiency despite the short contact time, especially for Cd2+ and Pb2+, with removal efficiencies of 68% and 39%, respectively. It shows a relatively lower efficacy for Zn2+ and Cr2+, with removal efficiencies of 10% and 27%, respectively. The addition of silver nanoparticles greatly improved the removal efficiency of Cd2+ (75%), Zn+2 (22%), and Cr2+ (33%). Moreover, the antibacterial efficacy test showed significant improvement after the nanosilver modification to reach a 100% bacterial-killing rate.

Development of biochar using herbal industry waste for removal of hexavalent chromium from aqueous solution: Column study

Biochar is an rich source of carbon formed through biomas’s thermal decomposition. There is a lot of scope of interest in developing biochar derived from biomass in various disciplines to address the most significant ecological challenges. In the present study herbal waste collected from herbal processing industry (Bangalore, India). So, this biomass will be no use after the extraction process. Hence, present work mainly concentrates the conversion this herbal waste to biochar (BC). Research highlights the BC was prepared from herbal industry waste using pyrolysis method. The obtained BC used as adsorbent for adsorption of Cr (VI) from aqueous solution. A characterization of BC was performed using XRD, SEM-EDS and FT-IR which confirms the material. The adsorption experiments were carried out using batch and fixed bed column. The experimental studies were carried out at room temperature with initial Cr (VI) concentrations (IC) of 10–120 ppm using an adsorbent dosage (AD) of 0.05–0.55 g, agitation speed of 150 rpm for contact time (CT) 15–165 min and temperature (20–40 °C). Then various parameters for column study like bed height, flow rate and IC were also studied. The maximum removal of Cr (VI) was 88 % found at a pH 2, AD 0.55g, CT 90 min, and IC 100 ppm at 30 °C. For column study: higher removal of Cr (VI) achieved by bed height (BH) of 6 cm and at lower flow rate (FR), of 3 mL/min.

Compositions, sources, and bioavailability of colloidal organic matter in Lake Taihu

Colloidal organic matter (COM) exists ubiquitously in natural waters, and plays a pivotal role in biogeochemical cycles. Lake Taihu is confronted with severe eutrophication and algal blooms. Field investigations were carried out in Lake Taihu and two inflow rivers for two years to identify the source of COM and explore the bioavailability of COM to algae. Compositions and sources of COM were analyzed through UV absorption coefficients and parallel factor analysis of three-dimensional excitation emission matrix spectra (3D EEMs-PARAFAC). Absorption coefficient a(350) of COM in rivers surpassed that in the lake, SUVA254 exhibited noteworthy seasonal variations, and SR indicated a stable autochthonous characteristic. Three components were identified by PARAFAC analysis: tryptophan-like (C1), humic-like (C2), and tyrosine-like (C3). Fluorescence indexes showed that C1 and C3 were mainly autochthonously produced and C2 was derived from allochthonous inputs. The bioassays were conducted to assess the bioavailability of COM to the dominant species, Microcystis aeruginosa. The results showed that colloids supplied rich carbon sources and trace metals, supporting the growth of Microcystis aeruginosa. The specific growth rate, Chl a content, and biological increment of Microcystis aeruginosa in 50 % colloid-added treatment exceeded those in 20 % and 75 % treatments. Simultaneously, the effective quantum yield (Fv/Fm) and the apparent photosynthetic electron transport rate (ETRmax) demonstrated that the photosynthetic activity of Microcystis aeruginosa was higher in 20 % treatment. These findings help in understanding the intricate mechanisms of COM in lake ecosystems, and provide the robust scientific foundation for water management and protection in Lake Taihu.

Sustainable manufacture and application of biochar to improve soil properties and remediate soil contaminated with organic impurities: a systematic review

Biochar production and application have become increasingly popular in the past 15 years. Biochar, derived from diverse biomass types, offers a rich carbon source created through thermal combustion. Biochar production primarily depends on pyrolysis conditions and feedstock type. This review focuses on the multifaceted aspects of biochar, encompassing hydrothermal carbonization, gasification, and pyrolysis temperatures in biochar production and its role in bioeconomy and soil remediation. Biochar has yielded valuable insights, notably in decreasing nutrient leaching, curbing greenhouse gas (GHG) emissions, reducing the bioavailability of environmental pollutants, sequestering carbon (C) in soils, and enhancing agricultural productivity. Consequently, it has emerged as a valuable commodity for the bioeconomy, which involves harnessing bioresources through bioengineering to create economically valuable products. As a marketable output, biochar finds application in energy, diverse biochar-based product manufacturing, and the agricultural sector. Thus, biochar production not only enhances soil quality but also unlocks additional revenue streams. This review underscores the critical role of feedstock selection and pyrolysis conditions in optimizing biochar production. Furthermore, it highlights biochar as a sustainable and effective tool for improving various soil types and remediating soil contamination caused by organic impurities, including persistent organic compounds and antibiotics.

Proteomes reveal metabolic capabilities of Yarrowia lipolytica for biological upcycling of polyethylene into high-value chemicals.

Sustainable processes for biological upcycling of plastic wastes in a circular bioeconomy are needed to promote decarbonization and reduce environmental pollution due to increased plastic consumption, incineration, and landfill storage. Strain characterization and proteomic analysis revealed the robust metabolic capabilities of Yarrowia lipolytica to upcycle polyethylene into high-value chemicals. Significant proteome reallocation toward energy and lipid metabolisms was required for robust growth on hydrocarbons with n-hexadecane as the preferential substrate. However, an apparent over-investment in these same categories to utilize complex depolymerized plastic (DP) oil came at the expense of protein biosynthesis, limiting cell growth. Taken together, this study elucidates how Y. lipolytica activates its metabolism to utilize DP oil and establishes Y. lipolytica as a promising host for the upcycling of plastic wastes.

Progress on Separation and Hydrothermal Carbonization of Rice Husk Toward Environmental Applications.

Owing to the increasing global demand for carbon resources, pressure on finite materials, including petroleum and inorganic resources, is expected to increase in the future. Efficient utilization of waste resources has become crucial for sustainable resource acquisition for creating the next generation of industries. Rice husks, which are abundant worldwide as agricultural waste, are a rich carbon source with a high silica content and have the potential to be an effective raw material for energy-related and environmental purification materials such as battery, catalyst, and adsorbent. Converting these into valuable resources often requires separation and carbonization; however, these processes incur significant energy losses, which may offset the benefits of using biomass resources in the process steps. This review summarizes and discusses the high value of RHs, which are abundant as agricultural waste. Technologies for separating and converting RHs into valuable resources by hydrothermal carbonization are summarized based on the energy efficiency of the process.

A Novel Hierarchically Lightweight Porous Carbon Derived from Egg White for Strong Microwave Absorption

Egg custard is a common dish on the dining table and exhibits a uniform porous structure after freeze-drying. The protein within egg custard is a rich source of carbon and nitrogen, and the custard’s unique microstructure and adjustable electrical properties make it a potential porous carbon precursor. Herein, nitrogen in situ doped porous carbons (NPCs) and potassium-carbonate-modified NPCs (PNPCs) are obtained through a simple gelation and carbonization process using egg white as the raw material. The unique morphologies of the porous carbon are inherited from the protein and include fibrous clusters, honeycomb holes, and a grooved skeleton. Their excellent impedance matching and effective internal loss make the obtained porous carbons good candidates for lightweight electromagnetic (EM) wave absorbers without the need to dope with metal elements. As a representative porous carbon, PNPC10-700 has multiple structures, including fibrous clusters, honeycomb holes, and a porous skeleton. Moreover, it achieves a maximum reflection loss value of −66.15 dB (with a thickness of 3.77 mm) and a broad effective absorption bandwidth of 5.82 GHz (from 12.18 to 18.00 GHz, with a thickness of 2.5 mm), which surpasses the reported values in most of the literature. Thus, gelation combined with the further carbonization of egg white (protein) is a new method for designing the morphology and EM properties of porous carbon absorbers.

Multi-aspect comparative analyses of two innovative methanol and power cogeneration systems from two different sources

This study aims to develop two economically viable processes with high thermodynamic efficiency for the cogeneration of methanol and electricity from coke oven gas and blast furnace gas. In process A, syngas is obtained from coke oven gas reforming, and blast furnace gas, after providing the required heat for the reformer, is injected into the methanol synthesis reactor as a rich carbon source. In process B, in addition to coke oven gas and blast furnace gas, additional hydrogen produced by the proton exchange membrane electrolyzer is injected into the methanol reactor to enhance CO2 conversion. The performance of the proposed systems is evaluated using parameters like energy efficiency, exergy efficiency, net CO2 emission, and total production cost. Results show that energy efficiencies for processes A and B are 53.53% and 67.4%, and their exergy efficiencies are 23% and 25.12%, respectively. Moreover, environmental analysis demonstrates that process B has a net CO2 emission of −1.818 kgCO2/kgmethanol, while for process A, this parameter is relatively higher, and it is positive. From the economic viewpoint, it is concluded that process B is more feasible, and the total production cost of methanol decreases by 55.51% compared to process A.

Process optimization, economic and environmental analysis of biodiesel production from food waste using a citrus fruit peel biochar catalyst

The concept of sustainably reusing food waste to produce value-added byproducts, such as biodiesel , was studied. Food waste is an organic-rich source of lipids. An optimization study of the extraction of oil from food waste using a solvent for biodiesel production was undertaken. A biochar catalyst derived from citron ( Citrus medica ) peel containing a rich carbon source. A biodiesel yield of 96.3% was obtained under the optimized reaction conditions of a 1:10 oil to methanol molar ratio , 4 w% catalyst loading, reaction temperature of 55 °C, and a reaction time of 52 min. The conditions were optimized by response surface methodology with a central composite design . The biochar catalyst maintained a significant biodiesel yield for four cycles. This techno-economic analysis found that the annual plant revenue was $24,140,000 for a project lifetime of 20 years, the payback time was 3.16 years, the internal rate of return after tax was 39.92%, and the net present value at 10.0% interest was $55,017,000. A minimum biodiesel selling price of 0.46 $/kg was used, and the environmental sustainability of the produced biodiesel was assessed by a life cycle assessment . The impact of global warming potential on the FW-based biodiesel scenario was −3.967 kg CO 2 equivalent. • Oil extraction and biodiesel production process parameters were optimized. • Biochar catalyst from waste Citrus medica peel was used for biodiesel production. • 10 MT/h biodiesel production plant payback period is 3.16 years with NPV 55.02 M$. • Process global warming was −3.967 kg CO 2 equiv (Well to Wheel).

Bio-Based Carbon Materials for High-Performance Supercapacitors.

Lignin, one of the components of natural plant biomass, is a rich source of carbon and has excellent potential as a valuable, sustainable source of carbon material. Low-cost lignosulfonate (LS) doped with polyaniline (PANI) has been used as a precursor to produce porous carbon. LS has a highly dispersed and sparse microstructure and can be accidentally doped with S atoms. N and S double-doped carbon can be directly synthesized with abundant mesopores and high surface area in a lamellar network using PANI as another doping source. This study explored the optimal conditions of LS/PANI material with different amounts of lignosulfonate and different carbonization temperatures. When the amount of lignosulfonate was 4 g and the carbonization temperature was 700 °C, graded porous carbon was obtained, and the electrochemical performance was the best. At 0.5 A/g, the specific capacitance reached 333.50 F/g (three-electrode system) and 242.20 F/g (two-electrode system). After 5000 charge/discharge cycles at 5 A/g, the material maintained good cycling stability and achieved a capacitance retention rate of 95.14% (three-electrode system) and 97.04% (two-electrode system). The energy and power densities of the SNC700 samples were 8.33 Wh/kg and 62.5 W/kg at 0.25 A/g, respectively, values that meet the requirements of today’s commercially available supercapacitor electrode materials, further demonstrating their good practicality. This paper provides an efficient double-doping method to prepare layered structures. Porous carbon is used for electrochemical energy storage devices.

Biopolymers Produced by Treating Waste Brewer’s Yeast with Active Sludge Bacteria: The Qualitative Analysis and Evaluation of the Potential for 3D Printing

Biopolymers are a suitable alternative for the ongoing problem of plastic accumulation, even though commercialization is difficult, which is reflected in the price of the product. However, costs can be reduced if active sludge bacteria and cheap, accessible substrates such as waste brewer’s yeast are used. Waste brewer’s yeast is a rich source of carbon and nitrogen and is widespread as a substrate in various industries. Thus, the cultivation of active sludge bacteria was performed on waste brewers’ yeast to obtain biopolymers that can be used in 3D printing. FT-IR, TG, and DSC analyses of produced polymers were conducted after extraction, as well as biogas and biomethane potential tests. Results of cultivation under various conditions show that biopolymer content is extremely heterogeneous. However, during cultivation in SBR, signals at 1741.3, 1709.6, 1634.3, and 1238 cm−1 were detected. Further analyses are needed, but when said results are compared to those of consulted scientific articles, there is an indication that at least a small amount of PHA is present in biomass produced in SBR. Biopolymers produced in SBR were used as a material for the 3D printing of a cube. Moreover, testing of the physical properties (Young’s modulus) of a 3D-printed cube was performed. After conducting experiments, it can be concluded that said process, although time-consuming, achieved the goal of printing a stable and rigid 3D-printed cube made from biopolymers. Further optimization of said process should focus on more detailed microbial selection as well as biopolymer extraction. In that way, isolation, purification, and identification techniques will be improved, which could achieve higher biopolymer yield and, thus, make biopolymers more accessible in various industries.

Enhanced Flux Pinning Performance of Bulk MgB2 via Immersion of Synthetic Motor Oil

The present investigation focuses on the incorporation of synthetic motor oil as an inexpensive, rich carbon source in bulk MgB2 superconductor and its effect on superconducting and flux pinning properties. A set of three MgB2 bulk samples were prepared from commercial high-purity powders of Mg metal and amorphous B powder utilizing a conventional in situ solid-state reaction process. Before sintering, the MgB2 samples were immersed in used and new synthetic motor oil for a standby time of 30 min and sintered in pure Ar atmosphere at 775 °C for 3 h. X-ray powder diffractometer (XRD) analysis confirmed that single-phase formation of MgB2 with a small shift in X-ray diffraction peaks especially at (110) towards the peak position due to the effect of carbon substitution into the boron sites in lattice for samples immersed in new and used synthetic oil. The magnetization measurements indicated the Tc (onset) value to somewhat decrease to 37.5 K as a result of carbon doping. Microstructural observations with scanning electron microscopy (SEM) suggested that fine nano-sized MgB2 grains improved self-field critical current density around 3.8 × 105 A/cm2 at 20 K for all samples studied. Further, the high-field critical current density (Jc) was improved especially for the sample immersed in used synthetic motor oil with the value of 2.7 × 104 A/cm2, 6 × 103 A/cm2 at 20 K, and at 3 T and 4 T, which is higher as compared to pure-MgB2 sample. In essence, the results signify that the bulk MgB2 samples immersed with used synthetic motor oil would improve the bulk performance at high magnetic fields indicating to be a viable option for industrial applications.

Principles and potential of thermal hydrolysis of sewage sludge to enhance anaerobic digestion

Sewage sludge is rich source of carbon, nutrients, and trace elements and can be subjected to proper treatment before disposal to fulfill government legislation and protect receiving environments. Anaerobic digestion (AD) is a well-adopted technology for stabilizing sewage sludge and recovering energy-rich biogas and nutrient-rich digestate. However, a slow hydrolysis rate limits the biodegradability of sludge. In the present study we have attempted to explain the potential of thermal hydrolysis to enhance anaerobic digestion of sewage sludge. Thermal pretreatment improves biodegradability and recycling of the sludge as an excellent energy and nutrients recovery source at reasonable capital (CAPEX) and operational (OPEX) costs. Other pretreatments like conventional (below/above 100 °C), temperature-phased anaerobic digestion (TPAD), microwave and chemically mediated thermal pretreatment have also been accounted. This review provides a holistic overview of sludge's characterization and value-added properties, various techniques used for sludge pretreatment for resource recovery, emphasizing conventional and advanced thermal pretreatment, challenges in scale-up of these technologies, and successful commercialization of thermal pretreatment techniques.

Assessment of methanol and electricity co-production plants based on coke oven gas and blast furnace gas utilization

This study aims to develop an economically viable novel process with high thermodynamic efficiency for the co-generation of methanol and electricity from coke oven gas (COG) and blast furnace gas (BFG). For this purpose, two processes are proposed to utilize COG and BFG. In process A, syngas is obtained from COG reforming, and BFG, after providing the required heat for the reformer, is injected into the methanol synthesis reactor as a rich carbon source. In process B, in addition to the above-mentioned, additional hydrogen is injected into the methanol reactor to enhance carbon dioxide conversion. The performance of the proposed systems is evaluated using energy efficiency, exergy efficiency, net CO2 emission, and total production cost. Results show that energy efficiencies for processes A and B are 53.53% and 72.8%, and their exergy efficiencies are 23% and 26%, respectively. Moreover, environmental analysis demonstrates that process B has a net CO2 emission of −1.82 kgCO2/kgmethanol, while for process A, this parameter is relatively higher, and it is positive. From the economic viewpoint, it is concluded that process B is more feasible, and the total production cost of methanol decreases by 87.62% compared to process A. Also, it can be deduced that in the case of utilizing additional hydrogen electricity and methanol production from COG and BFG is interesting from the thermodynamic and economic point of view, and due to negative net CO2 emission, it is environmentally desirable, too.

Adsorption performance of red mud magnetic composite material modified by Spirit‐based distillers' grains for low‐concentration phosphorus in water

AbstractBackgroundResearch on phosphate removal has focused on high‐phosphorus wastewater, which has difficulty meeting the discharge standard through one‐step processing. Herein, the rich carbon source of spirit‐based distillers' grains was used to reduce and roast red mud (RM) to prepare magnetic adsorption material (MRM), aiming to improve the adsorption performance of RM on low‐concentration phosphorus in water and to facilitate the separation and recovery of the adsorbent.ResultsThe characterization results of MRM indicated that the high‐temperature decomposition of macromolecular minerals in RM exposed more active sites of metal ions. Compared with unmodified samples, the specific surface area and saturation magnetization of MRM increased by 3.64 and 9.21 times, respectively;this provided more active sites for phosphorus adsorption by MRM and gave the material magnetic separation ability. The results of adsorption experiments showed that MRM had a wide applicable pH range and good selectivity for phosphorus adsorption, and the phosphorus removal rate was 4.97 times that of RM. The adsorption process of phosphorus by MRM was more in line with the Langmuir isotherm adsorption model and the quasi‐second‐order kinetic equation, as it was a process of spontaneous endothermic entropy increase. The phosphorus removal mechanism included chemical precipitation, coordination exchange, physical adsorption, and electrostatic attraction.ConclusionMRM has good adsorption performance for low concentrations of phosphorus in water and provides an effective method for the resource utilization of red mud and spirit‐based distillers' grains. © 2022 Society of Chemical Industry (SCI).

Effect of high-carbon co-substrates on anaerobic co-digestion stability and performance

In this study, the anaerobic co-digestion of a mixture of sawdust, Chlorella microalgae and cow manure was examined. Sawdust was added to the mixture to increase the amount of available carbon. This study has been designed to determine the impact of incorporating cellulosic material as a rich source of carbon into main substrates. Using co-digestion to create a carbon/nitrogen (C/N) gradient in the influent, a relationship between substrate composition and biogas production was investigated. In this study, 19 reactors of 500 ml capacity were filled to a level of 350 ml and operated at a mesophilic temperature of 37.5°C. Total solids (TS) in the digester feed were 3.8% and retention time in the reactors was 30 days. Design Expert 13 software and mixture design was used to design the experiments. Adding sawdust to the reactors (7–10%) improved the C/N ratio of the mixture in the reactors to an optimal value (22) and produced 25–35% more biogas. The maximum average amount of gas produced per day from a mixture of 8.3% sawdust, 33.3% algae and 58.3% cow manure was 231 ml. Adding sawdust when the TS is low in organic load prevents the reactors from acidifying, increases the stability and improves biogas output.

A comparative study on the performance of acid catalysts in the synthesis of levulinate ester using biomass‐derived levulinic acid: a review

AbstractNon‐renewable resources have adverse effects on the environment, which result in global warming. Research has been shifted toward sustainable resources and lignocellulosic biomass is the best example of this. Lignocellulosic biomass is inexpensive, abundantly available and a rich source of carbon, which makes society less dependant on the use of fossil fuels. It is necessary for society to stop using petroleum‐based technologies and start developing more biomass‐based technologies. Lignocellulosic biomass can be converted into levulinic acid through various methods. Various value‐added chemicals are synthesized from levulinic acid, such as levulinate esters, acrylic acid, β‐acetyl acrylic acid, 1,4‐pentanediol, 2‐methyl tetrahydrofuran, γ‐valerolactone, etc. Among these, levulinate esters have received much attention owing to their broad applications as fuel additives, plasticizers and solvents in the pharmaceutical industries. Levulinate esters can be synthesized from the esterification reaction of levulinic acid and alcohol in the presence of either liquid or solid acid catalysts. Heterogeneous catalysts are favoured above homogeneous catalysts because of their properties, like being easy to separate, having good catalytic activity, being non‐corrosive to the reactor and having good recyclability. The performance of various heterogeneous catalysts such as zirconia, heteropolyacids, zeolite, carbonaceous material, resins and biocatalysts is reported in detail in the review. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd

Multiwalled Carbon Nanotube Based Solid- Phase Extraction Cartridges and its Application in Waste Water Analysis

Isolation of different organic impurity from industrial waste water was carried out using solid phase extraction (SPE) cartridges and analyzed by reverse phase high performance liquid chromatography. Kalonji oil-a rich source of carbon, easily available in nature and cheap is used as a naturally occurring precursor for the synthesis of Multiwalled Carbon Nanotubes (MWCNTs) in laboratory by chemical oil vapor deposition technique (COVD) by direct pyrolysis at 800°C in an inert gas (Hydrogen) atmosphere. The obtained MWCNTs were purified by acid treatment and characterized by different analytical tools such as XRD (X-ray diffraction), SEM (Scanning Electron Microscope) and FTIR (Fourier Transform Infra-Red Spectroscopy), BET surface area analyser.These MWCNTs used directly to prepare solid phase extraction cartridges in laboratory and studied its application in isolation of organic impurities (Aniline and Phenol) from industrial waste water followed its identification by RP - HPLC (Reverse phase High performance liquid chromatography analysis).

RHIZOCTONIA SOLANI OF POTATO AND ITS MANAGEMENT: A REVIEW

Potatoes are an annual and the most cultivated tuberous crop worldwide. Potatoes play an important role to fulfil the world’s basic food requirements because of enriched nutrients and delicious taste. Rhizoctonia solani is the most virulent and widely distributed soil-borne fungus that causes severe yield losses of potatoes globally. Several management practices have been adopted to overcome the yield losses inflicted by this fungus. Biocontrol agents play a significant role as mycoparasites and activate defense mechanisms through disease resistance genes to suppress pathogens. Compost is also applied as a soil amendment that increases soil fertility through the addition of organic matter in soil and nutrients uptake in organic form. Besides, it is a rich source of carbon and nitrogen which can address soil erosion, nutrients and organic matter depletion issues and restores soil fertility by adding organic matter and reducing the incidence of soil-borne pathogens in the soil. Biochar utilization in the agriculture sector is increasing day by day because of its great potential for disease suppression. Both biochar and compost are used commercially to improve plant growth and suppress potato diseases caused by R. solani. Therefore, in this review, we discussed the symptoms on potatoes, epidemiology and biological characteristics of R. solani and summarized to date control strategies mainly focusing on biological, chemical, biochar and compost approaches.

Carbon Transfer Processes of Food Web and Trophic Pathways in a Tropical Eutrophic Seagrass Meadow

Seagrass meadows provide important habitats and rich organic carbon sources for consumers at different trophic levels but are threatened by accelerating eutrophication in coastal waters. Nevertheless, at present, carbon transfer processes throughout the food web and trophic pathways in eutrophic seagrass meadows are still poorly known. To resolve this issue, carbon sources of different trophic communities in a eutrophic tropical seagrass meadow [Xincun (XC) bay, South China Sea] under eutrophication were examined in summer and winter using dual stable isotopes. The δ13C value of omnivores and carnivores overlapped more with that of herbivores and planktivores/filter feeders, which mainly overlapped with that of epiphytes in summer and macroalgae in winter. Meanwhile, epiphytes and macroalgae exhibited high biomass and corresponding highest contribution to herbivores, omnivores, and carnivores in summer and winter, respectively. These results suggest that the grazing food chain was the main trophic pathway in this eutrophic seagrass meadow, and that the transfer of carbon flow in the grazing food chain was mainly dominated by the proliferating epiphytes or macroalgae carbon. In contrast, the contribution of seagrass to detritivores in both seasons was higher than that of other food sources. Our findings suggest that in eutrophic tropical seagrass meadows, the proliferation of epiphytes or macroalgae induced by high nutrient loading, as well as their seasonal changes, has a greater impact on the transfer of carbon in the grazing food chain than that in the detritus food chain, and the seagrass fueled the food web mainly through the detritus food chain.