Search Results (17)

Basic inventory is required for proper understanding and utilization of Earth’s natural resources, especially with increasing soil degradation and species loss. Soil carbon is newly refined at >30,000 Gt C (gigatonnes C), ten times above prior totals. Soil organic carbon (SOC) is up to 24,000 Gt C, plus plant stocks at ~2400 Gt C, both above- and below-ground, hold >99% of Earth’s biomass. On a topographic surface area of 25 Gha with mean 21 m depth, Soil has more organic carbon than all trees, seas, fossil fuels, or the Atmosphere combined. Soils are both the greatest biotic carbon store and the most active CO₂ source. Values are raised considerably. Disparity is due to lack of full soil depth survey, neglect of terrain, and other omissions. Herein, totals for mineral soils, Permafrost, and Peat (of all forms and ages), are determined to full depth (easily doubling shallow values), then raised for terrain that is ignored in all terrestrial models (doubling most values again), plus SOC in recalcitrant glomalin (+25%) and friable saprock (+26%). Additional factors include soil inorganic carbon (SIC some of biotic origin), aquatic sediments (SeOC), and dissolved fractions (DIC/DOC). Soil biota (e.g., forests, fungi, bacteria, and earthworms) are similarly upgraded. Primary productivity is confirmed at >220 Gt C/yr on land supported by Barrow’s “bounce” flux, C/O isotopes, glomalin, and Rubisco. Priority issues of species extinction, humic topsoil loss, and atmospheric CO₂ are remedied by SOC restoration and biomass recycling via (vermi-)compost for 100% organic husbandry under Permaculture principals, based upon the Scientific observation of Nature. Full article

Glomalin-related soil proteins (GRSP) are an important microbial carbon source for soil organic carbon (SOC) and can also protect SOC by promoting the formation of soil aggregates. However, there is a lack of systematic research on how the contribution of GRSP to SOC changes during grassland degradation and restoration. This study analyzed the changes in SOC, total glomalin-related soil protein (GRSPt), easily extractable glomalin-related soil protein (GRSPe) contents, and the ratios of GRSPe/SOC and GRSPt/SOC at different aggregate fractions in the 0–10 cm and 10–20 cm soil layers during the process of grassland degradation and restoration (from natural Sogong grass patches→degraded bare soil patches→transitional weed patches→naturally restored Sogong grass patches/artificially restored grass patches), to explore the contribution of GRSP to SOC at the aggregate scale during grassland succession. (1) With grassland degradation, the mean weight diameter (MWD) and the contents of SOC and GRSP in all aggregate fractions significantly decreased (p < 0.05); the natural restoration method was more effective in improving MWD than the artificial restoration method; for the SOC content in large aggregates and the GRSPt and GRSPe contents in different aggregate fractions, the artificial restoration method was more effective than the natural restoration method. (2) The contents of GRSPe and GRSPt in all aggregate fractions were significantly and linearly positively correlated with SOC content (p < 0.01). Moreover, during grassland degradation and restoration, the correlation between GRSPt and SOC in large aggregates first increased and then decreased. Notably, the correlation between GRSP and SOC in all aggregate fractions was significantly higher under the natural restoration method compared to the artificial restoration method. (3) During grassland degradation and restoration, the contents of GRSPe and GRSPt in the aggregate fractions of the 0~10 cm soil layer showed a clear decrease and increase, respectively. The change patterns of GRSPe/SOC and GRSPt/SOC were opposite to each other. Redundancy analysis revealed that total nitrogen (TN) was the factor that explained the highest variance in GRSP content, SOC content, and the GRSPe/SOC ratio across the aggregate fractions, while total phosphorus (TP) was the factor with the strongest explanatory power for the GRSPt/SOC ratio. This study found that the process of grassland degradation and restoration significantly altered the MWD, GRSP content in different aggregate fractions, SOC content, and the contribution of GRSP to SOC, with the contribution of GRSP to SOC showing an opposite trend to the change in GRSP content. Moreover, TN and TP were the main factors influencing GRSP changes. This study provides a scientific basis for assessing the carbon sequestration potential and selecting restoration methods for degraded grasslands. Full article

Overcoming the oxygen diffusion limit of approximately 200 µm remains one of the most significant and intractable challenges to be overcome in tissue engineering. The fabrication of hydrogel microtissues and their assembly into larger structures may provide a solution, though these constructs are not without their own drawbacks; namely, these hydrogels are rapidly degraded in vivo, and cells delivered via microtissues are quickly expelled from the area of action. Here, we report the development of an easily customized protocol for creating a protective, biocompatible hydrogel barrier around microtissues. We show that calcium carbonate nanoparticles embedded within an ECM-based microtissue diffuse outwards and, when then exposed to a solution of alginate, can be used to generate a coated layer around the tissue. We further show that this technique can be fine-tuned by adjusting numerous parameters, granting us full control over the thickness of the hydrogel coating layer. The microtissues’ protective hydrogel functioned as hypothesized in both in vitro and in vivo testing by preventing the cells inside the tissue from escaping and protecting the microdroplets against external degradation. This technology may provide microtissues with customized properties for use as sources of regenerative therapies. Full article

As the regulator of water and nutrient changes in the active layer after permafrost degradation, root signaling substances affect the plant–soil carbon allocation mechanism under climate warming, which is a key issue in the carbon source/sink balance in permafrost regions. To explore how plant root signaling substances regulate carbon allocation in plants and soils under permafrost degradation, the changes in carbon allocation and root signaling substances in the plants and soils of peatland in different permafrost regions at the time of labeling were studied by in situ ¹³C labeling experiments. The results showed that the fixed ¹³C of Larix gemlini, Carex schumidtii, and Sphagnum leaves after photosynthesis was affected by permafrost degradation. In regions with more continuous permafrost, the trend of the L. gemlini distribution to underground ¹³C is more stable. Environmental stress had little effect on the ¹³C accumulation of Vaccinium uliginosum. Nonstructural carbohydrates, osmotic regulatory substances, hormones, and anaerobic metabolites were the main root signaling substances that regulate plant growth in the peatlands of the three permafrost regions. The allocation of carbon to the soil is more susceptible to the indirect and direct effects of climate and environmental changes, and tree roots are more susceptible to environmental changes than other plants in isolated patches of permafrost regions. The physical properties of the soil are affected by climate change, and the allocation of carbon is regulated by hormones and osmotic regulators while resisting anoxia in the sporadic regions of permafrost. Carbon allocation in discontinuous permafrost areas is mainly regulated by root substances, which are easily affected by the physical and chemical properties of the soil. In general, the community composition of peatlands in permafrost areas is highly susceptible to environmental changes in the soil, and the allocation of carbon from the plant to the soil is affected by the degradation of the permafrost. Full article

In chlorophenol wastewater treatment, adding easily degradable carbon sources, such as methanol, ethanol, sodium acetate, and sodium propionate, significantly improves the chlorophenol removal efficiency. This study systematically compares these conventional carbon sources in different sequencing batch reactors to understand their specific effects on both 2,4,6-trichlorophenol (2,4,6-TCP) degradation efficiency and microbial abundance. In a 35-day experiment, as a carbon source, ethanol exhibited a lower 2,4,6-TCP degradation concentration (77.56 mg/L) than those of methanol, sodium acetate, and sodium propionate, which achieved higher degradation concentrations: 123.89 mg/L, 170.96 mg/L, and 151.79 mg/L, respectively. As a carbon source, sodium acetate enhanced extracellular polymeric substance production (200.80 mg/g·VSS) by microorganisms, providing protection against the toxicity of chlorophenol and resulting in a higher 2,4,6-TCP removal concentration. Metagenomics identified crucial metabolic genes, including PcpA, chqB, Mal-r, pcaI, pcaF, and fadA. The abundance of genera containing the chqB gene correlated positively with the metabolic capacity for 2,4,6-TCP. Moreover, small molecular carbon sources such as methanol, sodium acetate, and sodium propionate promoted the enrichment of genera with functional genes. Full article

Biodegradation of phenol is an effective method for removing this toxicant from contaminated sites. Phenol is a toxic compound for living cells, so many bacteria degrade phenol in relatively low concentrations, up to 0.75 g L⁻¹. The Rhodococcus opacus strain 1CP is an effective destructor of a wide range of pollutants. In the absence of a carbon source in the medium, cells of the R. opacus 1CP strain easily form cyst-like resting cells (CLC). The purpose of this work was to evaluate the viability of cells during long-term storage and the efficiency of the process of phenol destruction by R. opacus 1CP cells germinating after dormancy. Resting cells were obtained by simple cultivation in a rich medium followed by storage under static conditions. This is a simple approach to obtain a large amount of biomass. Decomposition of phenol proceeded via catechol followed by ortho-cleavage of aromatic ring. The induction of three phenol hydroxylases was detected by RT-PCR in cells germinated in a mineral medium with phenol as the carbon source. The stability of the genome of cells germinating after dormancy is shown by box-PCR. Dormant R. opacus 1CP cells, both suspended and immobilized, can be directly used for the decomposition of phenol after 4–12 months storage. In addition to phenol, after 9 months of storage, immobilized germinating cells easily metabolized 4-chlorophenol and 2,4,6-trichlorophenol. The results demonstrate a potential and simple approach toward achieving long-term storage of cells for further use in bioremediation. Full article

Nitrocellulose (NC) is a conservative material that is used in a variety of applications, such as coating agents, biodegradable plastics, and propellant main charge. Nitrocellulose raw materials are easily obtained from lignocellulose sources, most notably cotton and wood pulp. The egg carton, a recycled paper waste designed for packaging and transporting eggs, is used in this study to make nitrocellulose in pulp form. The effects of different nitration durations (40, 50, and 60 min) from egg carton pulp bleached with various KOH concentrations (0.6 M, 1.0 M, and 1.5 M) on NC properties were evaluated. The accelerant properties of the NC of nitration time in 50 min were studied in a rice husk charcoal briquette. Rice husk charcoal briquettes are made in various ratios with nitrocellulose as an accelerant (97:3, 96:4, and 95:5). The NC was characterized using Fourier transform infrared (IR) spectroscopy and thermogravimetric (TG) analysis. 1.0 M of bleached egg carton pulp has the highest cellulose content (86.94%) with the presence of crystalline structure of cellulose at peak 1430 cm⁻¹ after the bleaching process. Meanwhile, different nitration times revealed that 50 min had the highest nitrogen content (7.97%) with a 1.23 degree of substitution (DS) value. Based on its TG analysis, NC 50 has met the requirements for use as an accelerant for briquettes, with an onset temperature of 91.60 °C and a weight loss of 62.60%. Infrared at peak 1640 cm⁻¹ confirmed the presence of NO₂ groups in nitrocellulose successfully formed by nitration. After the addition of nitrocellulose, the calorific value of the briquette increased from 13.54% to 15.47%. Fixed carbon and volatile matter showed the same pattern. The combustion of nitrocellulose-briquette has also been demonstrated by Td10% of degradation, which degraded between 310 and 345 °C. Full article

SSCN is a new type of self-sensitive photocatalyst. It consists of oxygenated carbon nitride-containing microspheres inside and polymerized triazine dye (TBO) formed on its surface by in situ polymerization. The presence of TBO endows SSCN with a wide range of optical responses. However, the TBO would self-degrade under light, making SSCN extremely unstable in photocatalytic reactions and limiting the practical application of SSCN. The introduction of phosphorus into the structure of SSCN significantly improved the electron–hole separation efficiency and reduced the self-degradation of surface TBO. Phosphorus-doped self-sensitive carbon nitride microspheres (P-SSCN) are easily synthesized by a one-pot solvothermal method—the phosphorus source was added to the precursor solution of SSCN. This resulting material was used for the photodegradation of tetracycline hydrochloride (TC-HCl) for the first time, giving improved visible light sensitivity and high stability in the photocatalytic process. This provides a new method for modifying self-sensitive carbon nitride carbon. Full article

The ion exchange resin is mainly composed of carbon, and it can form carbon material after calcination in the isolation of oxygen. Meanwhile, the nitrogen doping of metal-based carbon materials has attracted extensive attention in activating peroxymonosulfate (PMS) to produce active groups in the degradation of refractory organic pollutants. In this study, the used D001 resin served as the source of carbon material and catalyst carrier, cobalt ions adsorbed by impregnation, and then mixed with dicyandiamide and carbon balls formed by calcined (N-Co/D001CB). After nitrogen doping, cobalt exists in the form of cobalt sulfide with high crystallinity, and the serious problems of skeleton shrinkage and internal blockage are significantly alleviated. Under certain catalytic reaction conditions, the degradation rate of ibuprofen in one hour was more than 95%, which was significantly higher than that of cobalt. Finally, quenching experiments found that SO₄⁻· is the main pathway for pollutant degradation, followed by ·OH, and there also exists the contributions of ·O₂⁻ and ¹O₂. In summary, the catalyst was prepared easily and had efficient catalytic activity, but it also recycled its resources with a low disposal cost of used D001CB, realizing the purpose of recycling waste materials and applying them in pollutant treatment. Full article

Effective vegetation restoration plays an important role in maintaining and improving soil nutrients and can promote the fixation of soil organic carbon (SOC) and its fractions in degraded soil areas. To understand the influence of Eucalyptus plantation on SOC and its fractions in severely degraded soil in Leizhou Peninsula, China, vegetation restoration with Eucalyptus (RE: Eucalyptus–shrub ES, Eucalyptus–grass EG, and Eucalyptus–Dicranopteris ED) was chosen as the research object, and natural vegetation restoration without Eucalyptus (RNE: shrub S, grass G, and Dicranopteris D) nearby was used as the control group. SOC and its fractions in different vegetation types were compared and analyzed after sample plot surveys and sample determination, and the driving forces of SOC and its fractions were discussed. SOC, dissolved organic carbon (DOC), microbial biomass carbon (MBC), easily oxidized organic carbon (EOC), and particulate organic carbon (POC) in RE were significantly different from those in RNE, increasing by 194.4%, 36.3%, 111.0%, 141.6%, and 289.9%, respectively. The order of SOC, EOC, DOC, MBC, and POC content in RE was ES > EG > ED. SOC and its fractions were positively correlated with leaf litter cover and biomass, and soil organic matter. SOC, total nitrogen, available nitrogen, total phosphorus, available phosphorus, and enzyme activities were negatively correlated with microbial diversity but were not significantly correlated with soil bulk density and microbial richness. Structural equation modeling analysis results showed that soil enzyme activity was a direct driving force of SOC and its fractions. The input of carbon sources from leaf litter and soil properties were indirect factors that affected SOC and its fractions by affecting microbial characteristics and enzyme activities. Thus, planting Eucalyptus in harsh environments, where natural restoration is difficult, can be an effective measure for early vegetation restoration. Full article

The rotating biological contactor (RBC) is resistant to toxic chemical and shock loadings, and this results in significant organic and nutrient removal efficiencies. The RBC system offers a low-energy footprint and saves up to 90% in energy costs. Due to the system’s low-energy demand, it is easily operable with renewable energy sources, either solar or wind power. An RBC was employed to degrade pollutants in domestic wastewater through biodegradation mechanisms in this study. The high microbial population in the RBC bioreactor produced excellent biological treatment capacity and higher effluent quality. The results showed that the RBC bioreactor achieved an average removal efficiency of 73.9% of chemical oxygen demand (COD), 38.3% of total nitrogen (TN), 95.6% of ammonium, and 78.9% of turbidity. Investigation of operational parameters, disk rotational speed, HRT, and SRT, showed the biological performance impact. Disk rotational speed showed uniform effluent quality at 30–40 rpm, while higher values of disk rotational speed (>40 rpm) resulted in lower effluent quality in COD, TN, and turbidity. The longer hydraulic retention time and sludge retention time (SRT) facilitated higher biological performance efficiency. The longer SRTs enabled the higher TN removal efficiency because of the higher quantity of microbial biomass retention. The longer SRT also resulted in efficient sludge-settling properties and reduced volume of sludge production. The energy evaluation of the RBC bioreactor showed that it consumed only 0.14 kWh/m³, which is significantly lower than the conventional treatment methods; therefore, it is easily operable with renewable energy sources. The RBC is promising substitute for traditional suspended growth processes as higher microbial activity, lower operational and maintenance costs, and lower carbon foot print enhanced the biological performance, which aligns with the stipulations of ecological evolution and environment-friendly treatment. Full article

Fenton reaction is a powerful technology for pollutants’ removal from water. However, the cost of H₂O₂ becomes one of the major stumbling blocks in its application. H₂O₂ has a relatively high price and is easily decomposed during transportation and use; therefore, in situ synthesis of H₂O₂ could improve economic benefits effectively. In this study, a Fe/Ni/Pd ternary metal-doped graphitic carbon nitride (FeNi-Pd@CN) is prepared, and in situ H₂O₂ generation using formic acid as hydrogen sources for organics removal was proved. The catalyst is advantageous, as H₂O₂ could accumulate to 1.69 mmol/L in 150 min when pumping air rather than oxygen gases in other studies. Furthermore, 92.0% of Acid Red 73 (200 mg/L) and 93.2% of tetracycline hydrochloride (10 mg/L) could be removed in 150 min without any pH adjustment. Characterization results show that the catalyst has good stability in metal leaching and reuse tests. It is proved that •OH and •O₂⁻ are the main reactive oxygen species, and a synergistic effect between Fe and Ni exists that enhances ROS generation for organics degradation. This work offers a promising method to remove refectory organic contaminants from industrial wastewater. Full article

Ionizing radiation has become the most effective way to modify natural and synthetic polymers through crosslinking, degradation, and graft polymerization. This review will include an in-depth analysis of radiation chemistry mechanisms and the kinetics of the radiation-induced C-centered free radical, anion, and cation polymerization, and grafting. It also presents sections on radiation modifications of synthetic and natural polymers. For decades, low linear energy transfer (LLET) ionizing radiation, such as gamma rays, X-rays, and up to 10 MeV electron beams, has been the primary tool to produce many products through polymerization reactions. Photons and electrons interaction with polymers display various mechanisms. While the interactions of gamma ray and X-ray photons are mainly through the photoelectric effect, Compton scattering, and pair-production, the interactions of the high-energy electrons take place through coulombic interactions. Despite the type of radiation used on materials, photons or high energy electrons, in both cases ions and electrons are produced. The interactions between electrons and monomers takes place within less than a nanosecond. Depending on the dose rate (dose is defined as the absorbed radiation energy per unit mass), the kinetic chain length of the propagation can be controlled, hence allowing for some control over the degree of polymerization. When polymers are submitted to high-energy radiation in the bulk, contrasting behaviors are observed with a dominant effect of cross-linking or chain scission, depending on the chemical nature and physical characteristics of the material. Polymers in solution are subject to indirect effects resulting from the radiolysis of the medium. Likewise, for radiation-induced polymerization, depending on the dose rate, the free radicals generated on polymer chains can undergo various reactions, such as inter/intramolecular combination or inter/intramolecular disproportionation, b-scission. These reactions lead to structural or functional polymer modifications. In the presence of oxygen, playing on irradiation dose-rates, one can favor crosslinking reactions or promotes degradations through oxidations. The competition between the crosslinking reactions of C-centered free radicals and their reactions with oxygen is described through fundamental mechanism formalisms. The fundamentals of polymerization reactions are herein presented to meet industrial needs for various polymer materials produced or degraded by irradiation. Notably, the medical and industrial applications of polymers are endless and thus it is vital to investigate the effects of sterilization dose and dose rate on various polymers and copolymers with different molecular structures and morphologies. The presence or absence of various functional groups, degree of crystallinity, irradiation temperature, etc. all greatly affect the radiation chemistry of the irradiated polymers. Over the past decade, grafting new chemical functionalities on solid polymers by radiation-induced polymerization (also called RIG for Radiation-Induced Grafting) has been widely exploited to develop innovative materials in coherence with actual societal expectations. These novel materials respond not only to health emergencies but also to carbon-free energy needs (e.g., hydrogen fuel cells, piezoelectricity, etc.) and environmental concerns with the development of numerous specific adsorbents of chemical hazards and pollutants. The modification of polymers through RIG is durable as it covalently bonds the functional monomers. As radiation penetration depths can be varied, this technique can be used to modify polymer surface or bulk. The many parameters influencing RIG that control the yield of the grafting process are discussed in this review. These include monomer reactivity, irradiation dose, solvent, presence of inhibitor of homopolymerization, grafting temperature, etc. Today, the general knowledge of RIG can be applied to any solid polymer and may predict, to some extent, the grafting location. A special focus is on how ionizing radiation sources (ion and electron beams, UVs) may be chosen or mixed to combine both solid polymer nanostructuration and RIG. LLET ionizing radiation has also been extensively used to synthesize hydrogel and nanogel for drug delivery systems and other advanced applications. In particular, nanogels can either be produced by radiation-induced polymerization and simultaneous crosslinking of hydrophilic monomers in “nanocompartments”, i.e., within the aqueous phase of inverse micelles, or by intramolecular crosslinking of suitable water-soluble polymers. The radiolytically produced oxidizing species from water, •OH radicals, can easily abstract H-atoms from the backbone of the dissolved polymers (or can add to the unsaturated bonds) leading to the formation of C-centered radicals. These C-centered free radicals can undergo two main competitive reactions; intramolecular and intermolecular crosslinking. When produced by electron beam irradiation, higher temperatures, dose rates within the pulse, and pulse repetition rates favour intramolecular crosslinking over intermolecular crosslinking, thus enabling a better control of particle size and size distribution. For other water-soluble biopolymers such as polysaccharides, proteins, DNA and RNA, the abstraction of H atoms or the addition to the unsaturation by •OH can lead to the direct scission of the backbone, double, or single strand breaks of these polymers. Full article

The demand for carbon capture is increasing over time due to rising CO${}_2$ levels in the atmosphere. Even though fossil emission could be decreased or even eliminated, there is a need to start removing CO${}_2$ from the atmosphere. The removed CO${}_2$ could be either stored permanently to a reservoir (CCS, Carbon Capture and Storage) or utilized as a raw material in a long-lasting product (CCU, Carbon Capture and Utilization). The capture of CO${}_2$ could be done by direct air capture, or capturing CO${}_2$ from biogenic sources. Amine absorption is the state-of-the-art method to capture CO${}_2$, but it has some drawbacks: toxicity, high heat demand, and sorbent sensitivity towards impurities such as sulfur compounds and degradation in cyclic operation. Another potential solvent for CO${}_2$ could be water, which is easily available and safe to use in many applications. The problem with water is the poorer solubility of CO${}_2$, compared with amines, which leads to larger required flow rates. This study analyzed the technical feasibility of water absorption in a counterflow bubble column reactor. A dynamic, one-dimensional multiphase model was developed. The gas phase was modeled with plug flow assumption, and the liquid phase was treated as axially dispersed plug flow. CO${}_2$ capture efficiency, produced CO${}_2$ mass flow rate, and the product gas CO${}_2$ content were estimated as a function of inlet gas and liquid flow rate. In addition, the energy consumption per produced CO${}_2$-tonne was calculated. The CO${}_2$ capture efficiency was improved by increasing the liquid flow rate, while the CO${}_2$ content in product gas was decreased. For some of the studied liquid flow rates, an optimum gas flow rate was found to minimize the specific energy consumption. Further research is required to study the integration and dynamical operation of the system in a realistic operation environment. Full article

A mixed culture utilizing 1,4-dioxane as a sole carbon and energy source was obtained from the activated sludge at a textile wastewater treatment plant. The biodegradation of 1,4-dioxane was characterized by a model based on the Monod equation. The effects of the presence of easily degradable carbon sources other than 1,4-dioxane were investigated using dextrose. Structural analogs commonly found in 1,4-dioxane-containing wastewater such as tetrahydrofuran (THF), 2-methyl-1,3-dioxolane, and 1,4-dioxene were also evaluated for their potential effects on 1,4-dioxane biodegradation. The presence of dextrose did not show any synergetic or antagonistic effects on 1,4-dioxane biodegradation, while the structural analogs showed significant competitive inhibition effects. The inhibitory effects were relatively strong with heptagonal cyclic ethers such as THF and 2-methyl-1,3-dioxolane, and mild with hexagonal cyclic ethers such as 1,4-dioxene. It was also shown that the treatment of 1,4-dioxane in the raw textile wastewater required 170% more time to remove 1,4-dioxane due to the co-presence of 2-methyl-1,3-dioxolane, and the extent of delay depended on the initial concentration of 1,3-doxolane. Full article