Semi-continuous anaerobic co-digestion of thermal and thermal-alkali processed organic fraction of municipal solid waste: Methane yield, energy analysis, anaerobic microbiome

The semi-continuous anaerobic co-digestion (AcoD) of thermal and thermal-alkali pretreated organic fraction of municipal solid waste (OFMSW) and sewage sludge (SS) was studied under varying hydraulic retention times (HRT) and organic loading rates (OLR Three semi-continuous digesters were operated under control (non-pre-treated), thermally pretreated (125 °C), and thermal-alkali pretreated (125°C-3g/L NaOH) conditions at variable OLRs at 2.5, 4.0, 5.1, and 7.6 kgVS/m3.d and corresponding HRTs of 30, 20, 15, and 10 days. The 10 and 43% higher methane yield (0.445 m3/kgVS) and 11 and 57% higher VS removal (52%) was achieved for thermal-alkali pretreated digester at 5.1 kgVS/m3.d OLR over thermally pretreated (0.408 m3/kgVS, 45% VS removal) and control digesters (0.310 m3/kgVS, 33% VS removal), respectively. Thermal and thermal-alkali digesters failed on increasing the OLR to 7.6 kgVS/m3.d, whereas the control digester becomes upset at 5.1 kgVS/m3.d OLR. The metagenomic study revealed that Firmicutes, Bacteroidetes, Chloroflexi, Euryarchaeota, Proteobacteria, and Actinobacteria were the predominant bacterial population, whereas Methanosarcina and Methanothrix dominated the archaeal community. Energy balance analysis revealed that thermal alkali pretreatment showed the highest positive energy balance of 114.6 MJ/ton with an energy ratio of 1.25 compared with thermally pretreated (81.5 MJ/ton) and control samples (-46.9 MJ/ton). This work pave the way for scaleup of both thermal and thermal-alkali pre-treatment at 125 °C to realize the techno-economic and energy potential of the process.

Biochar and Chlorella increase rice yield by improving saline-alkali soil physicochemical properties and regulating bacteria under aquaculture wastewater irrigation

The combined effects of biochar and Chlorella under aquaculture wastewater irrigation in improving saline-alkali soil physicochemical properties, microbial communities, and rice yield, is not yet clear. This study utilized soil physicochemical indicators and gene sequencing to examine the effect of salinity stress, biochar and Chlorella under aquaculture wastewater irrigation on soil properties, bacterial community compositions, and rice production. Treatments included three factors in a randomized complete block design with three replications: (i) Biochar - 40 tons ha -1 (BW) versus no-biochar (BN); (ii) Salinity - 3‰ salinity (SH) versus 1‰ salinity (SL); and (iii) Chlorella - with 107 cells mL -1 Chlorella (CW) versus no-Chlorella (CN). The results revealed that increased salinity adversely affected the soil nutrients (TOC, NO3⁻-N, NH4+-N, Olsen-P), and enzyme activity (urease, sucrase, catalase), resulting in a 9.67% reduction in rice yield compared to SL treatment. However, the close correlation between alterations in soil bacterial communities, functions, and soil physicochemical properties, as well as rice yield, indicated that biochar and Chlorella promoted rice yield by enhancing the physicochemical properties of saline-alkali soil and bacterial community when irrigated with aquaculture wastewater: (1) addition of biochar increased the146.05% rice yield by increasing TOC content, the complexity of bacterial co-occurrence patterns, nitrogen fixation potential, and nitrification potential, (2) addition of Chlorella increased TOC, NO3⁻-N, NH4+-N, enhanced urease, sucrase, catalase activity, and nitrification potential to increased rice yield by 60.29%, and (3) compared with the treatment T3 (SHBNCN), the treatments with biochar (BW) and Chlorella (CW) increased the yield by 561.30% and 445.03% under 1‰ and 3‰ salinity, respectively. These findings provide novel perspectives on the capacity of biochar and Chlorella to improve saline-alkali soil properties and increase rice yield irrigated with aquaculture wastewater.

Effects of biochar application on nitrogen transformation and N2O emission in a coastal saline-alkali soil

The application of biochar can improve soil fertility and benefit sustainable agricultural development and carbon neutrality simultaneously. To better understand the effects of biochar addition on nitrogen transformation and N2O emission in a coastal saline-alkali soil and its potential mechanisms, we conducted a 60-day laboratory incubation experiment with six treatments, i.e., ammonium sulfate (N 150 mg·kg-1), ammonium sulfate + 0.4% (weight/weight) biochar, ammonium sulfate + 0.6% biochar, ammonium sulfate + 0.8% biochar, ammonium sulfate + 1.6% biochar, and ammonium sulfate + 0.2% biochar and 0.2% organic fertilizer (based on equivalent N basis). The results showed that soil nitrogen transformation was mainly affected by biochar addition at the early stage of incubation. Biochar addition significantly increased the contents of nitrate and ammonium. Biochar addition significantly increased soil net nitrification rate, but the magnitude of such increases decreased with increasing biochar addition level. Similar temporal change patterns of N2O emissions were observed in all treatments, and the N2O emissions mainly occurred in the first 30 days of incubation. Compared with the CK, biochar addition significantly reduced the cumulative N2O emission, and the decrement increased with increasing biochar addition levels. In conclusion, the effects of biochar and nitrogen fertilizer addition on soil nitrogen transformation and N2O emission varied with the application rate. Biochar addition with a rate of 0.8% (W/W) increased soil inorganic nitrogen content and decreased soil N2O emission. It could provide theoretical basis and reference for the formulation of reasonable plans for the improvement and utilization of biochar in coastal saline-alkali soil.

Preparation and characterization of ZSM-5 molecular sieve using coal gangue as a raw material via solvent-free method: Adsorption performance tests for heavy metal ions and methylene blue

Coal gangue is a kind of solid waste produced in the process of coal mining and washing. Its silicon aluminum silicon aluminum oxide content is high, respectively, which are suitable for resource utilization as raw materials for Si-Al molecular sieving. In this paper, a novel, simple, low-cost, and environmentally friendly process was carried out to prepare ZSM-5 zeolite by solvent free method after calcination, acid leaching, and alkali melting. The obtained samples were characterized by Energy Dispersive Spectrometer (EDS), Inductively Coupled Plasma (ICP), Thermo-gravimetry Analysis (TG), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectrometer (FTIR) X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and N2 adsorption isotherm. The characteristics of the raw materials and the adsorption mechanism of the prepared samples were characterized. Through a series of pretreatment such as calcined acid leaching and alkali melting of the raw materials, the silicon-aluminum ratio of the sample reaches 1.749, and the maximum specific surface area of the sample can reach 252.59 m2/g. The obtained samples were used to adsorb heavy metal ions and methylene blue solution, and the removal rate of lead ions and methylene blue solution was more than 95%. The theoretical maximum adsorption capacity of Pb ion, methylene blue solution and copper ion can reach 232.56 mg/g and 118.34 mg/g. The adsorption process is mainly chemical adsorption. The product could be suitable for removing both heavy metal ions and cationic dyes from the wastewater and had broad application prospects.

Development of dual-functional core-shell electrospun mats with controlled release of anti-inflammatory and anti-bacterial agents for the treatment of corneal alkali burn injuries

In this study, a novel dual-drug carrier for the co-administration of an anti-inflammatory and antibiotic agent consisting of core-shell nanofibers for the treatment of cornea alkali burns was designed. The core-shell nanofibers were prepared via coaxial electrospinning of curcumin-loaded silk fibroin as the core and vancomycin-loaded chitosan/polyvinyl alcohol (PVA) as the shell. Electron microscopy (SEM and TEM) images confirmed the preparation of smooth, bead-free, and continuous fibers that formed clear core-shell structures. For further studies, nanofiber mats were cross-linked by heat treatment to avoid rapid disintegration in water and improve both mechanical properties and drug release. The release profile of curcumin and vancomycin indicated an initial burst release, continued by the extended release of both drugs within 72 hours. Rabbit corneal cells demonstrated high rates of proliferation when evaluated using a cell metabolism assay. Finally, the therapeutic efficiency of core/shell nanofibers in healing cornea alkali burn was studied by microscopic and macroscopic observation, fluorescence staining, and hematoxylin-eosin assay on rabbit eyes. The anti-inflammatory activity of fabricated fibers was evaluated by enzyme-linked immunosorbent assay and Immunofluorescence analysis. In conclusion, using a robust array of in vitro and in vivo experiments this study demonstrated the ability of the dual-drug carriers to promote corneal re-epithelialization, minimize inflammation, and inhibit corneal neovascularization. Since these parameters are critical to the healing of corneal wounds from alkali burns, we suggest that this discovery represents a promising future therapeutic agent that warrants further study in humans.

Ultrasound-assisted preparation of protein-polyphenol conjugates and their structural and functional characteristics

Herein, ultrasound-assisted conventional covalent binding methods (alkali treatment, free radical mediation, and an enzymatic method) were used to prepare soybean protein isolate (SPI)-(-)-epigallocatechin gallate (EGCG) conjugates to investigate the enhancement effect of the ultrasound synergistic treatment. In addition, the influence of EGCG grafting on the structure and properties of SPI was evaluated via reactive group analysis, spectral analysis, surface hydrophobicity measurements, emulsification property assessment, and α-glucosidase inhibition analysis. The obtained results revealed that the enzymatic method produced the highest polyphenol grafting content among the conventional techniques. Meanwhile, ultrasound treatment increased the amount of grafted polyphenol species during the alkali treatment and free radical mediation procedure, decreased the grafting efficiency in the enzymatic method, and maximized the grafting efficiency during the alkali treatment. In addition, reactive group and spectral analyses demonstrated that EGCG formed C-N and C-S bonds with SPI and decreased the α-helix content in the protein structure, thereby increasing the molecular flexibility of SPI. It also produced hydrogen bonds and hydrophobic interactions, as demonstrated by the results of molecular docking. Furthermore, the EGCG grafting of SPI conducted under the ultrasound-assisted conditions endowed SPI with unique functional characteristics, including good emulsification and antioxidant properties and high α-glucosidase inhibitory activity, while the ultrasound-assisted alkali treatment resulted in the optimal functional properties. The results of this study provide new insights into the effective preparation of SPI-EGCG complexes with multiple functionalities, thereby expanding the scope of high-value SPI utilization.

Mechanism of microbial regulation on methane metabolism in saline-alkali soils based on metagenomics analysis

Saline-alkali soils constitute a globally important carbon pool that plays a critical role in soil carbon dioxide (CO2) and methane (CH4) fluxes. However, the relative importance of microorganisms in the regulation of CH4 emissions under elevated salinity remains unclear. Here, we report the composition of CH4 production and oxidation microbial communities under five different salinity levels in the Yellow River Delta, China. This study also obtained the gene number of microbial CH4 metabolism via testing the soil metagenomes, and further investigated the key soil factors to determine the regulation mechanism. Spearman correlation analysis showed that the soil electrical conductivity, salt content, and Na+, and SO42- concentrations showed significantly negative correlations with the CO2 and CH4 emission rates, while the NO2--N concentration and NO2-/NO3- ratio showed significantly positive correlations with the CO2 and CH4 emission rates. Metabolic pathway analysis showed that the mcrA gene for CH4 production was highest in low-salinity soils. By contrast, the relative abundances of the fwdA, ftr, mch, and mer genes related to the CO2 pathway increased significantly with rising salinity. Regarding CH4 oxidation processes, the relative abundances of the pmoA, mmoB, and mdh1 genes transferred from CH4 to formaldehyde decreased significantly from the control to the extreme-salinity plot. The greater abundance and rapid increase of methanotrophic bacteria compared with the lower abundance and slow increase in methanogenic archaea communities in saline-alkali soils may have increased CH4 oxidation and reduced CH4 production in this study. Only CO2 emissions positively affected CH4 emissions from low- to medium-salinity soils, while the diversities of CH4 production and oxidation jointly influenced CH4 emissions from medium- to extreme-salinity plots. Hence, future investigations will also explore more metabolic pathways for CH4 emissions from different types of saline-alkali lands and combine the key soil enzymes and regulated biotic or abiotic factors to enrich the CH4 metabolism pathway in saline-alkali soils.

Degradation of 2,4-DCP by immobilized laccase on modified biochar carrier

Rape straw was used as the raw material for the biochar in this study, which was then changed using acid, alkali, and magnetic techniques. The laccase was attached using the adsorptions-crosslinking process, and the three modified biochars served as the carriers. The ideal circumstances for laccase immobilization were explored, and both biochar and immobilized laccase's characteristics were examined. The removal of 2,4-dichlorophenol (2,4-DCP) by immobilized laccase from modified biochar and its degradation products were researched. The main conclusions are as follows: the optimal concentration of glutaraldehyde (GLU) was 4%, and the pH was four, and the enzyme dosage was 1.75 mg/mL for the immobilized laccase of acid-modified biochar (SBC@LAC). The optimal concentration of GLU was 5%; the pH was four, and the enzyme dosage was 2 mg/mL for immobilized laccase from alkali-modified biochar (JBC@LAC). The optimal concentration of GLU was 5%; the pH was four, and the enzyme dosage was 1.75 mg/mL for immobilized laccase from magnetically modified biochar (CBC@LAC). SEM images could show the changes in the surface morphology of biochar caused by three modification methods. The BET results demonstrated that acid and magnetic modification increased the specific surface area of biochar, and alkali modification mainly expanded the pore size of biochar. FT-IR and XRD showed that modification and laccase loading had little effect on the structure of biochar. The stability of immobilized laccase was better than that of free laccase in acid-base, heat, and storage. Among the three modified biochar immobilized laccases, JBC@LAC showed the best acid-base stability and thermal stability, and the relative enzyme activity changed the least when pH and temperature conditions changed. The storage stability of SBC@LAC is the best. After 30 days of storage, the relative enzyme activity is still 83%. The removal rates of 2,4-DCP were 57, 99, and 63%, respectively, by SBC@LAC, JBC@LAC, and CBC@LAC. After five reuses, the removal rates of 2,4-DCP by SBC@LAC, JBC@LAC and CBC@LAC were 26, 42, and 27%, respectively. The intermediate products of 2,4-DCP degradation by immobilized laccase were p-phenol, p-benzoquinone and maleic acid.

White targeted chromatographic screening method of Molnupiravir and its metabolite with degradation kinetics characterization and in-silico toxicity

SARS-CoV-2 virus triggered a worldwide crisis, with world nations putting up massive efforts to halt its spread. Molnupiravir (MLN) was the first oral, direct-acting antiviral drug approved for nasopharyngeal SARS-CoV-2 infection with favorable safety and tolerability profile. This study aims at determination of MLN and N4-hydroxycytidine (NHC), its main degradation product and its main metabolite, using sensitive, simple, and green HPLC-DAD method. Moreover, under different stress conditions using NaOH, HCl, neutral, H2O2, dry heat and sun light, the method was applied for MLN assay along with kinetics degradation investigation. The linearity range for MLN and NHC were both 0.1-100 µg/mL with LOD and LOQ of 0.013 & 0.043 and 0.003 & 0.011 µg/mL, for MLN and NHC, respectively. MLN was found to be extremely vulnerable to alkali hydrolysis compared with acid and dry heat degradation. In contrast, MLN was stable under conditions of oxidative, neutral, and sunlight-induced deterioration. Acid and alkali-induced degradation followed pseudo first-order kinetics model. In addition, LC-MS-UV was used to suggest the mechanism of the stress-induced degradation route and to characterize the eluted degradation products. Toxicities of both MLN and its degradation products were evaluated using ProTox-II and they were found to be negligibly harmful. The proposed HPLC-DAD was effectively used for the analysis of MLN in commercial pharmaceutical formulations. The proposed method for MLN determination after greenness and whiteness appraisal was found to be superior compared to the reported methods for MLN analysis.

Synthesis process-based mechanical property optimization of alkali-activated materials from red mud: A review

Repeated red mud (RM) stockpile accidents have sounded an alarm that a healthy alumina industry requires secure RM disposal. Unfortunately, the flawed mechanical properties of RM-based alkali-activated materials (RM-AAM) with bulk RM incorporation have impeded the ideal large-volume, low-risk utilization of RM and the provision of sustainable binders for communities. By reviewing a wide range of studies, this work provides insights into establishing a mature synthesis technique for optimizing the mechanical properties of RM-AAM. Brief evaluations of the nature and the current RM-AAM synthesis systems were conducted. The following emphasis is on addressing the influence characteristics and mechanisms of the known RM-AAM synthesis factors, including RM pre-activation, precursor composition, alkali activator property, preparation process treatment, and curing regime, on the mechanical properties of RM-AAM. Further optimization suggestions on each aspect of the synthesis process and the final complete set of synthesis technology that could best enhance the mechanical properties of RM-AAM were proposed. The general limitations of current research on developing a mature RM-AAM synthesis technique were identified, along with possible solutions.

Valorization of loquat seeds by hydrothermal carbonization for the production of hydrochars and aqueous phases as added-value products

In the framework of circular bio-economy, waste loquat seeds were utilized for the production of two added-value products. The seeds were hydrothermally carbonized at a temperature range of 150-250 °C and time range 2-6 h and the resultant hydrochars and aqueous phases were characterized using various methods. The optimum higher heating value of 30.64 MJ kg-1, ash content of 1.99 wt % and alkali index of 0.05 were achieved for the hydrochar prepared at 250 °C and 6 h, establishing its suitability for energy-related applications. The aqueous phase obtained at 250 °C and 6 h achieved 90% scavenging of the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and had a IC50 value of 43.71 μg mL-1. Principal component analysis showed that the production of phenols, ketones, alkenes and organic acids was favored at >200 °C, whereas furans and aldehydes were primarily formed at 150 °C. Conclusively, both added-value products were obtained at the same optimum hydrothermal carbonization conditions of 250 °C and 6 h treatment time. In a bio-refinery context, this has the practical implication that both bio-products be obtained simultaneously, without the need to switch between different temperatures and residence times.

[Effects of Biochar and Soil Conditioner on Coastal Barren Saline-alkali Soil]

This study aimed to quantify the biological improvement and availability from a soil amendment substance for barren severe saline-alkali soils. A field experiment was conducted to apply biochar (B) and soil conditioner (C) rich in humic substances to pioneer crops and oil sunflower planted in the coastal barren severe saline-alkali area of the North China Low Plain. The six treatments included single or combined application of two-level biochar rates (0 and 1.25 kg·m-2) and three-level soil conditioner rates (0, 0.83, and 1.66 kg·m-2) at the start of the experiment. Soil samples were collected at 30 cm per layer and sampling from 0 to 90 cm after the oil was collected. The results revealed that the application of biochar increased the saline concentration of the 0-30 cm and 60-90 cm soil layers, whereas the soil conditioner significantly decreased the saline concentration of the 0-30 cm soil layers. Neither biochar nor conditioner showed a significant impact on soil pH. Biochar exhibited varying impacts on soil nutrients, that is, significantly inhibiting soil nitrification, which resulted in soil NO3--N decreasing while NH4+-N increased significantly, along with no significant impact on soil organic matter content (SOM) in the 0-90 cm soil profile. The application of soil conditioner exerted positive effects on improving SOM in the 0-30 cm layer and NO3--N in the 0-90 cm soil depth when the conditioner rate was at 1.66 kg·m-2. Either the sole application or the co-application of biomass and conditioner, along with their interaction, exhibited an increasing trend for the NH4+-N, available phosphorus (Olsen-P), and available potassium (Kex) contents, also seen in the 0-90 cm soil profile, although the increase effect for the three nutrients was primarily attributed to biochar. Soil conditioner was more effective in increasing SOM and reducing saline in the 0-30 cm soil layer. The application of a higher amount of conditioner accelerated soil nitrification, whereas biochar was applied essentially as a nitrification inhibitor. Therefore, the co-application of biochar with soil conditioner would be an effective practice for improving soil fertility, preventing soil nitrification, and deterring nitrate leaching, as well as reducing saline for topsoil, which would be a basis for developing soil amendments to control saline and a fertile soil environment for pioneer crops planted in coastal barren severe saline-alkali areas.

Interactions between flue gas desulfurization gypsum and biochar on water infiltration characteristics and physicochemical properties of saline-alkaline soil

The application of flue gas desulfurization gypsum (FGDG) improves the soil structure, reduces soil pH, and accelerates soil salt leaching. Biochar amendment to soil can affect the soil infiltration rate, increase soil porosity, decrease soil bulk density, and enhance the water retention capacity. This study investigated the interactive effect of FGDG and biochar on water infiltration characteristics and physicochemical properties as well as determined the optimal amendment rate as a saline-alkaline soil conditioner. Seven experimental schemes were designed, and the newly reclaimed cultivated soil from Pingtan Comprehensive Experimental Zone in Fujian Province, China, was used in an indoor soil column experiment to simulate soil infiltration. Five models were employed to describe the infiltration process. The power function was used to represent the dynamic process of the wetting front. The conclusions of this study are as follows: (1) there was a reduction in the infiltration capacity of saline-alkaline soil (sandy soil) in each treatment, and the application of FGDG alone had the highest inhibition effect compared to the control (CK). The Kostiakov model provides the best fit for the experimental data of soil cumulative infiltration. (2) All treatments increased the total porosity and water content of saline-alkali soil, with the combined application of FGDG and biochar found to be more effective. (3) The application of FGDG alone or in combination with biochar decreased the pH and increased the electrical conductivity of the saline-alkali soil significantly, with the combined application having the most significant effect. In contrast, soil amended with biochar alone had minimal effect on the pH and EC of the soil. (4) The best improvement ratio was achieved with the F1B2 combination (75 g/kg FGDG + 30 g/kg biochar).

Mitigation of N2O emission from granular organic fertilizer with alkali- and salt-resistant plant growth-promoting rhizobacteria

AIM

Organic fertilizer application significantly stimulates nitrous oxide (N2O) emissions from agricultural soils. Plant growth-promoting rhizobacteria (PGPR) strains are the core of bio-fertilizer or bio-organic fertilizer, while their beneficial effects are inhibited by environmental conditions, such as alkali and salt stress observed in organic manure or soil. This study aims to screen alkali- and salt-resistant PGPR that could mitigate N2O emission after applying strain-inoculated organic fertilizer.

METHODS AND RESULTS

Among the 29 candidate strains, 11 (7 Bacillus spp., 2 Achromobacter spp., 1 Paenibacillus sp., and 1 Pseudomonas sp.) significantly mitigated N2O emissions from the organic fertilizer after inoculation. Seven strains were alkali tolerant (pH 10) and five were salt tolerant (4% salinity) in pure culture. Seven strains were selected for further evaluation in two agricultural soils. Five of these seven strains could significantly decrease the cumulative N2O emissions from Anthrosol, while six could significantly decrease the cumulative N2O emissions from Cambisol after the inoculation into the granular organic fertilizer compared with the non-inoculated control.

CONCLUSIONS

Inoculating alkali- and salt-resistant PGPR into organic fertilizer can reduce N2O emissions from soils under microcosm conditions. Further studies are needed to investigate whether these strains will work under field conditions, under higher salinity, or at different soil pH.

Elemental sulfur redox bioconversion for selective recovery of phosphorus from Fe/Al-bound phosphate-rich anaerobically digested sludge: Sulfur oxidation or sulfur reduction?

The biological oxidation of elemental sulfur (S0) to sulfate and the reduction of S0 to sulfide provide a potential route for extracting and reclaiming phosphorus (P) from anaerobically digested sludge (ADS). However, the treatment performance, stability, and cost-effectiveness of the two opposing bioprocesses based on S° for selective P recovery from ADS remain unclear. This study aimed to compare the roles of S0-oxidizing bacteria (S0OB) and S0-reducing bacteria (S0RB) in liberating insoluble P from ADS through single-batch and consecutive multibatch experiments. Changes in P speciation in the sludge during the biological extraction processes were analyzed by using complementary sequential extraction and P X-ray absorption near-edge spectroscopy. Results showed that S0OB treatment extracted more phosphate from the sludge compared with S0RB treatment, but it also released a considerable amount of metal cations (e.g., heavy metals, Mg2+, Al3+, Ca2+) and negatively affected sludge dewaterability due to intense sludge acidification and cell lysis. At pH 1.2, the S0OB treatment released 92.9% of P from the sludge, with the dissolution of HAP, Fe-PO4, Mg3(PO4)2, and P-fehrrihy contributing 26.8%, 22.1%, 12.8%, and 10.5%, respectively. The S0RB treatment released 63.6% of P from the sludge at pH 7.0, with negligible dissolution of metal cations, thereby avoiding costly purification of the extract and alkali neutralization for pH adjustment. This treatment involved the replacement of phosphates bounded with Fe-PO4 (FePO4 and P-fehrrihy) and Al-PO4 (P-Alumina and AlPO4) with biogenic sulfides, with contributions of 72.7%, and 20.9%, respectively. Consecutive bioprocesses for P extraction were achieved by recirculating the treated sludge. Both S0OB and S0RB treatments did not affect the extent of sludge dewatering but considerably weakened the dewatering rate. The S0OB-treated sludge exhibited prolonged filtration time (from 3010 s to 9150 s) and expressing time (from 795 s to 4690 s) during compression dewatering. After removing metal cations using cation exchange resin (CER) and neutralizing using NaOH, a vivianite product Fe3(PO4)2·8H2O (purity: 84%) was harvested from the S0OB-treated extract through precipitation with FeSO4·7H2O. By contrast, a vivianite product Fe3(PO4)2·8H2O (purity: 81%) was directly obtained from the S0RB-treated extract through precipitation with FeSO4·7H2O. Ultimately, 79.8 and 57.9wt% of P were recovered from ADS through S0OB extraction-CER purification-alkali neutralization-vivianite crystallization, and S0RB extraction-vivianite crystallization, respectively. Collectively, biological S0 reduction is more applicable than biological S0 oxidation for selectively reclaiming P from Fe/Al-associated phosphate-rich ADS due to better cost-effectiveness and process simplicity. These findings are of significance for developing sludge management strategies to improve P reclamation with minimal process inputs.

Analysis on the salt tolerance of Nitraria sibirica Pall. based on Pacbio full-length transcriptome sequencing

KEY MESSAGE

Nitraria sibirica Pall. regulates its tolerance to salt stress mainly by adjusting ion balance, modifying cell wall structure, and activating signal transduction pathways. N. sibirica, as a typical halophyte, can not only effectively restore saline-alkali land, but also has high economic value. However, studies on its salt tolerance at combining molecular and physiological levels were limited. In this study, the salt tolerance of N. sibirica was analyzed based on Pacbio full-length transcriptome sequencing, and the salt tolerance in the physiological level was verified by key genes. The results showed that 89,017 full-length transcripts were obtained, of which 84,632 sequences were annotated. A total of 86,482 coding sequences (CDS) were predicted and 6561 differentially expressed genes (DEGs) were identified. DEGs were significantly enriched in "sodium ion homeostasis", "response to osmotic stress", "reactive oxygen species metabolic process", "defense response by cell wall thickening", "signal transduction", etc. The expression levels for most of these DEGs increased under salt stress. A total of 69 key genes were screened based on weighted gene co-expression network analysis (WGCNA), of which 33 were first reported on salt tolerance. Moreover, NsRabE1c gene with the highest expression level was selected to verify its salt tolerance. Over-expression of NsRabE1c gene enhanced the germination potential and root length of transgenic Arabidopsis thaliana plants without salt treatment as compared to those of Col-0 and AtRabE1c mutant. The expression levels of NsRabE1c decreased in the growth stagnation phase, while significantly increased in the growth recovery phase under salt stress. We predicted that NsRabE1c gene help N. sibirica resist salt stress through the regulation of plant growth. The results of this study deepen the understanding of salinity resistance in N. sibirica.

Cation-stimulated drug delivery via lipid assembly comprising macrocyclized disaccharides - A DFT study

In the attempt to create a delivery system for an alkali-cation stimulated drug release, a computational study was conducted, aiming for the evaluation of synthetic access towards glycolipid crown ethers analogs and their potential for coordination-induced changes of packing constraints for molecular assemblies. The results disfavor amide-linkages for the creation of macrocycles around the inter-glycosidic bond of a disaccharide. Conformational changes upon cation coordination of the macrocycle decrease the intersection area for easily accessible macrocycles based on lactose. This leads to shrinking intersection areas upon alkali complexation. Maltose-based analogs, on the other hand, exhibited the targeted increase of the glycolipid intersection area and, hence, may be considered as a promising resource.

Ultrahighly Alkali-Tolerant NOx Reduction over Self-Adaptive CePO4/FePO4 Catalysts

Catalyst deactivation caused by alkali metal poisoning has long been a key bottleneck in the application of selective catalytic reduction of NOx with NH3 (NH3-SCR), limiting the service life of the catalyst and increasing the cost of environmental protection. Despite great efforts, continuous accumulation of alkali metal deposition makes the resistance capacity of 2 wt % K2O difficult to enhance via merely loading acid sites on the surface, resulting in rapid deactivation and frequent replacement of the NH3-SCR catalyst. To further improve the resistance of alkali metals, encapsulating alkali metals into the bulk phase could be a promising strategy. The bottleneck of 2 wt % K2O tolerance has been solved by virtue of ultrahigh potassium storage capacity in the amorphous FePO4 bulk phase. Amorphous FePO4 as a support of the NH3-SCR catalyst exhibited a self-adaptive alkali-tolerance mechanism, where potassium ions spontaneously migrated into the bulk phase of amorphous FePO4 and were anchored by PO43- with the generation of Fe2O3 at the NH3-SCR reaction temperature. This ingenious potassium storage mechanism could boost the K2O resistance capacity to 6 wt % while maintaining approximately 81% NOx conversion. Besides, amorphous FePO4 also exhibited excellent resistance to individual and coexistence of alkali (K2O and Na2O), alkali earth (CaO), and heavy metals (PbO and CdO), providing long durability for CePO4/FePO4 catalysts in flue gas with multipollutants. The cheap and accessible amorphous FePO4 paves the way for the development and implementation of poisoning-resistant NOx abatement.

Imidazole-octyl mixed-mode stationary phase based on macroporous silica for the purification of ovomucoid and ovotransferrin

A process-simplified hard template approach was established to synthesize the monodisperse macroporous silica microspheres with homogeneous structures by twice alkali-thermal treatment and calcination routes. Porous vinyl-functionalized polysesquioxane microspheres (V-PMSQ) were synthesized through a hydrolyzation-polycondensation method and used as templates. The template particles with large aperture and high pore volume were obtained by adjusting the pH value and reaction time of the twice alkali-thermal reaction. After calcination, monodisperse silica microspheres with an average pore size of 30 nm, homogeneous pore structures, and narrow particle size distribution were fabricated, which can be directly used as chromatographic matrices without classification. After that, a new reversed-phase/strong anion-exchange (RP/SAX) mixed-mode stationary phase Sil-S-VOIM was prepared by bonding the 1-vinyl-3-octyl-imidazole ligands to the above silica microspheres through a "thiol-ene" click reaction. The performance of the Sil-S-VOIM column was evaluated by one acidic protein (transferrin) and two basic proteins (lysozyme, α-chymotrypsin) and compared to a single imidazole-modified Sil-S-VIM column and an octyl-modified Sil-C8 column, respectively. Due to the synergistic effect of electrostatic repulsion and hydrophobic interactions, baseline separations of the above proteins were observed only on the Sil-S-VOIM column, with resolutions of 2.55 and 2.01 between lysozyme and transferrin, and between transferrin and α-chymotrypsin, respectively, indicating good selectivity and separation ability compared with single-mode stationary phases. It was applied to the isolation of egg white samples with peaks identified by SDS-PAGE and MALDI-TOF-MS. The results showed that the selective retention and isolation of ovomucoid and ovotransferrin were successfully achieved, with yields of 78.8% and 67.2%, respectively. The protocol described in this work is simpler, faster, and has higher protein recovery. Overall, this new mixed-mode stationary phase provided a promising potential for the separation and determination of intact proteins.

The influence of stress factors on selected phenotypic and genotypic features of Listeria monocytogenes - a pilot study

BACKGROUND

Listeria monocytogenes are Gram-positive rods, widespread in the environment due to their wide tolerance to changing conditions. The apilot study aimed to assess the impact of six various stresses (heat, cold, osmotic, acid, alkali, frozen) on phenotypic features: MIC of antibiotics (penicillin, ampicillin, meropenem, erythromycin, co-trimoxazole; gradient stripes), motility, ability to form a biofilm (crystal violet method) and growth rate (OD and quantitative method), expression level of sigB (stress induced regulator of genes), agrA, agrB (associated with biofilm formation) and lmo2230, lmo0596 (acid and alkali stress) (qPCR) for three strains of L. monocytogenes.

RESULTS

Applied stress conditions contributed to changes in phenotypic features and expression levels of sigB, agrA, agrB, lmo2230 and lmo0596. Stress exposure increased MIC value for penicillin (ATCC 19111 - alkaline stress), ampicillin (472CC - osmotic, acid, alkaline stress), meropenem (strains: 55 C - acid, alkaline, o smotic, frozen stress; 472CC - acid, alkaline stress), erythromycin (strains: 55 C - acid stress; 472CC - acid, alkaline, osmotic stress; ATCC 19111 - osmotic, acid, alkaline, frozen stress), co-trimoxazole (strains: 55 C - acid stress; ATCC 19111 - osmotic, acid, alkaline stress). These changes, however, did not affect antibiotic susceptibility. The strain 472CC (a moderate biofilm former) increased biofilm production after exposure to all stress factors except heat and acid. The ATCC 19111 (a weak producer) formed moderate biofilm under all studied conditions except cold and frozen stress, respectively. The strain 55 C became a strong biofilm producer after exposure to cold and produced a weak biofilm in response to frozen stress. Three tested strains had lower growth rate (compared to the no stress variant) after exposure to heat stress. It has been found that the sigB transcript level increased under alkaline (472CC) stress and the agrB expression increased under cold, osmotic (55 C, 472CC), alkali and frozen (472CC) stress. In contrast, sigB transcript level decreased in response to acid and frozen stress (55 C), lmo2230 transcript level after exposure to acid and alkali stress (ATCC 19111), and lmo0596 transcript level after exposure to acid stress (ATCC 19111).

CONCLUSIONS

Environmental stress changes the ability to form a biofilm and the MIC values of antibiotics and affect the level of expression of selected genes, which may increase the survival and virulence of L. monocytogenes. Further research on a large L. monocytogenes population is needed to assess the molecular mechanism responsible for the correlation of antibiotic resistance, biofilm formation and resistance to stress factors.

Antimicrobial, function, and crystalline analysis on the cellulose fibre extracted from the banana tree trunks

Bioactive substances such as phenolic compounds, antioxidants, and antibacterial agents are found in natural fibres. In this study, banana fibre was extracted from the trunks of banana plants. Antibacterial activity, FTIR, XRD, and SEM analysis were performed to characterize the banana cellulose fibre, and also raw and alkali-treated banana fibre composite was fabricated with an epoxy matrix. Results of the antibacterial analysis indicate that this banana cellulose fibre strongly impedes bacterial growth with elevated inhibitory zones. The primary peaks observed at 1170 cm-1 and 1426 cm-1 by FTIR analysis correspond to C-O stretching, O-H bending, aliphatic ether, secondary alcohol, and carboxylic acid. The morphological analysis reveals the fibre quality, and the EDX analysis confirms the elements present in the banana cellulose fibre. The XRD results demonstrated a more significant proportion (76.8%) of the amorphous region. This study indicates that banana cellulose fibre could be a promising source of antimicrobial compounds. In addition, the mechanical properties of alkali-treated banana fibre composite were preferable to raw fibre composite by an average of 3% for this banana fibre composite. As a result, this composite can be used to manufacture automobile interior components, as it can reduce the sanitizing periods of interior components during winter months.

Structural and impedance spectroscopic investigations of eco-friendly alkali phosphoborate glass-ceramics containing zirconium ion

Glass-ceramics with novel composition xZrO2.7P2O5.19CaO.24Na2O.(50-x)B2O3 (x = 0, 2, 4, 6, and 8 mol%) have been synthesized using melt quench technique. The synthesized compositions were characterized and analyzed by X-ray diffraction, field emission scanning electron microscopy, infrared absorption, and impedance spectroscopy. X-ray diffraction profiles of prepared samples confirm the existence of phases corresponding to Na3Ca6(PO4)5 crystal (with crystallite size ~ 23 nm). Infrared absorbance spectra reveal the presence of phosphate and borate units (PO3, PO4, BO3, BO4) in the glass matrix. Different dielectric parameters such as dielectric loss, electric modulus, and tangent loss were evaluated. Their variations with temperature and frequency confirm the non- Debye relaxation behavior of prepared samples. A phenomenal description of the capacitive behavior was studied by considering the circuit having a parallel combination of constant phase element and bulk resistance. The conduction is found to be governed by overlapping large polaron tunneling (OLPT) and follow OLPT model. The results indicate that ZrO2 substituted alkali phosphoborate glass-ceramics can be used as eco-friendly and safe dielectric materials.

Total hip arthroplasty using an alkali- and heat-treated titanium Zweymüller stem with no trochanteric shoulder: results at 5-year follow-up

BACKGROUND

A trochanteric shoulder is 1 of the characteristics of the original Zweymüller femoral stem for total hip arthroplasty (THA). There have been few clinical reports of THA using recently available versions of Zweymüller-type stems with eliminated trochanteric shoulder.

METHODS

82 consecutive THAs with a Zweymüller-type stem without trochanteric shoulder were analyzed. The stem was made of alkali- and heat-treated titanium, straight, tapered, with rectangular cross-section. Survivorship was estimated with the Kaplan-Meier method.

RESULTS

76 of 82 hips (92.7%) were followed for more than 5 years or until revision. 35 of 82 hips (42.7%), were revised and the predominant reason for revision was aseptic loosening of the femoral stem (34 of 35 hips, 97.1%). Survival with revision for any reason as the endpoint was 71.3% (95% CI, 51.8% to 80.1%) at 5 years.

CONCLUSIONS

The survival of the modified Zweymüller-type stem with no trochanteric shoulder was unacceptably low.

Nutrient runoff loss from saline-alkali paddy fields in Songnen Plain of Northeast China via different runoff pathways: effects of nitrogen fertilizer types

The application of nitrogen (N) fertilizer aggravates the nutrient runoff loss from paddy, causing serious agricultural non-point source pollution, and leading to a serious decline in water quality. The global area of saline-alkali paddy has expanded, but the response of nutrient loss via runoff to N-fertilizer applications in saline-alkali paddy is still unclear. This study conducted a 147-day field experiment to evaluate the nutrient runoff loss from saline-alkali paddy with different N-fertilizer application strategies in Songnen Plain of Northeast China. Regardless of N-fertilizer types, the nutrient loss via rainfall runoff in the entire rice-growing season was significantly (p < 0.05) higher than that via artificial drainage. The N and phosphorus (P) concentrations in runoff water were correlated with salinity and alkalinity. Especially, pH had a significant positive correlation with total-P (TP) (r = 0.658, p < 0.01). In the entire rice-growing season, the TN runoff losses in urea (U), microbial fertilizer (MF), and inorganic compound fertilizer (ICF) treatments were significantly (p < 0.05) lower compared with carbon-based slow-release fertilizer (CSF) and organic-inorganic compound fertilizer (OCF), respectively. Meanwhile, the TP runoff losses in OCF and ICF treatments were significantly (p < 0.05) lower than U and MF, respectively. Overall, the application of ICF is a better choice to avoid N and P losses via runoff from saline-alkali paddy fields.

Purification and characterization of an alkali-organic solvent-stable laccase with dye decolorization capacity from newly isolated Lysinibacillus fusiformis W11

A new Lysinibacillus fusiformis strain with abundant laccase activity was isolated from soil under forest rotted leaf and identified as L. fusiformis W11 based on its 16S rRNA gene sequence and physiological characteristics. The laccase LfuLac was purified and characterized. The optimum temperature and pH of LfuLac on guaiacol were 45 °C and pH 9, respectively. LfuLac kept 78%, 88%, 92%, 74%, and 47% of activity at pH 7-11, respectively, suggesting the alkali resistance of the enzyme. The effects of various metal ions on LfuLac showed that Cu2+, Mg2+, and Na+ were beneficial to laccase activity and 10 mM Cu2+ increased the activity of LfuLac to 216%. LfuLac showed about 90% activity at 5% organic solvents and more than 60% activity at 20%, indicating its resistance to organic solvents. In addition, LfuLac decolorized different kinds of dyes. This study enriched our knowledge about laccase from L. fusiformis W11 and its potential industrial applications.

Variations in bacterial diversity and community structure in the sediments of an alkaline lake in Inner Mongolia plateau, China

Alkaline lakes are a special aquatic ecosystem that act as important water and alkali resource in the arid-semiarid regions. The primary aim of the study is to explore how environmental factors affect community diversity and structure, and to find whether there are key microbes that can indicate changes in environmental factors in alkaline lakes. Therefore, four sediment samples (S1, S2, S3, and S4) were collected from Hamatai Lake which is an important alkali resource in Ordos' desert plateau of Inner Mongolia. Samples were collected along the salinity and alkalinity gradients and bacterial community compositions were investigated by Illumina Miseq sequencing. The results revealed that the diversity and richness of bacterial community decreased with increasing alkalinity (pH) and salinity, and bacterial community structure was obviously different for the relatively light alkaline and hyposaline samples (LAHO; pH < 8.5; salinity < 20‰) and high alkaline and hypersaline samples (HAHR; pH > 8.5; salinity > 20‰). Firmicutes, Proteobacteria and Bacteriodetes were observed to be the dominant phyla. Furthermore, Acidobacteria, Actinobacteria, and low salt-tolerant alkaliphilic nitrifying taxa were mainly distributed in S1 with LAHO characteristic. Firmicutes, Clostridia, Gammaproteobacteria, salt-tolerant alkaliphilic denitrifying taxa, haloalkaliphilic sulfur cycling taxa were mainly distributed in S2, S3 and S4, and were well adapted to haloalkaline conditions. Correlation analysis revealed that the community diversity (operational taxonomic unit numbers and/or Shannon index) and richness (Chao1) were significantly positively correlated with ammonium nitrogen (r = 0.654, p < 0.05; r = 0.680, p < 0.05) and negatively correlated with pH (r = -0.924, p < 0.01; r = -0.800, p < 0.01; r = -0.933, p < 0.01) and salinity (r = -0.615, p < 0.05; r = -0.647, p < 0.05). A redundancy analysis and variation partitioning analysis revealed that pH (explanation degrees of 53.5%, pseudo-F = 11.5, p < 0.01), TOC/TN (24.8%, pseudo-F = 10.3, p < 0.05) and salinity (9.2%, pseudo-F = 9.5, p < 0.05) were the most significant factors that caused the variations in bacterial community structure. The results suggested that alkalinity, nutrient salt and salinity jointly affect bacterial diversity and community structure, in which one taxon (Acidobacteria), six taxa (Cyanobacteria, Nitrosomonadaceae, Nitrospira, Bacillus, Lactococcus and Halomonas) and five taxa (Desulfonatronobacter, Dethiobacter, Desulfurivibrio, Thioalkalivibrio and Halorhodospira) are related to carbon, nitrogen and sulfur cycles, respectively. Classes Clostridia and Gammaproteobacteria might indicate changes of saline-alkali conditions in the sediments of alkaline lakes in desert plateau.

Water-Soluble Alkali Lignin as a Natural Radical Scavenger and Anticancer Alternative

Several phytochemicals, which display antioxidant activity and inhibit cancer cell phenotypes, could be used for cancer treatment and prevention. Lignin, as a part of plant biomass, is the second most abundant natural biopolymer worldwide, and represents approximately 30% of the total organic carbon content of the biosphere. Historically, lignin-based products have been viewed as waste materials of limited industrial usefulness, but modern technologies highlight the applicability of lignin in a variety of industrial branches, including biomedicine. The aims of our preliminary study were to compare the antioxidant properties of water-soluble alkali lignin solutions, before and after UV-B irradiation, as well as to clarify their effect on colon cancer cell viability (Colon 26), applied at low (tolerable) concentrations. The results showed a high antioxidant capacity of lignin solutions, compared to a water-soluble control antioxidant standard (Trolox) and remarkable radical scavenging activity was observed after their UV-B irradiation. Diminishment of cell viability as well as inhibition of the proliferative activity of the colon cancer cell line with an increase in alkali lignin concentrations were observed. Our results confirmed that, due to its biodegradable and biocompatible nature, lignin could be a potential agent for cancer therapy, especially in nanomedicine as a drug delivery system.

Critical parameters affecting the thermal resistance of alkali-activated aluminosilicate wastes: Current understanding and future directions

Many research articles and reviews have recognized alkali-activated materials (AAMs) as eco-friendly alternative binders to ordinary Portland cement (OPC) due to their economic andenvironmental advantages. However, few literature surveys reported the physical, mechanical and microstructural changes that occur after the exposure of AAMs to elevated temperatures. Owing to the wide diversity in the properties of aluminosilicates, alkali-activation conditions, and additives, a deep survey is needed to understand how different factors can affect the performance of AAMs under elevated temperatures. Therefore, this review extensively discusses the impact of recent critical parameters, including aluminosilicate compositions, aggregate type and mineral, micro, and nano additives, on the behavior of AAMs under thermal load. It can be concluded that regardless of alkali-activator type and concentration, alkali-activated fly ash shows higher thermal resistance than alkali-activated metakaolin and slag. Moreover, the presence of an adequate amount of calcium can increase the thermal stability of AAMs, while the iron has a varying effect on the thermal resistance of AAMs, either positively or negatively. Compared with all additives and aggregates, using waste glass and lightweight aggregates enhanced the thermal resistance of AAMs. Howerver, some types of aggregate having a binding ability which increase the residual strength after heat exposure. Considering the fineness of materials, evaluating the role of nano and micro materials on the properties of AAMs at high temperatures is reviewed. Based on this survey, several promising topics for future work are suggested.

Remediating petroleum hydrocarbons in highly saline-alkali soils using three native plant species

Phytoremediation of total petroleum hydrocarbons (TPHs) contamination is a process that uses the synergistic action of plants and rhizosphere microorganisms to degrade, absorb and stabilize pollutants in the soil, and has received increasing attention in recent years. However, this technology still has some challenges under certain conditions (e.g., highly alkaline and saline environments). The present study was selected three native plant species (alfalfa, tall fescue, and ryegrass) to remediate petroleum pollutants in greenhouse pot experiments. The results indicate that TPH contamination not only inhibited plant growth, soil chemical properties and soil fertility (i.e. lower plant biomass, chlorophyll, pH, and electrical conductivity), but also increased the malondialdehyde, glutathione, and antioxidant enzyme activities (catalase and polyphenol oxidase). Further, correlation analysis results illustrated that TPH removal was strongly positively correlated with chlorophyll, soil fertility, and total organic carbon, but was negatively correlated with dehydrogenase, polyphenol oxidase, pH, and electrical conductivity. The highest TPHs removal rate (74.13%) was exhibited by alfalfa, followed by tall fescue (61.79%) and ryegrass (57.28%). The degradation rates of short-chain alkanes and low rings polycyclic aromatic hydrocarbons (PAHs) were substantially higher than those of long-chain alkanes and high rings PAHs. The findings of this study provide valuable insights into petroleum decontamination strategies in the highly saline - alkali environments.

Repurposing carbonate-based waste for producing an innovative binder: optimization and characterization

This study reports the full recycling of dolomite waste (DW) in the fabrication of a novel cementitious material through a facile and eco-efficient method. The proposed technique includes mixing different alkali-activators (i.e., NaOH and Na2SiO3) with DW powder, followed by curing at room temperature. Based on the alkali-activator type, sodium oxide concentration, and curing time, the formulated mixtures yield a wide range of compressive strengths. When DW powder is mixed with different contents of NaOH (2.5, 5, and 7.5 wt.% Na2O), the resulting hardened materials exhibited modest compressive strengths (less than 11 MPa) due to the formation of the gaylussite Na2CO3·CaCO3·5H2O phase. Concerning the other chemical activator (Na2SiO3), a significant improvement in the compressive strengths of the resulted hardened materials was detected. This was ascribed to the formation of calcium silicate hydrate, with a high binding capacity, through the exchange reaction between Na2SiO3 and CaCO3 inside DW. The sample activated with Na2SiO3 (silica modulus of 1.5) equivalent to Na2O of 7.5 wt.% offered the highest 90-day compressive strength (34 MPa). At silica modulus lower or higher than 1.5, a noticeable decrease in the performance of the hardened materials was observed, which could be attributed to the alter in binding phase composition. Overall, the present work presented a new approach in utilizing the available and low cost carbonate-based wastes as main precursors in the family of promising alkali-activated materials.

Alternative Splicing for Leucanthemella linearis NST1 Contributes to Variable Abiotic Stress Resistance in Transgenic Tobacco

Leucanthemella linearis is a marsh plant in the family Compositae. It has good water and moisture resistance and ornamental properties, which makes it one of the important materials for chrysanthemum breeding and genetic improvement. The NST1 (NAC secondary wall enhancement factor 1) gene is associated with the thickening of the secondary walls of fiber cells in the plant ducts and the secondary xylem and plays an important role in plant stress resistance. In this study, two variable spliceosomes of the NST1 gene were identified from a chrysanthemum plant by using bioinformatics, qRT-PCR, transgene, and paraffin section methods to explore the molecular mechanism of the variable splicing of NST1 under abiotic stress. The results show that only three amino acids were found to be different between the two LlNST1 variants. After being treated with salt, drought, and low temperatures, analysis of the expression levels of the LlNST1 and LlNST1.1 genes in Ll showed that LlNST1.1 could respond to low temperatures and salt stress and had a weak response to drought stress. However, the expression level of LlNST1 under the three treatments was lower than that of LlNST1.1. LlNST1 transgenic tobacco showed increased saline-alkali resistance and low-temperature resistance at the seedling stage. LlNST1.1 transgenic tobacco also showed enhanced saline-alkali resistance and drought resistance at the seedling stage. In conclusion, the functions of the two variable spliceosomes of the NST1 gene are very different under abiotic stress. Therefore, this study verified the function of the variable spliceosome of NST1 and improved the stress resistance of the chrysanthemum plant under examination by regulating the expression of the NST protein, which lays a material foundation for the improvement of plant stress resistance materials and has important significance for the study of the resistance of chrysanthemum plants to abiotic stress.

Sequential extraction of labile and recalcitrant fractions of soil organic matter: A case study focusing on antimony (Sb) in humic acids, fulvic acids and humin fractions of long-term aged contaminated soils

Soil organic matter (SOM) plays a key role in environmental chemistry of macro and micro nutrients as well as heavy metal (loids). In this research, a modified sequential extraction scheme was used to isolate labile and recalcitrant SOM from organic rich soils after 18 months of ageing with antimony. Humic substances were extracted with a mixture of 0.5 M sodium hydroxide +0.1 M sodium pyrophosphate solution from soils. Then soils deprived of humic substances were sequentially subjected to extraction with glycerol, citric acid, pre-treated with acid and extracted with boiling alkali mixture. The humic acids (HA) and fulvic acids (FA) of isolated SOM fractions were separated and HAs been characterized using FTIR, 1H NMR, and UV-VIS. Acid-alkali treatment of the most recalcitrant SOM fraction (A1-ROM) led to the extraction of sparingly soluble, highly aromatic compound with considerable amounts of N (44% of the extractable N), possibly due to the breakdown of bounds between aromatic rings and amine functional groups. Nevertheless, the highest content of C and TOC was associated with the glycerol extractable SOM. Substantial amounts of Fe and Al were extracted with glycerol, resulting in a dramatic rise of Sb in SOM extracts. The largest increase (60%) in Sb concentrations was observed after the removal of Fe with citric acid. The humic substances (HS) were responsible for 63% of extractable Sb, whereas even after exhaustive alkali extractions 22% of the total Sb remained in the residual humin fraction. Within the HS fraction, 95% of antimony was associated with the low molecular weight FAs. Antimony concentrations in organic fractions correlated significantly with TOC and N contents, possibly due to the role of amine functional groups in Sb complexation. The results of this research highlight the importance of Fe-Al-SOM bridging and humin fraction in sequestration of Sb in recalcitrant SOM pools.

Artificial humic acid promotes growth of maize seedling under alkali conditions

Salinization of cropland is one of the major abiotic stresses affecting global agricultural sustainability, posing a serious threat to agricultural productivity and food security. Application of artificial humic acid (A-HA) as plant biostimulants has been increasingly attracting farmers and researchers. However, its regulation of seed germination and growth under alkali stress has rarely received attention. The purpose of this study was to investigate the response of maize (Zea mays L.) seed germination and seedling growth after the addition of A-HA. The effects of A-HA on seed germination, seedling growth, chlorophyll contents and osmoregulation substance under black and saline soil conditions were studied by soaking maize in solutions with and without various concentrations of A-HA. Artificial humic acid treatments significantly increased the seed germination index and dry weight of seedlings. The effects of maize root in absence and presence of A-HA under alkali stress were also evaluated using transcriptome sequencing. GO and KEGG analyzes were performed on differentially expressed genes, and the reliability of transcriptome data was verified by qPCR analysis. Results showed that A-HA significantly activated phenylpropanoid biosynthesis, oxidative phosphorylation pathways and plant hormone signal transduction. Moreover, Transcription factor analysis revealed that A-HA induced the expression of several transcription factors under alkali stress which had a regulatory effect on the alleviation of alkali damage in the root system. Overall, our results suggested that soaking seeds with A-HA can alleviate alkali accumulation and toxicity in maize, constituting a simple and effective strategy to mitigate saline toxicity. These results will provide new insights for the application of A-HA in management to reduce alkali-caused crop loss.

Characterization of Two Marine Lignin-Degrading Consortia and the Potential Microbial Lignin Degradation Network in Nearshore Regions

Terrestrial organic carbon such as lignin is an important component of the global marine carbon. However, the structural complexity and recalcitrant nature of lignin are deemed challenging for biodegradation. It has been speculated that bacteria play important roles in lignin degradation in the marine system. However, the extent of the involvement of marine microorganisms in lignin degradation and their contribution to the oceanic carbon cycle remains elusive. In this study, two bacterial consortia capable of degrading alkali lignin (a model compound of lignin), designated LIG-B and LIG-S, were enriched from the nearshore sediments of the East and South China Seas. Consortia LIG-B and LIG-S mainly comprised of the Proteobacteria phylum with Nitratireductor sp. (71.6%) and Halomonas sp. (91.6%), respectively. Lignin degradation was found more favorable in consortium LIG-B (max 57%) than in LIG-S (max 18%). Ligninolytic enzymes laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP) capable of decomposing lignin into smaller fragments were all active in both consortia. The newly emerged low-molecular-weight aromatics, organic acids, and other lignin-derived compounds in biotreated alkali lignin also evidently showed the depolymerization of lignin by both consortia. The lignin degradation pathways reconstructed from consortium LIG-S were found to be more comprehensive compared to consortium LIG-B. It was further revealed that catabolic genes, involved in the degradation of lignin and its derivatives through multiple pathways via protocatechuate and catechol, are present not only in lignin-degrading consortia LIG-B and LIG-S but also in 783 publicly available metagenomic-assembled genomes from nine nearshore regions. IMPORTANCE Numerous terrigenous lignin-containing plant materials are constantly discharged from rivers and estuaries into the marine system. However, only low levels of terrigenous organic carbon, especially lignin, are detected in the global marine system due to the abundance of active heterotrophic microorganisms driving the carbon cycle. Simultaneously, the lack of knowledge on lignin biodegradation has hindered our understanding of the oceanic carbon cycle. Moreover, bacteria have been speculated to play important roles in the marine lignin biodegradation. Here, we enriched two bacterial consortia from nearshore sediments capable of utilizing alkali lignin for cell growth while degrading it into smaller molecules and reconstructed the lignin degradation network. In particular, this study highlights that marine microorganisms in nearshore regions mostly undergo similar pathways using protocatechuate and catechol as ring-cleavage substrates to drive lignin degradation as part of the oceanic carbon cycle, regardless of whether they are in sediments or water column.

Developing interpretable machine learning-Shapley additive explanations model for unconfined compressive strength of cohesive soils stabilized with geopolymer

This paper seeks to develop an interpretable Machine Learning (ML) model for predicting the unconfined compressive strength (UCS) of cohesive soils stabilized with geopolymer at 28 days. Four models including Random Forest (RF), Artificial Neuron Network (ANN), Extreme Gradient Boosting (XGB), and Gradient Boosting (GB) are built. The database consists of 282 samples collected from the literature with three different types of cohesive soil stabilized with three geopolymer categories including Slag-based geopolymer cement, alkali-activated fly ash geopolymer and slag/fly ash-based geopolymer cement. The optimal model is selected by comparing their performances with each other. The values of hyperparameters are tuned by Particle Swarm Optimization (PSO) algorithm and K-Fold Cross Validation. Statistical indicators show the superior performance of the ANN model with three metrics performance such as coefficient of determination R2 = 0.9808, Root Mean Square Error RMSE = 0.8808 MPa and Mean Absolute Error MAE = 0.6344 MPa. In addition, a sensitivity analysis was performed to determine the influence of different input parameters on the UCS of cohesive soils stabilized with geopolymer. The order of feature effect can be ordered in descending order using the Shapley additive explanations (SHAP) value as follows: Ground granulated blast slag content (GGBFS) > Liquid limit (LL) > Alkali/Binder ratio (A/B) > Molarity (M) > Fly ash content (FA) > Na/Al > Si/Al. The ANN model can obtain the best accuracy using these seven inputs. LL has a negative correlation with the growth of unconfined compressive strength, whereas GGBFS has a positive correlation.

Self-alkali-activated self-cementation achievement and mechanism exploration for the synergistic treatment of the municipal solid waste incineration fly ashes and the arsenic-contaminated soils

The feasibility and potential mechanisms of the self-alkali activation brought by municipal solid waste incineration (MSWI) fly ashes to the self-cementation of arsenic-contaminated soils were quantitatively evaluated and comprehensively analyzed to avoid the additional application of the alkali activators and binder materials traditionally. The employment of the two kinds of precursor materials achieved the self-alkali-activated self-cementation ('double self') under ambient conditions. The largest compressive strength (MPa) of 25.64 and lowest leaching toxicities (mg/L) of 21.05, 2.86, 0.08, 0.02, 2.05, and 0.34 for Zn, Cu, Cr, Cd, Pb, and As were obtained in the solidified matrix. Geopolymerization kinetics of the 'double self' cementation can be mathematically fitted by the Johnson-Mehl-Avrami-Kolmogorov model. CaClOH and halite in the MSWI fly ashes set up the self-alkali activation by reacting with the kaolinite and quartz in soils contaminated with arsenic by forming layered hydration and three-dimensional geopolymerization products to push for self-cementation.

Self-cementation of gold tailings activated by nonthermal plasma irradiated calcium (hydro)oxide

The alkalinity of CaO is commonly insufficient in alkali-activating raw soils or minerals for the formation of cementation or geopolymerization. In this study, nonthermal plasma (NTP) irradiation was employed to activate traditional CaO to enhance its efficacy in alkali activation and further intensify the self-cementation of gold tailings. The solidification/stabilization (S/S) of the gold tailings-based matrix activated by NTP-CaO was better than that of CaO. The NTP irradiation enhanced the surface hydroxyl groups and oxygen atoms, decreased the binding energy, formed nanoparticles, and significantly changed the morphologies of the calcium activator. The dosage of the NTP-irradiated CaO (NTP-CaO) directly affected the self-cemented solidification/stabilization of gold tailings. The Johnson-Mehl-Avrami-Kolmogorov model was appropriate for analysing the NTP-CaO-activated geopolymerization kinetics of gold tailings. Three-dimensional (3D) structural minerals covered with small pores were determined in the NTP-CaO-activated cemented samples. The employment of NTP-CaO facilitated the formation of aluminosilicate geopolymers during the self-cementation of gold tailings according to comprehensive characterization strategies. The study achieves the efficient self-remediation of gold tailings by activating calcium precursors, which further solves the contradiction between salinization and alkali activation in the field of noncalcined cementitious materials.

Optimization of protein recovery from sewage sludge via controlled and energy-saving ultrasonic-alkali hydrolysis

The abundant protein in excess sludge can be recovered to prepare high value-added products. However, this sustainable treatment method still has large challenges, such as high energy consumption. In this work, the classical batch operation (BO) and semi-batch operation (SBO) modes were adopted and compared for ultrasonic-alkali hydrolysis. The results showed that the reaction time of SBO significantly decreased to half of that of BO with the same efficiency (ca. 70 %), indicating that SBO was much more energy-efficient. Moreover, analysis of the nitrogen solubility index and trichloroacetic acid-soluble nitrogen index demonstrated that the further proteolysis of protein under SBO was limited. Furthermore, the first-order reaction model fitted the hydrolysis data well (R2 ≥ 0.91) for both modes, in which the rate constant of SBO (k = 0.44 min^-1) was 2.3 times that of BO. Finally, the properties of both products met the standards of foaming extinguishers.

A sustainable strategy for recovery of phosphorus as vivianite from sewage sludge via alkali-activated pyrolysis, water leaching and crystallization

A sustainable strategy for P recovery from sewage sludge via alkali-activated pyrolysis, water leaching and crystallization was proposed, and a high value-added product of vivianite was recovered. Effects of the type and dose of alkali activator on P transformation during sludge pyrolysis were investigated. 50 wt% dose of KHCO₃ was determined as the alkali-activated pyrolysis condition. The content of water-soluble P (referred to as Water-P) in biochar derived from raw sludge (referred to as RS) and ferric sludge (Fenton's reagent conditioned sludge, referred to as FS) by KHCO₃-activated pyrolysis at different temperatures was compared. The Fe element in the Fenton's reagent enhanced the content of Fe-bound P in the dewatered sludge, which was readily transformed into potassium phosphate during KHCO₃-activated pyrolysis, thus increasing the Water-P content in the biochar derived from FS. The proportions of Water-P to total P in the biochar samples obtained by KHCO₃-activated pyrolysis of RS and FS at 600 °C were 72.5% and 96.2%, respectively, which were notably higher than those in the biochar samples obtained by direct pyrolysis of RS and FS (3.5% and 0.5%), respectively. The water leaching solution of biochar obtained by KHCO₃-activated pyrolysis of FS at 600 °C was purified to remove impurity elements, and vivianite with high purity was finally recovered by crystallization. A total P recovery efficiency of 88.08% was achieved throughout the process from sewage sludge to the final vivianite product. This study proposes a promising and sustainable approach for realizing the recovery of high value-added product vivianite from sewage sludge.

Study on adsorption and recovery utilization of phosphorus using alkali melting-hydrothermal treated oil-based drilling cutting ash

Oil-based drill cutting ash (OBDCA) was treated by alkali melting-hydrothermal method and used as novel adsorbent (AM-HT-OBDCA) for the recovery of phosphorus (P) in water body. The experiment parameter for preparation of AM-HT-OBDCA was optimized, including alkali melting ratio (M_OBDCA: M_NaOH), alkali melting temperature and hydrothermal temperature. The adsorption process of phosphorus on AM-HT-OBDCA was fit well with the pseudo-second-order model and the Langmuir model. The calculated theoretic adsorption capacity of phosphorus on AM-HT-OBDCA was 62.9 mg/g. The adsorption behavior was spontaneous and endothermic. The effect of pH value and interfering ions on the adsorption of phosphorus in AM-HT-OBDCA was investigated. The main existing form of adsorbed phosphorus on AM-HT-OBDCA was sodium hydroxide extraction form phosphorus (NaOH-P), including iron form phosphorus (Fe-P) and aluminum form phosphorus (Al-P). Precipitation and ligand exchange were the main mechanisms of phosphorus adsorption on AM-HT-OBDCA. The AM-HT-OBDCA used for phosphorus adsorption (AM-HT-OBDCA-P) could be further utilized as fertilizer to promote plant growth. The results of this study provide fundamental data and evaluation support for resource utilization of OBDCA. These results will also provide a reference for the adsorption and recovery utilization of phosphorus using solid waste-based adsorbent.

Synergistic influence of diatomite and MoS2 nanosheets on the self-alkali-activated cementation of the municipal solid waste incineration fly ash and mechanisms

The solidification/stabilization technique recommended for the disposal of municipal solid waste incineration (MSWI) fly ashes in developed countries was inappropriate for the treatment in most developing counterparts. In this study, the diatomite and MoS₂ nanosheets were synergistically employed to activate the self-alkali-activated cementation of the MSWI fly ashes to achieve efficient solidification, the immobilization of heavy metals (HMs), and the inhibition of chloride release. The compressive strength of 28.61 MPa and the leaching toxicities (mg/L) of Zn, Pb, Cu, Cd, and Cr of 2.26, 0.87, 0.5, 0.06, and 0.22 were obtained from the hardened mortars. Diatomite significantly influenced the self-alkali-activated cementation of the MSWI fly ashes while MoS₂ nanosheets played both roles in intensifying the stabilization of HMs and strengthening the binding process by inducing the formation of sodalite and kaolinite, enhancing the growth rates of nucleation, and transforming the layered cementation to the partial and full three-dimensional cementation in the hardened matrix. This study not only verified the feasibility of diatomite and MoS₂ in activating the self-alkali-activated cementation of the MSWI fly ashes but also supplied a reliable technique for the harmless disposal and efficient utilization of MSWI fly ashes in developing countries.

Pb2+ and Cr3+ immobilization efficiency and mechanism in red-mud-based geopolymer grouts

Herein, a green geopolymer composite was prepared using red mud and granulated blast furnace slag by immobilizing Pb²⁺ and Cr³⁺ to improve the utilization rate of red mud for heavy metal solidification and grouting engineering. The mechanical strength, leaching characteristics, and immobilization mechanisms of geopolymer grouts were investigated via Fourier transform infrared spectroscopy, X-ray diffraction, magic angle spinning-nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy-energy-dispersive spectroscopy. Results demonstrate that the mechanical strength of the red-mud-based grout first increased and then decreased with an increasing alkali activator modulus. Moreover, red mud could participate in the geopolymerization reaction because of its aluminosilicate component. Furthermore, both Pb²⁺ and Cr³⁺ improved the mechanical strength of red-mud-based grouts at contents of 0.4 and 0.6 wt%, respectively. However, the mechanical strength drastically decreased when the dosages for both were 1.0 wt%. These chemical fractions of Pb²⁺ and Cr³⁺ evidence that the soluble and exchangeable fractions could be converted to a carbonate-bound fraction, iron-manganese oxide, and an organic fraction; however, the immobilization rates reached 91.46% and 95.86%, respectively. The characterization results confirm the participation of Pb²⁺ and Cr³⁺ in the geopolymerization, and Pb²⁺ and Cr³⁺ were immobilized by the chemical bonding and physical sealing effects.

Shift in rhizospheric and endophytic microbial communities of dominant plants around Sunit Alkaline Lake

Alkaline lakes are a special type of extreme saline-alkali ecosystem, and the dominant plants store a large number of microbial resources with salinity-tolerant or growth-promoting properties in the littoral zones. In this study, high-throughput sequencing technology and molecular ecological networks were used to analyze the bacteria and fungi from different rhizocompartments of three dominant plants along the salinity gradient in the littoral zones of Sunit Alkali Lake. The study found that fungal communities were more tolerant of environmental abiotic stress, and salinity was not the main environmental factor affecting the composition of microbial communities. Mantel test analysis revealed that SOC (soil organic carbon) was the primary environmental factor affecting the rhizosphere bacterial community as well as the rhizosphere endophyte bacteria and fungi, while CO₃^2- (carbonate ions) had a greater impact on the rhizosphere fungal communities. In addition, keystones identified through the associated molecular network play an important role in helping plants resist saline-alkali environments. There were significant differences in the metabolic pathways of microorganisms from different rhizocompartments predicted by the PICRUSt2 database, which may help to understand how microorganisms resist environmental stress. This study is of great importance for understanding the salt environments around alkaline lakes and excavating potential microbial resources.

Nitrogen migration and transformation in a saline-alkali paddy ecosystem with application of different nitrogen fertilizers

With the increasing transformation of saline-alkali land into paddy, the nitrogen (N) loss in saline-alkali paddy fields becomes an urgent agricultural-environmental problem. However, N migration and transformation following the application of different N fertilizers in saline-alkali paddy fields remains unclear. In this study, four types of N fertilizers were tested to explore the N migration and transformation among water-soil-gas-plant media in saline-alkali paddy ecosystems. Based on the structural equation models, N fertilizer types can change the effects of electrical conductivity (EC), pH, and ammonia-N (NH₄⁺-N) of surface water and/or soil on ammonia (NH₃) volatilization and nitrous oxide (N₂O) emission. Compared with urea (U), the application of urea with urease-nitrification inhibitors (UI) can reduce the potential risk of NH₄⁺-N and nitrate-N (NO₃^--N) loss via runoff, and significantly (p < 0.05) reduce the N₂O emission. However, the expected effectiveness of UI on NH₃ volatilization control and total N (TN) uptake capacity of rice was not achieved. For organic-inorganic compound fertilizer (OCF) and carbon-based slow-release fertilizer (CSF), the average TN concentrations in surface water at panicle initiation fertilizer (PIF) stage were reduced by 45.97% and 38.63%, respectively, and the TN contents in aboveground crops were increased by 15.62% and 23.91%. The cumulative N₂O emissions by the end of the entire rice-growing season were also decreased by 103.62% and 36.69%, respectively. Overall, both OCF and CSF are beneficial for controlling N₂O emission and the potential risks of N loss via runoff caused by surface water discharge, and improving the TN uptake capacity of rice in saline-alkali paddy fields.

Mitigating soil salinity stress with titanium gypsum and biochar composite materials: Improvement effects and mechanism

Titanium gypsum and biochar are considered effective amendments for mitigating soil salinity stress. However, the knowledge is inadequate regarding their efficiency and application as an improvement. In this study, TG-B composite was prepared by using industrial by-products titanium gypsum and biochar as raw materials and then modified by ball milling method, to characterize its microscopic characteristics and explore the improvement effect on saline-alkali soil and plant growth. Besides, we explored the mechanism of TG-B in improving saline-alkali soil and the dynamic balance of the solution reaction process. Our results showed that the CaSO₄·2H₂O particles in TG-B were finer, dispersed evenly, and contacted fully with soil gelatinous particles, which was more conducive to the improvement of saline-alkali soil. The results of TG-B with different ball milling ratios and different materials dosages indicated that the application rate of TG-B was 5%, and the optimum ratio of TG-B was TG: B (mass ratio) = 10:1, with the best soil improvement effect. The pot experiment proved that the indicators of indicating soil salinity such as pH, EC, SAR, and soluble Na⁺ decreased by 20.74%, 77.24%, 68.77%, and 44.70%, respectively, thus playing a good role in improving saline-alkali soil. In addition, pot experiments demonstrated that compared with the control group, the soil porosity and soil moisture content in the TG-B group increased by 15.95% and 38.71%, respectively, and further improve the structure and diversity of soil bacterial community when compared with titanium gypsum and biochar alone. Finally, the application of TG-B promoted the germination and growth of rice significantly through the synergistic effects of composite material components. These results all suggested that the application of TG-B was an effective strategy to improve soil salinity and promote plant growth. Therefore, it might provide new insights into the utilization of solid waste resources to improve saline-alkali lands.

Catalytic oxidation effect of MnSO4 on As(III) by air in alkaline solution

The catalytic oxidation effect of MnSO₄ on As(III) by air in an alkaline solution was investigated. According to the X-ray diffraction (XRD), scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analysis results of the product, it was shown that the introduction of MnSO₄ in the form of solution would generate Na_0.55Mn₂O₄·1.5H₂O with strong catalytic oxidation ability in the aerobic alkaline solution, whereas the catalytic effect of the other product MnOOH is not satisfactory. Under the optimal reaction conditions of temperature 90°C, As/Mn molar ratio 12.74:1, air flow rate 1.0 L/min, and stirring speed 300 r/min, As(III) can be completely oxidized after 2 hr reaction. The excellent catalytic oxidation ability of MnSO₄ on As(III) was mainly attributed to the indirect oxidation of As(III) by the product Na_0.55Mn₂O₄·1.5H₂O. This study shows a convenient and efficient process for the oxidation of As(III) in alkali solutions, which has potential application value for the pre-oxidation of arsenic-containing solution or the detoxification of As(III).

Pig farm biogas slurry can effectively reduce the pH of saline-alkali soils

Pig farm biogas slurry is being increasingly used as a potent organic fertilizer for sustainable agriculture under circular economy. However, the effect of biogas slurry on soil pH is currently controversial, and the underlying mechanisms especially in saline-alkali soils are not well understood. A saline-alkali soil (pH = 9.2, EC = 2.0 ms/cm) was selected for soil column (0-50 cm) experiments with (BS) and without (CK) addition of pig farm biogas slurry to investigate the soil pH change and its driving factors. Our results show that the soil pH under CK ranged between 9.1 and 9.5 across different soil depths. Compared to CK, the BS-treated soil had lower pH at 0-20 cm depth and higher pH at 20-30 cm depth (P < 0.01). The soil NH4+-N concentrations were negatively correlated with pH values under BS (P < 0.01), indicating that the oxidation of ammonium mainly contributed to the decrease of soil pH. Interestingly, the anions, such as Cl^-, SO42- and NO3-, were accumulated in the topsoil (0-20 cm) under BS, resulting in the changed correlations of these anions with Na⁺ when compared to the control. FT-IR and ¹³C-NMR spectra uncovered that carboxyl, amide C, and total alkyl C groups may be responsible for reducing pH of the saline-alkali soil tested. The soil surface morphology confirmed a much tighter granular aggregate microstructure when mixing the biogas slurry with the soil. Overall, we concluded that from the perspective of soil pH, the utilization of biogas slurry for improving saline-alkali soil is feasible and sustainable.

Integrated microbiological and metabolomics analyses to understand the mechanism that allows modified biochar to affect the alkalinity of saline soil and winter wheat growth

In order to understand the mechanism that allows modified biochar (BC) to enhance the salt tolerance and growth of crops in saline-alkali soil, we tested the effects of ordinary BC, nanoparticle-size BC, acidified BC (HBC), and acidified nanoparticle-size BC on winter wheat growth and the soil properties by combining microbiological and metabolomics analyses. The results showed that compared with the control with no BC, the plant height increased by 17.33 % under HBC and the proportion of large soil aggregates increased by 1.25-2.83 times. HBC increased the relative abundances of some dominant genera of bacteria (e.g., Streptococcus) and fungi (e.g., Mycothermus), as well as functions such as bacterial metabolic genetic information processing and cellular processes, and reduced the abundance of pathotrophic fungi. Metabolomics analysis showed that HBC upregulated various metabolites (including amino acids and their derivatives, lipids, flavonoids, and organic acids) and five main metabolic pathways. Among the KEGG pathways, the pyrimidine metabolism pathway was significantly upregulated, as well as crop leaf metabolism, β-alanine metabolism, and valine, leucine, and isoleucine metabolism, and the antioxidant levels and resistance to salt-alkali stress were enhanced in winter wheat leaves. Partial least squares-path modeling suggested that HBC affected the growth of winter wheat by significantly changing the soil physicochemical properties and microbial structure (path coefficients of 0.566 and 0.512, respectively).

Soil properties, microbial diversity, and changes in the functionality of saline-alkali soil are driven by microplastics

With the intensification of microplastic (MP) pollution, the impact of MPs on soil ecosystems has garnered considerable attention. We investigated the effects of two commonly used MPs, polyethylene (PE) and polypropylene (PP), at different sizes and doses, on the properties and microbial communities in saline-alkali soil. We found that MP treatment significantly reduced the electrical conductivity but somewhat enhanced the enzyme activities and effective nutrient content of the soil. Microbial diversity is affected by the type, dose, size and interaction of MPs, with fungi being more sensitive than bacteria. Under high-dose PE treatment, the dominant bacteria and fungi enriched, and the diversity indexes declined significantly. Meanwhile, under high-dose PP treatment, several unique bacteria and fungi with low abundance were observed, which eventually increased the diversity indexes. Moreover, PE exerted a stronger effect on bacterial function than PP. High-dose PE treatment suppressed the nitrogen fixation potential of soil bacteria. However, high-dose PP treatment promoted that. In conclusion, our findings showed that PE exerts a stronger negative effect on saline-alkali soil ecosystems than PP. Our findings help bridge the knowledge gap in the impact of MPs on saline-alkaline soils and provide guidance for the rational use of agricultural plastics in saline-alkaline soils.

Investigation of agro-forestry and construction demolition wastes in alkali-activated fly ash bricks as sustainable building materials

Production of burnt clay bricks, cement and burning of agricultural/forestry wastes are responsible for major greenhouse gases emission. The present work investigate the effect of treated rice straw and forestry leaves in alkali-activated fly ash bricks with construction & demolition wastes for non-load bearing partitions walls at elevated temperature of 800 °C. 1-4 wt% incorporated agro-forestry wastes fly ash bricks with 10 and 20 wt% ground granulated blast slag (GGBFS) addition shows compressive strength ranging from 8 to 15 MPa. The thermal conductivity of the panels with 1-4 wt% agro-forestry addition varies from 0.4 to 0.5 W/m.K. The sound transmission class (STC) of 20 mm thick agro-forestry waste fly ash samples depict moderate sound insulation properties over the range of 24 to 37 dB. The wallette units of burnt clay bricks and agro-forestry based fly ash bricks show load carrying capacity of 360 kN, 273 kN and 195 kN, 110 kN at temperatures of 35 °C and 800 °C respectively. The present study shows a potential green solution toward sustainable building materials in construction sector leading to reduced depletion of fertile soil used in production of burnt clay bricks.