Inoculating exogenous bacterium Brevibacillus laterosporus ZR-11 at maturity stage accelerates composting maturation by regulating physicochemical parameters and indigenous bacterial community succession.

Brevibacillus laterosporus ZR-11, a bio-control strain, was innovatively inoculated at maturity stage of composting to clarify its effect on physicochemical parameters and indigenous bacterial community structure in compost pile. Results revealed that ZR-11 inoculum rapidly increased pile temperature to 52 ºC and raised germination index (GI) value to beyond 85% on day 3, thereby achieving higher pile temperature and GI in the inoculated group than the non-inoculated group almost along maturity stage, and also decreased C/N ratio of the inoculated group to below 20 by composting end (day 8). Also, ZR-11 succeeded in colonizing compost pile along maturity stage. These suggested that ZR-11 as inoculum at maturity stage could accelerate compost maturation and have a potential to participate in bio-fertilizer production. High-throughput sequencing indicated that bacterial community structure experienced substantial succession in the inoculated and non-inoculated groups, and Firmicutes, Proteobacteria, and Actinobacteria were the dominant phyla in the two groups during maturity stage, with their abundances higher in the inoculated group. Saccharomonospora and Ammoniibacillus abundance increased on day 3 while Actinomadura abundance increased on day 6 in the inoculated group. As verified statistically, pile temperature and pH were key factors closely linked to dominant genera abundance, where Saccharomonospora and Ammoniibacillus abundance were positively correlated to pile temperature, while Actinomadura abundance was positively correlated to pile pH. Thus, it was inferred that ZR-11 inoculum could improve parameters such as temperature and pH to modify dominant genera abundance, thus regulating indigenous bacterial community succession, which might in turn promote compost maturation.

Stability of exogenous Cadmium in different vineyard soils and its effect on grape seedlings.

Cadmium (Cd) being potentially toxic heavy metal, has become increasingly serious to vineyard soil and grapes in recent years. Soil type is one of the main factors affecting the absorption of Cd in grapes. To investigate the stabilization characteristics and form changes of Cd in different types of vineyard soils, a 90-days incubation experiment was conducted after exogenous Cd addition to 12 vineyard soils from typical vineyards in China. The inhibition of exogenous Cd on grape seedlings was determined based on the pit-pot incubation experiment (200 kg soil per pot). The results demonstrate that Cd concentration in all the sampling sites did not exceed the national screening values (GB15618-2018; i.e., 0.3 mg/kg when pH was lower than 7.5, 0.6 mg/kg when pH was higher than 7.5);. Cd in Fluvo-aquic soil 2, Red soils1, 2, 3 and Grey-Cinnamon soil is dominated by acid-soluble fraction, but was mainly in residual fraction in the remain soils. Throughout the aging process, proportion of the acid-soluble fraction increased and then decreased, while proportion of the residual fraction decreased and then increased, after exogenous Cd was added. The mobility coefficients of Cd in Fluvo-aquic soil 2 and Red soil 1, 2 increased 2.5, 3 and 2 folds, after exogenous Cd addition, respectively. Compared with CK (control), the correlation between total Cd content and its different fractions was relatively weak in the Cdl (low concentration) and Cdh (high concentration) groups. Poor Cd stabilization and strong inhibition of seedling growth rate were observed in Brown soil 1, black soil, red soil 1 and cinnamomic soil. Fluvo-aquic soil 2, 3 and Brown soil 2 showed good Cd stability and small inhibition effect on grape seedlings. These results show that Cd stability in soils and inhibition rate of grape seedlings by Cd are strongly influenced by soil type.

Shifts in bacterial diversity characteristics during the primary and secondary fermentation stages of bio-compost inoculated with effective microorganisms agent.

Microbial inoculation was an effective way to improve product quality of composting and solve traditional composting shortage. However, the effect mechanism of microbial inoculation on compost microorganisms remains unclear. Here, Shifts in bacterial community, metabolic function and co-occurrence network during the primary and secondary fermentation stages of bio-compost inoculated with effective microorganisms (EM) agent were analyzed by high-throughput sequencing and network analysis. Microbial inoculation promoted organic carbon transformation in early stage of secondary fermentation (days 27 to 31). The beneficial biocontrol bacteria were main dominant genera at the second fermentation stage. Microbial inoculation can be good for the survival of beneficial bacteria. Inoculation with microbes promoted amino acid, carbohydrate and lipid metabolism, and inhibited energy metabolism and citrate cycle (TCA cycle). Microbial inoculation could enhance complexity of bacterial network and enhance mutual cooperation among bacteria during composting.

Combined effects of ferrihydrite coating and ionic type on the transport of compost-derived dissolved organic matter in saturated porous media.

Field application of manure compost introduces a large quantity of dissolved organic matter (DOM), which can affect the migration of DOM-associated contaminants. In this study, the transport of humic acid (HA) and compost-derived dissolved organic matter (CDOM) in two porous media under various conditions, including ionic types, ionic strength, and influent concentrations, were investigated by column experiments and modeling analysis. Increasing Na+ concentration did not affect the transport of CDOM and HA in quartz sands, but inhibited CDOM transport in ferrihydrite (Fh)-coated sands. The retention recoveries of CDOM in Fh-coated sands were not changed with increasing NaCl concentration, suggesting that the adsorption of CDOM on Fh-coated sands caused by increasing NaCl concentration was a reversible process. Ca2+ could reduce the mobility of CDOM and HA through bridge bonding and electrostatic interaction. CDOM had a higher mobility than HA in quartz sands under CaCl2 conditions because the aggregation stability of CDOM was stronger than that of HA. The ferrihydrite coating increased the roughness of sand surface, resulting in lower mobility of CDOM in the Fh-coated sands than in quartz sands. A part of CDOM adsorbed onto Fh-coated sand was strongly bound through ligand exchange-surface complexation. The pore volume of CDOM required to saturate adsorption sites onto the Fh-coated sand depends on the influent CDOM concentration. The influent CDOM with higher concentration required less pore volume to achieve adsorption equilibrium. Modeling analysis suggested that the types of deposition sites provided by Fh-coated sand are mainly irreversible sites. Our findings demonstrated that CDOM transport in the sand columns may change the porous medium's physicochemical properties and alter the hydrochemistry conditions. Therefore, these factors mentioned above should not be ignored when evaluating the environmental risks of CDOM.

Long-Term Application of Bio-Compost Increased Soil Microbial Community Diversity and Altered Its Composition and Network.

The influence of bio-compost on the diversity, composition and structure of soil microbial communities is less understood. Here, Illumina MiSeq sequencing and a network analysis were used to comprehensively characterize the effects of 25 years of bio-compost application on the microbial diversity of soil and community composition. High dosages of bio-compost significantly increased the bacterial and fungal richness. The compositions of bacterial and fungal communities were significantly altered by bio-compost addition. Bio-compost addition enriched the relative abundance of beneficial microorganisms (such as Sphingomonas, Acidibacter, Nocardioides, etc.) and reduced the relative abundance of harmful microorganisms (such as Stachybotrys and Aspergillus). Electrical conductivity, soil organic matter and total phosphorus were the key factors in shaping soil microbial community composition. The bacterial network was more complex than fungal network, and bacteria were more sensitive to changes in environmental factors than fungi. Positive interactions dominated both the bacterial and fungal networks, with stronger positive interactions found in the bacterial network. Functional prediction suggested that bio-composts altered the soil bacterial-community metabolic function with respect to carbon, nitrogen and phosphorus cycles and fungal community trophic modes. In conclusion, suitable bio-compost addition is beneficial to the improvement of soil health and crop quality and therefore the sustainability of agriculture.

Comparison of the Total, Diazotrophic and Ammonia-Oxidizing Bacterial Communities Between Under Organic and Conventional Greenhouse Farming.

Organic greenhouse farming is an innovative system that may maintain a high yield and healthy agroecosystem. There have been no rigorous studies on the comparison of total and nitrogen-cycling bacterial community in vegetable soils between organic and conventional farming management at large scale. A survey of bacterial community and nitrogen cycles from soils under organic and conventional greenhouse farming was performed at 30 sites, covering seven soil types with 4 to 18 years of organic farming history. Communities of the total, diazotrophs and ammonia-oxidizing bacteria were studied with high-throughput sequencing of the 16S rRNA, nifH and amoA genes, respectively. Organic greenhouse farming did not influence alpha diversities. Beta diversities among the total (26/30) and diazotrophic (17/19) bacteria differed between farming systems, but compositional differences in ammonia-oxidizing bacteria between the two farming systems were only detected at 6 sites. Despite the effects of farming system on most bacterial genera were varied across different sites, organic greenhouse farming persistently selected for a few genera, possibly for the biodegradation of organic carbon with high molecular weight (Hyphomicrobium, Rubinisphaera, Aciditerrimonas, Planifilum, Phaselicystis, and Ohtaekwangia), but against putative ammonia oxidizing (Nitrosospira, Nitrosopumilus) and diazotrophic (Bradyrhizobium) bacterial genera, as determined by 16S rRNA analysis. Diazotrophic bacteria affiliated with nifH cluster 1J were preferentially associated with organic greenhouse farming, in contrast to Paenibacillus borealis. In summary, this study provides insights into the complex effects of organic greenhouse farming on the total, diazotrophic and ammonia oxidizing bacterial communities across different environmental context.

Key factors and microscopic mechanisms controlling adsorption of cadmium by surface oxidized and aminated biochars.

Modified biochar has great potential for adsorbing cadmium (Cd) in the aquatic environment, but the micro-immobilization mechanisms, driven by surface modifications, remain unclear. There has been no attempt to determine the key adsorption factors by integrating the numerous physiochemical indicators. In this study, surface oxidized biochar (OPBC) and surface aminated biochar (APBC) were prepared from porous biochar (PBC), and the Cd adsorption mechanisms by the modified biochars at the molecular and electronic scales were investigated. The adsorption capacity of APBC and OPBC for Cd was 23.54 and 19.04 mg g-1, respectively, which was about three times higher than that of PBC. Macroscopically, physicochemical adsorption and intraparticle diffusion dominated the Cd adsorption, and surface properties, such as functional groups, were identified as key factors controlling adsorption. Microscopically, the adsorption of Cd mainly occurred in regions rich in π electrons, lone pair electrons and electron donor groups. The interaction between carboxyl and Cd dominated the adsorption performance of OPBC, while the Cd2+-π interaction was weakened by increasing the π electron electrostatic potential of aromatic rings. The lone pair electrons of the amino groups dominated the complexation of APBC with Cd, and the π electron electrostatic potential was almost unaffected.

Coupling interaction between porous biochar and nano zero valent iron/nano α-hydroxyl iron oxide improves the remediation efficiency of cadmium in aqueous solution.

Based on the interaction between mesoscopic biochar materials and nanomaterials, the synergistic mechanism of the two materials in the process of cadmium remediation was studied. K2CO3 activated porous biochar (KBC) loaded with nano-zero-valent iron (nZVI)/nano-α-hydroxy-iron oxide (nHIO) was studied. Macroscopically, batch adsorption experiments were carried out to describe the adsorption properties of the composites. Microscopically, the changes of surface chemical states were characterized by electron microscopy, XRD, FTIR and XPS. Combining the macroscopic and microscopic characteristics, the synergistic mechanism between biochar and nZVI/nHIO was comprehensively analyzed. The strong synergistic effects between biochar and nano-zero-valent iron (nZVI)/nano-α-hydroxy-iron oxide (nHIO) were found, which improved the removal efficiency of cadmium (Cd) in aqueous solution. The results showed that the loading of nZVI/nHIO reduced the specific surface area to 178.6 m2 g-1 and 272.2 m2 g-1, respectively, but the adsorption capacity of Cd increased to 22.37 mg g-1 and 26.43 mg g-1, respectively, which was more than three times that of KBC (7.02 mg g-1). The interaction between nZVI/nHIO and Cd was enhanced by the complexation of surface functional groups, but the coupling effects were different. The coupling mechanism of Cd on nZVI@KBC was complexation - reduction. Cd was partly reduced in the removal process. While for nHIO@KBC, the existence of Fe (III) on the surface of biochar increased the number and species of oxygen-containing functional groups and enhanced complexation. The existence of synergistic mechanism will provide theoretical basis for the preparation of high efficient nanocomposites and expand the application of nanomaterials in the field of environment.

Characterization and evaluation of surface modified materials based on porous biochar and its adsorption properties for 2,4-dichlorophenoxyacetic acid.

In this study, the effect of surface modification on the properties of porous biochar was studied, and these modification techniques were synthetically evaluated by principal component analysis. The results showed that surface modification significantly affected the surface and adsorption properties of porous biochar. Potassium carbonate activated porous biochar (KBC) was modified by surface oxidation, surface amination, loading nano-zero valent iron (nZVI) and loading nano-iron oxyhydroxide (nHIO). The surface modification affected the pore structure, especially the micropores. Surface modification influenced the oxygen-containing functional groups, amino, and metal-O significantly. It also changed the diffusion of 2,4-dichlorophenoxyacetic acid (2,4-D) on the biochar surface. The specific surface area was not the only factor determining the adsorption capacity. Surfaces rich in oxygen-containing functional groups would favor the adsorption of 2,4-D by biochar. The adsorption of biochars on 2,4-D were determined by π-π interaction, chemisorption and hydrogen bonding. The synthetic properties of modified biochar were evaluated by principal component analysis, and the comprehensive performance was in order of NKBC > OKBC > KBC > BC > nHIO@KBC > nZVI@KBC. Structural activation, surface amination and surface oxidation can improve the comprehensive properties of biochar.

Environmentally persistent free radicals mediated removal of Cr(VI) from highly saline water by corn straw biochars.

Heavy metal ions coexisting with salts in the contaminant water are difficult to remove due to the interference of salts. Herein, biochars were pyrolyzed by corn straw at different temperatures, aiming to remove Cr(VI) in the presence of salts. Results show that biochars had surprisingly selective adsorption of Cr(VI). X-ray photoelectron and X-ray absorption near edge spectra revealed that Cr(VI) was reduced to Cr(III). All the adsorption was conducted at pH ∼ 7, which differed from the previous studies that Cr(VI) could only be reduced at pH 2-4. Environmental persistent free radicals (EPFRs) on biochars were found to play the role in reducing Cr(VI) in neutral solutions, which was confirmed by electron spin resonance and free radical quenching. The biochar with EPFRs reveals a highly selective removal of Cr(VI), which has implications for the remediation of contaminated water. This work provides a new insight into biochar's properties and potential environmental applications.

Structural and adsorption characteristics of potassium carbonate activated biochar.

Potassium carbonate activated biochar (450 °C, 600 °C and 750 °C) and nonactivated biochar (600 °C) were prepared by using corn stalk as the raw material. These biochar samples were labeled as KBC450, KBC600, KBC750 and BC600. The physical and chemical properties of the biochar were strongly influenced by the activation of potassium carbonate. After activation with potassium carbonate, the aromatic, hydrophobic and non-polar properties of the biochar were enhanced to form an aromatized non-polar surface, and the aromatic properties were enhanced with the increase of the pyrolysis temperature. The outside surface of the activated biochar was similar to that of porous sponge with a mesoporous-microporous composite structure inside. The specific surface area of KBC600 was 5 times that of BC600, and KBC750 had a maximum surface area of 815 m2 g-1. Batch adsorption experiments showed that the adsorption capacity of KBC for naphthalene increased with the increase of pyrolysis temperature. The adsorption capacity of the biochar for naphthalene showed a significant positive correlation with O/C and (O + N)/C. KBC750 with the strongest surface hydrophobicity and the largest specific surface area had the largest adsorption capacity of 130.7 mg g-1. Physical adsorption and π-π EDA were the main adsorption mechanisms.

Characterization and 2D structural model of corn straw and poplar leaf biochars.

The integrated experimental methods were used to analyze the physicochemical properties and structural characteristics and to build the 2D structural model of two kinds of biochars. Corn straw and poplar leaf biochars were gained by pyrolysing the raw materials slowly in a furnace at 300, 500, and 700 °C under oxygen-deficient conditions. Scanning electron microscope was applied to observe the surface morphology of the biochars. High temperatures destroyed the pore structures of the biochars, forming a particle mixture of varying sizes. The ash content, yield, pH, and surface area were also observed to describe the biochars' properties. The yield decreases as the pyrolysis temperature increases. The biochars are neutral to alkaline. The biggest surface area is 251.11 m2/g for 700 °C corn straw biochar. Elemental analysis, infrared microspectroscopy, solid-state C-13 NMR spectroscopy, and pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) were also used to study the structural characteristics and build the 2D structural models of biochars. The C content in the corn straw and poplar leaf biochars increases with the increase of the pyrolysis temperature. A higher pyrolysis temperature makes the aryl carbon increase, and C=O, OH, and aliphatic hydrocarbon content decrease in the IR spectra. Solid-state C-13 NMR spectra show that a higher pyrolysis temperature makes the alkyl carbon and alkoxy carbon decrease and the aryl carbon increase. The results of IR microspectra and solid-state C-13 NMR spectra reveal that some noticeable differences exist in these two kinds of biochars and in the same type of biochar but under different pyrolysis temperatures. The conceptual elemental compositions of 500 °C corn straw and poplar leaf biochars are C61H33NO13 and C59H41N3O12, respectively. Significant differences exist in the SEM images, physicochemical properties, and structural characteristics of corn straw and poplar leaf biochars.

Adsorption Mechanisms of Dodecylbenzene Sulfonic Acid by Corn Straw and Poplar Leaf Biochars.

Biochar is an eco-friendly, renewable, and cost-effective material that can be used as an adsorbent for the remediation of contaminated environments. In this paper, two types of biochar were prepared through corn straw and poplar leaf pyrolysis at 300 °C and 700 °C (C300, C700, P300, P700). Brunaer-Emmett-Teller N2 surface area, scanning electron microscope, elemental analysis, and infrared spectra were used to characterize their structures. These biochars were then used as adsorbents for the adsorption of dodecylbenzene sulfonic acid (DBSA). The microscopic adsorption mechanisms were studied by using infrared spectra, 13C-nuclear magnetic resonance spectra, and electron spin resonance spectra. The surface area and pore volume of C700 (375.89 m²/g and 0.2302 cm³/g) were the highest among all samples. Elemental analysis results showed that corn straw biochars had a higher aromaticity and carbon to nitrogen (C/N) ratio than the poplar leaf biochars. High temperature caused the increase of carbon content and the decrease of oxygen content, which also gave the biochars a higher adsorption rate. Pseudo-second order kinetic provided a better fit with the experimental data. Adsorption isotherm experiments showed that the adsorption isotherm of C300 fit the linear model. For other biochars, the adsorption isotherms fitted Langmuir model. Biochars with high temperatures exhibited enhanced adsorption capacity compared with ones at low temperatures. The qmax values of biochars to DBSA followed the order of P700 > C700 > P300. The adsorption mechanisms were complex, including partition, anion exchange, the formation of H bonds, covalent bonds, and charge transfer. The adsorption by covalent bonding might be the key mechanism determining the adsorption capacity of P700.

Adsorption and coadsorption mechanisms of Cr(VI) and organic contaminants on H3PO4 treated biochar.

The study of simultaneous removal of heavy metals and organic contaminants has practical applications due to the coexistence of complex pollutants in the wastewater or soil. In this work, biochar was prepared to study the removal efficiencies of Cr(VI), naphthalene (NAP) and bisphenol A (BPA) in the single or mixed systems. H3PO4-treated biochar presented a much higher adsorption capacity of the pollutants than the untreated biochar and also showed a high resistance to coexisting salts. The maximum adsorption capacities for Cr(VI) and BPA were 116.28 mg g-1 and 476.19 mg g-1, respectively. Coadsorption experiments revealed that the presence of organic pollutants caused a limited decrease (∼10%) of removal efficiency of Cr(VI) and no further decrease was observed with higher concentrations of organic pollutants, while the presence of Cr(VI) had little impact on the removal of NAP. Infrared spectra and molecular simulation demonstrated that Cr(VI) was mainly adsorbed on the biochar via chemical complexation, while the organic pollutants through π-π interaction. Unexpectedly, the addition of Cr(VI) increased the removal efficiency of BPA, probably due to the increased H-bond interactions between BPA and the biochar through bridge bonds of oxygenic groups from CrO42-.

In vivo evaluation of early disease progression by X-ray phase-contrast imaging in the adjuvant-induced arthritic rat.

PURPOSE: To study the early change of bone matrix and soft tissue around articulation in adjuvant-induced arthritic (AIA) rats non-invasively by X-ray phase-contrast imaging (XPCI), a new imaging method. MATERIALS AND METHODS: Adjuvant-induced arthritis was established in male Sprague-Dawley (SD) rats (n=6, age 40 days) by subcutaneous injection of Freund's complete adjuvant (FCA) into the left hindpaw. In vivo XPCI evaluation of the early soft tissue and bone changes in AIA rats was consecutively performed and correlated with changes in volumes of right hindpaws and body weights. In comparison, the changes in the AIA rats were also evaluated with absorption-contrast imaging using the same X-ray source as XPCI and conventional radiography at the same time. After the imaging evaluation, AIA rats were subjected to histological examination. RESULTS: There was significant difference between the score of XPCI and the other two methods in demonstrating soft tissue (P<0.01), bone details (P<0.01) and lesions (P<0.001). By day 10 after subcutaneous injection of FCA, bone changes in the right hindpaw were not obvious, but swelling of soft tissue appeared. By day 12, bone erosion in the articular facet and the area around the articular facet, was detected, along with osteoporosis, and swelling of soft tissue was aggravated. By day 14 bone erosions became fused and expanded, especially in the margin area around the articular facet. At day 16 bone erosion still existed. Joint interspaces seemed wider than normal, and swelling of soft tissue was significant. By day 18 periosteal new bone formation was seen definitely, destruction of bone decreased, bone density around the articular was enhanced, and swelling of soft tissue was relieved. XPCI could clearly distinguish all these alterations, which could not be demonstrated by absorption-contrast imaging and conventional radiography. During the test period, the volume of the right hindpaw and the body weight of the AIA rats also changed significantly compared with the normal rat. Histological examination confirmed that adjuvant-induced arthritis had occurred in all rats of the adjuvant group. CONCLUSION: Osteoporosis, bone erosion and periosteal new bone formation take place at the early stage of adjuvant-induced arthritis. XPCI can evaluate non-invasively these subtle bone changes that are "blind areas" for conventional radiography.