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Graphical abstract Highlights • Ag/Bi 4 O 7 /g-C 3 N 4 ternary metal/non-metal Z-scheme heterojunction was prepared. • A photodeposition experiment confirmed Z-scheme heterojunction in Ag/Bi 4 O 7 /g-C 3 N 4. • Ag adhered to g-C 3 N 4 nanosheets, constructing plasmonic metal/semiconductor system. • The visible-light photoreduction of aqueous Cr(VI) is enhanced. • The ternary Ag/Bi 4 O 7 /g-C 3 N 4 nanosheets have favorable cycling stability. Abstract In this paper, we successfully constructed a ternary metal/non-metal nanomaterial which can synergize Z-scheme heterojunction and plasmonic metal/semiconductor for enhancing visible light photoreduction of aqueous Cr(VI). The as-formed ternary metal/non-metal nanomaterial was composed of g-C 3 N 4 nanosheets mutual modified by Ag nanoparticles and Bi 4 O 7. In the ternary nanomaterial, g-C 3 N 4 nanosheets and Bi 4 O 7 fabricated Z-scheme heterojunction, g-C 3 N 4 nanosheets and Ag nanoparticles formed plasmonic metal/semiconductor system, synchronously. The photodeposition experiments were designed to indirect demonstrate the Z-scheme heterojunction via photocatalytic oxidation and reduction deposition reactions, AgNO 3 was used as the electron acceptor and Pb(NO 3) 2 as the electron donor, photocatalytic reduction product and oxidation product were selectively deposited on g-C 3 N 4 nanosheets and Bi 4 O 7 , respectively, revealing the Z-scheme heterojunction was definite formed. In addition, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), UV–vis absorption, and Fourier-transform infrared spectroscopy (FTIR) were studied to indicate that the plasmonic metal/semiconductor system was existent in the ternary nanomaterial. The visible light photoreduction of ternary Ag/Bi 4 O 7 /g-C 3 N 4 nanosheets was evaluated by photoreducing aqueous Cr(VI). The photoreduction results show that the ternary Ag/Bi 4 O 7 /g-C 3 N 4 nanosheets is much higher than the pristine bulk g-C 3 N 4 and g-C 3 N 4 nanosheets. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Biochar impeded the vertical migration of ARPB from top soil to lower soil. • Polyvalent phage targeted inactivation of ARPB along different soil layers. • Biochar amendment with phage therapy synergistically eliminated ARG risk. • Combined treatment maintained the diversity of the bacteria community. Abstract The vertical migration of antibiotic resistance pathogenic bacteria (ARPB) and antibiotic resistance genes (ARGs) in the surface soil-vadose soil system has become a new threat to ecological safety and public health; there is an imperative need to develop an efficient technique for targeted control and inactivation of ARPB in these systems. In this work, undisturbed soil columns (0 ∼ −5 m) were constructed to investigate the impact of biochar amendment or/and polyvalent bacteriophage (ΦYSZ-KK) therapy on the vertical control and inactivation of tetracycline-resistant Escherichia coli K-12 and chloramphenicol-resistant Klebsiella pneumonia K-6. The simultaneous application of polyvalent phage and biochar impeded the vertical migration of ARPB from the top soil to lower soil layers and stimulated the ARPB dissipation in the soil column. After 60-day incubation, levels of ARPB and ARGs decreased significantly in the soil column by magnitudes of 2-6. Additionally, high throughput sequencing indicated that the simultaneous application of biochar and phage clearly maintained the structure and diversity of the soil microbial communities (p < 0.05). This work therefore demonstrates that the application of a biochar/phage combination is an environmentally friendly, efficacious measure for the control and inactivation of ARPB/ARGs in vertical soil column systems. [ABSTRACT FROM AUTHOR]

The emerging mixed contamination of antibiotics and microplastics in greenhouse soil has made the control of antibiotic resistant gene (ARG) transmission a novel challenge. In this work, surfactant sophorolipid was applied to enhance the dissipation of tetracycline (TC) and tet genes in the presence of microplastics in greenhouse soil. During 49 days of incubation, soil bacteria and phages were both found to be the crucial reservoirs of ARGs. Meanwhile, microplastic’s presence significantly inhibited the dissipation of TC and ARGs in the soil. However, sophorolipid application was proved to outweigh the negative impact caused by microplastic existence, and lead to the highest dissipation of soil TC and ARGs. Significant positive correlation was detected between the dissipation rate of water-soluble and exchangeable TC content and bacteria/phage co-mediated ARG levels. This also held true between the two fractions of soil TC and the ratio of ARG level in the bacteria to that in the phages (B ARGs /P ARGs ). The opposite impacts of microplastic presence and sophorolipid amendment on the TC/ARG dissipation found in this work provides new information for understanding ARG transmission between bacteria and phages in the mixed contaminated greenhouse soil. [ABSTRACT FROM AUTHOR]

Landfills are perfect sites to study the effect of human migration on fluctuation of antibiotic resistance genes (ARGs) as they are the final destination of municipal waste. For example, large-scale human migration during the holidays is often accompanied by changes in waste dumping having potential effects on ARG abundance. Three landfills were selected to examine fluctuation in the abundance of fifteen ARGs and Intl 1 genes for 14 months in Nanjing, eastern China. Mass human migration, the amount of dumped waste and temperature exerted the most significant effects on bimonthly fluctuations of ARG levels in landfill sites. As a middle-sized cosmopolitan city in China, millions of college students and workers migrate during holidays, contributing to the dramatic increases in waste production and fluctuation in ARG abundances. In line with this, mass migration explained most of the variation in waste dumping. The waste dumping also affected the bioaccessibility of mixed-compound pollutants that further positively impacted the level of ARGs. The influence of various bioaccessible compounds on ARG abundance followed the order: antibiotics > nutrients > metals > organic pollutants. Concentrations of bioaccessible compounds were more strongly correlated with ARG levels compared to total compound concentrations. Improved waste classification and management strategies could thus help to decrease the amount of bioaccessible pollutants leading to more effective control for urban ARG dissemination. [ABSTRACT FROM AUTHOR]

Considering the potential threat of vegetables growing in antibiotic-polluted soil with high abundance of antibiotic-resistant genes (ARGs) against human health through the food chain, it is thus urgent to develop novel control technology to ensure vegetable safety. In the present work, pot experiments were conducted in lettuce cultivation to assess the impedance effect of biochar amendment on soil sulfonamides (SAs), antibiotic-resistant bacteria (ARB), and ARG enrichment in lettuce tissues. After 100 days of cultivation, lettuce cultivation with biochar amendment exhibited the greatest soil SA dissipation as well as the significant improvement of lettuce growth indices, with residual soil SAs mainly existing as the tightly bound fraction. Moreover, the SA contents in roots and new/old leaves were reduced by one to two orders of magnitude compared to those without biochar amendment. In addition, isolate counts for SA-resistant bacterial endophytes in old leaves and sul gene abundances in roots and old leaves also decreased significantly after biochar application. However, neither SA resistant bacteria nor sul genes were detected in new leaves. It was the first study to demonstrate that biochar amendment can be a practical strategy to protect lettuce safety growing in SA-polluted soil with rich ARB and ARGs. [ABSTRACT FROM AUTHOR]

Soils are exposed to various types of chemical contaminants due to anthropogenic activities; however, research on persistent organic pollutants and the existence of antibiotic resistance genes (ARGs) is limited. To our knowledge, the present work for the first time focused on the bioremediation of soil co-contaminated with pyrene and tetracycline/sulfonamide-resistance genes. After 90 days of incubation, the pyrene concentration and the abundance of the four ARGs ( tet W, tet M, sul I, and sul II) significantly decreased in different treatment conditions ( p < 0.05). The greatest pyrene removal (47.8%) and greatest decrease in ARG abundance (from 10 −7 to 10 −8 ARG copies per 16S rRNA copy) were observed in microcosms with a combination of bacterial and sophorolipid treatment. Throughout the incubation, pyrene bioaccessibility constantly declined in the microcosm inoculated with bacteria. However, an increased pyrene bioaccessibility and ARG abundance at day 40 were observed in soil treated with sophorolipid alone. Tenax extraction methods and linear correlation analysis indicated a strong positive relationship between the rapidly desorbing fraction ( F r ) of pyrene and ARG abundance. Therefore, we conclude that bioaccessible pyrene rather than total pyrene plays a major role in the maintenance and fluctuation of ARG abundance in the soil. [ABSTRACT FROM AUTHOR]

Highlights: [•] Enhanced anaerobic bioremediation of a red paddy soil polluted with PAHs. [•] 1% (w/w) methyl-β-cyclodextrin (MCD) and 20mM nitrate addition acted as solubility-enhancing agent and electron acceptor respectively. [•] Tenax extraction and a first-three-compartment modeling were applicable to explore the rate-limiting factors in the biodegradation. [•] Lack of PAH-degraders hindered biodegradation in control and MCD addition treatments. [•] Inadequate bioaccessible PAHs was vital rate-limiting factor in nitrate addition treatments. [Copyright &y& Elsevier]

To enhance the removal efficiency of 2,2′,4,4′-tetrabromodiphenylether (BDE47) in aqueous solutions, novel attapulgite-supported Fe/Ni bimetallic nanoparticles (A-Fe/Ni), which were characterized by a core–shell nanoparticle structure and with an average diameter of 20–40 nm, were synthesized for use in BDE47 degradation. The presence of attapulgite in bimetallic systems could reduce Fe/Ni nanoparticle aggregation and enhance their reactivity. BDE47 was degraded with a significant improvement in removal efficiency of at least 96% by A-Fe/Ni that played a reductive role in the reaction. The degradation kinetics of BDE47 by A-Fe/Ni complied with pseudo-first-order characteristics. To better understand the removal mechanism, detailed analyses were performed for several influential parameters. The improved dosage of A-Fe/Ni was found to be beneficial, and higher values of initial concentration, pH, and methanol/water ratio hindered the degradation rate, which, for example, decreased significantly in mixtures with a methanol proportion higher than 50%. The identification of BDE47 degradation products revealed a stepwise debromination from n -bromo-DE to ( n -1)-bromo-DE as a possible pathway, wherein the para-Br was more easily eliminated than ortho-Br. Our findings provide insight into the removal mechanism and evidence for polybrominated diphenyl ether debromination by clay–Fe/Ni bimetallic nanoparticles. [ABSTRACT FROM AUTHOR]

Earthworm intestinal bacteria and indigenous soil bacteria work closely during various biochemical processes and play a crucial role in maintaining the internal stability of the soil environment. However, the response mechanism of these bacterial communities to external pesticide disturbance is unknown. In this study, soil and earthworm gut contents were metagenomically sequenced after exposure to various concentrations of nitrochlorobenzene (0–1026.7 mg kg−1). A high degree of similarity was found between the microbial community composition and abundance in the worm gut and soil, both of which decreased significantly (P < 0.05) under elevated pesticide stress. The toxicity sharing model (TSM) showed that the toxicity sharing capacity was 97.4–125.7 % and 100.4–130.2 % for E genes (genes in the worm gut) and E met (degradation genes in the worm gut) in the earthworm intestinal microbiome, respectively. This indicated that the earthworm intestinal microbiome assisted in relieving the pesticide toxicity of the indigenous soil microbiome. This study showed that the TSM could quantitatively describe the toxic effect of pesticides on the earthworm intestinal microbiome. It provides a new analytical model for investigating the ecological alliance between earthworm intestinal microbiome and indigenous soil microbiome under pesticide stress while contributing a more profound understanding of the potential to use earthworms to mitigate pesticide pollution in soils and develop earthworm-based soil remediation techniques. [Display omitted] • Pesticide stress caused significant variation of earthworm intestinal microbiome. • Earthworm intestinal microbiome contained nitrochlorobenzene degradation genes. • Pesticide stress reduced the microbial association. • Degradation genes in earthworm gut were key to resist pesticide stress. [ABSTRACT FROM AUTHOR]

Microbial community assembly contributes to the restoration and rehabilitation of the disturbed ecosystems. However, the viral assembly mechanism and its difference from bacterial communities under soil contamination have not been previously reported. Here, clean, light and heavy chromium (Cr)-contaminated soils were collected from two Cr slag sites and adjacent soils in northwestern and southwestern China. Through metagenome and virome sequencing analysis, we found that the alpha diversity of bacterial genes (including overall genes and Cr detoxifying genes) showed no clear variance (p > 0.05) across soils, indicating the functional redundancy in the bacterial communities. The assembly of both the bacteria and virus taxa were primarily controlled by deterministic process across soils The assembly of bacterial genes turned from stochastic processes to deterministic processes when the Cr content increased in soils. By contrast, the assembly of viral genes altered from deterministic processes in clean soil into stochastic processes in Cr-contaminated soils. Virus-host linkage results showed that the niche breadth of bacteria and viruses was closely related. The normalized stochasticity ratio of viral functional assembly was positively correlated with the Simpson index of the bacteria (p < 0.05). The results suggested that the stochasticity of viral functional assembly was conducive to facilitating the functional redundancy of bacterial communities and their evolution toward the deterministic direction. [Display omitted] • Bacteria maintained functional redundancy under Cr exposure. • Deterministic process dominated the assemblies of bacterial and viral taxa. • Bacterial and viral genes were driven by distinct processes due to Cr exposure. • Viral communities facilitated the functional redundancy of host bacteria. [ABSTRACT FROM AUTHOR]