Surface functionalization and shape modifications are the key strategies being utilized to overcome the limitations of semiconductors in advanced oxidation processes (AOP). Herein, the uniform α-Fe₂O₃ nanocrystals (α-Fe₂O₃–NCs) were effectively synthesized via a simple solvothermal route. Meanwhile, the sulfonic acid functionalization (SAF) and the impregnation of α-Fe₂O₃–NCs on g-C₃N₄ (α-Fe₂O₃–NCs@CN-SAF) were achieved through complete solvent evaporation technique. The surface functionalization of the sulfonic acid group on g-C₃N₄ accelerates the faster migration of electrons to the surface owing to robust electronegativity. The incorporation of α-Fe₂O₃–NCs with CN-SAF significantly enhances the optoelectronic properties, ultrafast spatial charge separation, and rapid charge transportation. The α-Fe₂O₃-HPs@CN-SAF and α-Fe₂O₃-NPs@CN-SAF nanocomposites attained 97.41% and 93.64% of Cr (VI) photoreduction in 10 min, respectively. The photocatalytic efficiency of α-Fe₂O₃–NCs@CN-SAF nanocomposite is 2.4 and 2.1 times higher than that of pure g-C₃N₄ and α-Fe₂O₃, respectively. Besides, the XPS, PEC and recycling experiments confirm the excellent photo-induced charge separation via Z-scheme heterostructure and cyclic stability of α-Fe₂O₃–NCs@CN-SAF nanocomposites.

The honeybee has economic importance both for the commercial value of bee products and for its role in the pollination of agricultural crops. Despite the fact that the fungicides are widely used in agriculture, studies comparing the effects of this group of pesticides on bees are still scarce. There are many gaps preventing the understanding of bees’ responses to exposure to fungicides, including the influence of the age of the exposed workers. However, this study aimed to compare the effects of residual concentrations of pyraclostrobin on young and old bees of Africanized Apis mellifera. The parameters analyzed were the survival rates, as well as the histopathological and histochemical changes in midgut of orally exposed workers to different sublethal concentrations of this strobilurin fungicide: 0.125 ng a.i./μL (C1), 0.025 ng a.i./μL (C2) e 0.005 ng a.i./μL (C3). The results showed a significant decrease in the longevity only for old bees exposed to the three concentrations of pyraclostrobin. After the five-day exposure period, the fungicide induced sublethal effects in the midgut only from the old bees. These effects were the increase both in cytoplasmic vacuolization of digestive cells and morphological changes in the nests of regenerative cells, which reflected in the higher lesion index of organ for groups C1 and C2. Additionally, there was a reduction in total protein staining in the intestinal epithelium in C1 and C2. At the same exposure period, the midgut of young bees presented only a reduction in the staining of neutral polysaccharides in the group C1. Concluding, old workers are more sensitive to the fungicide than young workers. This study showed different responses according to worker age, which can affect the maintenance of colony health. Future studies should take into account the age of the workers to better understand the effects of fungicides on bees.

Microbial degradation is an important pathway for the attenuation of polybrominated diphenyl ethers (PBDEs) in natural soils. In this study, the compound-specific stable isotope analysis (CSIA) was applied to characterize microbial degradation of BDE-153, one of the prevailing and toxic PBDE congeners, in natural wetland soils. During the 45-day incubation, the residual percentages of BDE-153 decreased to 67.9% and 73.6% in non-sterilized soils spiked with 1.0 and 5.0 μg/g, respectively, which were both much lower than those in sterilized soils (96.0% and 97.2%). This result indicated that microbial degradation could accelerate BDE-153 elimination in wetland soils. Meanwhile, the significant carbon isotope fractionation was observed in non-sterilized soils, with δ¹³C of BDE-153 shifting from −29.4‰ to −26.7‰ for 1.0 μg/g and to −27.2‰ for 5.0 μg/g, respectively, whilst not in sterilized soils. This phenomenon indicated microbial degradation could induce stable carbon isotope fractionation of BDE-153. The carbon isotope enrichment factor (εc) for BDE-153 microbial degradation was first determined as −7.58‰, which could be used to assess the microbial degradation and bioavailability of BDE-153 in wetland soils. Based on δ¹³C and εc, the new methods were developed to dynamically and quantitatively estimate degradation degree and bioavailability of BDE-153 during degradation process, respectively, which could exclude interference of physical processes. This work revealed that CSIA was a promising method to investigate in situ microbial degradation of PBDEs in field studies.

Cadmium (Cd) contamination in paddy soil becomes increasingly prominent in recent years, which endangers the safe production of food crops. Cd-tolerant endophytes are ideal mediators for decreasing Cd content in rice plants, but their effects on the rice endophytic microbial community and gene expression profile have not yet been well elucidated. In this study, 58 endophytic bacteria from rice seeds were isolated and characterized. Five strains of them were selected based on their potential growth-promoting traits and strong Cd tolerance that could grow well under 4 mM Cd²⁺. By 16S ribosomal RNA (rRNA) identification, these five strains were designated as Enterobacter tabaci R2-7, Pantoea agglomerans R3-3, Stenotrophomonas maltophilia R5-5, Sphingomonas sanguinis R7-3 and Enterobacter tabaci R3-2. Pot experiments in relieving Cd stress in rice plants showed that the S. maltophilia R5-5 performed the strongest potential for reducing the Cd content in root and blade by 81.33% and 77.78%, respectively. The endophytic microbial community diversity, richness and composition were significantly altered in S. maltophilia R5-5 inoculated rice plants. Reverse-transcription qPCR (RT-qPCR) showed that the expression of Cd transporters, OsNramp5 and OsHMA2, were down-regulated in S. maltophilia R5-5-innoculated rice roots. The results indicate that the inoculation of endophytic bacteria S. maltophilia R5-5 provides a reference for alleviating the heavy metal contamination in paddy fields and can be a better alternative for guaranteeing the safe production of crops. Changes in the relative abundance of Cd-resistant microorganisms and the expression of Cd transporters might be the intrinsic factors affecting cadmium content in rice.

Analysis of the transcriptome of organisms exposed to toxicants offers new insights for ecotoxicology, but further research is needed to enhance interpretation of results and effectively incorporate them into useful environmental risk assessments. Factors that must be clarified to improve use of transcriptomics include assessment of the effect of organism sex within the context of toxicant exposure. Amphipods are well recognized as model organisms for toxicity evaluation because of their sensitivity and amenability to laboratory conditions. To investigate whether response to metals in crustaceans differs according to sex we analyzed the amphipod Parhyale hawaiensis after exposure to AgCl and Ag nanoparticles (AgNP) via contaminated food. Gene specific analysis and whole genome transcriptional profile of male and female organisms were performed by both RT-qPCR and RNA-seq. We observed that expression of transcripts of genes glutathione transferase (GST) did not differ among AgCl and AgNP treatments. Significant differences between males and females were observed after exposure to AgCl and AgNP. Males presented twice the number of differentially expressed genes in comparison to females, and more differentially expressed were observed after exposure to AgNP than AgCl treatments in both sexes. The genes that had the greatest change in expression relative to control were those genes related to peptidase and catalytic activity and chitin and carbohydrate metabolic processes. Our study is the first to demonstrate sex specific differences in the transcriptomes of amphipods upon exposure to toxicants and emphasizes the importance of considering gender in ecotoxicology.

Polluted urban river systems might be a strong source of atmospheric methane (CH₄) and nitrous oxide (N₂O), but so far only a few urban river systems have been quantified with regard to their source strength for greenhouse gases (GHGs). In this study, we measured loads of dissolved inorganic nitrogen and organic carbon, dissolved oxygen (DO) concentrations, and fluxes of CH₄ and N₂O from an urban river in Beijing, China during the course of an entire year. Fluxes calculated using the floating chamber approach or via the diffusion method with measurements of river water GHG concentrations showed comparable temporal variations. However, the flux magnitude based on the diffusion method was found to strongly depend on the underlying parameterization of the gas transfer velocity. In view of the large differences while applying different methodologies to estimate surface water GHG fluxes further studies are still needed to prove and eventually quantify the systematic errors which are likely caused by either the chamber technique or the approaches of individual diffusion models. For both the floating chamber and the diffusion-based flux estimates, strong seasonal variations in CH₄ and N₂O fluxes from the river surface were observed, with fluxes ranging from 3 to 8374 μg C m⁻² h⁻¹ for CH₄ and 1–3986 μg N m⁻² h⁻¹ for N₂O. The CH₄ fluxes were strongly negatively correlated with the DO concentration (P < 0.01). The highest N₂O fluxes were observed at times with low CH₄ fluxes (i.e., in spring and autumn). Annual CH₄ and N₂O fluxes totaled 19.3–79.4 and 17.4–44.8 kg C (N) ha⁻¹ yr⁻¹, respectively. These high fluxes are in agreement with estimates from the few other studies carried out for urban river systems to date and indicate that urban polluted river systems are a significant regional source of atmospheric GHGs.

In this study, the seasonal characteristics of microbial community compositions at different sites in a river under anthropogenic disturbances (Maozhou River) were analyzed using Illumina HiSeq sequencing. Taxonomic analysis revealed that Proteobacteria was the most abundant phylum in all sites, followed by Actinobacteria, Bacteroidetes, Chloroflexi, Acidobacteria and Firmicutes. The variations of the community diversities and compositions between the seasons were not significant. However, significant differences between sites as well as water and sediment samples were observed. These results indicated that sites under different levels of anthropogenic disturbances have selected distinct bacterial communities. pH, dissolved oxygen (DO), concentrations of total nitrogen (TN) and heavy metals were the main factors that influence the diversity and the composition of bacterial community. Specifically, the relative abundance of Proteobacteria was negatively correlated with pH and DO and positively correlated with TN, while Actinobacteria and Verrucomicrobia showed the opposite pattern. Moreover, positive correlations between the relative abundances of Firmicutes and Bacteroidetes and the concentration of heavy metals were also found. Results of functional prediction analysis showed no significant differences of the carbon, nitrogen and phosphorus metabolism across the sites and seasons. Potential pathogens such as Vibrio, Arcobacter, Acinetobacter and Pseudomonas were found in these samples, which may pose potential risks for environment and human health. This study reveals the effect of anthropogenic activities on the riverine bacterial community compositions and provides new insights into the relationships between the environmental factors and the bacterial community distributions in a freshwater ecosystem under anthropogenic disturbances.

Laboratory studies demonstrated that the mussels were good model organisms in revealing microplastics (MPs) uptake and toxicity. However, only limited field study data on the MPs in benthic marine mesoherbivores collected from mangrove forests are currently available. In this study, the MPs in the snails (Ellobium chinense) organs, rather than the shell, from a mangrove forest were dominant fraction (maximum reaching to 60%). Unexpectedly, no significant linear relationships were found between the levels of MPs in the organs of the snails and the levels in the sediment/tidal water. Further studies were done to explore the sources of the MPs in snail organs. MPs in snail organs at both the landward (interior) and seaward (exterior) zones mainly origin from the pore water. Moreover, the MPs found in the snails showed no relevance to the particulate matter (PM) collected from pore water. The findings reported here imply that both the MPs and PM in pore water affect the extent of MPs enter into the organs of benthic marine mesoherbivores collected from mangrove forest.

Estrogens, which are extensive in the eco-environments, are a category of high-toxic emerging contaminants that induce metabolic disorders and even carcinogenic risks in wildlife and humans. Here we investigate whether fungus-secreted laccase can be used as a green catalyst to eliminate a representative estrogen, 17β-estradiol (E2). A white-rot fungus Trametes hirsuta La-7 with high laccase-productivity, was isolated from pig manure-contaminated soil. Extracellular laccase activity expressed by strain La-7 was 65.4 U·mL⁻¹ for a 3 d inoculation under the optimal fermentation parameters. The concentrated-crude laccase from Trametes hirsuta La-7 (CC-ThLac) was capable of effectively metabolizing E2 at pH 4–6, and the apparent pseudo first-order reaction rate constant and half-life values were respectively 0.027–0.055 min⁻¹ and 25.86–12.67 min (R² > 0.98). The mass measurement of high-resolution mass spectrometry in combination with ¹³C-isotope labeling identified that the main by-products of E2 metabolism were dimers, trimers, and tetramers, which are consistent with radical-driven C–C and/or C–O–C covalent coupling pathway, involving the initial enzymatic production of phenoxy radical intermediates and then the successive oxidative-oligomerization of radical intermediates. The formation of oligomers dramatically reduced the estrogenic activity of E2. Additionally, CC-ThLac also exhibited high-efficiency metabolism capability toward E2 in the natural water and pig manure, with more than 94.4% and 91.0% of E2 having been metabolized, respectively. These findings provide a broad prospect for the clean biotechnological applications of Trametes hirsuta La-7 in estrogen-contaminated ecosystems.

In the past two decades, more and more attentions have been paid to soil-derived greenhouse gases (GHGs) including carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) because there are signs that they have rising negative impacts on the sustainability of the earth surface system. Farmlands, particularly paddy soils, have been regarded as the most important emitter of GHGs (nearly 17%) due to a large influx of fertilization and the abundance in animals, plants and microorganisms. Geobacter, as an electroactive microorganism widely occurred in soil, has been well studied on electron transport mechanisms and the direct interspecies electron transfer. These studies on Geobacter illustrate that it has the ability to be involved in the pathways of soil GHG emissions through redox reactions under anaerobic conditions. In this review, production mechanisms of soil-derived GHGs and the amount of these GHGs produced had been first summarized. The cycling process of CH₄ and N₂O was described from the view of microorganisms and discussed the co-culture relationships between Geobacter and other microorganisms. Furthermore, the role of Geobacter in the production of soil-derived GHGs is defined by biogeochemical cycling. The complete view on the effect of Geobacter on the emission of soil-derived GHGs has been shed light on, and appeals further investigation.