Highly efficient phosphorous removal in constructed wetland with iron scrap: Insights into the microbial removal mechanism.

Excessive phosphorus (P) in surface water can lead to serious eutrophication and economic losses. Iron-based constructed wetland (CW) is considered as a promising solution to eliminate P effectively due to the advantage of low-cost. However, there is limited available information on the microbial removal mechanism of P in iron-based CW up to now. Therefore, CW with iron scrap was constructed to investigate the treatment performance and microbial removal mechanism in this study. Results showed that efficient and stable P removal (97.09 ± 1.90%) was achieved in iron scrap-based CW during the experiment period, which was attributed to the precipitation of iron and P and improved microbially mediated P removal. Metagenomic analysis showed that microbial diversity was enhanced and phosphate accumulating organisms (e.g., Dechloromonas and Tetrasphaera) were enriched in CW with iron scrap, which explained higher P removal reasonably. In addition, the abundance of genes involved in the P starvation (e.g., phoB), uptake and transport (e.g., pstB) were enhanced in iron scrap-based CW. Enrichment analysis demonstrated that phosphotransferase pathway was also significantly up-regulated in CW with iron scraps, indicating that the energy supply of microbial P removal was enhanced. These findings provide a better understanding of the microbial removal mechanism of P in iron-based CW.

MiR-937-3p promotes metastasis and angiogenesis and is activated by MYC in lung adenocarcinoma.

BACKGROUND: Non-small cell lung cancer (NSCLC) is still one of the diseases with the highest mortality and morbidity, and lung adenocarcinoma (LUAD) accounts for more than half of all NSCLC cases in most countries. miRNA can be used as a potential biological marker and treatment for lung adenocarcinoma. However, the effect of miR-937-3p to the invasion and metastasis of LUAD cells is not clear. METHODS: miRNA microarray is used to analyze the expression of miRNA in lung adenocarcinoma tissue. Transwell migration, Wound-healing assay and Western blot analysis are used to analyze cell migration, invasion and epithelial-mesenchymal transition (EMT) capabilities. Tube formation is used to assess angiogenesis ability. In addition, dual luciferase reporter gene detection is used to identify the potential binding between miRNA and target mRNA. In vivo experiments were performed on male NOD/SCID nude mice by tail vein injection to establish a transplanted tumor model. The CHIP experiment is used to verify the transcription factors of miRNA. RESULT: In our study, miR-937-3p was high-regulated in LUAD cell lines and tissues, and its expression level was related to tumor progression. We found that miR-937-3p high-expression has an effect on cell invasion and metastasis. In molecular mechanism, miR-937-3p causes SOX11 reduction by directly binding to the 3'-UTR of SOX11.In addition, MYC affects miR-937-3p transcription by binding to its promoter region. CONCLUSIONS: Our research shows that miR-937-3p is mediated by MYC and can control the angiogenesis, invasion and metastasis of LUAD by regulating SOX11, thereby promoting the progress of LUAD. We speculate that miR-937-3p can be used as a therapeutic target and potential biomarker for LUAD.

Optimizing agricultural biomass application to enhance nitrogen removal in vertical flow constructed wetlands for treating low-carbon wastewater.

Agricultural biomass waste in rural areas has been identified as an economical solid carbon sources in constructed wetlands (CWs) for treating low C/N ratio domestic sewage. However, little information is available regarding its optimal utilization as a media amendment for enhancing nitrogen removal in CWs. In this study, vertical flow CWs with different walnut peel amendment proportions (0%, 25%, 50%, 75%) were developed to explore the effects of biomass dosage on the treatment performance, nitrous oxide (N2O) emission and microbial metabolites. Results showed that the addition of biomass significantly enhanced the denitrification performance in all CWs, and the higher total nitrogen (TN) removal efficiency (91.14-97.16%) was achieved in CWs with the optimal dosage of 25%. While the addition of biomass resulted in a slight increase in N2O emission (20.56-270.13 µg m-2 h-1) compared with control systems. Additionally, the biomass addition increased the accumulation of extracellular polymeric substances (EPS) by facilitating microbial processes. Higher total EPS production was observed in CW with 25% biomass, and the proportion of tightly bound EPS (48%) dominated in the total EPS in different CWs.

Distributions and interactions of dissolved organic matter and heavy metals in shallow groundwater in Guanzhong basin of China.

Groundwater as the primary source of fresh water particularly in semi-arid regions is heavily threatened by various pollutants such as dissolved organic matter (DOM) and heavy metals due to anthropogenic activities. In this study, 113 shallow groundwater samples were collected from Guanzhong basin of China to explore spatial distributions and interactions of DOM and heavy metals (Fe, Mn and Cu). Fluorescence excitation-emission spectrophotometry with parallel factor analysis showed that DOM in groundwater mainly contained three humic-like and two protein-like substances with an average dissolved organic carbon (DOC) concentration of 12.85 mg L-1. Average Mn and Cu concentrations in groundwater were 19.92 µg L-1 and 7.05 µg L-1 with an increasing trend from west to east, whereas Fe concentration in central regions was much higher (34.23 µg L-1). Structural equation modeling analysis indicated that DOM in groundwater could be significantly affected by surface water, and heavy metals were influenced by urbanization. Moreover, DOM could strongly influence the bioavailability, migration, and transformation of Mn in groundwater. These findings would be beneficial for the effective utilization and protection of groundwater resources.

Circular RNA LPAR3 sponges microRNA-198 to facilitate esophageal cancer migration, invasion, and metastasis.

In this study, we explored expression and functions of circular RNA LPAR3 (circLPAR3) in esophageal squamous cell carcinoma (ESCC). The differential expression of circular RNAs (circRNAs) in 10 ESCC and corresponding paracarcinoma tissues was analyzed through circRNA microarray, then the candidate circRNAs were detected and verified through quantitative RT-PCR, and a novel circRNA was screened, which was circLPAR3. Circular RNA LPAR3 showed apparently high expression in ESCC tissues and cells, which was closely correlated with the clinical stage and lymph node metastasis of ESCC patients. Circular RNA LPAR3 was mainly located in the cytoplasm of ESCC cells, which was more stable than the baseline gene. Circular RNA LPAR3 upregulated MET gene expression through sponge adsorption of microRNA (miR)-198, activated the RAS/MAPK and the PI3K/Akt pathways, and promoted ESCC cell migration, invasion, and metastasis in vivo and in vitro. However, it had no effect on ESCC cell proliferation. Circular RNA LPAR3 can regulate the miR-198-MET signal axis to promote the migration, invasion, and metastasis of esophageal cancer cells, which can thereby serve as a potential diagnostic and therapeutic target of esophageal cancer.

Recent advances in the enhanced nitrogen removal by oxygen-increasing technology in constructed wetlands.

Constructed wetland has attracted more and more attention for wastewater purification due to its low construction cost and convenient operation recently. However, the unique waterflooding structure of constructed wetland makes the low dissolved oxygen level, which limits the effect of nitrogen removal in the system. Therefore, it is necessary to develop the oxygen-increasing technology to overcome the drawback in constructed wetlands. In this review, the mechanism of nitrogen removal in constructed wetland is discussed and oxygen is main influence factor is concluded. In addition, oxygen-increasing technologies in recent advances which improve the nitrogen removal efficiency greatly, are emphatically introduced. Finally, some future perspectives about oxygen-increasing techniques are also put forward in order to provide reference for further research and engineering application.

MicroRNA-1204 promotes cell proliferation by regulating PITX1 in non-small-cell lung cancer.

MicroRNA-1204 (miR-1204), a member of the PVT1 region, may improve B cell differentiation and metastasis in breast cancer. However, the role of miR-1204 in non-small-cell lung cancer (NSCLC) and its mechanism remain unclear. The GEO public database was first employed to find differentially expressed genes. The expression level of miR-1204 in patient tissues and NSCLC cell lines was determined using qRT-PCR. Cell proliferation assays were performed to investigate the impact of miR-1204 on cell growth. Bioinformatics analysis and dual-luciferase reporter assays were conducted to find potential target genes. Finally, we performed in vivo experiments to identify the effect of miR-1204 on tumor formation in nude mice. It was first found that miR-1204 was overexpressed in NSCLC tissues and cells. miR-1204 increased the proliferation of NSCLC cells and reduced cell cycle arrest in vitro. PITX1 (paired like homeodomain 1) was found as a potential target gene. In addition, PITX1 was also found to be low in expression in NSCLC tissues and cells. To show that PITX1 reversed the function of miR-1204 in promoting proliferation, confirmatory experiments were performed. Moreover, high miR-1204 and low PITX1 expression was highly correlated with tumor size, lymph node metastasis, and the TNM stage in patients diagnosed with NSCLC. Our results suggested that upregulated miR-1204 in NSCLC is associated with NSCLC progression and promotes NSCLC cell proliferation by downregulating PITX1. miR-1204 may act as a poor prognostic factor and a potential therapeutic target for NSCLC.

Electrically Switched Ion Exchange Based on Carbon-Polypyrrole Composite Smart Materials for the Removal of ReO4- from Aqueous Solutions.

A simple and rapid process of ReO4- (as a surrogate of TcO4-) removal from aqueous solutions based on the electrically switched ion exchange (ESIX) method has been demonstrated in this work. Activated carbon-Polypyrrole (AC-PPy) was synthesized from activated carbon and pyrrole by electrodeposition method which was served as an electrically switched ion exchanger for ReO4- removal. The characterization results show that the AC-PPy composite exhibited an excellent loading capacity and a high stability for ions uptake and release. Chronoamperometric studies show that the ESIX treatment could be completed within 60 s, demonstrating the rapid uptake and release of ions. Uptake and release of ReO4- was verified by electrochemical quartz crystal microbalance with dissipation shift (EQCMD) studies. By modulating the electrochemical potential of the AC-PPy, the uptake and release of ReO4- ions can be controlled. Similar trends of uptake and release of ReO4- were observed in cyclic voltammetry (-0.4 to 0.8 V) for five cycles with the EQCMD. X-ray photoelectron spectroscopy (XPS) confirmed the process of ReO4- removal in the AC-PPy composite. Conclusively, the smart material shows excellent efficiency and selectivity for the removal of ReO4- from aqueous solutions.

Intensified nutrients removal in constructed wetlands by integrated Tubifex tubifex and mussels: Performance and mechanisms.

The synergy of Tubifex tubifex (T. tubifex) and mussels on SFCWs (named SFCW-MT) performance was well studied in laboratory throughout a year. The SFCW-MT were steady operated with high TN and TP treatment, with the removal efficiencies of 37.85 ±â€¯5.22% and 39.26 ±â€¯5.20% even in winter. The mussels had excellent NH4-N removal efficiency, and avoid the shortage of NH4-N removal with T. tubifex in winter. Simultaneously, the SFCW-MT improved the NO3-N treatment by 51% than that in control group. The plant growth was improved in SFCW-MT, which reflected in the improvement of total chlorophyll contents and plant heights. The N and P absorbed by wetland plants and adsorbed by substrate were both increased with mussels. Microbial analysis results revealed that, the mussels could keep the abundance of nitrifiers despite the negative effect of T. tubifex. On that basis, the improved proportions of denitrifiers (Firmicutes) have a significantly recognized role in NO3-N transformation in SFCW-MT. The gut and membrane sections of mussels, as well as T. tubifex, also has proportions of denitrifiers and part of nitrifiers, and thus changed the microbial community in substrate. This evidence indicated that the co-existence of T. tubifex and mussels have potential application for simultaneous removal of NH4-N and NO3-N in CWs.

Rapid and efficient removal of Pb(II) from aqueous solutions using biomass-derived activated carbon with humic acid in-situ modification.

This study developed an humic acid (HA) in-situ modified activated carbon adsorbent (AC-HA) for the rapid and efficient removal of Pb(II) from aqueous media, and adsorption mechanisms are discussed. The physicochemical characteristics of activated carbons (AC) were investigated via N2 adsorption/desorption, scanning electron microscopy (SEM), Boehm's titration method and Fourier transform infrared spectroscopy (FTIR). AC-HA exhibited richer oxygen-containing functional groups than the original AC. In addition, the removal performance of AC-HA (250.0mg/g) toward Pb(II) was greatly improved compared with the original AC (166.7mg/g). The batch adsorption study results revealed that the Pb(II) adsorption data were best fit by the pseudo-second-order model of kinetics and Langmuir isotherm of isothermals, and therefore, the effect of the solution pH was studied. The superior performance of AC-HA was attributed to the HA modification, which contains numbers of groups and has a strong π-π interaction binding energy with AC and Pb(II) species. The adsorption mechanisms were confirmed via the XPS study. More importantly, the modified method is simple and has a low cost of production.

Efficient stabilization of arsenic migration and conversion in soil with surfactant-modified iron-manganese oxide: Environmental effects and mechanistic insights.

The use of iron-manganese oxide (FMO) as a promising amendment for remediating arsenic (As) contamination in soils has gained attention, but its application is limited owing to agglomeration issues. This study aims to address agglomeration using surfactant-modified FMO and investigate their stabilization behavior towards As and resulting environmental changes upon amendments. The results confirmed the efficacy of surfactants and demonstrated that cetyltrimethylammonium-bromide-modified FMO significantly reduced the leaching concentration of As by 92.5 % and effectively suppressed the uptake of As by 85.8 % compared with the control groups. The ratio of the residual fraction increased from 30.5-41.6 % in unamended soil to 67.9-69.2 %. The number of active sites was through the introduction of surfactants and immobilized As via complexation, ion exchange, and redox reactions. The study also revealed that amendments and the concentration of As influenced the soil physicochemical properties and enriched bacteria associated with As and Fe reduction and changed the distribution of C, N, Fe, and As metabolism genes, which promoted the stabilization of As. The interactions among cetyltrimethylammonium bromide, FMO, and microorganisms were found to have the greatest effect on As immobilization.

Natural product fargesin interferes with H3 histone lactylation via targeting PKM2 to inhibit non-small cell lung cancer tumorigenesis.

Non-small cell lung cancer (NSCLC) is one of the most common malignant tumors. There is an urgent need to find more effective drugs that inhibit NSCLC. Fargesin (FGS) has demonstrated anti-tumor effects; however, its efficacy and the molecular mechanism of inhibiting NSCLC are unclear. Herein, we investigated FGS' inhibitory effects on NSCLC by CCK8 and EdU assays and cell cycle analysis of A549 cells in vitro and in a nude mouse tumor transplantation model in vivo. FGS (10-50 µM) significantly inhibited cell proliferation and down-regulated expression levels of CDK1 and CCND1. Transcriptomic analysis showed that FGS regulated the cell metabolic process pathway. Differential metabolites with FGS treatment were enriched in glycolysis and pyruvate pathways. Cell metabolism assay were used to evaluate the oxygen consumption rate (OCR), Extracellular acidification rate (ECAR) in A549 cells. FGS also inhibited the production of cellular lactate and the expression of LDHA, LDHB, PKM2, and SLC2A1. These genes were identified as important oncogenes in lung cancer, and their binding to FGS was confirmed by molecular docking simulation. Notably, the over-expression and gene silencing experiments signified PKM2 as the molecular target of FGS for anti-tumorigenesis. Moreover, the H3 histone lactylation, were correlated with tumorigenesis, were inhibited with FGS treatment. Conclusively, FGS inhibited the aerobic glycolytic and H3 histone lactylation signaling pathways in A549 NSCLC cells by targeting PKM2. These findings provide evidence of the therapeutic potential of FGS in NSCLC.

Critical role of benthic fauna in enhancing nanoplastics removal in constructed wetland: Performance, fate and mechanism.

The presence of nanoplastics (NPs) in wastewater poses a considerable risk to ecosystems. Although constructed wetlands (CWs) have the potential to removal NPs, their efficiency is limited by insufficient consideration of ecosystem integrity. Herein, three typical benthic fauna (Corbicula fluminea, Chironomus riparius and Tubifex tubifex) were added to CWs to improve the ecological integrity of CWs, and further enhance the ecological benefits. Results indicated that the addition of C. fluminea, C. riparius and T. tubifex increased NPs removal by 19.14 %, 17.02 %, and 15.76 % than that without benthic faunas, respectively. Based on fluorescence signal analysis, the presence of benthic fauna could intake NPs, and enhanced the adsorption of NPs by plants. The addition of C. fluminea significantly increased catalase (1541.82 ± 41.35 U/g), glutathione S-transferase (0.34 ± 0.02 U/g), and superoxide dismutase (116.33 ± 6.91 U/g) activities (p < 0.05) as a defense mechanism against NPs-induced oxidative stress. Metagenomic analysis revealed that the abundances of key enzymes involved in glycolysis, the tricarboxylic acid cycle, and polystyrene metabolism pathways were increased when C. fluminea was added, corresponding to the microbial degradation of NPs. Overall, the results of this study implied that the benthic fauna can efficiently remove NPs from wastewater in CWs.

New insights for simultaneous nutrient removal enhancement and greenhouse gas emissions reduction of constructed wetland by optimizing its redox environment through manganese oxide addition.

Manganese oxide (MnOx) is receiving increased interest in the nutrient removal of constructed wetlands (CWs); however, its service effectiveness for simultaneous greenhouse gas (GHG) emissions reduction is still vague. In this study, three vertical flow CWs, i.e., volcanics (CCW), manganese sand uniformly mixing with volcanics (Mn-CW) and MnOx doped volcanics (MnV-CW), were constructed to investigate the underlying mechanisms of MnOx on nutrient removal enhancement and greenhouse gas (GHG) emissions reduction. The results showed that the MnOx doped volcanics optimized the oxidation-reduction potential surrounding the substrate (-164.0 ∼ +141.1 mv), and resulted in the lowest GHG emissions (CO2-equivalent) from MnV-CW, 16.8-36.5 % lower than that of Mn-CW and CCW. This was mainly ascribed to mitigation of N2O produced during the NO3--N reduction process, according to results of 15N stable isotope labeling. Analysis of the microbial community structure revealed that due to the optimized redox conditions through chemical doping of MnOx on volcanics, the abundance of microbe involved in denitrification and Mn-oxidizing process in the MnV-CW was significantly increased at genus level, which led to a higher Mn cycling efficiency between biogenic MnOx and Mn2+, and enhanced denitrification efficiency and N2O emission reduction. This study would help to understand and provide a preferable reference for future applications for manganese-based CW.

Enhanced removal of phenanthrene and nutrients in wetland sediment with metallic biochar: Performance and mechanisms.

Polycyclic aromatic hydrocarbon (PAHs) are persistent organic pollutants and pose high risk in aquatic environment. The utilization of biochar is a strategy for PAHs-contaminated remediation but is challenging due to the adsorption saturation and reoccurrence of PAHs desorbed back into water. In this study, iron (Fe) and manganese (Mn) were provided as electron acceptors for biochar modification to enhance anaerobic biodegradation of phenanthrene (Phe). Results revealed that, the Mn(Ⅳ) and Fe(Ⅲ) modification improved the removal of Phe by 24.2% and 31.4% than that of biochar, respectively. Additionally, nitrate removal was improved by 19.5% with Fe(Ⅲ) amendment. The Mn-and Fe-biochar decreased Phe contents by 8.7% and 17.4% in sediment, 10.3% and 13.8% in biochar than that of biochar. Much higher DOC contents were observed with Mn- and Fe-biochar, which provided bioavailable carbon source for microbes and contributed to microbial degradation of Phe. The greater degree of humification, higher proportions of humic and fulvic acid like components in metallic biochar participated in electron transport and further enhancing the degradation of PAHs. Microbial analysis proved the high abundance of Phe-degrading bacteria (e.g. PAH-RHDα, Flavobacterium and Vibrio), nitrogen removal microbes (e.g. amoA, nxrA, and nir), Fe and Mn bioreduction or oxidation (e. g. Bacillus, Thermomonas, Deferribacter) with metallic biochar. Based on the results, the Fe and Mn modification, especially Fe-modified biochar provided well performance for PAHs removal in aquatic sediment.

The increased oxygen vacancy by morphology regulation of MnO2 for efficient removal of PAHs in aqueous solution.

Manganese dioxide (MnO2) is considered to have a promising future in degrading polycyclic aromatic hydrocarbons (PAHs) in aqueous phase because of its low cost and environmental friendliness. In this study, various MnO2 morphologies were prepared, and their removal performance and mechanism were evaluated using benzo(a)pyrene (B[a]P) as model molecule. Results showed that nanoflower MnO2 with higher concentration of oxygen vacancies exhibited better oxidative and easier oxygen migration properties, and thus enhanced PAHs removal by 14.28%-43.21% compared with other MnO2 samples. Additionally, the transformation rate of PAHs is correlated with their ionization potential (IP) values. Further mechanism studies showed that the degradation of B[a]P by MnO2 process was first to form a combination and then oxidized by non-radical Mn species and superoxide radical (O2-•) to produce degradation product (B[a]P-6-one and B[a]P-6,12-quinone). The specific surface area was not the main factor affecting the removal of B[a]P by MnO2 and oxidation was the main removal mechanism of degrading B[a]P by MnO2. Mn3+ and absorbed oxygen (Oabs) played an important role in the process of removing PAHs by MnO2. Additionally, synergistic effects of oxygen vacancy and Mn3+could be benefit for transforming Oabs to O2-•, leading to the efficient degradation of PAHs.

Enhancement of perfluorooctanoic acid and perfluorooctane sulphonic acid removal in constructed wetland using iron mineral: Performance and mechanisms.

Polyfluoroalkyl substance (PFAS) pose a threat to the aquatic environment due to their environmental persistence. The removal of PFAS using constructed wetlands (CWs) has received interest, but the adsorption saturation and limited removal capacity of the substrate is frequently challenging. To enhance the microbial degradation and performance of the substrate, different configurations of iron minerals were used as substrate to remove perfluorooctane sulphonic acid (PFOS) and perfluorooctanoic acid (PFOA) from CWs. The addition of iron minerals resulted in elimination of 57.2% and 63.9% of PFOS and PFOA in the effluent, respectively, which were 35.0% and 36.8% higher than that of control. Moreover, up to 85.4%, 86%, and 85.1% of NH4+, NO3-, and phosphorus, respectively, was removed using iron minerals. The enhanced electron transfer in iron mineral-based CWs was confirmed by a 61.2% increase in cytochrome C reductase content and an increased Fe(III)/Fe(II) ratio. Microbial analysis showed that the proportions of microbes with PFAS removal capacity (e.g. Burkholderiae and Pseudomonas), and the key pathways of the TCA cycle and glycolysis were increased in iron mineral-based CW. Based on these findings, we conclude that supplementation with iron mineral could enhance PFOA and PFOS removal in CWs.

Releasing and Assessing the Toxicity of Polycyclic Aromatic Hydrocarbons from Biochar Loaded with Iron.

Iron (Fe)-loaded biochar has garnered attention for its potential applications in recent years. However, the pyrolysis process of Fe-loaded biochar generates polycyclic aromatic hydrocarbons (PAHs), which can have adverse effects on both human health and the environment. This study explored the correlation between Fe loading and PAH production in Fe-loaded biochar. The results indicate that increasing Fe loading in biochar reduces the PAH concentration, with the most significant decrease observed in naphthalene (0.02-0.08 mg/kg). This reduction can be attributed to the decrease in precursor compounds (e.g., C2H2), substitution of the C=O bond by Fe-O, and a decrease in the dissolved organic matter concentration (3.19-10.76 mg/L) with Fe loading. When Fe loading increased from 0 to 10%, the ecological toxicity of biochar increased by 33.48% due to an elevated production of dibenzo[a,h]anthracene, which poses a significant risk to human health. Therefore, it is imperative to take into consideration the ecological risk of PAHs prior to the application of Fe-loaded biochar. This study presents a comprehensive risk assessment of Fe-loaded biochar and provides valuable insights into the optimization of its production and safe application.

Enhanced benzofluoranthrene removal in constructed wetlands with iron- modified biochar: Mediated by dissolved organic matter and microbial response.

Polycyclic aromatic hydrocarbons (PAHs) pose a high risk to ecosystems owing to their adverse environmental effects. The use of biochar in constructed wetlands (CWs) to remove PAH has received increased interest, but is frequently challenging because of saturation adsorption. To enhance the microbial degradation, electron acceptors are provided. This study aimed to remove a representative PAH, benzofluoranthrene (BbF), using iron-modified biochar as a supplement to the CW substrate. Results revealed that iron-mediated biochar based CWs increased the removal of BbF by 20.4 % and ammonium by 25.6 %. The BbF retained in substrate with biochar (36.6 % higher content) and further removed with iron modification (40.6 % lower content). Iron-modified biochar increased dissolved organic carbon content, particularly low-aromaticity, and low-molecular-weight organic matters (25.7 % higher tryptophan-like material), which contributed to PAH degradation by microorganisms. Microbial analysis confirmed that iron-mediated biochar enriched the abundance of microbes (e.g., Cellulomonas, Actinotalea, and Sphingomonas) and key enzymes (e.g., catA, lipV, and sdhA) that are involved in PAH degradation. Higher proportion of iron-reducing bacteria (e. g., Thiobacillus, Rhodobacter) played a significant role in driving microbial iron cycle, which was beneficial for PAHs removal. Based on the results, we confirmed that the use of iron-modified biochar in CWs enhance PAH removal.

Distribution, sources, ecological risk and microbial response of polycyclic aromatic hydrocarbons in Qingdao bays, China.

Bay ecosystem has garnered significant attention due to the severe threat posed by organic pollutants, particularly polycyclic aromatic hydrocarbons (PAHs). However, there is a dearth of information regarding the extent of PAHs pollutant risk and its impact on microbial communities and metabolism within this environment. In this study, the distribution, sources, ecological risk, and microbial community and metabolic response of PAHs in Jiaozhou Bay, Aoshan Bay, and Lingshan Bay in Qingdao, China were investigated. The results showed that the average concentration of ∑PAHs ranged from 120 to 614 ng/L across three bays, with Jiaozhou and Aoshan Bay exhibiting a higher risk than Lingshan Bay due to an increased concentration of high-molecular-weight PAHs. Further analysis revealed a negative correlation between dissolved organic carbon concentration and ∑PAHs concentration in water. Metagenomic analysis demonstrated that higher levels of PAHs can lead to decreased microbial diversity, while the abundance of PAHs-degrading bacteria is enhanced. Additionally, the Erythrobacter, Jannaschia and Ruegeria genera were found to have a significant correlation with low-molecular-weight PAH concentrations. In terms of microbial metabolism, higher PAH concentrations were beneficial for carbohydrate metabolic pathway but unfavorable for amino acid metabolic pathways and membrane transport pathways in natural bay environments. These findings provide a foundation for controlling PAHs pollution and offer insights into the impact of PAHs on bacterial communities and metabolism in natural bay environments.