Bibliometric insights into the evolution of uranium contamination reduction research topics: Focus on microbial reduction of uranium.

Confronting the threat of environment uranium pollution, decades of research have yielded advanced and significant findings in uranium bioremediation, resulting in the accumulation of tremendous amount of high-quality literature. In this study, we analyzed over 10,000 uranium reduction-related papers published from 1990 to the present in the Web of Science based on bibliometrics, and revealed some critical information on knowledge structure, thematic evolution and additional attention. Methods including contribution comparison, co-occurrence and temporal evolution analysis are applied. The results of the distribution and impact analysis of authors, sources, and journals indicated that the United States is a leader in this field of research and China is on the rise. The top keywords remained stable, primarily focused on chemicals (uranium, iron, plutonium, nitrat, carbon), characters (divers, surfac, speciat), and microbiology (microbial commun, cytochrome, extracellular polymeric subst). Keywords related to new strains, reduction mechanisms and product characteristics demonstrated the strongest uptrend, while some keywords related to mechanism and performance were clearly emerging in the past 5 years. Furthermore, the evolution of the thematic progression can be categorized into three stages, commencing with the discovery of the enzymatic reduction of hexavalent uranium to tetravalent uranium, developing in the groundwater remediation process at uranium-contaminated sites, and delving into the research on microbial reduction mechanisms of uranium. For future research, enhancing the understanding of mechanisms, improving uranium removal performance, and exploring practical applications can be considered. This study provides unique insights into microbial uranium reduction research, providing valuable references for related studies in this field.

A Prussian blue analog-based copper-aluminum layered double hydroxide for cesium removal from water: fabrication, density functional theory-based molecular modeling, and the adsorption mechanism.

A new type of adsorbent, a Prussian blue analog-based copper-aluminum layered double hydroxide (PBA@CuAl-LDH), was successfully synthesized using a one-step method for the removal of radioactive Cs+ from wastewater. The adsorption performance, characteristics and the underlying adsorption mechanism of PBA@CuAl-LDH were systematically examined. The results showed that PBA@CuAl-LDH exhibited excellent adsorption performance, with a maximum adsorption capacity of 109.2 mg g-1. Over 85% of PBA@CuAl-LDH can be recycled, and the material exhibited only a 6.6% loss in adsorption performance. The adsorption process was well-fitted using the pseudo-second-order kinetic model and the Freundlich isotherm model, revealing the surface heterogeneity of the composite adsorbent. A molecular model of PBA@CuAl-LDH was constructed by combining density functional theory and multiple instrumental characterization techniques. Our results indicate that PBA crystals can be generated between layers and on the surface. Ion exchange was revealed as the main adsorption mechanism of Cs+ by PBA@CuAl-LDH. Specifically, the interstitial spaces of the PBA crystals generated between the layers and on the surface played an important role in ion exchange. These findings provide concrete theoretical support for radioactive pollution control and have significant value in directing the fabrication of cesium removal materials and their future engineering application.

A Multiplex Quantitative Polymerase Chain Reaction for the Rapid Differential Detection of Subgroups A, B, J, and K Avian Leukosis Viruses.

Avian leukosis (AL), caused by avian leukosis virus (ALV), is a contagious tumor disease that results in significant economic losses for the poultry industry. Currently, ALV-A, B, J, and K subgroups are the most common in commercial poultry and cause possible coinfections. Therefore, close monitoring is necessary to avoid greater economic losses. In this study, a novel multiplex quantitative polymerase chain reaction (qPCR) assay was developed to detect ALV-A, ALV-B, ALV-J, and ALV-K with limits of detection of 40, 11, 13.7, and 96 copies/µL, respectively, and no cross-reactivity with other ALV subtypes and avian pathogens. We detected 852 cell cultures inoculated with clinical samples using this method, showing good consistency with conventional PCR and ELISA. The most prevalent ALV strain in Hubei Province, China, was still ALV-J (11.74%). Although single infections with ALV-A, ALV-B, and ALV-K were not found, coinfections with different subgroup strains were identified: 0.7% for ALV-A/J, 0.35% for ALV-B/J, 0.25% for ALV-J/K, and 0.12% for ALV-A/B/K and ALV-A/B/J. Therefore, our novel multiplex qPCR may be a useful tool for molecular epidemiology, clinical detection of ALV, and ALV eradication programs.

Response of the soil microbial community to petroleum hydrocarbon stress shows a threshold effect: research on aged realistic contaminated fields.

Introduction: Microbes play key roles in maintaining soil ecological functions. Petroleum hydrocarbon contamination is expected to affect microbial ecological characteristics and the ecological services they provide. In this study, the multifunctionalities of contaminated and uncontaminated soils in an aged petroleum hydrocarbon-contaminated field and their correlation with soil microbial characteristics were analyzed to explore the effect of petroleum hydrocarbons on soil microbes. Methods: Soil physicochemical parameters were determined to calculate soil multifunctionalities. In addition, 16S high-throughput sequencing technology and bioinformation analysis were used to explore microbial characteristics. Results: The results indicated that high concentrations of petroleum hydrocarbons (565-3,613 mg•kg-1, high contamination) reduced soil multifunctionality, while low concentrations of petroleum hydrocarbons (13-408 mg•kg-1, light contamination) might increase soil multifunctionality. In addition, light petroleum hydrocarbon contamination increased the richness and evenness of microbial community (p < 0.01), enhanced the microbial interactions and widened the niche breadth of keystone genus, while high petroleum hydrocarbon contamination reduced the richness of the microbial community (p < 0.05), simplified the microbial co-occurrence network, and increased the niche overlap of keystone genus. Conclusion: Our study demonstrates that light petroleum hydrocarbon contamination has a certain improvement effect on soil multifunctionalities and microbial characteristics. While high contamination shows an inhibitory effect on soil multifunctionalities and microbial characteristics, which has significance for the protection and management of petroleum hydrocarbon-contaminated soil.

Virulent Phage vB_EfaS_WH1 Removes Enterococcus faecalis Biofilm and Inhibits Its Growth on the Surface of Chicken Meat.

Enterococcus faecalis is a potential animal and human pathogen. Improper use of antibiotics encourages resistance. Bacteriophages and their derivatives are promising for treating drug-resistant bacterial infections. In this study, phylogenetic and electron microscopy analyses of phage vB_EfaS_WH1 (WH1) isolated from chicken feces revealed it to be a novel phage in the family Siphoviridae. WH1 showed good pH stability (4-11), temperature tolerance (4-60 °C), and broad E. faecalis host range (60% of isolates). Genome sequencing revealed a 56,357 bp double-stranded DNA genome with a G+C content of 39.21%. WH1 effectively destroyed E. faecalis EF01 biofilms, even at low concentrations. When WH1 was applied at 1 × 105 to 1 × 109 PFU/g to chicken breast samples stored at 4 °C, surface growing E. faecalis were appreciably eradicated after 24 h. The phage WH1 showed good antibacterial activity, which could be used as a potential biocontrol agent to reduce the formation of E. faecalis biofilm, and could also be used as an alternative for the control of E. faecalis in chicken products.

Nitrogen-doped carbon materials prepared using different organic precursors as catalysts of peroxymonosulfate to degrade sulfamethoxazole: First-time performance leading to the incorrect selection of the best catalyst.

Nitrogen-doped carbon materials are effective catalysts for peroxymonosulfate (PMS) activation to eliminate organic contaminants. In this research, the activity of nitrogen-doped carbon materials was significantly improved by optimizing the carbon source, and the reusability of the catalyst is used to select the best catalyst instead of depending on the performance in the first use, for avoiding the "short-life" catalyst with great initial activity. Fixing ferric nitrate nonahydrate and melamine as the metal and nitrogen sources, four catalysts were prepared using glucose, glucosamine hydrochloride, dopamine, and trimesic acid as the carbon sources, respectively. Based on the performance in PMS activation for sulfamethoxazole (SMX) removal, in the first use, the activity was Fe-DA-CN (carbon source: dopamine) > Fe-BTC-CN (carbon source: trimesic acid) > Fe-GLU-CN (carbon source: glucosamine) > Fe-DGLU-CN (carbon source: glucose). With no washing for the second time use, the activity was Fe-BTC-CN (0.135 min-1) â‰« Fe-DA-CN (0.037 min-1) > Fe-GLU-CN (0.032 min-1) > Fe-DGLU-CN (0.017 min-1). The large specific surface area, superior graphitization, and high CO/C-N group content endow Fe-BTC-CN with high ability in PMS activity. Surface-bound radicals are responsible for SMX elimination, and most of the SMX degradation intermediates have lower ecotoxicity than SMX.

Prevalence of Extended-Spectrum ß-Lactamase-Resistant Genes in Escherichia coli Isolates from Central China during 2016-2019.

The emergence and dissemination of Escherichia coli (E. coli) strains that produce extended-spectrum beta-lactamases (ESBLs) represents a major public health threat. The present study was designed to evaluate the prevalence and characteristics of ESBL-producing Escherichia coli isolates from chickens in central China during 2016-2019. A total of 407 E. coli strains isolated from 581 chicken swabs were identified conventionally and analyzed for various cephalosporin susceptibility by disk-diffusion assay. ESBL-producing strains were screened using the double=disk synergy test and ESBL-encoding genes were carried out by PCR/sequencing. A total of 402 E. coli isolates exhibited strong resistance to first- to fourth-generation cephalosporins and monobactam antibiotics, especially cefazolin (60.69%), cefuroxime (54.05%), cefepime (35.14%), ceftriaxone (54.30%), and aztreonam (40.29%). Piperacillin/tazobactam (1.72%) was the most effective drug against the strains, but the resistance rates increased each year. Among the isolates, 262 were identified as ESBL producers and the isolation rates for the ESBL producers increased from 63.37% to 67.35% over the four years. CTX-M (97.33%) was the most prevalent type, followed by TEM (76.72%) and SHV (3.05%). The most common ESBL genotype combination was blaTEM + blaCTX-M (74.46%), in which the frequency of carriers increased steadily, followed by blaCTX-M + blaSHV (3.05%). In addition, the most predominant specific CTX-M subtypes were CTX-M-55 (48.47%) and CTX-M-1 (17.94%), followed by CTX-M-14 (11.01%), CTX-M-15 (8.02%), CTX-M-9 (6.11%), CTX-M-65 (4.58%), and CTX-M-3 (1.15%). Moreover, a novel multiplex qPCR assay was developed to detect blaCTX-M, blaTEM, and blaSHV, with limits of detection of 2.06 × 101 copies/µL, 1.10 × 101 copies/µL, and 1.86 × 101 copies/µL, respectively, and no cross-reactivity with other ESBL genes and avian pathogens. The assays exhibited 100% sensitivity and specificities of 85%, 100%, and 100% for blaCTX-M, blaTEM, and blaSHV, respectively. In conclusion, our findings indicated that ESBL-producing E.coli strains isolated from chickens in central China were highly resistant to cephalosporins and frequently harbored diversity in ESBL-encoding genes. These isolates can pose a significant public health risk. The novel multiplex qPCR method developed in this study may be a useful tool for molecular epidemiology and surveillance studies of ESBL genes.

Research on the remediation of cesium pollution by adsorption: Insights from bibliometric analysis.

While nuclear energy with zero carbon emissions will continue to occupy an indispensable position in future scenarios for power generation, the proper disposal of nuclear waste is still highly challenging in many countries. Adsorption is currently one of the primary methods used for removal of cesium from wastewater. However, no available literature has systematically summarized advances and outlooks on the adsorptive removal of cesium, and research issues such as relevant adsorption mechanisms remain largely unexplored. In this study, a bibliometric analysis was used to quantitatively analyze 10141 publications in the Web of Science Core Collection that were published from 1900 to 2022. Current publication trends and active countries, most influential authors and institutions, journal distribution, and research hotspots and trends were reviewed and summarized. The results for the conceptual structure and evolution of investigations in this field showed three distinct periods of rapid development in recent decades. The first period concerned the scope, degree, and influences of pollution by cesium and the development of natural adsorbents. The second period included the exploration and verification of adsorption mechanisms, the fabrication and optimization of new materials, and the application of density functional theory for chemical calculations. The third period involved the development of more advanced biodegradable, nanoscale and synthetic materials with great potential for use as adsorbents as well as advances in engineering applications. Notably, the study showed that it is necessary to further enhance application-driven laboratory investigations. Future directions for research were proposed, such as the investigation of complex adsorption mechanisms, development of new materials, and engineering applications of materials developed in the laboratory. The findings will provide valuable insights and serve as a reference for researchers and policymakers as they address the adsorptive remediation of cases of pollution by cesium.

Theoretical and experimental investigations of enhanced uranium(VI) adsorption using a nitrogen doping strategy.

With the ongoing development and utilization of nuclear energy, uranium pollution has become an increasingly serious issue. Although many adsorbents are able to remove hexavalent uranium (U(VI)) from aqueous solution, the development of a high capacity adsorbent exhibiting superior stability would be beneficial. Grafting poly(amidoxime) (PAO) onto reduced graphene oxide (rGO) provides suitable U(VI) adsorption performance but the PAO is prone to agglomeration. The present work used density functional theory calculations to predict that PAO would bond with pyrrolic N atoms in nitrogen-doped rGO (N-rGO). To confirm this, PAO-grafted rGO (PAO-rGO) and PAO-grafted N-rGO (PAO-N-rGO) were prepared and characterized and the successful grafting of PAO on N-rGO was demonstrated. Adsorption experiments demonstrated that PAO-N-rGO exhibit superb U(VI) adsorption performance compared with the original PAO-rGO under acidic conditions. As for competing metal ions, Cu2+, Al3+, and Ca2+ have a greater impact on U(VI) adsorption than Na+, Mg2+, and K+ both for PAO-rGO and PAO-N-rGO. The maximum adsorption capacities of PAO-rGO and PAO-N-rGO for U(VI) were calculated to be 1500.26 and 1545.95 mg g-1, respectively. The mechanism of nitrogen doping promoting uranium(VI) adsorption can be attributed to enhanced PAO grafting and improvement of adsorption performance of the rGO. This work demonstrates that nitrogen doping is a viable strategy for enhancing the U(VI) adsorption performance of PAO-rGO.

Occurrence of polycyclic aromatic compounds and potentially toxic elements contamination and corresponding interdomain microbial community assembly in soil of an abandoned gas station.

Bacteria, archaea and fungi usually coexist in various soil habitats and play important roles in biogeochemical cycle and remediation of contamination. Despite their significance, their combined bioassembly pattern, ecological interactions and driving factors in contaminated soils still remain obscure. To fill the gap, a systemic investigation on the characteristics of microbial community including bacteria, archaea and fungi, assembly patterns and environmental driving factors was conducted in an abandoned gas station soils which were contaminated by polycyclic aromatic compounds and potentially toxic elements for decades. The results showed that the soils were contaminated excessively by benzo[a]pyrene (0.46-2.00 mg/kg) and Dibenz[a,h]anthracene (0.37-1.30 mg/kg). Multitudinous contaminant-degrading/resistant microorganisms and unigenes were detected, indicating potential of the soils to mitigate the pollution. Compared with fungi and archaea, the bacteria had higher community diversity and were more responsive to seasonal shifts. Functional genes (nidB, nahAb, nahAa, adhP, adh, adhC, etc.) involved in biodegradation were highly enriched in summer (1.96% vs 1.80%). The co-occurrence network analysis showed summer communities exhibit a more robust network structure and positive interactions than winter communities. The fungi Neocucurbitaria, Penicillium, Fusarium, Chrysosporium, Knufia, Filobasidium, Wallemia and Rhodotorula were identified as the keystone taxa, indicating that fungi also had important positions in the interdomain molecular ecological networks of both seasons. The network topological properties and |ßNTI| (66.7%-93.3% greater than 2) results indicated the deterministic assembly processes of the microbial communities in the contaminated soil. Acenaphthylene, benzo[b]fluoranthene, indeno[1,2,3-cd]perylene, benzo[g,h,i]pyrene and 9-fluorenone were the key environmental factors driving the deterministic assembly processes of the interdomain microbial community in the contaminated soil. These findings extended our knowledge of interdomain microbial community assembly mechanisms and ecological patterns in natural attenuation and provide valuable guidance in associated bioremediation strategies.

Vertical distribution characteristics and interactions of polycyclic aromatic compounds and bacterial communities in contaminated soil in oil storage tank areas.

Polycyclic aromatic compound (PAC) contamination in soil as a result of oil spills is a serious issue because of the huge global demand for fossil energy. This study assessed the vertical variation in polycyclic aromatic hydrocarbons (PAHs), derivatives of PAHs (dPAHs) and bacterial community structure in deep soil with long-term contamination by oil spillage. Our results suggest that the content of total PACs ranged from 1196.6 µg/kg to 14980.9 µg/kg and decreased with depth at all sites. PAHs were the most abundant PACs, with a mean concentration of 6640.7 µg/kg, followed by oxygenated PAHs (mean 156.3 µg/kg) and nitrated PAHs (mean 33.4 µg/kg). PAHs are mainly low molecular weight PACs such as naphthalene, fluorene and phenanthrene, while derivatives of PAHs are all low molecular weight PACs and mainly oxygenated PAHs. Low molecular weight PAHs were an important source of dPAHs under specific conditions. The bacterial community structure showed higher bacterial diversity and lower bacterial richness in shallow soil (2-6 m in depth) than in deep soil (8-10 m in depth). Spearman's analysis confirmed that dramatic bacterial community shifts are a response to contamination. At the genus level, the presence of PACs highly selected for Pseudomonas, belonging to Proteobacteria. Moreover, functional predictions based on Tax4Fun revealed that soil with long-term contamination had a strong potential for PAC degradation. In addition, statistical analysis showed that oxidation-reduction potential (Eh) was closely related to variations of bacterial community composition and function. Finally, Ramlibacter, Pseudomonas, Pseudonocardia, c_MB-A2-108, f_Amb-16S-1323, and Qipengyuania were identified by cooccurrence network analysis as keystone taxa contributing to the maintenance of bacterial ecological function. Together, our results provide evidence of tight bacterial effects of PAHs and dPAHs and a more complete understanding of the fate of PACs in deep contaminated soils.

Occurrence of polycyclic aromatic compounds and interdomain microbial communities in oilfield soils.

Soil polycyclic aromatic compound (PAC) pollution as a result of petroleum exploitation has caused serious environmental problems. The unclear assembly and functional patterns of microorganisms in oilfield soils limits the understanding of microbial mechanisms for PAC elimination and health risk reduction. This study investigated the polycyclic aromatic hydrocarbons (PAHs) and substituted PAHs (SPAHs) occurrence, and their impact on the bacteria-archaea-fungi community diversity, co-occurrence network and functionality in the soil of an abandoned oilfield. The results showed that the PAC content in the oilfield ranged from 3429.03 µg kg-1 to 6070.89 µg kg-1, and risk assessment results suggested a potential cancer risk to children and adults. High molecular weight PAHs (98.9%) and SPAHs (1.0%) contributed to 99.9% of the toxic equivalent concentration. For microbial analysis, the abundantly detected degraders and unigenes indicated the microbial potential to mitigate pollutants and reduce health risks. Microbial abundance and diversity were found to be negatively correlated with health risk. The co-occurrence network analysis revealed nonrandom assembly patterns of the interdomain microbial communities, and species in the network exhibited strong positive connections (59%). The network demonstrated strong ecological linkages and was divided into five smaller coherent modules, in which the functional microbes were mainly involved in organic substance and mineral component degradation, biological electron transfer and nutrient cycle processes. The keystone species for maintaining microbial ecological functions included Marinobacter of bacteria and Neocosmospora of fungi. Additionally, benzo [g,h,i]pyrene, dibenz [a,h]anthracene, indeno [1,2,3-cd]perylene and total phosphorus were the key environmental factors driving the assembly and functional patterns of microbial communities under pollution stress. This work improves the knowledge of the functional pattern and environmental adaptation mechanisms of interdomain microbes, and provides valuable guidance for the further bioremediation of PAC-contaminated soils in oilfields.

Fabrication and investigation of novel monochloroacetic acid fortified, tripolyphosphate-crosslinked chitosan for highly efficient adsorption of uranyl ions from radioactive effluents.

Chitosan crosslinked with potassium tripolyphosphate (CTPP) and monochloroacetic-acid-modified chitosan crosslinked with potassium tripolyphosphate (MCTPP) were synthesized for removing UO22+ from acidic radioactive effluents. The influential factors, operational requirements, and interactive mechanisms of the adsorption process were systematically investigated. The mesh-structured composites adsorbed UO22+ most effectively at pH 5.0. The maximum adsorption capacities for pure chitosan, CTPP, and MCTPP were 374.93, 780.89, and 1487.72 mg/g, respectively. Batch experiments indicated that the pH and adsorbent dose strongly influenced UO22+ adsorption. MCTPP could adsorb most UO22+ within 15 min, and equilibrium was reached by ~1 h. The adsorption isotherms indicated that UO22+ adsorption by MCTPP may be an endothermic single-layer adsorption process. Moreover, common metal ions in single-metal systems only slightly affected this process. The results of instrumental characterization and natural water application suggested that the highly developed pore structure and abundant tripolyphosphate groups in synthesized composites were dominant adsorption contributors besides amino and hydroxyl groups. Successful development of the novel material for efficiently adsorbing UO22+ and identification of the adsorption mechanism will provide valuable guidance to chitosan modification and further remediation practices of radioactive effluents.

Pilot-scale bioaugmentation of polycyclic aromatic hydrocarbon (PAH)-contaminated soil using an indigenous bacterial consortium in soil-slurry bioreactors.

Soil-slurry bioreactor based bioremediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soil was studied through laboratory and pilot-scale trials, in which the degradation mechanism was explored. Indigenous PAH-degrading consortium was firstly screened out and it degraded 80.5% of total PAHs in lab-scale bioreactors. Then a pilot-scale trial lasting 410 days was conducted in two bioreactors of 1.5 m3 to examine the operating parameters and validate the optimum running conditions. During the initial 200 days, the crucial running parameters affecting PAH removal were evaluated and selected. Subsequently, an average PAH removal rate of 93.4% was achieved during 15 consecutive batches (210 days) under the optimum running conditions. The kinetic analysis showed that the reactor under optimum conditions achieved the highest PAH degradation rate of 0.1795 day-1 and the shortest half-life of 3.86 days. Notably, efficient mass transfer of PAHs and high biodegradation capability by bioaugmented consortia in soil-slurry bioreactors were two key mechanisms for appreciable PAH removal performance. Under the optimal operating conditions, the degradation rate of low-molecular-weight (LMW) PAHs was significantly higher than high-molecular-weight (HMW) PAHs; when the mass transfer was limited, there was no significant difference between their degradation behaviors. Both microbial co-metabolism and collaborative metabolism might occur when all PAHs demonstrated low degradation rates. The findings provide insightful guidance on the future assessment and remediation practices of PAH-contaminated sites.

A strategy for enhancing the photoactivity of g-C3N4-based single-atom catalysts via sulphur doping: a theoretical study.

Single-atom catalysts (SACs) have received intense attention owing to their maximum utilization efficiency of metal atoms and high catalytic activity. Although SACs possess many merits, such as high activity, selectivity and stability in photocatalysis, the difficulty of fabricating atomically dispersed atom catalysts with a high level of metal loading limits their practical applications. Here, a sulphur-doping strategy was proposed to enhance the incorporation of single Pt atoms in monolayer graphitic carbon nitride (g-C3N4), and the structural, electronic and optical properties were investigated through density functional theory (DFT) calculations. This work verified that SACs based on sulphur-doped monolayer g-C3N4 (S-g-C3N4) exhibit a lower band gap energy, higher photocatalytic oxidation ability, easier charge separation, lower oxidation state of Pt atoms and wider light absorption range. This work provides a promising path for fabricating efficient g-C3N4-based photocatalytic SACs.

Synthesis and phosphate adsorption behaviour of Mg/Al-pillared montmorillonite loaded with La(OH)3.

Magnesium/aluminum-pillared montmorillonite loaded with lanthanum hydroxide (Mg/Al-MMT-La(OH)3) was synthesized using non-toxic raw materials by ion-exchange and co-precipitation for phosphate removal from wastewater. Some adsorbents were fabricated in different molar ratios of Mg to Al, analyzed using various characterizations, and investigated in batch adsorption experiments. The determined adsorption kinetics of the 1:4 Mg/Al-MMT-La(OH)3 composite fitted well with the Elovich model. In addition, the Langmuir model revealed the high adsorption efficiency of phosphate by the adsorbent with a maximum adsorption capacity of 79.33 mg/g. The negative value of ΔG° and positive value of ΔH° (64.25 kJ/mol) demonstrated that phosphate adsorption onto 1:4 Mg/Al-MMT-La(OH)3 was spontaneous and endothermic in nature. Moreover, when the molar ratio of PO43- to CO32- was 1:5, the phosphate adsorption capacity reduced by 53.5%, far exceeding the effect of NO2-, NO3-, Cl-, and SO42-. The addition of Al3+ caused a sharp decline in phosphate removal property by 81.9% when PO43-/Al3+ molar ratio was 1:5, however, the presence of other cations showed the negligible impact on it. The adsorption mechanism primarily involved ion exchange with intercalated anions and surface coordination with loaded hydroxides. Results proved that 1:4 Mg/Al-MMT-La(OH)3 material has a favourable application potential in the surface water remediation.

Microbial diversity and co-occurrence patterns in deep soils contaminated by polycyclic aromatic hydrocarbons (PAHs).

Numerous studies have enriched our knowledge of the microbial community composition and metabolic versatility of contaminated soil. However, there remains a substantial gap regarding the bioassembly patterns of the indigenous microbial community distribution in contaminated deep soils. Herein, the indigenous microbial community structure diversity, function, and co-occurrence relationships in aged PAH-contaminated deep soil collected from an abandoned chemical facility were investigated using high-throughput sequencing. The results showed that the dominant phyla in all samples were responsible for PAH degradation and included Proteobacteria (20.86%-81.37%), Chloroflexi (2.03%-28.44%), Firmicutes (3.06%-31.16%), Actinobacteria (2.92%-11.91%), Acidobacteria (0.41%-12.68%), and Nitrospirae (0.81%-9.21%). Eighty biomarkers were obtained by linear discriminant analysis of effect size (LEfSe), and most of these biomarkers were PAH degraders. Functional predictions using Tax4Fun indicated that the aged contaminated soil has the potential for PAH degradation. Statistical analysis showed that in contrast with the PAH concentration, edaphic properties (nutrients and pH) were significantly correlated (r > 0.25, P < 0.01) with the bacterial community and functional composition. Co-occurrence network analysis (modularity index of 0.781) revealed non-random assembly patterns of the bacterial communities in the PAH-contaminated soils. The modules in the network were mainly involved in carbon and nitrogen cycles, organic substance degradation, and biological electron transfer processes. Microbes from the same module had strong ecological linkages. Additionally, SAR202 clade, Thermoanaerobaculum, Nitrospira, and Xanthomonadales, which were identified as keystone species, played an irreplaceable role in the network. Overall, our results suggested that environmental factors such as nutrients and pH, together with ecological function, are the main factors driving the assembly of microbial communities in aged PAH-contaminated deep soils.

Post relocation of industrial sites for decades: Ascertain sources and human risk assessment of soil polycyclic aromatic hydrocarbons.

As a persistent organic pollutant, polycyclic aromatic hydrocarbons (PAHs) may still residually pollute industrial sites after relocation. This study investigated the contamination status of PAHs in the topsoils of three industrial legacy sites (the Shougang industrial ruins, the original Beijing coking plant area, and an abandoned gas station) that relocated more than 10 years ago from downtown Beijing. The sources of PAHs in the soil were qualitatively and quantitatively analyzed, and health risks were evaluated for different groups of people. The total concentration of 16 PAHs in the study area ranged from 371.1 ng g-1 to 4073.9 ng g-1. The pollution levels of the three study areas were abandoned gas station > Beijing coking plant > Shougang ruins. In terms of composition, low-ring aromatics accounted for the majority of the detected PAHs, and in the dry season, low-ring aromatics accounted for a higher proportion in the three areas than in the wet season. The comparison of the PAH diagnostic ratio and PMF model verification showed that the sources of PAHs in the Shougang ruins and the Beijing coking plant area were mainly those of biomass and coal combustion, accounting for 66.3% and 56.1% of the total detected PAHs, respectively; the PAH sources of the abandoned gas station storage tank area were largely that of petrol (33.9%) and diesel combustion (23.8%). Since these industrial sites were located in urban centers, this study also conducted a health risk assessment of the topsoil. The total carcinogenic risk range of the three contaminated sites was 1.41E-06 to 2.47E-05. Abandoned industrial sites have potential carcinogenic risks to human health. The government needs to conduct comprehensive risk assessments and remedial measures on soils of industrial legacy sites to achieve land reuse.

One-step synthesis of magnetic-TiO2-nanocomposites with high iron oxide-composing ratio for photocatalysis of rhodamine 6G.

In the study, a facile one-step method for synthesizing magnetic-TiO2-nanophotocatalysts was developed. With the same composing ratio of 0.5 and 0.35 (Fe:Ti, mole:mole), we prepared two types of magnetic-TiO2-nanocomposites as one-step synthesized FexOy-composed TiO2 (FexOy/TiO2-0.5 and FexOy/TiO2-0.35) and two-step synthesized core-shell FexOy@TiO2 (FexOy@TiO2-0.5 and FexOy@TiO2-0.35), and tested their performance in rhodamine 6G (R6G) photodegradation. X-ray diffraction (XRD) analysis showed that FexOy@TiO2-0.5 has the smallest crystallite size (16.8 nm), followed by FexOy@TiO2-0.5 (18.4 nm), FexOy/TiO2-0.35 (21.0 nm) and FexOy/TiO2-0.5 (19.0 nm), and X-ray photoelectron spectroscopy (XPS) suggested the decreasing percentage of Fe3O4 from 52.1% to 36.7%-47.2% after Ti-deposition treatment. The saturated magnetisms followed the order: FexOy@TiO2-0.5 > FexOy@TiO2-0.35 > FexOy/TiO2-0.5 > FexOy/TiO2-0.35. R6G photodegradation followed the first order kinetics and was slightly influenced by pH but significantly affected by initial photocatalyst concentration. FexOy/TiO2-0.35 achieved the highest removal efficiency for R6G (92.5%), followed by FexOy@TiO2-0.35 (88.97%), FexOy@TiO2-0.5 (60.49%) and FexOy/TiO2-0.5 (48.06%). Additionally, all these magnetic-TiO2-nanocomposites had satisfied magnetic recoverability and exhibited laudable reusability after 5-times reuse, even achieving higher R6G removal efficiencies from 97.30% to 98.47%. Our one-step method took only 75 min for nanocomposite synthesis, 90 min less than conventional two-step method, showing its feasibility as a practical method for magnetic-TiO2-nanocomposite synthesis in industrial application.

Contamination, Sources, and Health Risks Associated with Soil PAHs in Rebuilt Land from a Coking Plant, Beijing, China.

This study investigated the polycyclic aromatic hydrocarbon (PAH) pollution in the reconstructed land of an abandoned industrial site: a coking plant in Beijing. To meet the needs of urban development, many factories have had to be relocated from city centers, and abandoned industrial sites often need to be transformed into residential land or urban green space through a series of restoration measures. It is necessary to study the level of residual pollutants and potential risks associated with industrial reconstructed land. The concentration of 16 PAHs in the study area ranged from 314.7 to 1618.3 µg/kg, and the average concentration was still at a medium pollution level; the concentration of PAHs in the original coking workshop had the highest levels (1350.5 µg/kg). The PAHs in the soil were mainly low-ring aromatics, especially naphthalene and phenanthrene. The isomer method and principal component analysis indicated that PAHs in the topsoil were the result of coal and biomass combustion. The seven carcinogenic PAHs were the main contributors to the total toxicity equivalence. The genetic toxicity of benzo[a]pyrene was relatively low, and the results were related to the concentration level. There were potential carcinogenic risks for people of varying ages in this residential area. In total, gender differences were small, and the comprehensive lifetime cancer risk level was still acceptable. For the remaining plots at the study site, the daily intake of PAHs by construction workers was between 0.74⁻2.31 ng/kg bw/day, which requires further evaluation about ignored area occupational exposure to environmental pollutants.