Petroleum hydrocarbon pollution is a global problem. However, the effects of different petroleum pollution levels on soil microbial communities and ecological functions are still not clear. In this study, we analyzed the changes in microbial community structures and carbon and nitrogen transformation functions in oil-contaminated soils at different concentrations by chemical analysis, high-throughput sequencing techniques, cooccurrence networks, and KEGG database comparison functional gene annotation. The results showed that heavy petroleum concentrations (petroleum concentrations greater than 20,000 mg kg⁻¹) significantly decreased soil microbial diversity (p = 0.01), soil microbiome network complexity, species coexistence patterns, and prokaryotic carbon and nitrogen fixation genes. In medium petroleum contamination (petroleum concentrations of between 4000 mg kg⁻¹ and 20,000 mg kg⁻¹), microbial diversity (p > 0.05) and carbon and nitrogen transformation genes showed no evident change but promoted species coexistence patterns. Heavy petroleum contamination increased the Proteobacteria phylum abundance by 3.91%–57.01%, while medium petroleum contamination increased the Actinobacteria phylum abundance by 1.69%–0.26%. The results suggested that petroleum concentrations played a significant role in shifting soil microbial community structures, ecological functions, and species diversities.

Several studies have reported an association between residential surrounding particulate matter with an aerodynamic diameter ≤2.5 μm (PM₂.₅) and coronary heart disease (CHD). However, the underlying biological mechanism remains unclear. To fill this research gap, this study enrolled a residentially stable sample of 942 patients with CHD and 1723 controls. PM₂.₅ concentration was obtained from satellite-based annual global PM₂.₅ estimates for the period 1998–2019. MicroRNA microarray and pathway analysis of target genes was performed to elucidate the potential biological mechanism by which PM₂.₅ increases CHD risk. The results showed that individuals exposed to high PM₂.₅ concentrations had higher risks of CHD than those exposed to low PM₂.₅ concentrations (odds ratio = 1.22, 95% confidence interval: 1.00, 1.47 per 10 μg/m³ increase in PM₂.₅). Systolic blood pressure mediated 6.6% of the association between PM₂.₅ and CHD. PM₂.₅ and miR-4726-5p had an interaction effect on CHD development. Bioinformatic analysis demonstrated that miR-4726-5p may affect the occurrence of CHD by regulating the function of RhoA. Therefore, individuals in areas with high PM₂.₅ exposure and relative miR-4726-5p expression have a higher risk of CHD than their counterparts because of the interaction effect of PM₂.₅ and miR-4726-5p on blood pressure.

The immense production of plastic polymers combined with their discordancy with nature has led to vast plastic waste contamination across the geosphere, from the oceans to freshwater reservoirs, wetlands, remote snowpacks, sediments, air and multiple other environments. These environmental pollutants include microplastics (MP), typically defined as small and fragmented plastics less than 5 mm in size, and nanoplastics (NP), particles smaller than a micrometer. The formation of micro and nanoplastics in aqueous media to date has been largely attributed to fragmentation of plastics by natural (i.e., abrasion, photolysis, biotic) or industrial processes. We present a novel method to create small microplastics (≲ 5 μm) and nanoplastics in water from a wide variety of plastic materials using a small volume of a solubilizer liquid, such as n-dodecane, in combination with vigorous mixing. When the suspensions or solutions are subjected to ultrasonic mixing, the particle sizes decrease. Small micro- and nanoparticles were made from commercial, real world and waste (aged) polyethylene, polystyrene, polycarbonate and polyethylene terephthalate, in addition to other plastic materials and were analyzed using dark field microscopy, Raman spectroscopy and particle size measurements. The presented method provides a new and simple way to create specific size distributions of micro- and nanoparticles, which will enable expanded research on these plastic particles in water, especially those made from real world and aged plastics. The ease of NP and small MP formation upon initial mixing simulates real world environments, thereby providing further insight into the behavior of plastics in natural settings.

Currently, the evidence of the ingestion of microplastics (MPs) by organisms or the accumulation in different environmental compartments has been achieved using several methodological procedures. However, its uses have not been standardized across studies. In this study, we aim to assess and validate a protocol that can be useful for optimizing the identification and quantification procedures of polyethylene microplastics (PE MPs) in biological samples. Initially, considering that numerous studies filter samples previously digested in cellulosic membranes for isolation and analysis of MPs, we evaluated whether washing these membranes with different reagents could contribute to the complete detachment of particles, as well as to their dispersion in the obtained solutions. However, none of the tested reagents (dimethyl sulfoxide, acetone, ethyl alcohol and chloroform), including purified water, was able to completely remove the MPs adhered to the membranes or facilitate their dispersion in the solutions. On the other hand, we observed that the digestion of the membranes by acetonitrile constituted a procedure that prevents the loss of particles due to adherence, in addition to promoting good dispersion of MPs. Subsequently, we evaluated the use of Neubauer chambers for the quantification of MPs, having observed a good recovery rate (>92%) and results with insignificant variation, in PE MPs solutions with different concentrations (0.15; 0.075 and 0.0375 mg/mL). Ultimately, the validation of the proposed procedures took place from the evaluation of the accumulation of PE MPs in Astyanax spp. juveniles, having demonstrated the efficiency and sensitivity of the method proposed for this purpose. Subsequently, our study provides a methodological alternative that can optimize MPs quantifications in biological samples and reduce the generation of biased or unreliable results.

The composition of root exudates is modulated by several environmental factors, and it remains unclear how that affects beneficial rhizosphere or inoculated microorganisms under heavy metal (HM) contamination. Therefore, we evaluated the transcriptional response of Pseudomonas putida E36 (a Miscanthus x giganteus isolate with plant growth promotion-related properties) to Cd, Pb and Zn in an in vitro study implementing root exudates from M. x giganteus. To collect root exudates and analyse their composition plants were grown in a pot experiment under HM and control conditions. Our results indicated higher exudation rate for plants challenged with HM. Further, out of 29 organic acids identified and quantified in the root exudates, 8 of them were significantly influenced by HM (e.g., salicylic and terephthalic acid). The transcriptional response of P. putida E36 was significantly affected by the HM addition to the growth medium, increasing the expression of several efflux pumps and stress response-related functional units. The additional supplementation of the growth medium with root exudates from HM-challenged plants resulted in a downregulation of 29% of the functional units upregulated in P. putida E36 as a result of HM addition to the growth medium. Surprisingly, root exudates + HM downregulated the expression of P. putida E36 functional units related to plant colonization (e.g., chemotaxis, motility, biofilm formation) but upregulated its antibiotic and biocide resistance compared to the control treatment without HM. Our findings suggest that HM-induced changes in root exudation pattern may attract beneficial bacteria that are in turn awarded with organic nutrients, helping them cope with HM stress. However, it might affect the ability of these bacteria to colonize plants growing in HM polluted areas. Those findings may offer an insight for future in vivo studies contributing to improvements in phytoremediation measures.

To date, carbapenem-resistant Enterobacteriaceae have been found predominantly in clinical settings worldwide. Raoultella belongs to the Enterobacteriaceae family which can cause hospital-acquired infections, and carbapenem-resistant Raoultella spp. (CRR) is sporadically reported in the environment. We investigated the distribution and underlying resistance mechanisms of CRR in a wastewater treatment plant (WWTP) from eastern China between January 2018 and February 2019. A total of 17 CRR were isolated from 324 environmental samples, including Raoultella ornithinolytica (n = 15) and Raoultella planticola (n = 2). The detection of CRR was more frequent in the water inlet compared to anaerobic tank, aerobic tank, sludge thickener, activated sludge, mud cake storage area, and water outlet, and CRR was detected in mud cake stacking area. All CRR were resistant to imipenem, meropenem, ampicillin, piperacillin-tazobactam, cefotaxime, ceftazidime, trimethoprim-sulfamethoxazole and fosfomycin. Four different carbapenemase genes were identified, including blaKPC₋₂ (n = 13), blaNDM₋₁ (n = 8), blaNDM₋₅ (n = 1), blaIMP₋₄ (n = 1). Interestingly, isolated R. ornithinolytica from the WWTP were closely related to those reported from human samples in China. Plasmid analysis indicated that IncFII(Yp), IncP6, and IncU mediated blaKPC₋₂ spread, IncX3 and IncN2 mediated blaNDM spread in the environment. The core structure of the Tn3-ISKpn27-blaKPC₋₂-ISKpn6, ISAba125-blaNDM-bleMBL-trpF-dsbD were identified. The study provides evidence that Raoultella spp. may spread alarming carbapenem resistance in the environment and, therefore, the continuous surveillance for carbapenem resistance in the WWTP should be conducted, especially sludge.

Organic ultraviolet (UV) filters are used in personal care products, but they are also added to industrial products and are constantly released to the environment. This study analyses the occurrence of 8 widely used organic UV filters in seawater from three beaches on the Gran Canaria Island (Spain) and in three wastewater treatment plants (WWTPs) by taking samples from influents and effluents. It also discusses the target compounds’ post-treatment removal efficiencies. Sampling was carried out for 6 months and analytes were extracted by solid phase extraction with Sep-pak C18 cartridges. They were determined by ultra-high performance liquid chromatography coupled to mass spectrometry in tandem. The potential environmental hazard associated with the found concentrations was also assessed for marine organisms. Different target compounds were detected on the analysed beaches and in the wastewater. Benzophenone-3 (BP3) was the most recurrent compound in the seawater samples (frequency detection of 83%) and also in wastewater influents and effluents (measured in all the samples). However, the highest concentrations for seawater (172 μg L⁻¹) and influent wastewater (208 μg L⁻¹) corresponded to octocrylene, while methylene bis-benzotriazolyltetramethylbutylphenol was the compound most concentrated in secondary treatment effluent (34.0 μg L⁻¹) and BP3 in tertiary treatment effluent (8.07 μg L⁻¹). All the analysed samples showed that at least one target UV filter was present. Regarding the removal efficiencies of these compounds in the studied WWTPs, consistent differences between the target compounds were observed in influent concentration terms, where the average removal rates were higher than 50% for most of the compounds. Conventional treatment is unable to completely remove many studied compounds, while tertiary treatment acts as an additional elimination for some of them. An environmental hazard quotient above 1 was found for octocrylene, benzophenone-3 and 4-methylbenzylidene camphor, which indicates a potential high hazard for living species if these compounds are present.

Facing the challenge of global microplastics (MPs) pollution, full characterization of MPs biohazards is urgent. Recent intensive studies revealed that the toxicity depends on the material, size, and exposure concentration of MP. To better elucidate MPs biohazards, we investigated the impact of polystyrene-MPs of size 0.1 μm at a low dose of 50 μg/L on the neuromuscular, retinal, and reproductive phenotypes of fruit fly model, by voltage-clamped electrophysiology, electroretinogram, and reproductive assay, respectively. We found that MPs decreased the frequency of spontaneous junction currents of synapse and altered the receptor potential amplitude of the retina. Furthermore, MPs lowered the rate of embryo-laying of fruit flies. The differential gene expression of ligand-receptor interaction, endocytosis, phototransduction, and Toll/Imd signaling pathways might underlie these MPs-induced phenotypes. These findings call for further investigation on the potential biohazards of low-dose MPs.

Adipokines, cytokines secreted by adipose tissue, may contribute to obesity-related metabolic disease. The role of environmental phenols and parabens in racial difference in metabolic disease burden has been suggested, but there is limited evidence. We examined the cross-sectional associations of urinary phenols and parabens with adipokines and effect modification by race. Urinary concentrations of 6 phenols (bisphenol-A, bisphenol-F, 2,4-diclorophenol, 2,5-diclorophenol, triclosan, benzophenone-3) and 4 parabens (methyl-paraben, ethyl-paraben, propyl-paraben, butyl-paraben) were measured in 2002–2003 among 1200 women (mean age = 52.6) enrolled in the Study of Women's Health Across the Nation Multi-Pollutant Study. Serum adipokines included adiponectin, high molecular weight (HMW)-adiponectin, leptin, soluble leptin receptor (sOB-R). Linear regression models were used to estimate the adjusted percentage change in adipokines per inter-quantile range (IQR) increase in standardized and log-transformed levels of individual urinary phenols and parabens. Bayesian kernel machine regression (BKMR) was used to evaluate the joint effect of urinary phenols and parabens as mixtures. Participants included white (52.5%), black (19.3%), and Asian (28.1%) women. Urinary 2,4-dichlorophenol was associated with 6.02% (95% CI: 1.20%, 10.83%) higher HMW-adiponectin and urinary bisphenol-F was associated with 2.60% (0.48%, 4.71%) higher sOB-R. Urinary methyl-paraben was associated with lower leptin in all women but this association differed by race: 8.58% (−13.99%, −3.18%) lower leptin in white women but 11.68% (3.52%, 19.84%) higher leptin in black women (P interaction = 0.001). No significant associations were observed in Asian women. Additionally, we observed a significant positive overall effect of urinary phenols and parabens mixtures in relation to leptin levels in black, but not in white or Asian women. Urinary bisphenol-F, 2,4-dichlorophenol and methyl-paraben may be associated with favorable profiles of adipokines, but methyl-paraben, widely used in hair and personal care products, was associated with unfavorable leptin levels in black women. Future studies are needed to confirm this racial difference.

A large amount of plastic waste is generated yearly worldwide, and landfills are commonly used for the disposal of plastic waste. However, burying in landfill does not get rid of the plastic waste but leave the problem to the future. Previous works have showed that microplastics are presented in the landfill refuse and leachate, which might be potential sources of microplastics. In this work, characteristics of microplastic pollution in an informal landfill in South China were studied. Landfill refuse, underlying soil, leachate, and groundwater samples were collected from different sites within and around the landfill. Results show that microplastics in the landfill refuse and underlying soil varied from 590 to 103,080 items/kg and from 570 to 14,200 items/kg, respectively. Most of the microplastics are fibrous, small sized, and transparent. Polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) are major polymer types. Scanning electron microscope (SEM) images and Fourier Transform Infrared (FTIR) spectra of the microplastic samples indicate varying degree of weathering. Microplastic abundances in the landfill leachate and groundwater ranged from 3 to 25 items/L and from 11 to 17 items/L, respectively. Microplastics detected in the landfill leachate and groundwater are even smaller compared with those in the refuse and underlying soil and their polymer types are more diverse. This work demonstrated that microplastics presented in an informal landfill without sufficient protection can leak out to the surrounding environment. The microplastic pollution originated from informal landfills should receive more attentions.