Petroleum hydrocarbon (PH) contamination of soils remains a major threat to environmental health and food security. A two-years phytoremediation study was conducted on a crude oil polluted soil to assess changes in soil total petroleum hydrocarbon concentration (TPHₛₒᵢₗ) following use of pawpaw seed powder (PSP), moringa seed powder (MSP) and their combination (PSP + MSP) as organic stimulants in cowpea cultivation. The stimulants were tested at different application rates (100, 150, 200 and 250 g m⁻²), with the control (No stimulant) for their effectiveness in reducing TPHₛₒᵢₗ and accelerating the removal rate (R) of PH from soil. The TPHₛₒᵢₗ did not differ significantly (p < 0.05) among the treatments in year 1, but was highest in the control (11,600 mg kg⁻¹) and least in 200 g m⁻² PSP (7400.0 mg kg⁻¹). In year 2, mean TPHₛₒᵢₗ varied significantly (p < 0.05) and remained highest in control (7100 mg kg⁻¹) but lowest in 150 g m⁻² PSP (2700 mg kg⁻¹). Application of 150 g m⁻² PSP gave the highest R (78.2%), followed by 150 g m⁻² PSP+MSP (77.4%), and least by the control (42.7%) over two years of study. The average fresh pod yield of cowpea over two years was highest in 250 g m⁻² PSP (2416.67 kg ha⁻¹), followed by 150 g m⁻² PSP (2173.34 kg ha⁻¹) and least in control (1302.22 kg ha⁻¹). There was significant negative association between TPHₛₒᵢₗ and fresh pod yield (r = −0.403; p < 0.01). However, application of 150 g m⁻² PSP appeared most effective for enhanced phytoremediation of crude oil polluted soil and improvement of cowpea yield.

Tebuconazole is a broad-spectrum triazole fungicide that has been extensively applied in agriculture, but its toxicity on soil ecology remains unknown after repeated introduction to soil. This study investigated the degradation of tebuconazole and the changes in soil microbial community composition and functional diversity as well as network complexity in soil repeatedly treated with tebuconazole. Tebuconazole degraded slowly as the degradation half-life initially increased and then decreased during the four repeated treatments. High concentration of tebuconazole treatment significantly delayed the degradation of tebuconazole. The soil microbial functional diversity in tebuconazole-treated soils showed an inhibition-recovery-stimulation trend with increasing treatment frequency, which was related to the increased degradation rates of tebuconazole. Tebuconazole significantly decreased soil microbial biomass and bacterial community diversity, and this decreasing trend became more pronounced with increasing treatment frequency and concentration. Moreover, tebuconazole significantly decreased soil bacterial community network complexity, particularly at high concentration of tebuconazole treatment. Notably, four bacterial genera, Methylobacterium, Burkholderia, Hyphomicrobium, and Dermacoccus, were identified as the potential tebuconazole-degrading bacteria, with the relative abundances in the tebuconazole treatment significantly increasing by 42.1–34687.1% compared to the control. High concentration of tebuconazole treatment delayed increases in the relative abundances of Methylobacterium but promoted those of Burkholderia, Hyphomicrobium and Dermacoccus. Additionally, repeated tebuconazole treatments improved only four metabolic pathways, cell motility, membrane transport, environmental information processing, and xenobiotics biodegradation and metabolism, which were associated with the degradation of tebuconazole. The above results indicated that repeated tebuconazole treatments resulted in the significant accumulation of residues and long-term negative effects on soil ecology, and also emphasized the potential roles of dominant indigenous microbial bacteria in the degradation of tebuconazole.

Bisphenol A (BPA) is an endocrine disrupting chemical able to promote hormone-responsive tumors. The major route of BPA contamination being oral, the aim of the present study was to investigate BPA effects on oral cells. Here, we evaluated the impact of sub-chronic in vivo exposure to BPA and its in vitro effects on neoplastic and non-neoplastic oral cells. We evaluated the oral mucosa of mice chronically exposed to BPA (200 mg/L). The response of keratinocytes (NOK–SI) and Head and Neck (HN) Squamous Cell Carcinoma (SCC), HN12 and HN13 cell lines to BPA was examined. In vivo, BPA accumulated in oral tissues and caused an increase in epithelial proliferative activity. BPA disrupted the function of keratinocytes by altering pro-survival and proliferative pathways and the secretion of cytokines and growth factors. In tumor cells, BPA induced proliferative, invasive, pro-angiogenic, and epigenetic paths. Our data highlight the harmful effects of BPA on oral mucosa and, tumorigenic and non-tumorigenic cells. Additionally, BPA may be a modifier of oral cancer cell behavior by prompting a functional shift to a more aggressive phenotype.

The water and sediments of urban rivers are spatially heterogeneous because of the influence of environmental and anthropogenic factors. However, the spatial and functional diversity of bacterial communities in urban river sediments are unclear. We investigated the spatial distribution of microbial compositions in sediments in Qingdao section of the Dagu River, and the effects of sediment physiochemical properties on the variation were explored. Among the seven heavy metals analyzed, only the average concentration of Cd significantly exceeded the safety limit for sediments. The detailed composition and spatial distribution of bacterial communities fluctuated substantially between sites along the river. Bacterial datasets were separated into three clusters according to the environmental characteristics of sampling areas (the urbanized, scenic, and intertidal zones). For the urbanized zone, Acidobacteria, Firmicutes, Gemmatimonadetes, Bacteroidetes, and Gammaproteobacteria were significantly enriched, implying the effects of human activity. In the intertidal zone, Alphaproteobacteria and Deltaproteobacteria were significantly enriched, which are associated with S redox processes, as in the marine environment. Variation partitioning analysis showed that the amount of variation independently explained by variables of Na, Al, total S and Zn was largest, followed by sediment nutrients, while heavy metals and pH explained independently 13% and 9% of the variance, respectively. Overall, microbial structures in the Dagu River exhibited spatial variation and functional diversity as a result of natural and anthropogenic factors. The results will enable the prediction of the changes in urban river ecosystems that maintain their ecological balance and health.

Non-ferrous smelting is a primary cause of serious soil pollution. Contamination and health risks of heavy metals in soils around various types of non-ferrous smelteries in China were assessed using data from peer-reviewed papers published between 2000 and 2019. Development in the relevant environmental policy in China was discussed. The studied non-ferrous smelting sites were mainly located in provinces that produced non-ferrous metals on a large scale. The average concentrations of the heavy metals in soils around the non-ferrous smelteries (in mg per kg of soil) were as follows: Cd, 19.8; Cu, 265; Pb, 1536; and Zn, 1371; the concentrations greatly exceeded their corresponding background values. The smelting sites with high soil contamination in terms of metal concentrations, geo-accumulation (Igₑₒ), and pollution index (PI) were mainly distributed in several provinces of China, including Guangxi, Gansu, Hunan, Hubei, Chongqing, and Liaoning. Soils near smelteries that processed copper were the most polluted based on Igₑₒ and PI. The accumulation of Cd and Pb in soils around non-ferrous smelteries would pose potentially high risks to residents. A series of environmental policies have proven successful in lowering the emissions of contaminants from the non-ferrous in China. The findings of the study suggested that the strategies to control soil pollution around non-ferrous smelteries should primarily focus on Cd and Pb.

Perennial contaminated groundwater seepage is threatening the downstream ecosystem of the Kazipally Pharmaceutical industrial area located in South India. The sources of seepage are unknown for the last three decades that challenging the regulatory authorities and industries. In general, water quality monitoring and geophysical techniques are applied to identify the sources. However, these techniques may lead to ambiguous results and fail to identify the seepage sources, especially when the area is urbanized/paved, and groundwater is already contaminated with other leakage sources that have similar chemical compounds. In the present study, a novel and multidisciplinary approach were adopted that includes satellite-based Land Surface Temperature (LST) observations, field-based Electrical Resistivity Tomography (ERT), continuous Soil Electrical Conductivity (SEC) and Volumetric Soil Moisture (VSM%) measurements along with groundwater levels monitoring to identify the sources and to control the seepage. The integrated results identified that the locations with the Standard Thermal Anomaly (STA) in the range of −0.5 to -1 °C, VSM% >50%, SEC > 1.5 mS/cm, bulk resistivity < 12 Ω m with shallow groundwater levels < 3 m below ground level (bgl) are potentially contaminated perennial seepage sources. Impermeable sheet piles have been installed across the groundwater flow direction to control the seepage up to 1.5 m bgl, where groundwater frequently intercepts land surface. The quantity of dry season groundwater seepage has been declined by 79.2% after these interventions, which in turn minimized the treatment cost of 1,96,283 USD/year and improved the downstream ecosystem.

The recent emergence of plasmid-borne mobilized colistin resistance (mcr) genes largely challenges the clinical use of colistin. Monitoring the distribution of mcr genes in environment is important for aiding to develop effective control measures. In this study, we aimed to evaluate the occurrence of a recent reported mcr variant, mcr-10, in hospital sewage water. mcr-10 was identified in three Enterobacter roggenkampii strains with high-level colistin resistance (MIC ≥ 16 mg/L). The three strains were assigned to different sequence types suggesting a sporadic dissemination of mcr-10 in the sewage water. Pairwise comparisons of the predicted protein structures of ten mcr homologues revealed that MCR-10 shares a higher similarity with MCR-3, MCR-4, MCR-7, and MCR-9. Overexpression in Escherichia coli Top10 showed that the activity of mcr-10 against colistin is lower than that of mcr-9. mcr-10 expression can be specifically induced by colistin, and it was co-upregulated with phoPQ to mediate the high-level colistin resistance. The mcr-10 gene was detected on self-transmissible plasmids in two isolates and on the chromosome in the other one. Blasting in Genbank suggested that the two mcr-10-bearing plasmids (pECL981-1 and pECL983-1) were novel plasmids, and replicon typing showed that they belong to IncFIB-FII and IncFIB, respectively. Plasmid-curing assay evidence that pECL981-1 was lack of fitness cost for the host. Three novel types of the genetic context were found for the mcr-10 gene in the three isolates. The structure xerC-mcr10 was dominant in mcr-10-positive genomes (39/42) retrieved in Genbank, suggesting that xerC might be involved in the mobilization of mcr-10. To our knowledge, this is the first report of mcr-10-producing E. roggenkampii detected in hospital sewage water. Our study highlights that continuous monitoring of mcr genes in hospital sewage water is imperative for understanding and tackling the dissemination.

Plant leaf cuticles play a critical role in the accumulation and transport of atmospheric polycyclic aromatic hydrocarbons (PAHs). The relationship between the distribution and retained amount of PAHs on the leaf cuticles and the leaves micro-zone structures is still unclear. In this study, a confocal microscopic fluorescence spectral analysis (CMFSA) system with a spatial resolution of 200 nm was established as a direct and noninvasive means to determine the microscopic distribution and quantify the retained amount of benzo[a]pyrene (B[a]P) at Aegiceras corniculatum (Ac), Kandelia obovata (Ko) and Avicennia marina (Am) leaf cuticle micro-zones (0.096 mm²). The linear ranges for the established method were 10–1900 ng spot⁻¹ for Ac, 15–1700 ng spot⁻¹ for Ko and 30–1800 ng spot⁻¹ for Am, and the detection limits were 0.06 ng spot⁻¹ for Ac, 0.06 ng spot⁻¹ for Ko and 0.07 ng spot⁻¹ for Am. Notably, B[a]P formed clusters and unevenly distributed at the leaf cuticles. On the adaxial cuticles, B[a]P was mainly accumulated unevenly along the epidermis cell wall, and it was also distinctively distributed in the secretory cells around salt glands for Ac and Am. On the abaxial leaf cuticles, B[a]P was concentrated in the salt glands and stomata apart from being unevenly distributed in the epidermis cell wall. Moreover, the amount of B[a]P retained presented a negative correlation with the polarity of leaf cuticles, which resulted in the amount of B[a]P retained on the adaxial leaf cuticles being significantly higher than that on abaxial leaf cuticles. Our results provide a potential in situ method for investigating the distribution and retained amount of PAHs at plant leaf surface micro-zones, which would contribute to further studying and understanding the mechanism of migration and transformation of PAHs by plant leaves from a microscopic perspective.

Current study was carried out with an objective to remediate highly contaminated sludge with HMX and RDX obtained from an explosive manufacturing facility in North India employing indigenous microbes, Arthrobacter subterraneus (isolate no. S2-TSB-17) and Bacillus sonorensis (isolate no. S8-TSB-4) which were isolated from the same contaminated site. In-vessel composting of the explosive contaminated sludge was performed in 12 different bioreactors using cow manure and garden waste as bulking agents. 78.5% degradation of HMX was observed in reactor no. 2 with Bacillus sonorensis having combination of 10% sludge, 70% cow manure and 20% garden waste on 80th day. Two secondary metabolites Bis(hydroxymethyl)nitramine and methylene dinitramine were identified while studying the degradation pathway. Similarly, degradation of 91.2% was observed for RDX in reactor no. 11 with consortia of Arthrobacter subterraneus and Bacillus sonorensis on 80th day. During the study, release of significant nitrate and nitrite ions were observed. It has already been established that RDX and HMX degradation leads to release of nitrite/nitrate ions. The highest nitrite (reactor no. 11) and nitrate (reactor no. 2) release observed were 24.02 ± 0.05 mg/kg and 30.65 ± 0.99 mg/kg on 50th and 70th day, respectively. Scanning electron microscopic studies confirmed the attachment and presence of microbes with solid surface and no deformation in structure was observed in the microbial cells due to contamination stress. Findings of the study concluded that in-vessel composting assisted with native bacterial species can be a potential technology for the treatment of explosive contaminated sludge at the contaminated sites.

Urban black-odor water (BOW) is a typical phenomenon seen in the urban water environment; it is caused by excessive pollution by organic matter and other pollutants, such as nitrogen and phosphorous. Chromophoric dissolved organic matter (CDOM) is a major optical fraction of dissolved organic matter. In this study, optical properties and components of CDOM were obtained from 178 river samples collected from five cities in China, the sample were investigated using absorption and fluorescence spectroscopy. The collected included 89 ordinary water (OW) samples, 63 mild BOW (MBOW), and 26 heavy BOW (HBOW) samples. Significant differences were found in the absorption spectra of the HBOW, MBOW, and OW samples, particularly in their optical parameters (the slope of the spectrum (S₂₇₅₋₂₉₅), and the ratio of two absorption coefficients of CDOM (E₂:E₃)). Additionally, the fluorescence intensity of the humic acid-like component (F₅) and soluble microbial by product-like component (F₄) obtained via the fluorescence regional integration (FRI) method were 3 and 4.2 times higher in HBOW than in OW, respectively; this could be used as an indicator to distinguish OW from BOW in urban rivers. The results obtained using the redundancy method and the strong negative correlation between F₄ and dissolved oxygen (DO) (r = − 0.56) suggested that the composition of CDOM could change significantly under different urban water environments (p < 0.01). Different correlations were also found between F₅, and a355, E₂:E₃, S₂₇₅₋₂₉₅ in different BOW levels, suggesting that the optical parameters of CDOM were mainly determined by the polluted organic matter originating from terrestrial sources with large molecular humic acid-like compounds; optical parameter a355 could distinguish BOW from OW. These findings are conducive in understanding the dynamics of organic matter pollution and to discover the composition and optical properties of the CDOM in urban BOW and OW, thereby providing an effective method for tracking the spatial characteristics of BOW in urban rivers using remote sensing technologies in areas with multiple sources of pollution.