In this study, we assessed the impact of zinc oxide (ZnO) and iron oxide (FeO) (<36 nm) nanoparticles (NPs) as well as their sulphate salt (bulk) counterpart (0, 25, 100 mg/kg) on rice growth and seed quality as well as the microbial community in the rhizosphere environment of rice. During the rice growing season 2021–22, all experiments were conducted in a greenhouse (temperature: day 30 °C; night 20 °C; relative humidity: 70%; light period: 16 h/8 h, day/night) in rice field soil. Results showed that low concentrations of FeO and ZnO NPs (25 mg/kg) promoted rice growth (height (29%, 16%), pigment content (2%, 3%)) and grain quality parameters such as grains per spike (8%, 9%), dry weight of grains (12%, 14%) respectively. As compared to the control group, the Zn (2%) and Fe (5%) accumulations at their respective low concentrations of NP treatments showed stimulation. Interestingly, our results showed that at low concentration of both the NPs the soil microbes had more diversity and richness than those in the bulk treated and control soil group. Although a number of phyla were affected by the presence of NPs, the strongest effects were observed for change in the abundance of the three phyla for Proteobacteria, Actinobacteria, and Planctomycetes. The rhizosphere environment was notably enriched with potential streptomycin producers, carbon and nitrogen fixers, and lignin degraders with regard to functional groups of microorganisms. However, microbial communities mainly responsible for chitin degradation, ammonia oxidation, and nitrite reduction were found to be decreased. The results from this study highlight significant changes in several plant-based endpoints, as well as the rhizosphere soil microorganisms. It further adds information to our understanding of the nanoscale-specific impacts of important micronutrient oxides on both rice and its associated soil microbiome.

Hydrogen sulfide (H₂S) is a flammable, corrosive and lethal gas even at low concentrations (ppm levels). Hence, the capture and removal of H₂S from various emitting sources (such as oil and gas processing facilities, natural emissions, sewage treatment plants, landfills and other industrial plants) is necessary to prevent and mitigate its adverse effects on human (causing respiratory failure and asphyxiation), environment (creating highly flammable and explosive environment), and facilities (resulting in corrosion of industrial equipment and pipelines). In this review, the state-of-the-art technologies for H₂S capture and removal are reviewed and discussed. In particular, the recent technologies for H₂S removal such as membrane, adsorption, absorption and membrane contactor are extensively reviewed. To date, adsorption using metal oxide-based sorbents is by far the most established technology in commercial scale for the fine removal of H₂S, while solvent absorption is also industrially matured for bulk removal of CO₂ and H₂S simultaneously. In addition, the strengths, limitations, technological gaps and way forward for each technology are also outlined. Furthermore, the comparison of established carbon capture technologies in simultaneous and selective removal of H₂S–CO₂ is also comprehensively discussed and presented. It was found that the existing carbon capture technologies are not adequate for the selective removal of H₂S from CO₂ due to their similar characteristics, and thus extensive research is still needed in this area.

Engine start-stop (S&S) technology has been substantially incorporated into modern vehicles to save fuel during idling in congested urban areas because fuel economy regulations have become more stringent. However, the potential for increasing particle emissions after engine restarts, especially in cold environments, is of great concern. To investigate the effects of S&S systems on fuel consumption and tailpipe emissions, a chassis dynamometer was employed to measure the fuel consumption, particulate matter (PM), solid particle number (PN), particle number size distribution and black carbon (BC) for a typical gasoline direct injection vehicle when the S&S was on (S&S-on) and when the S&S was off (S&S-off) according to the worldwide harmonized light-duty test cycle in both hot (28 °C) and cold (5 °C) environments. S&S operation resulted in 3.1–4.3% fuel-savings at 28 °C but had a tendency to increase particulate emissions, especially of BC (21.8–31.8%) and PM (19.2–32.8%). Although PN emissions with S&S-on over the entire cycle were slightly lower than those with S&S-off, more particles were emitted during the engine restart moments. In a cold environment, the fuel-savings advantage of the S&S system was weakened, and the negative impacts on the particle emissions during the restart moment worsened. The S&S system resulted in higher abundances of accumulation mode particles, especially under cold ambient conditions. The relationship between the PN reduction rates and idling segments was determining to be exponential. Our results indicate that the S&S system, which may increase particle emissions during restarts, does save fuel, and that a comprehensive evaluation of the system in cold environments is needed to determine the serviceability of new engine technologies and after-treatments.

As a widely used pure elemental carbon in colloidal particles, carbon black was listed as a group 2B carcinogen by IARC in 2010. The most available mechanism information about carbon black and carcinogenesis are from in vivo or in vitro studies. However, few studies concerned the nanoparticle's real-ambient exposure causing systemic change and further affecting the target organ. Herein, we used an ex vivo biosensor assay to investigate the transcriptome change of primary bronchial epithelial cells after treatment with the plasma from workers with long-term occupational carbon black exposure history. Based on ex vivo biosensor assay and transcriptome sequencing, we found the effect of internal systemic environment on epithelial cells after carbon black exposure was an inflammatory response, which mainly activates cell cycle-related pathways. After exposure to carbon black, the internal systemic environment could activate cancer-related pathways like epithelial-mesenchymal transition, hypoxia, TNF-α signaling via NF-κB. The hub genes in the carbon black group (CDC20 and PLK1) and their correlation with the systemic environment were uncovered by constructing the protein-protein interaction network. Inflammatory cytokines, especially CRP, were strongly correlated with the expression of CDC20 and PLK1. Besides, we also find a strong correlation between CDC20 and cytokinesis-block micronucleus endpoints in peripheral blood (rho = 0.591, P < 0.001). Our results show that long-term carbon black exposure might activate cell cycle-related pathways through circulating inflammation and increase the risk of cancer, while the oxidative stress caused by diesel exhaust particles are mainly related to PAHs exposure. After exposure to carbon black, the systemic environment could activate cancer-related pathways like diesel exhaust particles, increasing the risk of lung cancer. These attempts might provide a further understanding of the indirect effect of chronic occupational inhaled carbon black exposure on pulmonary carcinogenesis.

Manure application increases the transfer risk of antibiotic resistance to farmland. Especially, its impact remains unclear when it occurs in arsenic (As)-contaminated paddy soils, which is considered as a global environmental problem. In this work, we investigated the fate of antibiotic resistance genes (ARGs) in As-antibiotic co-contaminated paddy soils under the application of manure from different sources (pig manure, cow dung, and chicken manure). Differences in the aliphatic carbon and electron-donating capacities of these dissolved organic matters (DOM) regulated the transformation of iron and As by both biotic and abiotic processes. The regulation by pig manure was stronger than that by cow dung and chicken manure. DOM regulation increased the abundance of As-related functional genes (arsC, arrA, aioA, and arsM) in the soil and accelerated the transformation of As speciation, the highest proportion of As(III) being 45%–61%. Meanwhile, the continuous selection pressure provided by the highly toxic As(III) increased the risk of ARGs and mobile genetic elements (MGEs) via horizontal gene transfer. As-resistant bacteria, including Bacillus, Geobacter, and Desulfitobacterium, were finally considered as potential host bacteria for ARGs and MGEs. In summary, this study clarified the synergistic mechanism of As-antibiotic on the fate of ARGs in co-contaminated paddy soils, and provided practical guidance for the proper application of organic fertilizers.

Coastal waters are confluences receiving large amounts of point and non-point sources of pollution. An attempt was made to explore microbial community interactions in response to carbon, nitrogen and metal pollution. Additionally, experiments were designed to analyze the influence of these factors on horizontal gene transfer (HGT). Shift in bacterial diversity dynamics by arsenic stress and nutrient addition in coastal waters was explored by metagenomics of microcosm setups. Phylogenetic analysis revealed equal distribution of Gammaproteobacteria (29%) and Betaproteobacteria (28%) in control microcosm. This proportional diversity from control switched to unique distribution of Gammaproteobacteria (44.5%)> Flavobacteria (17.7%)> Bacteriodia (11.92%)> Betaproteobacteria (11.52%) in microcosm supplemented with carbon, nitrogen and metal (C + N + M). Among metal-stressed systems, alpha diversity analysis indicated highest diversity of genera in C + N + M followed by N + M > C+M> metal alone. Arsenic and ampicillin sensitive E. coli XL1 blue and environmental strains (Vibrio tubiashii W85 and E. coli W101) were tested for efficiency of uptake of plasmid (P) pUCminusMCS (arsBᴿampᴿ) under varying stress conditions. Transformation experiments revealed that combined effect of carbon, nitrogen and metal on horizontal gene transfer (HGT) was significantly higher (p < 0.01) than individual factors. The effect of carbon on HGT was proved to be superior to nitrogen under metal stressed conditions. Presence of arsenic in experimental setups (P + M, P + N + M and P + C + M) enhanced the HGT compared to non-metal counterparts supplemented with carbon or nitrogen. Arsenic resistant bacterial isolates (n = 200) were tested for the ability to utilize various carbon and nitrogen substrates and distinct positive correlation (p < 0.001) was found between arsenic resistance and utilization of urea and nitrate. However, evident positive correlation was not found between carbon sources and arsenic resistance. Our findings suggest that carbon and nitrogen pollution in aquatic habitats under arsenic stress determine the microbial community dynamics and critically influence uptake of genetic material from the surrounding environment.

Household air pollution (HAP) arising from combustion of biomass fuel (BMF) is a leading cause of morbidity and mortality in low-income countries. Air pollution may stimulate pro-inflammatory responses by activating diverse immune cells and cyto/chemokine expression, thereby contributing to diseases. We aimed to study cellular immune responses among women chronically exposed to HAP through use of BMF for domestic cooking. Among 200 healthy, non-smoking women in rural Bangladesh, we assessed exposure to HAP by measuring particulate matter 2.5 (PM₂.₅), black carbon (BC) and carbon monoxide (CO), through use of personal monitors RTI MicroPEM™ and Lascar CO logger respectively, for 48 h. Blood samples were collected following HAP exposure assessment and were analyzed for immunoprofiling by flow cytometry, plasma IgE by immunoassay analyzer and cyto/chemokine response from monocyte-derived-macrophages (MDM) and -dendritic cells (MDDC) by multiplex immunoassay. In multivariate linear regression model, a doubling of PM₂.₅ was associated with small increments in immature/early B cells (CD19⁺CD38⁺) and plasmablasts (CD19⁺CD38⁺CD27⁺). In contrast, a doubling of CO was associated with 1.20% reduction in CD19⁺ B lymphocytes (95% confidence interval (CI) = -2.36, −0.01). A doubling of PM₂.₅ and BC each was associated with 3.12% (95%CI = −5.85, −0.38) and 4.07% (95%CI = −7.96, −0.17) decrements in memory B cells (CD19⁺CD27⁺), respectively. Exposure to CO was associated with increased plasma IgE levels (beta(β) = 240.4, 95%CI = 3.06, 477.8). PM₂.₅ and CO exposure was associated with increased MDM production of CXCL10 (β = 12287, 95%CI = 1038, 23536) and CCL5 (β = 835.7, 95%CI = 95.5, 1576), respectively. Conversely, BC exposure was associated with reduction in MDDC-produced CCL5 (β = −3583, 95%CI = −6358, −807.8) and TNF-α (β = −15521, 95%CI = −28968, −2074). Our findings suggest that chronic HAP exposure through BMF use adversely affects proportions of B lymphocytes, particularly memory B cells, plasma IgE levels and functions of antigen presenting cells in rural women.

This study demonstrated that nitrogen-doped carbon materials (NCMs) could effectively catalyze the chlorine elimination process in hexachloroethane (HCA) declorination in sulfide-containing environments for the first time. The kₒbₛ values of HCA dechlorination by sulfide in the presence of 10 mg/L NCMs were higher than that of no mediator at pH 7.3 by one or two orders of magnitude. The catalytic capabilities of NCMs on HCA dechlorination were evident in common ranges of natural pH (5.3–8.9) and it could be accelerated by the increase of pH but be suppressed by the presence of dissolved humic acid. Moreover, NCMs exhibited much better catalytic capability on HCA dechlorination compared to the carbon materials, mainly owing to the combined contributions of pyridine N, including enhanced nucleophilic attack to HCA molecule by generating newborn C–S–S and activation of HCA molecule by elongating C–Cl bonds. The functions of pyridine N in micron-sized NCMs with mesopores were better than in nano-sized NCMs on HCA dechlorination. These findings displayed the potential of NCMs, when released into sulfide-containing environments, may significantly increase the dechlorination of chlorinated aliphatic hydrocarbons.

Herein, a pH-independent interpenetrating polymeric networks (Fe-SA-C) were fabricated from graphitic biochar (BC) and iron-alginate hydrogel (Fe-SA) for removal of Cr(VI) and Pb(II) in aqueous solution. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and scanning electron microscope (SEM) results demonstrated that graphitic BC interpenetration increased surface porosity and distorted surfaces of Fe-SA, which boosted availability of hydroxyl (-OH) group. Fe³⁺ as a cross-linking agent of the alginate endowed Fe-SA-C with positive surfaces (positive zeta potential) and excellent pH buffering capacity, while excessive Fe³⁺ was soldered on Fe-SA-C matrix as FeO(OH) and Fe₂O₃. Cr(VI) removal at pH of 3 by Fe-SA-C (20.3 mg g⁻¹) were 30.3% and 410.6% greater than that by Fe-SA and BC, respectively. Fe-SA-C exhibited minor pH dependence over pH range of 2–7 towards Cr(VI) retention. Greater zeta potential of Fe-SA-C over Fe-SA conferred a better electrostatic attraction with Cr(VI). FTIR and XPS of spent sorbents confirmed the reduction accounted for 98.5% for Cr(VI) removal mainly due to participation of –OH. Cr(VI) reduction was further favored by conductive carbon matrix in Fe-SA-C, as evidenced by more negative Tafel corrosion potential. Reductively formed Cr(III) was subsequently complexed with carboxylic groups originating from oxidation of –OH. Thus, Cr(VI) removal invoked electrostatic attraction, reduction, and surface complexation mechanisms. Pb(II) removal with excellent pH independence was mainly ascribed to surface complexation and possible precipitation. Thus, the functionalized, conductive, and positively-charged Fe-SA-C extended its applicability for Cr(VI) and Pb(II) removal from aqueous solutions in a wide pH range. This research could expand the application of hydrogel materials for removal of both cationic and anionic heavy metals in solutions over an extended pH range.

Constructed wetlands (CWs) inoculated with exogenous microbes have great potential for removing pollutants in adverse environments. The rapid loss of functional bacteria and the high cost of repeated additions of inoculum, however, limit the practical application of this technology. In this study, C–F2 immobilized bacteria (i.e., immobilized salt-tolerant bacterium Alishewanella sp. F2 incorporated with a carbon source) were developed and utilized in CWs for solving the above problems. A 60-day experiment demonstrated that bioaugmented CWs (Bio-CWs) with the addition of C–F2 immobilized bacteria into the bottom gravel layer of CW microcosms (B-CF2 treatment) exhibited high nitrogen removal efficiency under a saline condition (electrical conductivity of 15 mS/cm). We measured mean nitrate nitrogen (NO₃⁻-N) and total nitrogen (TN) removal percentages of 97.8% and 88.1%, respectively, which were significantly (p < 0.05) higher than those in Bio-CWs with microbial inoculum (MI-F2 treatment, 63.5% and 78.2%) and unbioaugmented CWs (CK, 48.7% and 67.2%). The TN content of the entire plant was significantly (p < 0.05) increased in B-CF2 (636.06 mg/microcosm) compared with CK (372.06 mg/microcosm). The relative abundances of the genera Alishewanella (i.e., the exogenous bacterium, 5.5%), Clostridium-XlVa (8.8%) and Bacteroides (21.1%) in B-CF2 were significantly (p < 0.05) higher than in MI-F2 and CK, which improved the denitrification capacity of CWs. Overall, a high denitrification efficiency and durability were achieved in the newly developed Bio-CWs (i.e., B-CF2 treatment) with immobilized bacteria under saline conditions, which provides an alternative technology for the rapid removal of nitrogen from saline wastewater.