Carbon nanotubes (CNTs) have emerged recently as superior adsorbent materials for the removal of recalcitrant pollutants. The potential of combining the sorption capability of CNTs with bacterial degradation for pollutant removal, however, necessitates further investigation of the mechanisms of CNTs’ toxicity towards bacterial cells. In this study, we used a panel of stress-responsive recombinant Escherichia coli bioluminescence bacterial strains to explore the possible mechanisms of toxicity of multiwalled carbon nanotubes (MWCNTs). The effects of MWCNTs on markers of oxidative stress, protein, DNA, and membrane damage enabled the exposition of some of the mechanisms of their antimicrobial properties. Using both a bioluminescence bioreporter panel and live/dead staining, we observed that membrane damage played a role in the toxicity of MWCNTs. A subsequent viability study using three strains of bacteria—two gram-negative (Escherichia coli, Pseudomonas aeruginosa) and one gram-positive (Bacillus subtilis)—showed significant MWCNT toxicity in hypotonic water and phosphate-buffered saline solution, compared with the MWCNT toxicity towards the same bacteria incubated in isotonic-rich media. Using a field-emission scanning electron microscope, we demonstrated that membrane damage is caused largely by MWCNTs trapping bacteria and piercing the cell walls. As a result of our observations, we propose integrating MWCNTs and bacteria degradation for pollutant removal in nutrient-rich media to minimize the toxicity effect of CNTs.

Considering the highly complex flow structure of saltwater lakes during freshwater supplementation, a three-dimensional numerical model was developed to simulate suspended sediment transport in saltwater lakes. The model was validated using measurements of the salinity and sediment concentration during a pumping test at Yamdrok Lake. The simulation results were in quantitative agreement with the measured data. The observed and simulated results also indicated that the wind stress and vertical salinity gradient have a significant influence on salinity and sediment transport in a saltwater lake. The validated model was then used to predict and analyze the contributions of wind, the supplement flow rate and salinity stratification to the sediment transport process in Yamdrok Lake during continuous river water supplementation. The simulation results showed that after the sandy river water was continuously discharged into the saltwater lake, the lateral diffusion trends of the sediment exhibited three stages: linear growth in the inflow direction, logarithmic growth in the wind direction, and stabilization. Furthermore, wind was the dominant factor in driving the lake flow pattern and sediment transport. Specifically, wind can effectively reduce the area of the sediment diffusion zone by increasing the lateral sediment carrying and dilution capacities. The effect of inflow on the lake current is negligible, but the extent of the sediment turbidity zone mainly depends on the inflow. Reducing the inflow discharge can decrease the area of the sediment turbidity zone to proportions that far exceed the proportions of inflow discharge reductions. In addition, the high-salinity lake water can support the supplemented freshwater via buoyancy forces, which weaken vertical mixing and sediment settlement and increase lake currents and sediment diffusion near the surface.

Microplastics in the environment are a subject of intense research as they pose a potential threat to marine organisms. Plastic fibers from textiles have been indicated as a major source of this type of contaminant, entering the oceans via wastewater and diverse non-point sources. Their presence is also documented in terrestrial samples. In this study, the amount of microfibers shedding from synthetic textiles was measured for three materials (acrylic, nylon, polyester), knit using different gauges and techniques. All textiles were found to shed, but polyester fleece fabrics shed the greatest amounts, averaging 7360 fibers/m⁻²/L⁻¹ in one wash, compared with polyester fabrics which shed 87 fibers/m⁻²/L⁻¹. We found that loose textile constructions shed more, as did worn fabrics, and high twist yarns are to be preferred for shed reduction. Since fiber from clothing is a potentially important source of microplastics, we suggest that smarter textile construction, prewashing and vacuum exhaustion at production sites, and use of more efficient filters in household washing machines could help mitigate this problem.

Since marketization of the refined oil price, the Chinese government has used refined oil price adjustments to control air pollution. Using an event study analysis, we examine whether these price adjustments have impacted air quality. We test the abnormal returns of 12 price adjustments between 2014 and 2015 in 51 major cities of China. The results show that the impact on air quality of refined oil price decreases is larger than the impact of oil price increases. Although results indicate air quality has deteriorated, the impact is insignificant for most of the cities. Consequently, we conclude that price suspension of refined oil has had a negligible impact on air quality. This policy is not a viable method to improve the air quality in the short run.

Our study designed to study the potential of potassium dichromate (K₂Cr₂O₇) oral exposure to induce damage in male rat brain and to compare the possible protective role of vitamin C (VC) either pre and/or concurrent supply against (K₂Cr₂O₇) induced changes. Thirty male rats were divided into five groups. First control group received distilled water (C), second received 120 mg/kg b.wt (VC), third received 25 mg/kg b.wt K₂Cr₂O₇ (Cr), fourth group received VC together with K₂Cr₂O₇ by the same former doses (VC + Cr), and the fifth group received the same oral doses of VC 2 weeks prior to and along with K₂Cr₂O₇ for 6 weeks (VC + Cr pro/co treated). The obtained results revealed that K₂Cr₂O₇ induced a significant decrease in cholinergic activity, glutathione reductase GR activity, reduced glutathione content GSH and ATP levels. Furthermore, K₂Cr₂O₇ induced a significant increase in oxidative DNA damage indicated by 8-hydroxy 2′-deoxyguanosine (8OH2′dG) and formation of apoptotic DNA ladders, significant increase in malondialdehyde (MDA), protein carbonyl, and lactate dehydrogenase enzyme. Increased mRNA expression of pro-apoptotic genes, including caspase-3, p53, and Bax, unlike Bcl-2 expression, was decreased. K₂Cr₂O₇ increased caspase-3 and decreased Bcl-2 immuno-labeling. VC supply noticeably ameliorates K₂Cr₂O₇-induced changes which were more significantly in VC pro and concurrent supplement rather than VC concurrent supply only. Finally, it is concluded that K₂Cr₂O₇ oral administration induced oxidative apoptotic changes in rat brain and confirms the usefulness of VC pre and concurrent supply for the amelioration of K₂Cr₂O₇-induced events more significantly than VC concurrent supply only.

The simultaneous photocatalytic removal of nitrate from aqueous environment in presence of organic hole scavenger using TiO₂ has long been explored. However, the use of unmodified TiO₂ in such reaction resulted in non-performance or release of significant amount of undesirable reaction products in the process, a problem that triggered surface modification of TiO₂ for enhanced photocatalytic performance. Previous studies focused on decreasing rate of charge carrier recombination and absorption of light in the visible region. Yet, increasing active sites and adsorption capacity by combining TiO₂ with a high surface area adsorbent such as activated carbon (AC) remains unexploited. This study reports the potential of such modification in simultaneous removal of nitrates and oxalic acid in aqueous environment. The adsorptive behaviour of nitrate and oxalic acid on TiO₂ and TiO₂/AC composites were studied. The Langmuir adsorption coefficient for nitrate was four times greater than that of oxalic acid. However, the amount of oxalic acid adsorbed was about 10 times greater than the amount of nitrate taken up. Despite this advantage, the materials did not appear to produce more active photocatalysts for the simultaneous degradation of nitrate and oxalic acid. The photocatalytic activity of TiO₂ and its carbon-based composites was improved by combination with Cu₂O particles. Consequently, 2.5 Cu₂O/TiO₂ exhibited the maximum photocatalytic performance with 57.6 and 99.8% removal of nitrate and oxalic acid, respectively, while selectivity stood at 45.7, 12.4 and 41.9% for NH₄⁺, NO₂⁻ and N₂, respectively. For the carbon based, 2.5 Cu₂O/TiO₂-20AC showed removal of 12.7% nitrate and 80.3% oxalic acid and achieved 21.6, 0 and 78.4% selectivity for NH₄⁺, NO₂⁻ and N₂, respectively. Using the optimal AC loading (20 wt%) resulted in significant decrease in the selectivity for NH₄⁺ with no formation of NO₂⁻, which unveils that selectivity for N₂ and low/no selectivity for undesirable products can be manipulated by controlling the rate of consumption of oxalic acid. In contract, no nitrate reduction was observed with Cu₂O promoted TiO₂-T and its TiO₂-(T)-20AC, which may be connected to amorphous nature of TiO₂-T and perhaps served as charge carrier trapping sites that impeded activity.

This study was designed to monitor organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in riverine water of Lesser Himalaya along the altitude. Further, the sediment-water partitioning employing organic carbon and black carbon models were assessed. Results revealed higher water levels of organochlorine pesticides (0.07–41.4 ng L⁻¹) and polychlorinated biphenyls (0.671–84.5 ng L⁻¹) in Lesser Himalayan Region (LHR) of Pakistan. Spatially, elevated levels were observed in the altitudinal zone (737–975 masl) which is influenced by anthropogenic and industrial activities. Sediment-water partitioning of OCPs and PCBs were deduced using field data by employing one-carbon (fOCKOC) and two-carbon Freundlich models (fOCKOC + fBCKBCCWⁿF⁻¹). Results suggested improved measured vs predicted model concentrations when black carbon was induced in the model and suggested adsorption to be the dominant mechanism in phase partitioning of organochlorines in LHR.

Present manuscript represents the DFT studies on the oxidation reaction of camphene initiated by OH radical and fate of product radicals using M06-2X functional along with 6-31+G(d,p) basis set. Intrinsic reaction calculation is done for transition states involving OH-addition reactions which proceed via reaction complexes proceeding to the formation of transition states. The rate constant calculated by using canonical transition state theory at 298 K and 1 atm is found to be 5.67 × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ which is in good agreement with the experimental rate constant. The atmospheric lifetime of the titled molecule has also been reported in our work.

Many commercially available agro and household chemicals are used as pesticides, repellents, and growth inhibitors against insect pests. The repeated uses of these chemicals against insect pests have caused the development of resistance in them; they also cause ill effects on nontarget organisms. The present study was aimed to evaluate the antifeedant, larvicidal, pupicidal, and biochemical effects of the solvent extracts of Solanum xanthocarpum against third instar larvae of Helicoverpa armigera. Hexane, chloroform and ethyl acetate extracts were subjected to phytochemical analysis. The results revealed the presence of terpenoids, flavonoid, and quinone. Maximum antifeedant activity of 72.30% was recorded in chloroform extract followed by hexane (69.02%) and ethyl acetate (57.40%) extracts against H. armigera. Chloroform extracts of S. xanthocarpum showed more than 60% larvicidal and pupicidal activity against H. armigera. The effective chloroform extract was fractionated with increasing polarity of solvent system (hexane, chloroform, and ethyl acetate extracts). Based on the TLC profile, nine major fractions were isolated. The fourth fraction showed higher antifeedant, larvicidal, and pupicidal activity against H. armigera. The effective fraction reduced the hemolymph and gut protein concentration in a concentration-dependent manner (r ² 0.99). The effective fraction 4 showed 100% larvicidal activity at 500 ppm concentration with LC₅₀ value of 227.95 ppm. The fourth fraction did not show any toxic symptom or mortality of earthworm. Based on these results, this effective fraction could be used in the development of a pesticide formulation to control insect.

Health effects of methyl isocyanate (MIC) exposure were mostly reported on the one-time acute exposure in Bhopal population. Epidemiological survey conducted by the Indian apex body of health research has been reported as Technical Reports, which were lacking in peer review by the expert epidemiologic scientists. The present pilot survey was aimed to measure the health effects 30 years post disaster in MIC-exposed survivors. Questionnaire-based survey has captured every health complaint in 168 individuals and grouped as systemic functions for interpreting the long-term effects of MIC. Key health parameters, including reproductive outcome and respiratory/orthopedic/general morbidity, were prevalent among the severely exposed population compared to control and moderately exposed groups. The collective incidence of diabetes, hypertension, and cancer also was prevalent in the severely exposed group. Ophthalmic morbidity was almost similar in the three groups, rather with higher incidence in the control group, though not statistically significant. Among all health parameters, reproductive, ophthalmic, and respiratory effects were prevalent over others. Although the incidence of health problems has been declined among the survivors, long-term effect is apparent as scars of one-time acute exposure might trigger sequel of long-term effects. Additionally, acquisition of genetic rearrangements, survival of T cell sub-populations, variable latency of chemical effect on DNA nucleosides, nutritional status, occupational exposure, living environment, lifestyle, and overall gene–environment interaction might perturb individual immunity and favor onset of long-term illness in a scenario of background exposure to MIC. However, the exercise should be continued on a larger sample size for drawing a conclusive result on long-term MIC effect on survivors’ health.