An air sampling study was conducted to evaluate personal formaldehyde exposures in a group of office workers spread across five geographical locations in the USA. Passive badge samples for formaldehyde were collected on three participants in each location, as well as in the office and home indoor microenvironments of each participant over 3 individual days. Median personal 24-h formaldehyde concentrations ranged from 9.9 to 18 μg/m³. Personal 24-h formaldehyde concentrations in one location were significantly higher than concentrations measured in the other four locations; no significant differences existed between any of the other locations. The participants in this study spent an average of 53% of their daily time in their homes, 36% at their office, and 11% in other indoor and outdoor locations. A comparison of measured 24-h personal formaldehyde concentrations and a model of average exposure based upon measured concentrations in the indoor microenvironments suggested that both the home and office formaldehyde concentrations were a strong predictor (R² = 0.88) of overall personal exposure. The data from this study are representative of office workers in urban environments and can be used as background formaldehyde exposure levels (in the absence of specific sources) for both occupational and nonoccupational exposure assessments.

The primary aims of this present study were to evaluate the effect of oxygen limitation on the bacterial community structure of enrichment cultures degrading either benzene or toluene and to clarify the role of Malikia-related bacteria in the aerobic degradation of BTEX compounds. Accordingly, parallel aerobic and microaerobic enrichment cultures were set up and the bacterial communities were investigated through cultivation and 16S rDNA Illumina amplicon sequencing. In the aerobic benzene-degrading enrichment cultures, the overwhelming dominance of Malikia spinosa was observed and it was abundant in the aerobic toluene-degrading enrichment cultures as well. Successful isolation of a Malikia spinosa strain shed light on the fact that this bacterium harbours a catechol 2,3-dioxygenase (C23O) gene encoding a subfamily I.2.C-type extradiol dioxygenase and it is able to degrade benzene, toluene and ethylbenzene under clear aerobic conditions. While quick degradation of the aromatic substrates was observable in the case of the aerobic enrichments, no significant benzene degradation, and the slow degradation of toluene was observed in the microaerobic enrichments. Despite harbouring a subfamily I.2.C-type C23O gene, Malikia spinosa was not found in the microaerobic enrichments; instead, members of the Pseudomonas veronii/extremaustralis lineage dominated these communities. Whole-genome analysis of M. spinosa strain AB6 revealed that the C23O gene was part of a phenol-degrading gene cluster, which was acquired by the strain through a horizontal gene transfer event. Results of the present study revealed that bacteria, which encode subfamily I.2.C-type extradiol dioxygenase enzyme, will not be automatically able to degrade monoaromatic hydrocarbons under microaerobic conditions.

Quantum dots (QDs) have caused large challenges in clinical tests and biomedical applications due to their potential toxicity from nanosize effects and heavy metal components. In this study, the physiological responses of Phanerochaete chrysosporium (P. chrysosporium) to CdSe/ZnS QDs with either an inorganic sulfide NaHS or an organic sulfide cysteine as antidote have been investigated. Scanning electron microscope analysis showed that the hyphal structure and morphology of P. chrysosporium have obviously changed after exposure to 100 nM of COOH CdSe/ZnS 505, NH₂ CdSe/ZnS 505, NH₂ CdSe/ZnS 565, or NH₂ CdSe/ZnS 625. Fourier transform infrared spectroscopy analysis indicated that the existence of hydroxyl, amino, and carboxyl groups on cell surface could possibly conduct the stabilization of QDs in an aqueous medium. However, after NaHS or cysteine treatment, the cell viability of P. chrysosporium exposed to CdSe/ZnS QDs increased as compared to control group, since NaHS and cysteine have assisted P. chrysosporium to alleviate oxidative damage by regulating lipid peroxidation and superoxide production. Meanwhile, NaHS and cysteine have also stimulated P. chrysosporium to produce more antioxidant enzymes (superoxide dismutase and catalase), which played significant roles in the defense system. In addition, NaHS and cysteine were used by P. chrysosporium as sulfide sources to promote the glutathione biosynthesis to relieve CdSe/ZnS QDs-induced oxidative stress. This work revealed that sulfide sources (NaHS and cysteine) exerted a strong positive effect in P. chrysosporium against the toxicity induced by CdSe/ZnS QDs.

A theoretical approach was followed to optimize the design of a cylindrical photobioreactor for wastewater treatment based on algal culture. In particular, the problem of uneven light distribution that impairs algal growth was minimized by optimizing the area of uniform illumination distribution for a bioreactor design that can be enlarged without affecting its performance. The theoretical analysis was based on modeled simulations to determine the best configuration and illumination mode. The Monte Carlo method was used to simulate the illumination distribution inside the bioreactor, and the relationships between the width of the area with uniform illumination and related parameters were explored. Based on these theoretical considerations and predictions, an actual experimental photobioreactor was built containing a working area (where culture of Chlorella pyrenoidosa was enabled) and a catchment area for effluent. The performance of this bioreactor was tested with synthetic wastewater as a substrate. The light distribution was found to be relatively uniform inside the bioreactor, supporting excellent algal growth and resulting in maximum removal rates of 84.41% for total nitrogen, 99.73% for total phosphorus, 85.03% for NH₄⁺-N, and 75.94% for chemical oxygen demand (COD) over a period of 32 days of operation. The presented approach provides new insights for improving the efficiency and scalability of photobioreactors and promotes their development for wastewater treatment and resource utilization.

Environmental monitoring, using the techniques of remote sensing (RS) and geographic information systems (GIS), allows the production of time efficient, cost-effective, and reliable surveillance and tracking data. Anthropogenic activities appear to be the major trigger of environmental changes, including land use and land cover (LULC) changes, while natural causes have only a minor impact in most cases. The Omayed Biosphere Reserve (OBR) stands as one of the Egyptian protected areas most highly affected by massive unplanned human activities. Thus, the main objective of this study is to determine the spatio-temporal changes in the OBR over a 35-year period using five Landsat (5 ETM images and 8 OLI-TIRS) imageries, with the specific aim of measuring change rates, trends, and magnitudes of LULC changes between 1984 and 2019 with the topography for planning and selection of developmental strategies. The Normalised Difference Vegetation Index is used to identify the vegetation characteristics of different eco-regions and delivers useful information for the study of vegetation health and density. Normalised Difference Built-up Index can likewise be used to quote built-up areas. Unsupervised classification was used to classify LULC patterns. Six classes were recognised: water bodies, coastal sand, urban areas, cultivated land, newly reclaimed areas, and bare soil. Our results reveal that about 33.55% of OBR land cover has transformed into other forms. Cultivated land and urban regions increased by about 143.5 km² and 56.17 km² from 1984 to 2019, respectively. Meanwhile, bare soil decreased to around 209.5 km² in 2019. In conclusion, the conversion of bare soil into urban land and cultivated areas is the major change in the last 35 years in the OBR. Over the past three decades, the OBR has faced radical and imbalanced changes in its natural habitats. Therefore, monitoring and management of LULC changes are crucial for creating links between policy decisions, regulatory actions, and following LULC activities in the future, especially as many potential risks still exist in the remaining regions of the OBR.

The Johor Strait has experienced rapid development of various human activities and served as the main marine aquaculture area for the two countries that bordered the strait. Several fish kill incidents in 2014 and 2015 have been confirmed, attributed to the algal blooms of ichthyotoxic dinoflagellates; however, the cause of fish kill events after 2016 was not clarified and the causative organisms remained unknown. To clarify the potential cause of fish kills along the Johor Strait, a 1-year field investigation was conducted with monthly sampling between May 2018 and April 2019. Monthly vertical profiles of physical water parameters (temperature, salinity, and dissolved oxygen levels) were measured in situ at different depths (subsurface, 1 m, 5 m, and 8 m) depending on the ambient depth of the water column at the sampling stations. The spatial-temporal variability of macronutrients and chlorophyll a content was analyzed. Our results showed that high chlorophyll a concentration (up to 48.8 μg/L) and high biomass blooms of Skeletonema, Chaetoceros, Rhizosolenia, and Thalassiosira were observed seasonally at the inner part of the strait. A hypoxic to anoxic dead zone, with the dissolved oxygen levels ranging from 0.19 to 1.7 mg/L, was identified in the inner Johor Strait, covering an estimated area of 10.3 km². The occurrence of high biomass diatom blooms and formation of the hypoxic-anoxic zone along the inner part Johor Strait were likely the culprits of some fish kill incidents after 2016.

Copper carboxymethyl cellulose nanoparticles were prepared and characterized by FT-IR, XRD, SEM, TEM, and EDX techniques. Removal of tetracycline was obtained at 90% with optimized parameters of 500 μg/L concentration, 40 min contact time, 7.5 pH, 1.5 g/L dose, and 298 K temp. The adsorption followed Freundlich model very well in comparison to Langmuir. Tempkin model described good interactions between tetracycline and nanoparticles. Dubinin–Radushkevich isotherm confirmed the chemical nature of adsorption. The adsorption was pseudo-second order with a liquid film diffusion kinetics mechanism. The adsorption was endothermic and spontaneous as suggested by thermodynamics results. The supramolecular mechanism was developed for the process. Interestingly, the process was suitable at 7.5 pH with low contact time. These features of the adsorption made this process applicable at natural water conditions, making the process eco-friendly and feasible. Therefore, it may be an excellent method for the removal of tetracycline in any water system.

Flood is found to be a frequent phenomenon. Over the past few decades, Pakistan has been the home of climate-related disasters like floods. This paper attempts to examine the effect of floods on the rural communities; those are vulnerable to floods, and their livelihood patterns were damaged due to flooding events in Hazara Division. This research study assessed the causes, the impact, and the aftermath of flooding and their link with climate change in Hazara Division (Torghar, Kohistan, Mansehra, Abbottabad, and Haripur). The significance of environmental changes and flood’s threats were discovered and examined through the logistic regressions and then pathway analysis. The findings showed that floods, directly and indirectly, affected the livelihood, social standing, and physical and economic status of rural communities. Rise in poverty level is also reported in already vulnerable communities that further increase their exposure to risks and hazards. This study calls for local government strengthening, early warning systems, and (non)financial assistance in times of needs to minimize the floods risk and disastrous impacts on localities and resources.

The presence of nanoplastics (NPs) in various products and from the weathering of released plastic materials are of concern for the environment’s safety. The purpose of this study was to examine the biophysical effects of polystyrene NPs on freshwater mussels. Mussels were exposed to a range of concentrations of NPs (0.1, 0.5, 1, and 5 mg/L) for 24 h and allowed to depurate for 12 h in clean aquarium water. The digestive gland was isolated and analyzed for NPs, lipids, viscosity, protein aggregation, anisotropic changes (liquid crystals: LCs), and the oscillatory modulation in viscosity during the formation of self-organizing enzyme complex of fumarase, malate dehydrogenase, and citrate synthase. The results revealed that mussels accumulated NPs in the digestive gland and their levels were significantly correlated with lipids levels, LCs, the increase in the malate dehydrogenase/citrate synthase activity ratio, and oscillations in viscosity. Protein aggregation was also found to be correlated with lipid levels. The data suggests that the presence of NPs in the digestive gland involves changes in lipid content and LC formation and perturbs the normal oscillations in viscosity during sequential enzyme reactions of the above enzymes. It is concluded that the uptake of NPs in cells could disrupt the internal organization of cells which can interfere with the normal association of enzymes involved in energy metabolism.

In this work, we used TiO₂ nanobelts and P25 particles as titanium sources to combine with β-Bi₂O₃ to form β-Bi₂O₃/TiO₂ and β-Bi₂O₃/P25 composites. The prepared samples were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and UV-vis absorbance spectroscopy and fluorescence spectroscopy. The structure and performance of two composites were comparatively investigated, and the β-Bi₂O₃ molar ratios in them were optimized and their roles in them were studied. The results showed that the TiO₂ nanobelts and commercial TiO₂ (P25) particles combined with β-Bi₂O₃ nanosheets. The optimal molar ratios of Bi to Ti element in two kinds of composites are 1:1. The β-Bi₂O₃ in P25/β-Bi₂O₃ makes more contribution to the improvement of photocatalytic activity of them than that in β-Bi₂O₃/TiO₂ because P25 particles are distributed on β-Bi₂O₃ nanosheet more uniformly. The photocatalytic activities of β-Bi₂O₃/TiO₂ (0.02275 min⁻¹) and β-Bi₂O₃/P25 (0.02382 min⁻¹) are 3.72 times and 3.90 times than that of pure β-Bi₂O₃ (0.0061 min⁻¹) for EE2 removal. The enhanced photocatalytic activities of two kinds of composites are ascribed to photo-induced interfacial charge transfer on the heterojunction between β-Bi₂O₃ and TiO₂ or P25. From the economic view, β-Bi₂O₃/P25 composites are better than β-Bi₂O₃/TiO₂ because TiO₂ nanobelts in the β-Bi₂O₃/TiO₂ composite are obtained from P25 via extra hydrothermal treatment in strong alkaline environment. The free radical capture experiment indicated that the dominant reactive species are h⁺ and •O⁻₂ for EE2 removal by TiO₂/β-Bi₂O₃ and P25/β-Bi₂O₃ composites.