Pyrene (Pyr), a widely used tetracyclic aromatic hydrocarbon, enters soil in large quantities and causes environmental pollution due to its production and mining. In order to systematically study the biotoxicity of pyrene to model organisms Eisenia fetida in soil, experiments were carried out from four dimensions: animal, tissue, cell and molecule. Experimental results proved that the mortality rate increased with increasing concentration and time of exposure to pyrene, while the mean body weight and spawning rate decreased. Meanwhile, when the pyrene concentration reached 900 mg/kg, the seminal vesicle and longitudinal muscle of the earthworm showed obvious atrophy. Experimental results at the cellular level showed that pyrene induced cell membrane damage and Ca²⁺ influx triggered mitochondrial membrane depolarization and a surge in ROS levels. Oxidative stress causes damage to proteins and lipids and DNA inside cells. When the mortality rate was 91.67 %, the Olive Tail Movement (OTM) of the comet experiment reached 15. The results of molecular level tests showed that pyrene inhibited the activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) mainly by changing the microenvironment and secondary structure of amino acid Tyr 108. The weakened function of direct antioxidant enzymes may be the root cause of the excessive increase of reactive oxygen species (ROS) in cells. The systematic approach used in this study enriches the network of toxic pathways in toxicological studies, and basic data on the biological toxicity of pyrene can provide support for future soil contamination detection.

Sulfate (SO₄•⁻) and hydroxyl-based (HO•) radical are considered potential agents for As(III) removal from aquatic environments. We have reported the synergistic role of SO₄•⁻ and HO• radicals for As(III) removal via facile synthesis of biochar-supported SO₄•⁻ species. MoS₂−modified biochar (MoS₂/BC), iron oxide-biochar (FeOₓ@BC), and MoS₂−modified iron oxide-biochar (MoS₂/FeOₓ@BC) were prepared and systematically characterized to understand the underlying mechanism for arsenic removal. The MoS₂/FeOx@BC displayed much higher As(III) adsorption (27 mg/g) compared to MoS₂/BC (7 mg/g) and FeOx@BC (12 mg/g). Effects of kinetics, As(III) concentration, temperature, and pH were also investigated. The adsorption of As(III) by MoS₂/FeOx@BC followed the Freundlich adsorption isotherm and pseudo-second-order, indicating multilayer adsorption and chemisorption, respectively. The FTIR and XPS analysis confirmed the presence of Fe–O bonds and SO₄ groups in the MoS₂/FeOₓ@BC. Electron paramagnetic resonance (EPR) and radical quenching experiments have shown the generation of SO₄•⁻ radicals as predominant species in the presence of MoS₂ and FeOₓ in MoS₂/FeOx@BC via radical transfer from HO• to SO₄²⁻. The HO• and SO₄•⁻ radicals synergistically contributed to enhanced As(III) removal. It is envisaged that As(III) initially adsorbed through electrostatic interactions and partially undergoes oxidation, which is finally adsorbed to MoS₂/FeOx@BC after being oxidized to As(V). The MoS₂/FeOₓ@BC system could be considered a novel material for effective removal of As(III) from aqueous environments owing to its cost-effective synthesis and easy scalability for actual applications.

Environment can be affected by a variety of micropollutants. In this paper, we develop a system to assess the toxicity on an environmental sample, based on the expression of a nanoluciferase under the control of the STB5 promotor in a yeast. The STB5 gene encodes for a transcription factor involved in a pleiotropic drug resistance and in the oxidative stress response. The response of the modified yeast was assessed using 42 micropollutants belonging to different families (antibiotics, pain killers, hormones, plasticizers, pesticides, etc.). Among them, 26 induced an increase of the bioluminescence for concentration ranges from pg.L⁻¹ to ng.L⁻¹. Surprisingly, for concentrations higher than 100 ng.L⁻¹, no response can be observed, suggesting that other mechanisms are involved when the stress increases. Analyzing the different responses obtained, we highlighted six nonmonotonic types of responses. The type of response seems to be independent of the properties of the compounds (polarity, toxicology, molecular weight) and of their family. In conclusion, we highlighted that a cellular response exists for very low exposition to environmental concentration of micropollutants and that it was necessary to explore the cellular mechanisms involved at very low concentration to provide a better risk assessment.

Biochar has the potential to remediate heavy metals in agricultural soil and mitigate nitrous oxide (N₂O) emissions; however, the effects of biochar on heavy metal remediation, the soil microbial community and N₂O emissions are not completely understood. In this study, we conducted a pot experiment in which Glycine max L. (soybean) was cultivated in two cadmium (Cd)-contaminated soils (low, 3.14 mg kg⁻¹; high, 10.80 mg kg⁻¹) to investigate the effects of biochar on the bioremediation of Cd, N₂O emissions and the rhizosphere microbial community structure. The bioaccumulation of Cd in the plant shoots and roots increased with all biochar addition rates (0%, 1%, 5% and 10%); unexpectedly, the translocation capacity of Cd to the edible parts of the plant significantly decreased to 0.58 mg kg⁻¹, which was close to the edible threshold (0.4 mg kg⁻¹). The abundance and activities of functional marker genes of microbial nitrification (amoA) and denitrification (nirK, nirS and nosZ) were quantified with quantitative PCR, and we found that biochar addition reduced the precursor production of rhizoshpere N₂O by inhibiting the transcription of the nirK gene. In addition, the nitrogenase activity during anthesis (S) was significantly (P < 0.05) increased with 1% (v/v) biochar addition. Noticeably, biochar addition only changed the microbial community structure in the very first stage before eventually stabilize. This study highlighted that biochar has the potential ability to maintain the quality of agricultural crops, remediate Cd-contaminated soils and may help reduce N₂O emissions without disturbing the microbial community.

The remarkable journey of progression of mankind has created various impacts in the form of polluted environment, amassed heavy metals and depleting resources. This alarming situation demands sustainable energy resources and approaches to deal with these environmental hazards and power deficit. Pyrolysis and co-pyrolysis address both energy and environmental issues caused by civilization and industrialization. The processes use hazardous waste materials including waste tires, plastic and medical waste, and biomass waste such as livestock waste and agricultural waste as feedstock to produce gas, char and pyrolysis oil for energy production. Usage of hazardous materials as pyrolysis and co-pyrolysis feedstock reduces disposal of harmful substances into environment, reducing occurrence of soil and water pollution, and substituting the non-renewable feedstock, fossil fuels. As compared to combustion, pyrolysis and co-pyrolysis have less emission of air pollutants and act as alternative options to landfill disposal and incineration for hazardous materials and biomass waste. Hence, stabilizing heavy metals and solving the energy and waste management problems. This review discusses the pyrolysis and co-pyrolysis of biomass and harmful wastes to strive towards circular economy and eco-friendly, cleaner energy with minimum waste disposal, reducing negative impact on the planet and creating future possibilities.

This work demonstrated the development of nanofiber templated metal oxide nanocomposites by hydrothermal and calcination methods for photocatalytic degradation using Congo red (CR) as model pollutant. Herein, we developed PAN/CuO–ZnO nanocomposites by the electrospinning technique followed by heat treatment process i.e hydrothermal and calcination. The obtained nanofibrous composites were characterized by various analytical techniques such as X-Ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TG), High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Photoluminescence (PL) and UV–Vis diffuse reflectance spectroscopy (DRS) studies. The results demostrated that the nanocomposites obtained through calcination possess better optical response with robust electronic structures. This is due to the better charge separation of excited electron-hole pairs of p-n heterostructured PAN/CuO–ZnO hybrid nanocomposites. The photocatalytic efficiency is found to be 98% and 93% for nanocomposites obtained through calcination and hydrothermal methods respectively. The reusability studies confirmed the stability and viability of multiple utilizations of photocatalysts. Furthermore, the photocatalytic mechanism corroborated the photocatalytic properties of the integrated facile nanofibrous-metallic (PAN/CuO–ZnO) composites and hence can be implemented in water remediation effectively.

Previous nationwide studies have reported links between long-term concentrations of fine particulate matter (PM2.5) and COVID-19 infection and mortality rates. In order to translate these results to the state level, we use Bayesian hierarchical models to explore potential links between long-term PM2.5 concentrations and census tract-level rates of COVID-19 outcomes (infections, hospitalizations, and deaths) in Colorado. We explicitly consider how the uncertainty in PM2.5 estimates affects our results by comparing four different PM2.5 surfaces from academic and governmental organizations. After controlling for 20 census tract-level covariates, we find that our results depend heavily on the choice of PM2.5 surface. Using PM2.5 estimates from the United States EPA, we find that a 1 μg/m³ increase in long-term PM2.5 concentrations is associated with a statistically significant 26% increase in the relative risk of hospitalizations and a 34% increase in mortality. Results for all other surfaces and outcomes were not statistically significant. At the same time, we find a clear association between communities of color and COVID-19 outcomes at the Colorado census tract level that is minimally affected by the choice of PM2.5 surface. A per-interquartile range (IQR) increase in the percent of non-African American people of color was associated with a 31%, 43%, and 56% increase in the relative risk of infection, hospitalization, and mortality respectively, while a per-IQR increase in the proportion of non-Hispanic African Americans was associated with a 4% and 7% increase in the relative risk of infections and hospitalizations. The current disagreement among the different PM2.5 estimates is a key factor limiting our ability to link environmental exposures and health outcomes at the census tract level. These results have strong implications for the implementation of an equitable public health response during the crisis and suggest targeted areas for additional air monitoring in Colorado.

The present study aimed to assess the toxicity of seven UV-filters: zinc oxide nanoparticles (nZnO, particle size <100 nm), titanium dioxide nanoparticles (nTiO₂, primary particle size 21 nm), 2-ethylhexyl-4-methoxycinnamate (EHMC), 4-methylbenzylidene camphor (4-MBC), avobenzone (AVO), octocrylene (OCTO) and benzophenone-3 (BP-3) on three species: Aliivibrio fischeri (inhibition of bioluminescence), Phaeodactylum tricornutum (growth inhibition) and Ficopomatus enigmaticus (larval development success). Results showed nTiO₂ to be the most toxic for P. tricornutum (EC₅₀ 0.043 mg L⁻¹), while no effect was observed in A. fischeri and F. enigmaticus. EHMC was the most toxic to A. fischeri (EC₅₀ 0.868 mg L⁻¹ (15 min) and 1.06 mg L⁻¹ (30 min)) and the second most toxic to P. tricornutum. For F. enigmaticus, the lowest percentages of correct development resulted from 4-MBC exposure, with EC₅₀ of 0.836 mg L⁻¹. Overall, AVO induced low toxicity to every assessed species and OCTO was the least toxic for F. enigmaticus larvae. Considering the results obtained for F. enigmaticus, further larval development assays were performed with nZnO and EHMC under different light (light vs darkness) and temperature (20 and 25 °C) conditions, showing higher percentages of correct development at 25 °C, independently on light/darkness conditions. Under different temperature and photoperiod conditions, nZnO was more toxic than EHMC. Overall, nZnO and EHMC were among the most toxic UV filters tested and, when testing the effects of these UV-filters with temperature the results highlight that the impacts are liable to be lessened at higher temperatures (25 °C compared with 20 °C), in the case of this estuarine polychaete species. Nevertheless, further experiments are necessary to describe the effects of these two UV-filters at different organization levels, to study the toxicity of eventual degradation by-products and to provide more information on the combination of different stressors.

In the transportation sector, the share of biofuels such as biodiesel is increasing and it is known that such fuels significantly affect NOx emissions. In addition to NOx emission from diesel engines, which is a significant challenge to vehicle manufacturers in the most recent emissions regulation (Euro 6.2), this study investigates NO₂ which is a toxic emission that is currently unregulated but is a focus to be regulated in the next regulation (Euro 7). This manuscript studies how the increasing share of biofuels affects the NO₂, NOx, and NO₂/NOx ratio during cold-start (in which the after-treatment systems are not well-effective and mostly happens in urban areas). Using a turbocharged cummins diesel engine (with common-rail system) fueled with diesel and biofuel derived from coconut (10 and 20% blending ratio), this study divides the engine warm-up period into 7 stages and investigates official cold- and hot-operation periods in addition to some intermediate stages that are not defined as cold in the regulation and also cannot be considered as hot-operation. Engine coolant, lubricating oil and exhaust temperatures, injection timing, cylinder pressure, and rate of heat release data were used to explain the observed trends. Results showed that cold-operation NOx, NO₂, and NO₂/NOx ratio were 31–60%, 1.14–2.42 times, and 3–8% higher than the hot-operation, respectively. In most stages, NO₂ and the NO₂/NOx ratio with diesel had the lowest value and they increased with an increase of biofuel in the blend. An injection strategy change significantly shifted the in-cylinder pressure and heat release diagrams, aligned with the sudden NOx drop during the engine warm-up. The adverse effect of cold-operation on NOx emissions increased with increasing biofuel share.

As replacements for “old” organohalides, such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs), “new” organohalides have been developed, including decabromodiphenyl ethane (DBDPE), short-chain chlorinated paraffins (SCCPs), and perfluorobutyrate (PFBA). In the past decade, these emerging organohalides (EOHs) have been extensively produced as industrial and consumer products, resulting in their widespread environmental distribution. This review comprehensively summarizes the environmental occurrence and remediation methods for typical EOHs. Based on the data collected from 2015 to 2021, these EOHs are widespread in both abiotic (e.g., dust, air, soil, sediment, and water) and biotic (e.g., bird, fish, and human serum) matrices. A significant positive correlation was found between the estimated annual production amounts of EOHs and their environmental contamination levels, suggesting the prohibition of both production and usage of EOHs as a critical pollution-source control strategy. The strengths and weaknesses, as well as the future prospects of up-to-date remediation techniques, such as photodegradation, chemical oxidation, and biodegradation, are critically discussed. Of these remediation techniques, microbial reductive dehalogenation represents a promising in situ remediation method for removal of EOHs, such as perfluoroalkyl and polyfluoroalkyl substances (PFASs) and halogenated flame retardants (HFRs).