Uranium, a radionuclide, is a predominant element utilized for speciality requirements in industrial applications, as fuels and catalyst. The radioactive properties and chemical toxicity of uranium causes a major threat to the ecosystem. The hazards associated with Uranium pollution includes the cancer in bones, liver, and lungs. The toxicological properties of Uranium are discussed in detail. Although there are many methods to eliminate those hazards, this research work is aimed to describe the application of bioremediation methods. Bioremediation methods involve elimination of the hazards of uranium, by transforming into low oxidation form using natural microbes and plants. This study deeply elucidates the methods as bioleaching, biosorption, bioreduction and phytoremediation. Bioleaching process involves bio-oxidation of tetravalent uranium when it gets in contact with acidophilic metal bacterial complex to obtain leach liquor. In biosorption, chitin/chitosan derived sorbents act as chelators and binds with uranium by electrostatic attraction. Bio reduction employs a bacterial transformation into enzymes which immobilize and reduce uranium. Phytoremediation includes phytoextraction and phytotranslocation of uranium through xylems from soil to roots and shoots of plants. The highest uranium removal and uptake reported using the different methods are listed as follows: bioleaching (100% uranium recovery), biosorption (167 g kg⁻¹ uranium uptake), bioreduction (98.9% uranium recovery), and phytoremediation (49,639 mg kg⁻¹ uranium uptake). Among all the techniques mentioned above, bioleaching has been proved to be the most efficient for uranium remediation.

The increasing use of rare earth elements (REEs) in electric and electronic equipment has been associated with the presence of these elements in aquatic systems. The present study aimed to evaluate the toxicity of two REEs, Lanthanum (La) and Gadolinium (Gd), towards the mussel species Mytilus galloprovincialis. For this, the toxicity was assessed after a short-term exposure (14 days) to an environmentally relevant concentration of each element (10 μg/L), followed by a recovery period (14 days) in the absence of any contaminant. The measured biomarkers included energy-related parameters, activity of antioxidant and biotransformation enzymes, indicators of oxidative damage, levels of oxidized glutathione and neurotoxicity. After exposure mussels accumulated more La (0.54 μg/g) than Gd (0.15 μg/g). After recovery higher concentration decrease was observed for Gd (≈40% loss) compared to La exposed mussels (≈30% loss) which may be associated with lower detoxification capacity of mussels previously exposed to La. Mussels increased their metabolism (i.e., higher electron transport system activity) only after the exposure to Gd. Exposure to La and Gd resulted into lower energy expenditure, while when both elements were removed glycogen and protein concentrations decreased to values observed in non-contaminated mussels. Antioxidant and biotransformation capacity was mainly increased in the presence of Gd. This defense response avoided the occurrence of cellular damage but still loss of redox balance was found regardless the contaminant, which was re-established after the recovery period. Neurotoxicity was only observed in the presence of Gd with no effects after the recovery period. Results showed that a short-term exposure to La and especially to Gd can exert deleterious effects that may compromise specific biochemical pathways in aquatic species, such as M. galloprovincialis, but under low concentrations organisms can be able to re-establish their biochemical status to control levels after a recovery period.

Dissolved inorganic nitrogen (DIN) is considered the main factor that induces eutrophication in water, and is readily influenced by hydrodynamic activities. In this study, a 4-year field investigation of nitrogen dynamics in a turbulent river was conducted, and a laboratory study was performed in the approximately homogeneous turbulence simulation system to investigate potential mechanisms involved in DIN transformation under turbulence. The field investigation revealed that, contrary to NO⁻₃ dynamics, the NH⁺₄ concentrations in water were lower in flood seasons than in drought seasons. Further laboratory results demonstrated that limitation of dissolved oxygen (DO) caused inactive nitrification and active denitrification in static river sediment. In contrast, the increased DO levels in turbulent river intensified the mineralization of organic nitrogen in sediment; moreover, ammonification and nitrification were activated, while denitrification was first activated and then depressed. Turbulence therefore decreased NH⁺₄ and NO⁻₂ concentrations, but increased NO⁻₃ and total DIN concentrations in the overlying water, causing the total DIN to increase from 0.4 mg/L to maximum of 1.0 and 1.7 mg/L at low and high turbulence, respectively. The DIN was maintained at 0.7 and 1.0 mg/L after the 30-day incubation under low and high turbulence intensities (ε) of 3.4 × 10⁻⁴ and 7.4 × 10⁻² m²/s³, respectively. These results highlight the critical role of DO in DIN budgets under hydrodynamic turbulence, and provide new insights into the DIN transport and transformation mechanisms in turbulent rivers.

Fluorinated pesticides acquired a significant market share in the agrochemical sector due to the surge of new fluoroorganic ingredients approved in the last two decades. This growing trend has not been accompanied by a comprehensive scientific and regulatory framework entailing all their potential negative impacts for the environment, especially when considering the hazardous properties that may result from the incorporation of fluorine into organic molecules. This review aims to address the safe/hazardous dichotomy associated with fluorinated pesticides by providing an updated outlook on their relevancy in the agrochemical sector and how it leads to their role as environmental pollutants. Specifically, the environmental fate and distribution of these pesticides in the ecosystems is discussed, while also analysing their potential to act as toxic substances for non-target organisms.

Currently, 1.3 billion tonnes of food are thrown away each year, most of which are incinerated or landfilled causing large environmental, social, and economic issues. Therefore, the utilisation of food waste as biofertilisers, such as composts and digestates, is a solution to reduce the problems created by incineration and landfilling whilst simultaneously amending soils. The improper disposal of food wastes and bulking materials can contribute to high levels of contaminants within the end-product. Moreover, the food waste and bulking materials, themselves, may contain trace amounts of contaminants. These contaminants tend to have long half-lives, are easily mobile within soil and plants, can accumulate within the food supply chain, and have moderate to high levels of toxicity. This review aims to examine the current and emerging contaminants of high concern that impact the quality of food-waste fertilisers. The paper presents the volume of current and emerging contaminants of plastics, other physical (particulate) contaminants, heavy metals, pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), per- and polyfluoroalkyl substances (PFAS), and pathogens within food-waste composts and digestates. Due to the large extent of organic chemical contaminants and the unknown level of toxicity and persistence, the risk assessment of organic chemical contaminants in the food-supply chain remains largely unknown. This study has presented available data from literature of various contaminants found in food waste, and composts and digestates derived from food waste, and evaluated the data with current regulations globally. Overall, to reduce contaminants in composts and digestates, more studies are required on the implementation of proper disposal separation, effective composting and digestion practices, increased screening of physical contaminants, development of compostable plastics, and increased regulatory policies on emerging, problematic contaminants. Moreover, examination of emerging contaminants in food-waste composts and digestates is needed to ensure food security and reduce future human-health risks.

Plastic ingestion has been widely investigated to understand its adverse harms on fauna, but the role of fauna itself in plastic fragmentation has been rarely addressed. Here, we review and discuss the available experimental results on the role of terrestrial and aquatic macrofauna in plastic biofragmentation and degradation. Recent studies have shown how biting, chewing, and stomach contractions of organisms shatter ingested plastic along their digestive tracts. Gut microbial communities can play a role in biodegradation and their composition can shift according to the type of plastic ingested. Shifts in molecular weights, chemical bond forming and breaking, and changes in thermal modification detected in the plastic debris present in the faeces also suggest active biodegradation. A few studies have also shown interactions other than ingestion, such as burrowing, may actively or passively promote physical plastic fragmentation by fauna. We suggest that further investigations into the role of fauna in physical fragmentation and chemical degradation linked to active ingestion and gut associated microbiota metabolism, respectively, should be conducted to better evaluate the impact of these mechanisms on the release of micro- and nano-plastic in the environment. Knowledge on macrofauna other than marine invertebrates and terrestrial soil dwelling invertebrates is particularly lacking, as well as focus on broader types of plastic polymers.

The coastal megacity Shanghai is located in the center of the Yangtze River Delta, a dominant flame retardants (FRs) production region in China, especially for organophosphate esters (OPEs). This prompted us to investigate occurrence and seasonal changes of atmospheric OPEs in Shanghai, as well as to evaluate their sources, environmental behavior and fate as a case study for global coastal regions. Atmospheric gas and particle phase OPEs were weekly collected at two coastal sites - the emerging town Lingang New Area (LGNA), and the chemical-industry zone Jinshan Area (JSA) from July 2016–June 2017. Total atmospheric concentrations of the observed OPEs were significantly higher in JSA (median of 1800 pg m⁻³) than LGNA (median of 580 pg m⁻³). Tris(1-chloro-2-propyl) phosphate (TCPP) was the most abundant compound, and the proportion of three chlorinated OPEs were higher in the particle phase (55%) than in the gas phase (39%). The year-round median contribution of particle phase OPEs was 33%, which changed strongly with seasons, accounting for 10% in summer in contrast to 62% in winter. Gas and particle phase OPEs in JSA exhibited significant correlations with inverse of temperature, respectively, indicating the importance of local/secondary volatilization sources. The estimated fluxes of gaseous absorption were almost 2 orders of magnitude higher than those of particle phase deposition, which could act as sources of organic phosphorus to coastal and open ocean waters.

In the present study, we have successfully formulated a dual heterojunction of g-C₃N₄/BiOCl@MXene-Ti₃C₂ (GCBM) which was found to be highly active in the visible region. GCBM was found to be highly efficient for the degradation of an antibiotic, tetracycline (TC) as compared to the individual constituting units; g-C₃N₄ and BiOCl. Maximum of 97% TC degradation rate was obtained within 90 min of visible light irradiation for initial concentration of 10 mg/L of TC. Optical analysis exhibited that the synthesized heterojunction showed high absorption in the complete spectrum. The reactive species specified by the scavenger study showed the major involvement of •O₂⁻ and •OH radicals. The charge transfer mechanism showed that 2 schemes were majorly involvement in which Z-scheme was formed between g-C₃N₄ and BiOCl and Schottky junction was formed between g-C₃N₄ and Mxene-Ti₃C₂. The formation of Schottky junction helped in inhibiting the back transfer of photogenerated charges and thus, helped in reducing the recombination rate. The synthesized photocatalyst was found to be highly reusable and was studied for consecutive 5 cycles that generalized the high proficiency even after repetitive cycles.

Asphalt-surfaced areas such as roads have been reported as major non-combustion sources of reactive organic compounds in urban areas. Emission of latter compounds from asphalt is exacerbated due to exposure to sunlight and high temperature, contributing to negative human and environmental health outcomes. Furthermore, loss of asphalt components over time is linked to bitumen's aging that reduces service life of roads. Here, we introduce a designed bio-grafted-silica nano-filler derived from wood pellet as a sink for latter volatile compounds in an asphalt mixture. Molecular modeling calculations showed the remarkable adsorptive activity of the bio-grafted silica for trapping select asphalt volatiles, especially for the sulfur-containing aromatics and the oxygen-containing aromatics. Laboratory experiment revealed that the bitumen modified with bio-grafted silica exhibited up to 23% lower signs of aging. Thermogravimetric analysis proved that the modified bitumen exhibited a 16% reduction in mass loss compared to neat bitumen. Dynamic vapor sorption analysis also showed bio-grafted silica adsorbed higher amounts of a candidate volatile than pristine silica. The study outcomes highlights the advantages of a bio-derived modifier in asphalt to address concerns associated with the loss of hazardous compounds.

Primitive electronic waste (e-waste) dismantling activities have been shown to be an important emissions source for a variety of toxic organic compounds, including carcinogenic polycyclic aromatic hydrocarbons (PAHs). Previous studies have found that some nitrated PAHs (NPAHs) are more toxic than their parent PAHs, however, little attention has been paid to the formation of PAH derivatives during e-waste processing and there is a lack of comprehensive data from field observations. In this study, the spatial distribution, temporal trends and atmospheric fate of NPAHs and hydroxylated PAHs (OH-PAHs) were investigated at typical e-waste dismantling sites, with monitoring data collected over three consecutive years. Compared to background levels, higher levels of NPAHs and OH-PAHs were found in air samples from an e-waste dismantling industrial park, with their seasonal and annual changes shown to be affected by e-waste dismantling activities. Atmospheric PM₂.₅ particles were found to have high relative abundances of NPAHs (76.9%–95.1%) and OH-PAHs (73.3%–91.6%), with particle-bound concentrations ranging from 20.1 to 88.8 and 37.1 to 107 pg m⁻³, respectively. The most abundant NPAH isomers were found to be 9-Nitroanthracene and 2-Nitrofluoranthene, while OH-PAH isomers containing 2–4 rings were predominant. Source identification was performed based on the specific diagnostic ratios of NPAH isomers, confirming that NPAH and OH-PAH emissions have multiple sources, including emissions related to the e-waste dismantling process, atmospheric photochemical reactions and traffic emissions. Further research on the fate of such derivatives and their potential use as markers for source identification, is urgently required.