This study aims to analyze the impact of financial development, foreign direct investment, economic growth, electricity consumption, and trade openness on environmental quality for a panel of 59 Belt and Road Initiative (BRI) countries, over the period of 1980–2016. The presence of the environmental Kuznets curve (EKC) hypothesis is investigated. The cross-sectional augmented Dickey-Fuller (CADF) and cross-sectional Im, Pesaran, and Shin panel unit root test; the Westerlund cointegration test, the dynamic seemingly unrelated regression (DSUR) approach; and the Dumitrescu and Hurlin (Econ Model 29:1450–1460, 2012) panel causality approach are employed. It is found that the analyzed variables are stationary at first differences and are cointegrated. It is also found that an increase in financial development, foreign direct investment, and trade openness enhance environmental quality, while the increase in economic growth and electricity consumption degrade environmental quality. The presence of the EKC hypothesis for the selected panel countries is validated. Furthermore, the Dumitrescu-Hurlin (DH) panel causality test result confirmed the presence of bidirectional causality among economic growth, foreign direct investment, financial development, electricity consumption, and trade openness with environmental quality.

The photolysis of bis(2-ethylhexyl) phthalate (DEHP) under simulated sunlight in the presence of the natural water photoreactive constituents was investigated. The presence of nitrate or ferric ions facilitated the photodegradation of DEHP via oxidation by generation of •OH. The fulvic acids (FAs), at low concentrations, promoted the photolysis of DEHP via energy transfer from the photoreaction-generated ³FA*. However, the DEHP photolysis was inhibited with high concentrations of FAs since the excess FAs at the surface of solution could act as light screening agents to keep FAs in bulk solution from the light irradiation, further reducing the ³FA* generation. When low concentrations of FAs and chloride ions coexist, the reactive chloride species Cl• and Cl₂•⁻ could generate via energy transfer from ³FA* to chloride ions and react with DEHP to enhance its degradation. Furthermore, the direct and •OH-initiated DEHP photodegraded intermediates and end products were identified by HPLC-MS² and its corresponding photolysis pathways were proposed.

The use of pyrolysis to produce oil from sludge by the evaporation–condensation process is a promising technique. However, the resulting lipids are prone to be acidized under exposure to oxygen, which can affect their quality and use. To eliminate the need for this oil separation process, the present work uses blended pyrolysis to preserve the oil in the char and to prevent it from deteriorating. At the same time, metals are eliminated to a secure level of combustion emissions. The sludge was pyrolyzed into a sintering fuel through blended pyrolysis with SiO₂, Al₂O₃, and sand. These materials are the main components of the sintered ceramsite obtained. Therefore, the influence of these substances and residence time on lipid formation and metal residue in the char were investigated. Non-blended pyrolysis required a 40-min duration, whereas sand-pyrolysis required 10 min to achieve the same yield. The concentration of C₁₆:₀ produced by blended pyrolysis with sand reached 2177 mg kg⁻¹, which is 57% higher than that of non-blended pyrolysis. Blended pyrolysis with SiO₂ required at least 20 min to immobilize As metal. In summary, blended pyrolysis simplifies the process, reduces time, and produces char with lipid-rich and low metal leaching, which can be used as a sintering fuel.

Nitrogen loss in karst sloping farmland will lead to declining land productivity and environmental pollution, in which the nitrogen loss through underground pore fissures will directly lead to groundwater pollution. The characteristics of total nitrogen (TN) production were studied by simulating the “dual structure” microenvironment of sloping farmland in a karst region using an artificial rainfall simulation method. The results show that rainfall was the main driving factor of TN loss in karst sloping farmland. TN was mainly lost through underground pore fissures when the rainfall intensity was ≤ 30 mm · h⁻¹. TN was lost at the surface and underground when the rainfall intensity was ≥ 50 mm · h⁻¹, TN loss on the surface accounted for a large proportion, and the surface flow was the main carrier of TN loss. The TN loss underground is easily ignored because it is hidden underground. Therefore, TN loss belowground in karst sloping farmland should receive increased attention. It would be interesting to explore the influences of connectivity and type of underground pore fissure system on TN loss in karst sloping farmland. The prevention and control of TN loss in karst sloping farmland should be considered both at the surface and underground. Reducing the formation of slope flows and slowing rainwater filtration by increasing slope vegetation coverage can be considered to reduce TN loss. The results of this study provide a theoretical reference for agricultural non-point source pollution control in a karst region. Graphical abstract

The increasing trend of nanoparticle usage in science and technology has led to significant human exposure. Occupational exposure to iron oxides and silica dust has been reported in mining, manufacturing, construction, and pharmaceutical operations. The combined toxicological effects of nanoparticles and simultaneous exposure to other compounds have given rise to a new concern. Hence, the objective of this study was to investigate the toxicological effects of magnetite and polymorphous silicon dioxide nanoparticles in single and combined exposures. The polymorphous silicon dioxide nanoparticles were obtained from the milled quartz particles under 100 nm in diameter. The milled particles were purified through chloric and nitric acid wash processes. The toxic effects of the magnetite nanoparticles were investigated independently and in combination with quartz using the A₅₄₉ cell line for durations of 24 and 72 h, and using diverse concentrations of 10, 50, 100, and 250 μg/mL. MTT, ROS, mitochondrial membrane potential, and cell glutathione content assays were used to evaluate the amount of cell damage in this study. The statistical significance level in one-way ANOVA and independent t test was considered to be at the 5% confidence level. The size and purity of polymorphous silicon dioxide nanoparticles were measured by TEM and ICP-OES analysis, respectively. The particles’ diameters were under 100 nm and demonstrated a purity of higher than 99%. The toxicity results of this study showed a dependency on concentration and exposure duration in reducing the cell viability, cellular glutathione content, and mitochondrial membrane potential, as well as increasing the ROS generation in single and combined exposures with magnetite and polymorphous silicon dioxide nanoparticles. The toxic effects of combined exposure to these nanoparticles were less than the single exposures, and statistically significant antagonistic interactions were detected. Combined exposure to polymorphous silicon dioxide and magnetite nanoparticles, in comparison with their single exposures, could affect health in an antagonistic manner. Since this study has been the first of its kind, further studies investigating the health effects of single and combined exposures to these compounds are needed to verify our findings. Generally, studies such as this one could contribute to the field of combined toxicity effects.

A bibliometric analysis was performed to assess historical and recent research trends regarding e-waste studies from 1998 to 2018. Documents related to e-waste were identified from the Clarivate Analytics Web of Science© (WoS) database, and a total of 3311 academic articles was retrieved. The analysis was performed from four main aspects: (1) publication activity by year, by WoS category, and by geographic distribution; (2) journals; (3) most-cited papers; and (4) top 10 countries and author keyword analysis. The number of publications concerning e-waste issues has increased substantially over the last 20 years, especially in the environmental science category, and more than a third of the publications were produced in China (1181 records). Waste Management and Environmental Science & Technology were the most sought-after journals for disseminating the results. Studies related to “e-waste flow analysis,” “recycling,” “recovery of precious metals,” and “risk assessment of recycling areas” have been the most common for several years. The analysis of keywords suggested that there are many topics on electronic waste and that each country has presented a different focus of research. Overall, the bibliometric analysis proved to be an efficient tool with which to monitor historical and current research trends and to evaluate the sheer volume of currently existing scientific literature on e-waste topics.

In perspective of the issue of how to begin simultaneous nitrification, anammox, and denitrification (SNAD) rapidly, the sequencing batch biofilm reactor (SBBR) was adopted to enrich ammonia-oxidizing bacteria (AOB) and anammox bacteria (AnAOB) rapidly and to inhibit nitrite-oxidizing bacteria (NOB) after three phases (67 days) of culture, and the impacts of different low carbon-nitrogen ratios (COD/N) on denitrification performance of the process were investigated. The results showed that preventing the accumulation of nitrite (NO₂⁻-N) was the key to start SNAD successfully. The removal efficiencies of ammonia nitrogen (NH₄⁺-N) and total nitrogen (TN) in the system can reach more than 99% and 90%, respectively. Corresponding to COD/N = 0, 1 and 2, removal efficiencies of NH₄⁺-N were 99.6%, 99.5%, and 98.5% respectively and removal efficiencies of TN were 93.8%, 97.2%, and 98.1%, respectively; the total nitrogen removal rate (TNRR) was greater than 0.29 kg N m⁻³ day⁻¹. It indicates that the presence of a small amount of COD is beneficial to the denitrification of NO₃⁻-N without affecting the effect of simultaneous nitrification and anaerobic ammonium oxidation, which further improves the efficiency of nitrogen removal. High-throughput sequencing analysis showed that the ratios of AOB, AnAOB, and denitrifying bacteria were 7.3%, 20.1%, and 7.66%, respectively. Candidatus Kuenenia was the only genus of the SNAD reactor with anaerobic ammonium oxidation. AOB, Anammox, and heterotrophic denitrifying bacteria were present in the system, while ammonia oxidation and anaerobic ammonium oxidation played a dominant role in the denitrification process.

Green sorption media, which includes the utilization of renewable and recycled materials, can be used as a means for nutrient and copper removal in various low-impact development facilities. In this study, a green sorption media mixture consisting of recycled tire chip, expanded clay, and coconut coir was physiochemically evaluated for copper removal potential in stormwater runoff to deepen the understanding of its application potential. Isotherm, reaction kinetics, and life expectancy tests were conducted using both the media mixture and the individual components of the green sorption media. In addition, the media mixture was analyzed to determine its life expectancy. Isotherm test results revealed that the media mixture follows the Freundlich model and that the coconut coir had the highest affinity for copper. Distinct dynamic adsorption models were explored to determine the most suitable model for implementation based on a column test data set. Five dynamic adsorption models, including the Thomas, Clark, Bohart-Adams, Wolborska, and modified dose-response models, were investigated and the media mixture data collected in the column test were fitted into these five models, leading to the selection of the best model with the highest correlation. The modified dose-response model outperformed others in terms of the overall media mixture and the coconut coir. Life expectancy estimation showed that the media mixture has a life span of 2.13 years with the chosen influent conditions and can be applicable for improving the performance of water quality management in stormwater detention and retention ponds, bioswale, and other stormwater best management practices.

Sodium alginate (SA) is a linear biopolymer, which is the nontoxic, biodegradable, and rich in carboxyl and hydroxyl groups. In the paper, the SA-based hydrogel bead was prepared by the cationic hectorite clay and anionic sodium alginate with a simple ionic gelation method under freeze-drying, and the adsorption properties were evaluated by the removal of copper ions from aqueous solutions. The composites were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm (BET), thermal analysis (TG), and Fourier transform infrared spectroscopy (FT-IR). The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data and the Langmuir, Freundlich, Dubinin–Radushkevich (D-R), and Temkin models were applied to describe the adsorption isotherms. The results showed that the adsorption process was found to follow the Freundlich isotherm model and the maximum sorption capacity was observed to be 160.28 mg/g under the initial concentration from 10 to 700 mg/L at 45 °C. Adsorption kinetics data fitted well with pseudo-second-order rate model. The porous structure of the composite was responsible for the adsorption of Cu²⁺ ions. But the adsorption ability could be improved by pH. Finally, the adsorption mechanism was suggested. Graphical abstract

Honeybee (Apis mellifera L.) provides not only bee products of immense value but also render invaluable free service as cross-pollination and propagation of several cultivated and wild species, thereby, maintaining biological diversity. Bee larvae and adults might be killed or suffer various sublethal effects when placed in contact with pollen and nectar contaminated with insecticides. The present work was conducted to investigate the toxicity of seven insecticides on laboratory using oral toxicity test and their side effects on A. mellifera in cotton fields. Results indicated that lambda-cyhalothrin was the most toxic-tested pesticide, recording the lowest LC₅₀ and LC₉₀ values at all tested periods and the lowest LT₅₀ and LT₉₀ at all tested concentrations, followed by abamectin, spinosad, chlorpyrifos, and emamectin benzoate. On the other side, dipel and pyridalyl recording the highest LC₅₀ and LC₉₀ at all tested periods and the highest LT₅₀ and LT₉₀ at all tested concentrations. As for the application of pesticides in cotton fields, the tested pesticides significantly increased the number of dead workers in comparison with control. The tested pesticides significantly decreased bee foraging activities, i.e., number of foraging workers, number of worker collecting nectar, number of worker gathering pollen grains, area of broad workers, and honey bee yields. Dipel and pyridalyl were the most safety pesticides on honey bee workers in laboratory and field, so it could be introduced as a component in IPM programs of cotton pests.