This study analyzes the impact of economic growth, energy consumption, trade openness, and tourism on environmental degradation measured by CO₂ emissions by using annual data of 112 countries for the period 1995 to 2017. Furthermore, the study also analyzes the relationship of the variables as mentioned above in four income and five regional groups of the world. The findings confirm the existence of environmental Kuznets curve (EKC), and level of income (turning point) is also determined, which helps in the improvement of the environmental quality of selected sample countries. The results of the overall sample show that economic growth, use of energy, and tourism are proved to be harmful to the environment, whereas the result of trade openness is not statistically robust. Results of sub-samples are mixed. Findings of this study highlight some essential steps which must be taken by the government and international environmental agencies for the protection of the environment through efficient utilization of energy and sustainable tourism.

Exposure to air pollution is known to increase the risks for cardiovascular, pulmonary and metabolic diseases. Growing evidences also indicated that air pollution exposure during pregnancy could negatively impact on early embryonic development and children’s health. We performed RNA sequencing to identify deregulated mRNAs in air pollution-exposed rat embryos. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were used to analyse the potential cellular functions of deregulated mRNAs. Our analysis indicated that a total of 1678 mRNAs were differentially expressed on gestation day 9 upon in utero exposure to fine particulate matter of > 200 μg/m³, among which 1098 mRNAs were downregulated and 580 mRNAs were upregulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed gap junction, cell adhesion, axon guidance and the neurotrophin signalling pathway as key biological processes perturbed by air pollution exposure. Furthermore, reconstruction of the mRNA regulatory network highlighted the central roles of Tbx4, Bmp4, Sox10, Wnt9b, Bmp7 and Foxc2. These data suggested that embryonic mRNA deregulation may underlie the formation of air pollution-associated congenital defects.

The principal objective of this study was to investigate the strengthened remediation effect and relevant mechanism of P. aeruginosa on ryegrass (Lolium multiflorum Lam.) for soil contaminated by Cu-Pb-Cd compound heavy metals. The results showed that the complex heavy metals’ contamination had remarkable inhibiting effect on the growth of plants (P < 0.01), and the biomass of ryegrass’s stem and leaves declined by 28.2%, while that of roots decreased by 34.7% after 45 days. The inoculation of P. aeruginosa promoted the growth of ryegrass in polluted soil, in which the biomass recovered to the same level of that in normal plant; the activity of both catalase and urease in the soil also increased strikingly (by 29.3% and 75.7%, respectively); the ratio of residual heavy metals in the soil decreased, while the acid extractable heavy metals increased notably. Therefore, the absorption and accumulation of ryegrass to the heavy metals in soil were improved to some extent; the bioconcentration factor of Cu, Pb, and Cd in ryegrass increased by 35.9%, 55.6%, and 283.5%, respectively. The exterior microorganism allowed the accumulation of Cu, Pb, and Cd in shoots of ryegrass increasing remarkably, while in roots, only the accumulation of Pb increased by 16.3%, and that of both Cu and Cd decreased. Besides, in the P. aeruginosa-inoculated system, the transfer factor of Cu and Cd in plants increased strikingly, while that of Pb decreased.

We have demonstrated the potential leaching of eight compounds, one insecticide (flonicamid) and seven fungicides (myclobutanil, penconazole, boscalid, difenoconazole, trifloxystrobin, pyraclostrobin and fenpyroximate) trough a typical Mediterranean soil (Calcaric regosol). The concentrations found in leaching water were in all cases above the limit set by the EU in groundwater (0.1 μg L⁻¹). For this, the efficiency of different homogeneous (photo-Fenton and photo-Fenton-like) and heterogeneous (ZnO and TiO₂) photocatalytic systems was tested in deionized water to choose the most appropriate treatment to remove pesticide residues from leaching water. The efficiency was in the order: ZnO + S₂O₈²⁻ (pH 7) > TiO₂+ S₂O₈²⁻ (pH 7) > ZnO (pH 7) > TiO₂ (pH 7) > Fe³⁺ (pH 3) > Fe³⁺ (pH 5) > Fe²⁺ (pH 3) > Fe²⁺ (pH 5). Thus, in the subsequent experiment we focus on the efficacy of solar heterogeneous photocatalysis (ZnO/Na₂S₂O₈ and TiO₂/ Na₂S₂O₈) on their removal from leaching water. A fast removal was observed for all pesticides at the end of the photoperiod, noticeably higher in the case of ZnO system, with the exception of flonicamid, a recalcitrant pesticide where the degradation rate only reached about 20% after 240 min of solar exposure. Although the mineralisation of the initial dissolved organic carbon was not complete due to the presence of interfering substances in the leaching water, the conversion rate under ZnO/Na₂S₂O₈ treatment was about 1.3 times higher than using TiO₂/Na₂S₂O₈.

Radionuclide sorption by natural and modified clays is extensively accepted to be an important process from the radioactive waste point of view. This work focused on modification of natural attapulgite with a layered double hydroxide to produce a novel chemisorbent for Sr²⁺, Ni²⁺, and Co²⁺ removal from multicomponent solution. The structural and surface characteristics of both attapulgite (ATP) and modified attapulgite (LDH-ATP) were investigated using XRD, FTIR, SEM, and thermal analysis. Comparison of sorption features of Sr²⁺, Ni²⁺, and Co²⁺ onto ATP and LDH-ATP was achieved; the results indicated that LDH-ATP was the most efficient sorbent for Sr²⁺, Ni²⁺, and Co²⁺. Kinetic studies established that the sorption is fast and reaching >90% within 30 min. The sorption of Sr²⁺, Ni²⁺, and Co²⁺ are well defined by non-linear pseudo-second-order model and controlled by an intra-particle diffusion mechanism. The diffusivity was determined using homogeneous surface diffusion (HSDM) model and found in the order 10⁻¹³ m²/min; this confirmed that the sorption of the three ions is chemisorption process. LDH-ATP can be employed as a candidate chemisorbent for the removal of some metal ions from waste solution.

Phytochemicals is considered one of the most effective and safe alternative therapy against oxidative linked lung diseases. Ellagic acid (EA), an important component of fruits, nuts, and vegetables, are partly responsible for their beneficial health effects against oxidation-related diseases. In the present study, we investigated the ameliorative effect of EA on lung damage induced by carbon tetrachloride (CCl₄) in Wistar male albino rats. Thirty-six male rats (n = 36, 8-week old) were divided into 4 groups, each with 9 rats. The groups were: Control group: received standard diet; EA group: administered with EA (10 mg/kg body weight, intraperitoneal); CCl₄ group: administered with CCl₄ (1.5 mg/kg body weight, intraperitoneal); EA+CCl₄ group: administered with EA and CCl₄. . The rats were decapitated at the end of experimental period of 8 weeks and the lung tissues were examined. CCl₄-induced rats showed elevation in the expressions of inflammatory proteins, nuclear factor kappa b (NF-κB), cyclooxygenase-2 (COX-2), and pro-inflammatory cytokine, tumor necrosis factor alpha (TNF-α); and the indicator of lipid peroxidation, malondialdehyde (MDA). Intraperitoneal administration of EA significantly reduced the levels of these markers. EA administration increased the protein expression levels of nuclear factor erythroid 2-related factor 2 (Nrf-2) and enhanced the activity of glutathione (GSH) and catalase enzyme (CAT). In addition, EA administration increased the expression levels of the executioner protein of apoptosis, caspase-3, and decreasing pro-survival protein, B cell lymphoma-2 (Bcl-2). In conclusion, these results establishes the protective role of EA in the treatment of lung damage and that in the future, this may have the potential to be used as a medication for the prevention or attenuation of lung diseases. Graphical abstract

Fluoride (F) is a necessary trace element in the human body, which would lead to some diseases if human body lacks or accumulates it excessively (1–1.5 mg d⁻¹). Fluoride contamination in sediments has become more and more serious, which has potential hazards to human body. In this paper, a novel sorbent (loess) was proposed to immobilize trace element F in sediment. The effectiveness of loess on F stabilization was evaluated by decreasing F bioavailability in contaminated sediment. The loess and the sediment were mixed at different proportions for stabilization. About 70 days after the application of loess, the soil column was subject to simulate acid rain leaching test to observe the leaching-migration of F, which can be used to predict the leaching migration of F in the study area. The results showed that when the loess dose was 5 kg, the loess converted highly effective fractions of F (i.e., water-soluble and exchangeable fractions) into a more stable state (i.e., residual state). After 30 days of leaching with HNO₃ solution with pH at 3.0, the lowest concentration of F was found in the leachate of soil column with 2 kg loess application. Correlation analysis showed that the F concentration in soil column profile was affected by CaCO₃, EC, pH, and OM, of which, pH and CaCO₃ have greater influence than other factors.

This study investigated the removal of selenite from wastewater using the fungus Asergillus niger KP isolated from a laboratory scale inverse fluidized bed bioreactor. The effect of different carbon sources and initial selenite concentration on fungal growth, pellet formation and selenite removal was first examined in a batch system. The fungal strain showed a maximum selenite removal efficiency of 86% in the batch system. Analysis of the fungal pellets by field-emission scanning electron microscopy, field-emission transmission electron microscopy and energy-dispersive X-ray spectroscopy revealed the formation of spherical-shaped elemental selenium nanoparticles of size 65–100 nm. An increase in the initial selenite concentration in the media resulted in compact pellets with smooth hyphae structure, whereas the fungal pellets contained hair like hyphae structure when grown in the absence of selenite. Besides, a high initial selenite concentration reduced biomass growth and selenite removal from solution. Using an airlift reactor with fungal pellets, operated under continuous mode, a maximum selenite removal of 94.3% was achieved at 10 mg L⁻¹ of influent selenite concentration and 72 h HRT (hydraulic retention time). Overall, this study demonstrated very good potential of the fungal-pelleted airlift bioreactor system for removal of selenite from wastewater. Graphical abstract

Bicycle-sharing is regarded as a new mode of transportation with low-carbon and low-cost advantages, which could effectively alleviate traffic congestion. Understanding the factors and influence paths that affect users’ willingness to adopt bicycle-sharing is of great importance. This study aims to investigate how users’ environmental concern affects their willingness to adopt bicycle-sharing through the impacts of attitude, subjective norm, and perceived behavior control. The research model was constructed based on the theory of planned behavior model and validated by empirical data collected from 988 users in China utilizing structural equation modeling technique. The results show that users’ environmental concern is positively and significantly related to their attitude (β = 0.593, p < 0.001), subjective norm (β = 0.358, p < 0.001), and perceived behavior control (β = 0.508, p < 0.001) toward adopting bicycle-sharing. In turn, users’ attitude (β = 0.496, p < 0.001), subjective norm (β = 0.209, p < 0.001), and perceived behavior control (β = 0.206, p < 0.01) toward adopting bicycle-sharing all positively affect the intention to adopt bicycle-sharing. Based on these results, policy implications for improving the users’ acceptance and usage rate of bicycle-sharing and suggestions for future research are discussed.

Water-soluble ionic species (WSIS) have been used as potential markers for different source(s) and underlining process(es) emitting and transforming atmospheric aerosols. PM₁₀ aerosol sampling was performed once in a week for a complete one year, at a mid-altitude urban and a low-altitude rural location simultaneously in the Dhauladhar region of the North-Western Himalaya. Aerosol samples were analysed for major WSIS (anions: F⁻, Cl⁻, NO₃⁻, PO₄³⁻ and SO₄²⁻; cations: Na⁺, NH₄⁺, K⁺, Ca²⁺ and Mg²⁺) using the ion chromatography system. Results showed that WSIS constitutes around 15% of PM₁₀ aerosol load in the region. SO₄²⁻ contributes the maximum (~ 50%) followed by NO₃⁻ (~ 12.5%) and NH₄⁺ (~ 12.5%) to the total concentration of WSIS analysed. During all the seasons, average concentrations of PM₁₀ and associated WSIS were observed to be higher over the rural location in comparison to the urban location. The total concentration of WSIS was found to be maximum during the winter season. Principal component analysis performed on the WSIS concentration dataset revealed four major sources of PM₁₀-associated WSIS viz. re-suspension of soil or local sediments; conversion of pollutant gases (SOₓ, NOₓ and NH₃) to particles, i.e., secondary inorganic aerosol formation; evaporative loss or re-suspension of inorganic (NPK) fertilizers’ residues and biomass/crop-residue burning emissions in the Dhauladhar region of the North-Western Himalaya.