Earth is in the Anthropocene era and humankind deteriorates the global environment; thus, there is a dire need for sustainable policies at all levels. This study investigates the causal and long-run association between financial development, research and development expenditures, and carbon dioxide emission including energy intensity and income level for selected West Asia and Middle East (WAME) economies along the belt and road. The long-run panel estimation findings reveal that the research and development expenditures (R&D) are negatively associated with environmental degradation, as they significantly mitigate carbon emissions. In contrast, financial development contributes to environmental degradation. The findings validated the environmental Kuznets curve (EKC) phenomenon for the WAME economies considering R&D and financial development. Further, energy intensity exacerbates environmental quality. Additionally, the findings from Dumitrescu-Hurlin (DH) causal approach reveal bidirectional causal associations between financial development and carbon emissions and between R&D and emissions. The findings have implications for policy and practice to attain environmental sustainability in the selected WAME countries.

With the aim of developing generalized equation for predicting effect of pH on arsenic removal efficiency through adsorption process, this study presents experimental results on the arsenic removal efficiency using a natural sand (Skye sand which was earlier found to be very effective in removing arsenic from water) under varying pH conditions. Series of batch experiments were conducted with the Skye sand (naturally found in Victoria, Australia) as adsorbent and commercially available standard solution (diluted with deionised water) as arsenic contaminated water. It is observed that highest arsenic removal efficiency was achieved with arsenic contaminated water having a pH of 5.0, below and above which the removal efficiencies decreased following a convex parabolic pattern. Most of the other similar studies also found similar patterns with the varying pH values, achieving maximum Arsenic removal efficiencies for pH values ranging 4.0–8.0. All the experimental measured values of arsenic removals were converted to a standard scaling factor for pH, termed as “SFPH”. Study reveals that the SFPH values can be expressed as a second-order polynomial equation. Also, SFPH values for As(III) and As(V) are having insignificant differences.

The objective of the present study was the synthesis and characterization of chitosan-alginate-based cross-linked copolymer (CACC) for the effective removal of methylene blue (MB) from its aqueous solution. The CACC before and after the removal of MB was confirmed by in-depth characterization techniques. The thermal stability of the materials before and after adsorption of MB was determined by thermal gravimetric analysis. The solid–liquid phase interactions between CACC and MB during the adsorption/removal was observed employing several affecting operating parameters like the concentration of MB, CACC dose, pH, contact time and temperature were studied. Langmuir isotherm model described better MB adsorption onto CACC than the model of Freundlich model with determination coefficient R²-value of 0.990 in Langmuir equation. Thus, being an eco-friendly, biodegradable, biocompatible and low-cost material, the CACC could be a potential polymeric-based adsorbent for the effective removal of MB from its aqueous solution and wastewater.

Textile hemp (Cannabis sativa L.) is a non-edible multipurpose crop suitable for fiber production and/or phytoremediation on moderately heavy metal–contaminated soils. Experiments were conducted in nutrient solution to assess the short-term impact of silicon (Si), a well-known beneficial element, on plants exposed to 20 μM cadmium (Cd) in nutrient solution. Cd decreased plant growth and affected photosynthesis through non-stomatal effects. Cd translocation factor was higher than 1, confirming the interest of hemp for phytoextraction purposes. Additional Si did not improve plant growth after 1 week of treatment but decreased Cd accumulation in all organs and improved water use efficiency through a decrease in transpiration rate. Si had only marginal impact on Cd distribution among organs. It increased glutathione and phytochelatin synthesis allowing the plants to efficiently cope with oxidative stress through the improvement of Cd sequestration on thiol groups in the roots. Si may thus have a fast impact on the plant behavior before the occurrence of plant growth stimulation.

Consumption of meat from animals hunted with Pb ammunition can cause toxic accumulation with consequent health risks, even if relatively small amounts are consumed in each exposure. In El Palmar National Park, Argentina, invasive alien mammals, wild boar (Sus scrofa) and axis deer (Axis axis), are culled with Pb ammunition and their meat is consumed. In this study, we evaluated blood Pb concentrations in 58 consumers of culled game and examined Pb exposure risk according to their demographics, duty, and consumption habits. Likewise, the likelihood of exposure was evaluated by quantifying Pb concentrations in meat samples of seven culled axis deer. Twenty-seven participants (46%) had detectable blood Pb levels (limit of detection = 3.3 μg/dL), with an average 4.75 ± 1.35 μg/dL (geometric mean ± geometric S.D.); the average for all participants was 3.25 ± 1.51 μg/dL. Blood Pb concentrations were significantly higher in hunters, in participants who reported consuming game meat more than 5 times per week, and in participants who reported frequently consuming cured game meat (compared to cooked or pickled). Pb concentration varied significantly along the trajectory of the bullet in deer muscle, being highest at mid-point but with detectable Pb levels even in distant tissue samples (control), suggesting potential for dietary intake by consumers. These findings provide evidence of Pb exposure risk in consumers and emphasize the relevance of replacing Pb ammunition with non-toxic alternatives. This change would reduce dietary exposure in frequent consumers and allow the use of game meat as safe food for people whilst eliminating collateral risks to wild animals and the environment.

Although several studies explored the issue of CO₂/Ecological footprint convergence across the countries, study on biomass material footprint (BMF) convergence is scant. This study bridges this research gap by examining the “BMF convergence hypothesis” across 172 countries for the period from 1990 to 2017. To attain our objective, we use the novel Phillips and Sul (J Appl Econom 24(7):1153–1185, 2007a; Econometrica 75:1771–1855, 2007b) approach. We find that there is no evidence of convergence, while 172 countries are taken together. This implies that all the countries together are having different transition paths. Thus, Phillips and Sul test implements the clustering algorithms to identify the club convergence. Our results show the existence of six different steady-state (or club convergence) equilibriums for BMF. Thus, our findings show that climate change policies are required to be designed as per the existing clubs of the sample countries.

Bioavailability of environmental contaminants is attracting considerable scientific attention due to growing awareness of its importance for risk assessment. In this study, size-segregated airborne particles were collected from six point-source sites, an urban residential site, and a sub-urban site. Potential factors governing bioaccessibility of the particle-bound polycyclic aromatic hydrocarbons (PAHs) and organophosphorus esters (OPEs) in stimulated gastrointestinal and respiratory tracts were elucidated. Particle concentrations of PAHs and OPEs at the eight sites were 2.4-32.3 ng/m³ and 1.6-19.9 ng/m³, respectively. In fine particles (with aerodynamic diameter less than 2.5 μm), 4- to 6-ring PAHs were more strongly correlated with organic carbon (OC) than elemental carbon (EC); while 3- and 4-ring PAHs in coarse particles (2.5-10 μm) tended to associate with EC. OPEs mostly showed significant correlations with EC in both fine and coarse particles. OC and EC exerted a significantly restraining effect on the oral and inhalation bioaccessibility of most hydrophobic organic contaminants (HOCs) in fine particles due to sorption of HOC molecules to these components. Furthermore, the effects varied, which could depend either on the emission sources (for oral bioaccessibility of PAHs) or the physicochemical properties of HOCs (for bioaccessibility of OPEs and inhalation bioaccessibility of PAHs). Linear regression between OC/EC contents and HOC bioaccessibility indicated that EC should play a more important role in the inhalation bioaccessibility than the oral bioaccessibility. Particle size of airborne particles is a relatively less significant factor determining the bioaccessibility.

Suaeda salsa (L.) Pall., a typical halophyte plant in the Yellow River estuary, has high enrichment capacity for heavy metals. However, few studies have investigated the Cd absorption characteristics of S. salsa under different sediment burial and exogenous Cd input conditions, especially following the water-sediment regulation scheme (WSRS), which brought sediment burial and exogenous substances to the estuary. So, we established a greenhouse pot culture experiment with four sediment burial depths (0 cm, 3 cm, 6 cm, and 12 cm) and exogenous Cd input levels (0 mg·kg⁻¹, 0.5 mg·kg⁻¹, 1.0 mg·kg⁻¹, and 1.5 mg·kg⁻¹) and analyzed the leaf, stem, root, and total biomass; leaf, stem, and root Cd content; and storage, sediment Cd content, accumulation factor, root/leaf (R/L), root/stem (R/S), and stem/leaf (S/L) ratios to study the Cd absorption characteristics of S. salsa under the different sediment burial and exogenous Cd input. Results showed that high Cd content in roots, stems, and leaves was harmful to S. salsa growth, and then led to a decrease in biomass (characterized by stem, leaf, and total biomass). Suaeda salsa exhibited a survival strategy to deal with Cd toxicity, which involved the roots absorbing Cd from the sediment and storing it in stems and leaves (stem and leaf Cd content peaked at 0.5 mg·kg⁻¹ Cd input) at low Cd input, whereas roots stored more Cd and reduced Cd transport to stems and leaves at high Cd input. Therefore, we observed the maximum value of leaf (500.63 ± 19.15 g·m⁻²), stem (648.22 ± 50.08 g·m⁻²), and total biomass (1246.92 ± 55.49 g·m⁻²) in the treatment with 1.5 mg·kg⁻¹ Cd input and 3-cm sediment depth due to the Cd content in leaves and stems being relatively low. The accumulation factors of leaves, stems, and roots varied (0.39–0.99, 0.19–2.58, and 0.80–20.45, respectively), and most of the accumulation factors for roots and leaves and the R/L and R/S ratios were >1, which indicated that S. salsa had high enrichment levels of Cd, which mostly accumulated in the roots. Shallow or moderate burial depth was beneficial to S. salsa growth, but sediment burial was not beneficial to Cd absorption because the sum of leaf, stem, and root Cd storage was higher at 0-cm depth compared with the other depths. Variance analysis showed that the influence of Cd input on leaf, stem, root, and sediment Cd content and stem and root Cd storage was significant (P < 0.05), whereas sediment burial, interaction of sediment burial and Cd input on Cd content, storage, and biomass were not significant (P > 0.05). Therefore, we concluded that more attention should be paid to the control of sediment burial and heavy metal input, especially during the WSRS, in the Yellow River estuary.

The effects of the concentration of total suspended solids from municipal wastewater on the water infiltration process in a clayey soil were investigated as well as the suitability of infiltration models with different numbers of parameters. The experiment consisted of columns of soil of 20 cm long in which supply water and synthetic municipal wastewater with different concentrations of solids were applied. The soil was characterized with respect to particle size, porosity, soil and particle density, clay water-dispersed clay, and infiltration capacity. The accuracy of the Kostiakov, Kostiakov-Lewis, Horton, Phillip, Green-Ampt, and Swartzendruber infiltration models was assessed by using the statistical criteria: mean error (MAE), mean squared error (RMSE), determination coefficient (R²), index of agreement (d), and Akaike information corrected criterion (AICc). The results indicate that the application of wastewater rich in suspended solids reduces the macroporosity of the soil, due to the clogging of the pores, causing a reduction in the hydraulic conductivity of the saturated soil and the cumulative infiltration. Based upon the AICc, the Kostiakov-Lewis models proved to be the most appropriate, except for the treatment with the highest concentration of solids, in which the Swartzendruber model presented the lowest AICc. In general, the other statistical criteria corroborate this conclusion.