In this study, we investigated the effects of SiO₂ nanoparticles (SiO₂-NPs) (1, 10, 25, 50, and 100 mg/L) for 24 h in vitro on the motility parameters and oxidative stress markers such as total glutathione (TGSH), catalase (CAT), and malondialdehyde (MDA) of rainbow trout, Oncorhynchus mykiss sperm cells. Therefore, SiO₂-NPs were synthesized with sol-gel reaction from tetraethoxy orthosilicate (TEOS). The prepared nanoparticle structures were characterized for chemical structure, morphology and thermal behavior employing Fourier transform infrared spectroscopy, X-ray spectroscopy, scanning electron micrograph, and thermal analysis (DTA/TGA/DSC) techniques. After exposure, there was statistically significant (p < 0.05) decreases in velocities of sperm cells. CAT activity significantly (p < 0.05) decreased by 9.6% in sperm cell treated with 100 mg/L. In addition, MDA level significantly increased by 70.4% and 77.5% in sperm cell treated with 50 and 100 mg/L SiO₂-NPs, respectively (p < 0.05). These results showed that SiO₂-NPs may have toxic effect on rainbow trout sperm cells in 50 mg/L and more.

Millispherical nanocomposites are promising for water decontamination combining the high reactivity of the confined nanoparticles and the excellent hydrodynamic properties of the supporting host. However, the effect of three-dimensional (3-D) distribution of the nanoparticles inside the host on the performance of the nanocomposite was highly dependent on the specific decontamination process. In this study, four D201-ZVI nanocomposites from peripheral to uniform 3-D distributions of nZVI were prepared to evaluate the effect of 3-D distribution of the confined nanoparticles inside the host beads on the removal of EDTA-chelated Cu(II). The performance of Cu(II) removal increased with the 3-D distribution tailoring towards the peripheral region, which was also validated under various solution chemistry conditions in terms of initial pH, DO, and coexisting sulfate. The mechanism underlying the 3-D distribution effect may be ascribed to three perspectives. First, the dissolution of Fe was also higher from the peripherally distributed nZVI nanocomposites compared with the uniform ones. In addition, SEM-EDS analysis revealed the immobilization of Cu occurred at limited depth from the outermost surface of the composite beads, leading to the low spatial utilization of the inner core region. Furthermore, XRD and XPS analyses demonstrated the higher chemical utilization of nZVI for the outer-distributed nanocomposites owing to the shortened pathway for mass transfer. This study shed new light on the design and development of tunable nanocomposites of improved reactivity for water decontamination processes.

The ecological footprint, a measure of human demand on earth’s ecosystems, represents the amount of biologically productive land and sea area that is necessary to supply the resources a human population consumes and to mitigate associated waste. This study estimates the impact of economic growth and natural resources on Pakistan’s ecological footprint using an autoregressive distributive lag (ARDL) model for long-run estimation. The empirical findings indicate that natural resources have a positive effect on an ecological footprint that deteriorates environmental quality and that natural resources help to support the environmental Kuznets hypothesis (EKC). Bidirectional causality is found between natural resources and the ecological footprint, along with a long-run causality between biocapacity and the ecological footprint. The innovative findings have important implications for policy.

This research work aims to develop a biomaterial entrapped with iron nanoparticles by green synthesis method in which biomass act as both reducing and capping agent. Iron nanoparticles embedded in Citrus limetta peels were characterised using ICP-MS for determination of metal loading, XRD, XPS for crystallinity and oxidation states, TEM followed by FESEM-EDS for particle size and morphology. Sizes of nanoparticles were found to be in the range of 4–70 nm. Batch experiments were conducted to study the effect of different parameters such as contact time, amount of biomaterial and volume of chromium(VI) solution for 2500 mg L⁻¹ of Cr(VI). Complete reduction was attained for a contact time of 5 min with 1.5 g of biomaterial for initial concentration of 2500 mg L⁻¹. The experimental results inferred that 1 g of biomaterial completely reduced 33 mg of hexavalent Cr to trivalent Cr. XRD and XPS revealed that iron nanoparticles are in amorphous form while XPS confirms Fe⁰ state. The transition of Fe⁰ to Fe²⁺/Fe³⁺ during the treatment with chromium solution confirms the reduction of Cr⁶⁺ to Cr³⁺.

Gadfly petrels (Pterodroma spp.) are one of the most threatened and poorly studied seabird groups, and as marine predators, are exposed to biomagnified and bioaccumulated chemical pollutants from their prey. We quantified trace element concentrations in breast feathers of seven petrel species that breed in the southern hemisphere to quantify current concentrations. Selenium (Se) concentrations were significantly lower in chicks than adults; this was not observed for zinc (Zn) or lead (Pb). Overall, the species examined here exhibited similar concentrations of Se, with Pb and Zn concentrations more variable among species. The mean Se concentration in adult birds exceeded those thought to be potentially deleterious, and three species had concentrations that were above the assumed threshold for Pb toxicity. Further investigation of potentially toxic trace elements in gadfly petrels is warranted.

Electronic waste (E-waste) can be considered as challenging solid waste streams especially in some developing countries, including Iran. Several alternatives for collecting and processing E-waste have been developed and applied throughout the world. In this research, a model was developed according to fuzzy-AHP approach for the evaluation of different alternatives for E-waste’s collection and processing in Tehran, Iran. Three alternatives for processing section (including recycling, exporting, landfilling) and three alternatives for collection section (door-to-door, special event, permanent drop-off) were studied in terms of different economic, social, technical, and environmental criteria. To establish a database in the current research, a questionnaire survey was performed and then the relative importance of each alternative in terms of each criterion was evaluated. The obtained results indicated that in the section of collection and processing of E-waste, permanent drop-off and recycling have the highest priorities among studied alternatives, respectively. Also, economic and environmental criteria were determined as the most significant ones in collection and processing sections, respectively. Furthermore, the developed model can be considered as a practical tool that will help the decision makers to determine the most appropriate E-waste management alternatives when diverse criteria are partially or completely in conflict.

The influence of flue gas composition on the specific resistance of coal-fired fly ash is studied in this paper. We conclude that the negative electrons of NO₂ and SO₂ gases are strong. The probabilities of electron desorption on SO₂ and NO₂ negative ions are lower than that in air atmosphere at high temperature. Therefore, the introduction of SO₂ causes NO₂ to reduce the specific resistance value of coal-fired fly ash. When the pores on the surface of fly ash particles are filled with SO₂, no change will occur in NO₂, average pore size, pore volume, and specific surface area of fly ash particles, thereby resulting in fly ash that remains unchanged from the resistance value. When humidity increases, the surface conduction effect is greatly enhanced, and the specific resistance value is lowered considerably. Therefore, the specific resistance of dust can be reduced by humidification.

The phosphorus (P) fraction and its release characteristics from sediment in response to flood events across different land covers (i.e., reclaimed land with dominant vegetation of Phragmites australis and/or Typha orientalis, grassland with dominant vegetation of annual and perennial forbs, and bare land) in the lakeshore of Chaohu Lake were investigated. The results indicated that the re-flooding of a restored wetland led to P release. IP (inorganic P) was the major P fraction in the soils pre-flood and post-flood. For all the soil samples, the rank order of P fractions was Ca-P (P associated with calcium) > OP (organic P) > Fe/Al-P (P bound to Al, Fe, and Mn oxides and hydroxides). During flooding, Fe/Al-P contributed the most as the P release source in the soils and to the P sources for the overlying water. In reclaimed land, Fe/Al-P release correlated significantly with soil pH. In grassland, Fe/Al-P release correlated significantly with soil pH and Al content. In bare land, Fe/Al-P release correlated significantly with Al and clay content. The max TP release rates were also significantly influenced by land cover, and the values in bare land, grassland, and reclaimed land were 9.91 mg P m⁻² day⁻¹, 8.10 mg P m⁻² day⁻¹, and 5.05 mg P m⁻² day⁻¹, respectively. The results showed that the P release processes might be regulated by different factors across different land covers, and that the re-introduction of vegetation during wetland restoration must be taken into account prior to flood events to avoid an undesirable degradation of water quality.

Düzce is one of the cities located in the western Black Sea region of Turkey with a population of 377,610 in 2017 (TUIK, 2017). There is no satisfying scientific information available to address the contribution of primary and secondary sources of carbonaceous aerosols to the observed PM₁₀ levels in the city. The main objective of the study is to determine the levels and sources of carbonaceous aerosols in PM₁₀. For this purpose, PM₁₀ samples were collected at urban and suburban locations in Düzce during winter and summer season in 2015. Average summer OC and EC concentrations in the urban area were 9.5 and 1.3 μg m⁻³, respectively, while the corresponding concentrations were observed as 28.5 and 2.3 μg m⁻³, respectively for winter season. Summer mean OC and EC levels at the suburban site were 5.46 and 0.37 μg m⁻³, respectively, while those for winter were found as 6.68 and 0.61 μg m⁻³.The contributions of OC and EC to measured PM₁₀ levels were found in the range of 10% to 60% and 1% to 7%, respectively, at the urban station while the associated contributions were in the range of 10% to 50% and 0.6% to 6%, respectively, at the suburban station. The concentrations measured during winter months in both areas were found to be higher than those measured during summer months. The EC tracer method was used in order to estimate the SOC contribution. The contribution of SOC concentrations to the total PM₁₀ mass was found to be higher during winter in the urban area and during summer in the suburban area.

Widespread contamination of agricultural soil with Cd and As has resulted in substantial transfer and accumulation of these toxicants in rice grains. In the present study, we investigated the effects of chicken manure application on Cd and As concentrations and As speciation in the rice grains grown under different water conditions by pot experiment. Under aerobic condition, the application of chicken manure increased soil pH and soil Eh during most of the growth period of rice. Consequently, the application of chicken manure has little effect on total Cd, slightly decreased total As and inorganic As of rice grains when applied at rate of 2.0%. Under intermittent irrigation condition, the application of chicken manure increased soil pH and decreased soil Eh during most of the growth period of rice. Thus, chicken manure decreased total Cd, As, and inorganic As of rice grains. Besides, there was increased reduction of Cd and As with increase in the amount of chicken manure applied. Under flooded condition, the application of chicken manure increased soil pH before heading but decreased soil pH after heading. The application of chicken manure dramatically decreased total and inorganic As in rice grains, and slightly decreased Cd of rice grains. There was increased reduction of total As concentration with the increase in the amount of chicken manure applied. Meanwhile, the inorganic As concentration was the lowest when the concentration of chicken manure was 1.0%.