In this study, we analyze the time-varying causality linkages between energy consumption, economic growth, and environmental degradation in 33 Organization for Economic Co-operation and Development countries, spanning the period 2000 to 2013. The curve causality approach provides evidence of a significant environmental Kuznets curve in 25 countries in the case of the ecological footprint and in 23 countries in the case of the Environmental Performance Index. However, out of them, only Italy, Slovakia, and South Korea have traditional environmental Kuznets curve, in the form of an inverted U–shaped curve. For the remaining countries, different forms of curves are valid. In particular, an N-shaped curve appears to be valid between income and environmental degradation for nearly half of the sample, i.e., for Austria, Belgium, Chile, Estonia, Finland, France, Germany, Hungary, Luxembourg, Netherlands, Sweden, Switzerland, New Zealand, Turkey, and the USA. Additionally, bidirectional causality relationships are confirmed among all covariates in most countries. In view of the results, some crucial policy implications would be suggested, such as sustainable development that aims to make a balance between economic growth and environmental protection.

Since nitrosamine disinfection by products is highly carcinogenic, they have attracted considerable attention due to their increased presence in ambient waterways and potable water supplies. For the present study, the potential formation of nitrosamines from corresponding precursor secondary amines during ozonation was investigated. The results revealed that five nitrosamines were observed during the ozonation of their corresponding secondary amines. The molar yields initially increased and then decreased with longer contact times and higher ozone doses. These phenomena indicated that ozone not only promoted nitrosamine formation but also degraded the formed nitrosamines. High pH had a positive influence on nitrosamine formation at room temperature. Further, coexisting substances including nitrate, nitrite, humic acid, and tert-butanol inhibited the generation of nitrosamines due to hydroxyl radical (·OH) competition and scavengers, whereas in the presence of hydroxylamine, nitrosamine formation increased considerably without ozone due to its capacity for independent formation between secondary amines and hydroxylamine. Further, the generation of nitrosamines from secondary amines was primarily attributed to O₃ and ·OH oxidation, which was produced through the decomposition of ozone. The transformation pathways were mainly comprised of the indirect routes between the O₃/·OH intermediates. The findings of this study were helpful toward expanding the knowledge of nitrosamine formation during the corresponding precursor secondary amine ozonation process.

Central nervous system is sensitive and vulnerable to microwave radiation. Numerous studies have reported that microwave could damage cognitive functions, such as impairment of learning and memory ability. However, the biological effects and mechanisms of accumulative microwave radiation on cognitive functions were remained unexplored. In this study, we analyzed differential expressed proteins in rat models of microwave-induced cognitive impairment by iTRAQ high-resolution proteomic method. Rats were exposed to 2.856 GHz microwave (S band), followed by 1.5 GHz microwave exposure (L band) both at an average power density of 10 mW/cm² (SL10 group). Sham-exposed (control group), 2.856 GHz microwave-exposed (S10 group), or 1.5 GHz microwave-exposed (L10 group) rats were used as controls. Hippocampus was isolated, and total proteins were extracted at 7 days after exposure, for screening differential expressed proteins. We found that accumulative microwave exposure induced 391 differential expressed proteins, including 9 downregulated and 382 upregulated proteins. The results of GO analysis suggested that the biological processes of these proteins were related to the adhesion, translation, brain development, learning and memory, neurogenesis, and so on. The cellular components mainly focused on the extracellular exosome, membrane, and mitochondria. The molecular function contained the protein complex binding, protein binding, and ubiquitin-protein transferase activity. And, the KEGG pathways mainly included the synaptic vesicle cycle, long-term potentiation, long-term depression, glutamatergic synapse, and calcium signaling pathways. Importantly, accumulative exposure (SL10 group) caused more differential expressed proteins than single exposure (S10 group or L10 group). In conclusion, 10 mW/cm² S or L band microwave induced numerous differential expressed proteins in the hippocampus, while accumulative exposure evoked strongest responses. These proteins were closely associated with cognitive functions and were sensitive to microwave.

Trees can be used as good indicators to evaluate the increase in atmospheric heavy metal concentrations. In the last two decades, air pollution in the city of Ankara has rapidly increased with the ever-increasing traffic density. In the present study, the depositions of aluminum (Al), zinc (Zn), copper (Cu), cobalt (Co), iron (Fe), manganese (Mn), chrome (Cr), cadmium (Cd), sodium (Na), calcium (Ca), barium (Ba), phosphor (P), magnesium (Mg), arsenic (As), and boron (B) in the rings of oak trees were analyzed using a GBC Integra XL–SDS-270 ICP-OES device. The study found that heavy metal concentrations in tree rings varied over the past 20 years; furthermore, there was a significant relationship between the heavy metal concentrations in tree rings and the atmospheric heavy metal concentrations. There was an increase in the concentrations of nutritional elements (Na, P, and Mg) in 2010 when there was excessive precipitation. As a result, the concentrations of all elements in the woods of different ages were significantly different at a confidence interval of 95% for As, 99% for Cd, and 99.9% for other elements.

China is a massive mercury emitter, responsible for a quarter of the world’s mercury emissions, which transit the atmosphere and accumulate throughout its watercourses. The Changjiang (Yangtze) River is the third largest river in the world, integrating mercury emissions over its 1.8 × 10⁶ km² catchment and channelling them to the East China Sea where they can be buried. Despite its potential global significance, the importance of the East China Sea as a terminal mercury sink remains poorly known. To address this knowledge gap, total mercury and methylmercury concentrations were determined from 51 surface sediment samples revealing their spatial distribution, whilst demonstrating the overall pollution status of the East China Sea. Sedimentary mercury distributions beneath the East China Sea are spatially heterogeneous, with high mercury concentrations (> 25 ng g⁻¹) corresponding to areas of fine-grained sediment accumulation. In contrast, some sites of fine-grained sediment deposition have significantly lower values of methylmercury (< 15 ng g⁻¹), such as the Changjiang estuary and some isolated offshore areas. Fine-grained particles and organic matter availability appear to exert the dominant control over sedimentary mercury distribution in the East China Sea, whereas in situ methylation serves as an additional control governing methylmercury accumulation. Estimated annual sedimentary fluxes of mercury in the East China Sea are 51 × 10⁶ g, which accounts for 9% of China’s annual mercury emissions.

Biochar is frequently applied for the reduction of mercury (Hg) migration in soil; however, most of the studies only focused on the adsorption capacity evaluation of fresh biochar. We investigated the Hg adsorption capacities of biochar prepared from wheat straw, corn straw, and sunflower seed shells. Biochar aging was simulated via natural aging, high-temperature aging, and freeze-thaw aging. The adsorption capacities of all the aged biochar were increased, and wheat straw biochar and seed shells biochar treated with high-temperature aging (wBC-Ha500 and sBC-Ha600) and corn straw biochar treated with freeze-thaw aging (cBC-Fta500) showed an observable improvement on the equilibrium adsorption amounts. The kinetics of the fresh biochar samples fitted the pseudo-first-order kinetic model and the pseudo-second-order kinetic model, while the kinetics of the aged biochar samples fitted the pseudo-second-order kinetic model. Biochar adsorption capacity increased with higher initial concentrations and increasing temperatures. Elemental analysis, Fourier-transform infrared spectroscopy (FT-IR) spectra, cation-exchange capacity (CEC), surface area (SA), zeta potential, and X-ray photoelectron spectroscopy (XPS) showed that the aging mechanism consisted of hydroxylation and carboxylation caused by the functional groups on the biochar surface. According to the different climatic zones in China, wheat straw biochar and seed shell biochar are suitable for the tropical zone and the subtropical zone, while corn straw biochar is more suitable for the cold and the mid-temperate zones.

Solutions with 0.65 mM of the antituberculosis drug isoniazid (INH) in 0.050 M Na₂SO₄ at pH 3.0 were treated by electro-Fenton (EF) and UVA photoelectro-Fenton (PEF) processes using a cell with a BDD anode and a carbon-PTFE air-diffusion cathode. The influence of current density on degradation, mineralization rate, and current efficiency has been thoroughly evaluated in EF. The effect of the metallic catalyst (Fe²⁺ or Fe³⁺) and the formation of products like short-chain linear aliphatic carboxylic acids were assessed in PEF. Two consecutive pseudo-first-order kinetic regions were found using Fe²⁺ as catalyst. In the first region, at short time, the drug was rapidly oxidized by ●OH, whereas in the second region, at longer time, a resulting Fe(III)-INH complex was much more slowly removed by oxidants. INH disappeared completely at 300 min by EF, attaining 88 and 94% mineralization at 66.6 and 100 mA cm⁻², respectively. Isonicotinamide and its hydroxylated derivative were identified as aromatic products of INH by GC-MS and oxalic, oxamic, and formic acids were quantified by ion-exclusion HPLC. The PEF treatment of a real wastewater polluted with the drug led to slower INH and TOC abatements because of the parallel destruction of its natural organic matter content.

Urban streams are degraded through multiple mechanisms, including severely altered flow regimes, elevated concentrations of waterborne contaminants, removal of riparian vegetation and the loss of a mosaic of heterogeneous aquatic habitats. Engineering of urban stream reaches using concrete is a widespread and extreme case of deliberate alteration of flow regimes and concomitant habitat simplification. To assess the effect of such engineering practices on stream ecosystems, we compared aquatic macroinvertebrate communities from concrete-lined engineered urban reaches, non-engineered urban reaches with natural substrates and reference reaches flowing through minimally disturbed forested subcatchments and with natural substrates, in the Sydney metropolitan region, Australia. The communities from all urban reaches were impoverished and distinctly different from more diverse communities in forested reference reaches. Despite low aquatic habitat heterogeneity, engineered urban reaches had very high abundances of Diptera and some other tolerant taxa. Diptera and/or Gastropoda were dominant in non-engineered urban reaches. Multivariate community structures were dissimilar between the urban reaches and forested reference reaches and between non-engineered and engineered urban reaches. However, the low family-level richness and SIGNAL scores in both urban reach types indicated they were severely ecological impaired, whether engineered or not. Most macroinvertebrate taxa in the regional pool that were hardy enough to inhabit urban reaches with natural substrates were also present in nearby concreted reaches. The results add weight to the growing evidence that in urban landscapes, regional-scale changes in water quality and flow regimes limit the establishment of diverse macroinvertebrate communities, which cannot be addressed through the provision of increased reach-scale habitat heterogeneity.

Wastewater from a limestone-gypsum wet desulfurization system cannot be directly reused or discharged due to its high suspended matter content and complex water composition. Desulfurization wastewater evaporation in flue gas is an effective way to dispose wastewater. Multicomponent soluble chlorine salts exist in the desulfurization wastewater. During the evaporation, chlorine enters into the flue gas due to volatilization, which accelerates the enrichment rate of the Cl⁻ concentration in the desulfurization slurry and leads to an increase in wastewater production. This study explored the chlorine migration of various chlorine salt solutions and typical desulfurization wastewater at high temperature during the evaporation process of concentrated wastewater by a laboratory-scale tube furnace and a pilot-scale system. Results showed that when NaCl-evaporated substance was heated, the chlorine ion hardly volatilized. For the evaporated substances of CaCl₂ and MgCl₂ solutions, some of the crystal water was lost, and hydrolysis occurred to generate gaseous HCl. NH₄Cl was easily sublimed, and the decomposition temperature was lowest. A pilot study on spray evaporation of desulfurization wastewater in flue gas showed that the particle size of the evaporated product increased and the main particle size was within 2.5–10 μm with increasing flue gas temperature. Increasing the mass ratio of gas to liquid significantly reduced the particle size of the atomized particles, thereby reducing the average particle size of the evaporated particles. The HCl concentration increased with increasing flue gas temperature. When the flue gas temperature was 350 °C, the concentration of HCl was 40 ppm, and the escape rate of chlorine in the desulfurization wastewater was approximately 30% using typical wastewater from a limestone-gypsum wet desulfurization system.

Stable Hg(II)-containing flue gas has been successfully simulated by the plasma oxidation of Hg(0), and an effective solution for Hg(0) mercury fumes was obtained by combining the plasma with a ceramic nanomaterial. Characterization tests showed that the ceramic nanomaterial was mainly composed of silicon dioxide (SiO₂) with other minor constituents, including potassium mica (KAl₃Si₃O₁₁), iron magnesium silicate (Fe₀.₂₄Mg₀.₇₆SiO₃) and dolomite (CaMg(CO₃)₂). The nanomaterial had many tube bank structures inside with diameters of approximately 8–10 nm. The maximum sorption capacity of Hg(II) was 5156 μg/g, and the nanomaterial can be regenerated at least five times. During the adsorption, chemical adsorption first occurred between Hg(II) and sulfydryl moieties, but these were quickly exhausted, and Hg(II) was then removed by surface complexation and wrapped into Fe moieties. The pseudo-first-order kinetic model and the Langmuir equation had the best fitting results for the kinetics and isotherms of adsorption. This work suggests that the ceramic nanomaterial can be used as an effective and recyclable adsorbent in the removal of gaseous Hg(II).