Highly porous biochar (BC) structures have been prepared from inexpensive biomasses like rice straw, bamboo, sugarcane waste, and corn cob via a slow pyrolysis technique in nitrogenous atmosphere. A surface engineering technique has been applied to enhance the surface-to-volume ratio of each biochar sample and finally compared its characteristics through standard surface and elemental characterization techniques, viz. CHN (carbon, hydrogen, and nitrogen), FTIR (Fourier transform infrared spectroscopy), BET (Brunauer–Emmett–Teller), and SEM (scanning electron microscopy). All the biochar samples were observed to be highly carbonized and aromatized. Exfoliated structures were found to contain more elemental carbon (34.14–77.32%) than its native form (30.92–74.46%). Aromatic hydrocarbon, aromatic C=C, aromatics, aliphatic C–O, aliphatic hydrocarbon, and H-bonded OH groups were found to predominate in the surface of biochar structures independent of their precursor composition and extent of exfoliation. SEM micrographic images clearly ensured about the unoriented sheets like the morphology of different biochar samples. Although no significant structural difference was found to exist depending on their precursor compositions, quantitative enhancement of porosity was found to be observed after exfoliation. Both native (240.65 m²/g) and exfoliated (712.89 m²/g) biochars derived from sugarcane wastes were observed to have a maximum surface area in comparison to the biochars derived from rice straw (native, 22.08 m²/g; exfoliated, 29.92 m²/g), bamboo (native, 42.08 m²/g; exfoliated, 248.38 m²/g), and corn cob (native, 136.62 m²/g; exfoliated, 221.71 m²/g). Exfoliated biochars were found to be consistently more potent in comparison to its native form as per our comparative characterizations performed so far.

Petroleum hydrocarbons are potentially toxic for organisms due to the inherent properties, such as solubility, volatility, and biodegradability. The petroleum materials released from corroded old pipelines would pollute soils, shallow groundwater and air as a consequence, and threat the health of human and environment. Therefore, the removal of these compounds from environment is vital. The stability of these pollutants at the soil and their gradual accumulation over time would disrupt the normal function of the soil, such as reduced agricultural capability. In this research, the influence of two plant species (Bromus tectorum L. and Festuca arundinacea) with different amendments including arbuscular mycorrhizal fungi, alfalfa residues, and nutrient solution on the degradation rate of petroleum hydrocarbons in soil was studied. The results showed that the most effective treatment for petroleum remediation was related to B. tectorum L. plant when treated with mycorrhizal fungi and nutrient solution. The degradation rate during 40 days was about 83.27% when compared to the control. Arbuscular mycorrhizal associations are important in the restoration of degraded ecosystems because of the benefits to their symbiotic partners. This fungal phytotechnological mechanism is still in its infancy and there has been little research on aged-contaminated soils.

Traditional composting processes must be conducted with a bulking agent to ensure adequate air space for aeration. The bulking agent and composting materials are always completely mixed. A novel layered structure was introduced in sewage sludge composting, in which no bulking agent was used and bamboo charcoal was used as a separating material. Three lab-scale composting reactors (A: sawdust and sludge; B: bamboo charcoal and sludge; and C: sawdust, bamboo charcoal, and sludge) were continuously operated for 29 days. Several physicochemical parameters were investigated to evaluate the feasibility of layered composting with bamboo charcoal. The results indicated that the maximum temperatures during the thermophilic stage in treatments A, B, and C were 51.4, 50.9, and 51 °C, respectively. Layered composting with bamboo charcoal decreased the pH of the thermophilic stage from 8.98 in A to 8.75 in C, and delayed the peaks by about 120 h. The degradation rates of dissolve organic carbon (DOC) and dissolved nitrogen (DN) were 75 and 71.5% in treatment B, respectively, which were significantly higher than those of control group A (60 and 59.1%, respectively). The total NH₃ emissions of treatment C (2127.8 mg) were significantly lower than those of A (2522.8 mg). Our results suggested that layered composting using bamboo charcoal as a separating material could be an alternative strategy to the traditional composting method. Moreover, layered composting combined with sawdust could effectively reduce NH₃ emissions and N loss.

Oxidation flow reactors (OFRs) are increasingly used to study the formation and evolution of secondary organic aerosols (SOA) in the atmosphere. The OH/HO₂ and OH/O₃ ratios in OFRs are similar to tropospheric ratios. In the present work, we investigated the production of SOA generated by OH oxydation and ozonolysis of limonene in OFR as a function of OH exposure and O₃ exposure. The results are compared with those obtained from the simulation chambers. The precursor gas is exposed to OH concentrations ranging from 2.11 × 10⁸ to 1.91 × 10⁹ molec cm⁻³, with an estimated exposure time in the OFR of 137 s. In the environmental chambers, the precursor was oxidized using OH concentrations between 2.10 × 10⁶ and 2.12 × 10⁷ molec cm⁻³ over exposure times of several hours. In the overlapping OH exposure region, the highest SOA yields are obtained in the OFR, which is explained by the ozonolysis of limonene in the OFR. However, the yields decrease with the increase of OHexp in both systems.

Iron oxidation and reduction have important effects on soil organic carbon conversion in paddy soil during flooding and dry conditions. This study selected two paddy soil samples, one from the city of Yueyang of Hunan Province and one from the city of Haikou of Hainan Province, that differ significantly in iron content. During a 25-day incubation, the effects of Fe(II) and Fe(III) contents and changes in the levels of several major iron forms on soil dissolved organic carbon (DOC) levels and emission of CH₄ and CO₂ were observed. The ratio of Fe(II) content to all active Fe increased with an increase in Fe(II) content after soil flooding, and the proportion of all active Fe was significantly higher in the soil samples from Yueyang than in those from Haikou. In only 5 days, 92% of Fe(III) was converted to Fe(II) in Yueyang soil samples, and almost all Fe(III) had been transformed into Fe(II) by the end of incubation. Similar behaviors occurred in soil samples collected from Haikou, but Fe(II) represented only 59% of the active Fe by the end of incubation. In total, 2.2 g kg⁻¹ of organic carbon in the Yueyang soil sample was converted to CO₂ and CH₄, and the DOC content increased to 410% of its initial value by the end of incubation. In the Haikou soil, only 0.7 g kg⁻¹ of organic carbon was converted to CO₂ and CH₄, and its DOC content increased to 245% of its initial value by the end of incubation, which was a much smaller increase than observed for the Yueyang sample. Decomposition of organic carbon in the soil was closely related to iron reduction, and reduction of iron in soil significantly affected the conversion rate of organic carbon in soil.

This paper examines the relationship between carbon emissions and international tourism growth through the channels of globalization, energy consumption, and real income via testing the environmental Kuznets curve over the periods of 1995 to 2014 for 15 selected tourism destination states that prioritized tourism as a means of maximizing economic growth. Using the panel data analysis, results confirm globalization-tourism-induced EKC hypothesis for tourist destination states. This implies international tourism growth and carbon emissions, through the channels of energy consumption, globalization, and real income, are in a long-term equilibrium relationship. International tourism and squared term of real income have an inverse significant effect on carbon emission level, while energy consumption, globalization, and real income without squared term exert positive and significant effects on carbon emission level in the long-run. Thus, globalization-tourism-induced EKC hypothesis is suggested with credible policy suggestions in the case of tourist destination states.

The cultivation of tobacco has serious consequences for the environment: it impoverishes the soil by assimilating its nutrients, it involves an intensive use of highly polluting pesticides, it perturbs the ecosystem through deforestation, and it releases nicotine into the environment, which is toxic for humans. Italy is the first producer of raw tobacco in Europe and the Valtiberina area is among the most profitable. The first cultivations can be reconducted to the period around 1400. The objective of this experimental work is to verify the sustainability of tobacco cultivation near other crops using nicotine as an indicator. The nicotine on medicinal and wild plants adjacent to tobacco crops has been analyzed, assessing whether it is present or not and which is the concentration. To measure the nicotine present with ultra-high-performance liquid chromatography (UHPLC), LC/MS (liquid chromatography-mass spectrometry) method was used with LOQ (quantification limit) of 0.005 mg/kg. A total of 300 lots of aromatic herbs were sampled, and nicotine was detected in 82.3% of the samples in 2015 and 62.9% in 2016. Furthermore, in 2015, 121 samples of wild material were analyzed, of which 88.4% showed traces of nicotine. These first results indicate a possible potential threat for the population health. This shows that the tobacco cultivation should not be in close proximity to other plantation destined for nutrition, neither for man and nor animals. The elevated impact of nicotine on the ecosystem has negative consequences not only for the economy but it is also a potential public health threat.

As the largest oil field in China, Daqing oil field has been developed in the past six decades. The objectives of this study were to measure the levels of polycyclic aromatic hydrocarbons (PAHs) and assess their ecological risk of PAHs in vegetation soil and bare soil near oil well in Daqing and surrounding soil. Ten sites were selected from two types of soil in grassland: vegetation soil (VS, n = 5) and bare soil (BS, n = 5). The mean concentration of 16 PAHs (∑₁₆ PAHs) was 2240.2 μg/kg. The mean concentrations of eight carcinogenic PAHs (∑₈c PAHs) was 1312.3 μg/kg which accounts for 59% of ∑₁₆ PAHs. The sampling sites had higher proportions of high weight molecular ringed PAHs with higher proportions of benzo (a) pyren (BaP) and benzo (k) fluoranthene (BkF). The main source of PAHs was petroleum, coal/biomass combustion, and vehicular emission in these sampling sites. According to Canadian soil quality guidelines, 60% sites had a significant risk to human health. Moreover, 50% sites had high ecological risk and 30% sites were close to this critical value. Notably, PAH levels were significantly higher in VS than BS; moreover, VS had higher organic matter (OM) content, soil dehydrogenase (sDHA) activity, and lower pH and salt content. A structural equation model was established to explore the effects of soil properties on PAH concentration in VS. The result revealed that OM and sDHA were meaningful to enhance the adsorption and biological fixation of PAHs. This study will provide basic information on PAH level and potential application for phytoremediation.

Economic policy uncertainty (EPU) will affect the external business environment of economic entities, which in turn affects the decision-making of economic entities. Meanwhile, carbon emissions are closely related to the production decisions of microeconomic entities. Thus, studying the relationship between EPU and carbon emissions helps to clarify the impact of institutional factors behind carbon emissions, which is significant for achieving green development. Based on US sector data, we apply a novel parametric test of Granger causality in quantiles to analyze the relationship between EPU and carbon emissions (its growth and uncertainty). We find that there is an outstanding pattern of Granger-causality from the US EPU to the growth of carbon emissions in the tails of the growth distributions of carbon emissions in the industrial sector, residential sector, electric power sector, and transportation sector, except in the commercial sector. That is, carbon emissions are affected by EPU when the growth of carbon emissions is in a higher or lower growth period. Lastly, we find that the US EPU affects carbon emissions uncertainty over the entire conditional distribution for all sectors.

It is well documented that carbon emissions can be reduced by replacing conventional energy resources with renewable energy resources; thereby, the role of green technology is essential as it protect natural environment. Given that, the United Nations’ agenda of “green is clean” may be achievable by adoption of green technologies. The objective of the study is to examine the link between information and communication technology (ICT), economic growth, energy consumption, and carbon dioxide (CO₂) emissions in the context of South Korean economy, by using a novel Morlet wavelet approach. The study applies continuous wavelet power spectrum, the wavelet coherency, and the partial and the multiple wavelet coherency to the year during 1973–2016. The outcomes reveal that the connections among the stated variables progress over frequency and time domain. From the frequency domain point of view, the current study discovers noteworthy wavelet coherence and robust lead and lag linkages. From the time-domain sight, the results display robust but not consistent associations among the considered variables. From an economic point sight, the wavelet method displays that ICT helps to reduce environmental degradation in a medium and long run in the South Korean economy. This emphasizes the significance of having organized strategies by the policymakers to cope up with 2 to 3 years of the occurrence of the huge environmental degradation in South Korea.