The linkage between methane production activity and prokaryotic community structure in the soil within a shale gas field in China

Technology transfer for green investments: exploring how technology transfer through foreign direct investments can contribute to sustainable practices and reduced environmental impact in OIC economies

Estimating the asymmetrical influence of foreign direct investment is the primary goal of the current study. In addition, further controlled variables affect environmental degradation in OIC nations. Due to this, current research employs the asymmetric (NPARDL) approach and the data period from 1980 to 2021 to estimate about viability of the EKC (environmental Kuznets curve) theory. The study utilized greenhouse gas (GHG) including emissions of carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and ecological footprint as substantial parameters of environmental quality. A nonlinear link between foreign direct investments, trade openness, economic growth, urbanization, energy consumption, and environmental pollution with CO2, N2O, CH4, and ecological footprint in the OIC nations is confirmed by the study's outcomes, which however reveals inconsistent results. Furthermore, the results also show that wrong conclusions might result from disregarding intrinsic nonlinearities. The study's conclusions provide the most important recommendations for decision-makers.

Validation of environmental Philips curve in Pakistan: a fresh insight through ARDL technique

The tremendous increase of greenhouse gases puts adverse effects on environmental degradation, unemployment, and economic growth. Against this backdrop, and implementing the more recent estimation approach, the present study investigates the validity of the novel environmental Phillips curve (i.e., inverse relationship between unemployment and environmental degradation) carried by Kashem and Rahman (2020). The unique contribution of this research is to examine the three environmental indicators (CO₂, CH₄, and ecological footprint) as a dependent variable with the same independent variables, i.e., unemployment rate, energy consumption, economic growth, foreign direct investment, and globalization, from 1975 to 2014 in Pakistan. The results validate a negative relationship of unemployment rate with CO₂, CH₄, and ecological footprint in the long run that proves the existence of environment Philips curve for Pakistan. However, a positive association is observed for energy consumption and CO₂, CH₄, and ecological footprint. The positive connection of energy consumption and environmental indicators determined that not only CO₂ emissions rather CH₄ and ecological footprint play an equal role in environmental degradation. Furthermore, in the long run foreign direct investment improves environmental sustainability for CO₂, and ecological footprint thus proved the pollution halo hypothesis for Pakistan. Probing the effects of globalization that badly pollutes environmental sustainability. Therefore, the policymakers should focus on innovations and technological improvements to contemplate both environmental degradation and unemployment. There is a need for sudden actions for energy consumption plans in Pakistan for the nation's health, economic growth, and environmental sustainability.

Co-metabolic Effect of Glucose on Methane Production and Phenanthrene Removal in an Enriched Phenanthrene-Degrading Consortium Under Methanogenesis

Anaerobic digestion is used to treat diverse waste classes, and polycyclic aromatic hydrocarbons (PAHs) are a class of refractory compounds that common in wastes treated using anaerobic digestion. In this study, a microbial consortium with the ability to degrade phenanthrene under methanogenesis was enriched from paddy soil to investigate the cometabolic effect of glucose on methane (CH₄) production and phenanthrene (a representative PAH) degradation under methanogenic conditions. The addition of glucose enhanced the CH₄ production rate (from 0.37 to 2.25mg⋅L^-1⋅d^-1) but had no influence on the degradation rate of phenanthrene. Moreover, glucose addition significantly decreased the microbial α-diversity (from 2.59 to 1.30) of the enriched consortium but showed no significant effect on the microbial community (R ²=0.39, p=0.10), archaeal community (R ²=0.48, p=0.10), or functional profile (R ²=0.48, p=0.10). The relative abundance of genes involved in the degradation of aromatic compounds showed a decreasing tendency with the addition of glucose, whereas that of genes related to CH₄ synthesis was not affected. Additionally, the abundance of genes related to the acetate pathway was the highest among the four types of CH₄ synthesis pathways detected in the enriched consortium, which averagely accounted for 48.24% of the total CH₄ synthesis pathway, indicating that the acetate pathway is dominant in this phenanthrene-degrading system during methanogenesis. Our results reveal that achieving an ideal effect is diffcult via co-metabolism in a single-stage digestion system of PAH under methanogenesis; thus, other anaerobic systems with higher PAH removal efficiency should be combined with methanogenic digestion, assembling a multistage pattern to enhance the PAH removal rate and CH₄ production in anaerobic digestion.

Microbial community structure and co-occurrence are essential for methanogenesis and its contribution to phenanthrene degradation in paddy soil

Although polycyclic aromatic hydrocarbons (PAHs) degradation under methanogenesis is an ideal approach to remediating PAH-polluted soil, the contribution of methanogenesis to soil PAH elimination and the relationships between microbial ecological characteristics and PAH degradation during this process remain unclear. Here, we conducted a short-term (60 days) incubation using a paddy soil amended with phenanthrene and examined the effects of a specific methanogenic inhibitor (2-bromoethanesulfonate, BES) on this process. As treatment assessments, the methane production activity (MPA), phenanthrene degradation rate (PDR), and microbial ecological characteristics were determined. The results indicated that BES significantly inhibited both soil MPA and PDR, and we detected a positive relationship between MPA and PDR. Furthermore, BES significantly altered the soil microbial community structure, and it was the microbial community structure but not α-diversity was significantly correlated with soil MPA and PDR. BES decentralized the co-occurrence of bacterial genera but intensified the co-occurrence of methanogens. Moreover, certain bacterial taxa, including Bacteroidetes-vadinHA17, Gemmatimonas, and Sporomusaceae, were responsible for the MPA and PDR in this paddy soil. Collectively, these findings confirm the role of methanogenesis in PAH elimination from paddy soil, and reveal the importance of microbial co-occurrence characteristics in the determination of soil MPA and pollutant metabolism.

Trade-environment nexus in OIC countries: fresh insights from environmental Kuznets curve using GHG emissions and ecological footprint

Being closely correlated with income and economic growth, trade openness impacts the environmental quality through different means. The study analyzes the robustness of the environmental Kuznets curve (EKC) hypothesis in OIC countries by examining the extent to which trade openness influence environmental quality through different environmental indicators for the period 1991 to 2018. A new methodology dynamic common correlated effects (DCCE) is applied to resolve the issue of cross-sectional dependence (CSD). We have used greenhouse gas (GHG) emissions, carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) along with ecological footprint as indicators of environmental quality. Results of DCCE estimation identify a negative association of trade openness with CO₂, N₂O, and CH₄, while the positive relationship with the ecological footprint in overall OIC countries and higher income OIC countries. On the other hand, trade openness has a positive association with all environmental indicators in lower income OIC countries. Our findings confirm that inverted-U-shaped EKC exists in all groups of OIC countries when CO₂, CH₄, and ecological footprint are used as environmental indicators. However, a U-shaped EKC exists in overall OIC countries and lower income OIC countries when N₂O is used. Eventually, it is recommended that if OIC countries continue trade openness policies and energy sector reforms and maintain sustainable use of biocapacity; then, they will be able to combat environmental issues with the increase in income.