Based on the time series data of the Yangtze River Delta region from 1993 to 2015, this paper uses the state space model and the mediating effect model to investigate the time-varying effect and its mechanism of financial development (measured by two indicators: financial scale and financial efficiency), urbanization on carbon emissions. The results show a positive in the short term and negative in the long-run impact of financial scale on carbon emissions, while the impact of financial efficiency on carbon emissions is negative in the short term and positive in the long term, and the impact of urbanization on carbon emissions is always positive. Moreover, the results of mediating effect test demonstrate that urbanization is a positive partial mediating effect in the path of financial scale and financial efficiency influencing carbon emissions, and the mediating effect accounts for 71.64% and 61.69% of the total effect, respectively. The mediating effect of financial development includes chain effect and parallel effect; in the chain mediating effect, financial scale has a negative mediating effect with 27.40% of the total effect in the path of urbanization affecting carbon emissions, whereas financial efficiency plays a positive role with 2.07%; in the parallel mediating effect, the individual effect of financial scale and financial efficiency accounts for 24.39% and 1.05%, respectively.

Arsenic (As) is often found naturally as the co-contaminant in the uranium (U)-contaminated area, obstructing the bioremediation process. Although the U-contaminated environment harbors microorganisms capable of interacting with U which could be exploited in bioremediation. However, they might be unable to perform with their full potential due to As toxicity. Therefore, potential in arsenic resistance and oxidation is greatly desired among the microorganisms for a continued bioremediation process. In this study, arsenic-resistant bacteria were isolated from U ore collected from Bundugurang U mine, characterized and their As oxidation and U removal potentials were determined. 16S rRNA gene sequencing and phylogenetic analysis showed the affiliation of isolated bacteria with Microbacterium, Micrococcus, Shinella, and Bacillus. Except Bacillus sp. EIKU7, Microbacterium sp. EIKU5, Shinella sp. EIKU6, and Micrococcus sp. EIKU8 were found to resist more than 400 mM As(V); however, all the isolates could survive in 8 mM As(III). The isolates were found to readily oxidize As under different culture conditions and are also resistant towards Cd, Cr, Co, Ni, and Zn. All the isolates could remove more than 350 mg U/g dry cells within 48 h which were found to be highly dependent upon the concentration of U, biomass added initially, and on the time of exposure. Ability of the isolates to grow in nitrogen-free medium indicated that they can flourish in the nutrition deprived environment. Therefore, the recovery of isolates with the potent ability to resist and oxidize As from U ore might play an important role in toxic metal bioremediation including U.

Financial development is important for the growth of a country which indirectly affects the environment adversely through industrialization. However, in the presence of strong institutions, this adverse effect can be reduced. The main concern of the present study is to estimate the relation between CO₂ and financial development (FD) in the presence of economic institutions as an interactive term. A sample of 101 countries has been selected for econometric analysis for the period from 1995 to 2017. The cross-section dependence test statistics for dependency, CIPS and CADF for panel unit root test, Westerlund test to ascertain the long-run affiliations, and FMOLS to extract the long-run coefficients have been applied. Dumitrescu and Hurlin test is also employed to know about the causal nature of the panel series. The findings show that financial development has a positive relationship with CO₂. However, after inclusion of economic intuitions, the adverse impact of financial development on the environment is reduced. The study also confirms the presence of environmental Kuznets curve in the context of income and financial development. The findings imply that financial development can help to improve environment quality if it is accompanied with strong institutional framework such as assurance of property rights, government integrity, and liberalization in financial sector.

A problem that has been dragging in recent decades is the final disposal of the waste produced in the wastewater treatment process. In addition to its high amount of organic matter and nutrients, this waste, known as sewage sludge (SS), may also contain toxic compounds that, when in the environment, can cause deleterious effects to organisms and lead to severe and irreversible consequences to human health. In order to understand the potential of inducing cellular and chromosomal instabilities, the species Allium cepa was employed to assess the presence of toxic agents in SS samples. Seeds of A. cepa were exposed to several dilutions of aqueous extract of SSs from 5 wastewater treatment plants (WWTPs), whose characteristics of treated sewage and the technologies employed differ among them. The results obtained showed that all the studied SSs induced significant genotoxic and mutagenic alterations, even in smaller dilutions tested. With these results, it was also possible to observe that SSs from WWTPs that present system of activated sludge and receive sewage of industrial origin induced a greater number of toxicogenetic alterations in the test organism. The high frequencies of chromosomal and nuclear aberrations observed, induced by contaminants present in the SS, represent worrying results because it proves a direct action of this agent on the genetic material of the exposed organism. Therefore, the agronomic application of SS in agriculture requires additional and more effective technologies in order to promote its complete decontamination and its safe disposal in the environment.

This paper involves discovering effective and better reaction of the diesel engine at various velocities by having ideal values in a short period. Therefore, gene expression programming is used for modeling and presenting governing expression for the related factors. The effective parameters consist of engine speed, intake air temperature, rate of air over fuel, fuel mass, NOx emission, mechanical efficiency, and immediate infusion diesel engine used as a part of demonstrating. Gene expression programming and its values exactly predict output results and present precise formula. Moreover, the sensitivity analysis was performed to recognize the effectiveness of the factors for reducing NOx and increasing mechanical efficiency. In the sensitivity analysis, the methods such as partial correlation coefficient, standard regression coefficient, and the Sobol’-Jansen and distributed evaluation of local sensitivity analysis are all used. The obtained results show that air/fuel rate is more influential factor in both NOx emission and mechanical efficiency. Moreover, the difference between results of standard regression or partial correlation coefficients and Sobol’-Jansen or distributed evaluation methods is in nonlinearity effect or interactions among the factors.

The presence of cacodylic acid (dimethylarsinic acid, DMA) can be an important factor in limiting the abilities of young tree seedlings to adapt to unfavorable environmental conditions. For this reason, the aim of the study was to estimate the influence of different DMA additions (from 0.01 to 0.6 mM) to modified Knop solution to arsenic (As) and selected forms of this metalloid (As(III), As(V), DMA) phytoextraction by two-year-old Acer platanoides L. and Tilia cordata Miller seedlings. Additionally, the biomass and other elements important in As transport in plants were analyzed. Seedlings of both tree species were able to grow in all experimental systems except the one with the highest DMA concentration (0.6 mM). Exposure of tree seedlings was related to a general decrease in plant biomass. Phytoextraction of As in roots, stems, and leaves increased with a rise of DMA concentration in solution to the highest content of As in A. platanoides and T. cordata roots growing under 0.3 mM (135 ± 13 and 116 ± 14 mg kg⁻¹ dry weight). Arsenic was accumulated mainly in roots, thereby confirming bioconcentration factor values BCF > 1 for all tree seedlings treated with DMA. Exposure of plants to low DMA concentrations (0.01 and 0.03 mM) was related to the transport of this element to aboveground parts, while increased DMA concentration in other experimental systems led to the limitation of As transport to stems, as confirmed by translocation factor values TF < 1. Changes in many other elements such as boron, silicon, phosphorus, or sulfur concentration indicated the possible influence of DMA on the transport of As from roots to leaves. The obtained results show that DMA can be an important factor in modulating As phytoextraction in the studied tree species.

The aim of this paper is to augment the existing literature on convergence of CO₂ emissions, by adding carbon footprint per capita and ecological footprint per capita to the convergence debate. We use the residual augmented least squares regression to examine the stochastic convergence of the environmental indices in 27 OECD countries. Furthermore, in contrast to the previous studies which mainly used the conventional beta-convergence approach to examine conditional convergence, we use a beta-convergence method that is capable of identifying the actual number of countries that contribute to conditional convergence. The sigma-convergence of the environmental indices is also examined. The results suggest that conditional convergence exists in 12 countries for CO₂ emissions per capita, 15 countries for carbon footprint per capita and also 13 countries for ecological footprint per capita. There is evidence for sigma-convergence for all the three indicators. The policy implications of the results are discussed in the body of the paper.

This work aims to contribute to the existing literature by investigating at the impact of financial development on ecological footprint. To achieve this goal, we have employed Driscoll-Kraay panel regression model for a panel of 59 Belt and Road countries in the period from 1990 to 2016. The findings suggest that financial development increases ecological footprint. Moreover, economic growth, energy consumption, foreign direct investment (FDI), and urbanization pollute the environment by increasing ecological footprint. In addition, several diagnostic tests have been applied to confirm the reliability and validity of the results. From the outcome of the study, various policy implications have been proposed for Belt and Road countries to minimize the ecological footprint.

A photosynthetic algal (Chlorella vulgaris) microbial fuel cell (PAMFC) with double chambers was adopted for power production and removal of carbon and nitrogen in swine sewerage that could provide nutrients for the growth of C. vulgaris. C. vulgaris was expected to utilize carbon dioxide (CO₂) delivered from the anode chamber and generate oxygen as an electron acceptor by photosynthesis. PAMFC presented a maximum voltage output of 0.747 V and a maximum power density of 3720 mW/m³ at 240 h, much higher than that of the standalone MFC. 85.6%, 70.2%, and 93.9% removal of ammonia nitrogen, total nitrogen (TN), and total organic carbon (TOC), respectively, were obtained in the anode chamber of the PAMFC system, while the corresponding removal in MFC was 83.1%, 56.0%, and 87.2%, respectively. PAMFC also presented a much higher removal of ammonia nitrogen (68.7%) in the cathode chamber than MFC (47.5%). The results indicated the superiority of the PAMFC device for carbon and nitrogen removal.

Anaerobic ammonium oxidation coupled to ferric iron reduction (Feammox) has been assumed to play an important role in nitrogen removal from ecosystems. This study assessed the potential role of Feammox in nitrogen transformation in eutrophic lake sediment using an isotope tracing technique in sediment slurry incubation experiments. Feammox was discovered in eutrophic lake sediment. A significant correlation was found between Feammox rates and iron-reducing rates. Furthermore, the positive correlations between the abundance of iron-reducing bacteria (FeRB), such as Geobacteraceae spp. and Shewanella spp., and Feammox rates indicate that Feammox was mediated by FeRB. The potential rate of Feammox in the isotopic tracer incubation treatment was 0.23–0.43 mg N kg⁻¹ day⁻¹. The estimated nitrogen loss caused by Feammox accounts for 5.0–9.2% of the human-induced N input annually into the eutrophic lake. Feammox alone or coupled with anaerobic ammonium oxidation (anammox) and/or denitrification may have an essential role in the nitrogen cycle within eutrophic lake sediment.