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[en] Pakistan is the most polluted country according to the concentration of air pollution criterion and it has experienced a significant rise in economic growth during the recent years. This paper analyzes the nexus of CO2 emissions and economic growth using quarterly data over the period of 1960Q1–2014Q4. To provide conclusive policy recommendations, this study applied different econometric methodologies such as the quantile causality approach, the linear ARDL (autoregressive distribution lag) model and the quantile ARDL (QARDL) model. The results indicate evidence of causality running from economic growth to CO2 emissions at medium quantiles at the 5% level and at low and medium quantiles at the 10% significance level. Findings of linear and nonlinear ARDL models also support the transmission of growth to CO2 emissions in the long and short run. The Wald test for symmetry sustains the nonlinear ARDL model. Useful policy implications can be learned from the empirical findings.
[en] The interest in research on alcohol-based biofuels is on the rise. Fusel oil is a long-chain alcohol and a by-product of bioethanol synthesis. This study analyzed the effects of blended levels of fusel oil and biodiesel in diesel fuel on the performance and exhaust emissions of a single-cylinder diesel engine. The effects of input parameters (i.e., fusel oil content (%), biodiesel content (%), engine speed (rpm), and engine load (%), each at five levels) on response parameters (i.e., power, torque, fuel consumption, and emission factors, namely NOX, UHC, CO, and CO2) were investigated. Different levels were used for analyzing fusel oil (0, 5, 10, 15, and 20%), biodiesel (0, 5, 10, 15, and 20%), engine load (0, 25, 50, 75, and 100%), and engine speed (1400, 1700, 2000, 2300, and 2600 rpm). Response surface method (RSM) was employed to maximize engine performance and minimize exhaust emissions. A blend of D90F5 B5 (5% fusel oil, 5% biodiesel, and 90% petro-diesel) and engine speed of 2026 rpm at load 46% were predicted to be an optimal value. Using a 72% desirability function, optimum results for torque (14.2 Nm), power (3.37 kW), and brake-specific fuel consumption (356.9 g/kWh) were also obtained from RSM. Based on the optimized inputs, the optimized values of different output pollutants were 0.14 vol.% for CO, 1.62 vol.% for CO2, 23.7 ppm for UHC, and 85.17 ppm for NOX. The result illustrated that use of fusel oil decreased NOX emissions up to 20%, while UHC and CO emissions increased up to 32% and 22%, respectively. In addition, the use of fusel oil content (up to 10%) in the blended fuels improved the engine power by 5.6%.
[en] Ecological footprint has been widely accepted as an indicator of environmental performance in recent years since it considers carbon dioxide emissions, the collapse of fisheries, the change in land use, and deforestation. This paper investigates, if exists, the convergence in per capita ecological footprint among G20 countries by employing the annual data for the period 1961 to 2014. A bootstrap-based panel KPSS test with structural breaks and club convergence test are carried out. Eventually, this paper is expected to contribute to the literature of natural resources and ecology/environment by (1) monitoring the panel variable of ecological footprint, (2) launching stochastic and deterministic convergence analyses, and (3) estimating the club convergence parameters. In conclusion, the confirmative results in favor of environmental convergence are obtained by exhibiting the stochastic and deterministic convergences and deriving the output of merging clubs.
[en] Dark septate endophytes (DSEs) are a heterogeneous group of endophytic fungi that frequently colonize the roots of plants growing in trace metal element-contaminated soils. However, the functional role of DSEs in host plants growing in metal-stressed environments remains to be elucidated. In this study, two DSE strains of Phialophora mustea Neerg. (K36 and Z48) were separately inoculated in tomato (Lycopersicon esculentum Miller) seedlings under metal stress conditions (0, 5, 10 mg kg−1 Cd or 0, 300, 600 mg kg−1 Zn) to evaluate the effects of DSE inoculation on tomato seedlings in pot cultures. The results showed that DSE colonization increased tomato seedling biomass whether or not there was metal addition. DSE-inoculated tomatoes had a lower Cd and Zn accumulation in both the shoots and roots compared with their respective non-inoculated controls. Under metal stress conditions, DSE inoculation significantly enhanced the activities of antioxidant enzymes, such as superoxide dismutase (SOD) and peroxidase (POD), thus relieving the membrane lipid peroxidation damage caused by metal stress, and reduced the leaf malondialdehyde (MDA) concentrations more than that of the non-inoculated treatments. The results revealed that DSE enhanced metal tolerance and improved tomato plant growth, both by the reduced metal uptake into root and shoot accumulation and by the enhanced activities of antioxidant enzymes to eliminate reactive oxygen species (ROS) stress induced by excessive metals.
[en] Acrylonitrile (ACN) spills in marine environment have the potential to cause ecological hazards and consequences, but currently little is known about the disruptive effects of ACN on marine organisms. In the present study, we investigated the lethal and sublethal effects of ACN on juvenile flounder Paralichthys olivaceus. The results showed that the 96-h LC50 of ACN to P. olivaceus juveniles was 6.07 mg/L. The fish were then exposed to different sublethal concentrations (0.1, 0.2, and 0.4 mg/L) of ACN for 28 days and then transferred to clean seawater and keep in clean seawater for 14 days to simulate the conditions of a spill incident. Biomarkers (EROD, GST, SOD, AChE activity, and levels of LPO and DNA alkaline unwinding) were tested in liver and brain. The weight gain rates and specific growth rate of juvenile marine flounder exposed to ACN (≥ 0.1 mg/L) for 28 days decreased significantly, indicating that ACN had an inhibitory effect on juvenile growth. Deformity of fish tails was observed on individuals exposed to the highest concentration (0.4 mg/L ACN) for 14 days, and the malformation rate was 38% after 28-day exposure. The present study provides the first evidence that ACN causes inhibition of AChE activity in fish brain. Furthermore, the results showed that ACN can significantly inhibit SOD activity and cause lipid peroxidation and DNA damage in fish brain. The results indicated that brain is more sensitive to ACN toxicity compared to liver and provides a suitable tissue for biomonitoring. The biomarkers measured during the depuration period showed that the effects caused by ACN were reversible when the exposure concentration was lower than 0.4 mg/L. These results highlight the adverse effects of ACN in brain of fish, which should be considered in environmental risk assessment. Biomarkers including AChE activity, LPO, and DNA damage of brain tissue should be included in fish bioassays for toxic effect assessment of ACN spills.
[en] The toxicological assessment of plant products and pharmaceutical chemicals is a necessary requirement to ensure that all compounds are safe to be exposed to humans. Many countries are trying to reduce the use of animals; thus, alternative techniques, such as ex vivo tests, in vitro assays, and ex uteri embryos, are used. Toxicological assays using zebrafish embryos are an advantageous technique because they are transparent, have rapid embryonic development, and do not require invasive techniques. This paper comprehensively reviews how toxicity testing with plant products is conducted in zebrafish embryos. The search terms zebra fish, Danio rerio, zebrafish, zebra danio, Brachydanio rerio, zebrafish, and embryos were used to search for English-language articles in PUBMED, SCOPUS, and WEB OF SCIENCE. Twelve articles on plant product toxicity studies using zebrafish were selected for reading and analysis. After analyzing the articles and comparing with results in mammals, it was possible to prove the similarity among the results and thus corroborate the further development of zebrafish as a valid tool in toxicity tests.
[en] Advanced oxidation processes using semiconducting photocatalysts for the degradation of organic pollutants are a promising approach for the remediation of pesticide-contaminated wastewater. High photodegradation efficiency and stability of the photocatalyst are of key importance for practical application of the semiconductor. In this study, mesoporous TiO2/ZrO2 nanopowders were synthesized via two techniques; evaporation-induced self-assembly (EISA) and sol-gel using triblock copolymers Pluronic P123 and F127. The photodegradation activities of the composites were determined by employing the herbicide chloridazon as a model compound. Due to well-developed mesoporosity, the TiO2/ZrO2 nanocomposite synthesized by EISA displays high surface area and small crystallite sizes leading to higher photocatalytic activity than pristine TiO2 prepared under similar condition and commercial Degussa P25 nanopowder. The optimum amount of zirconium required for the highest activities was identified and found to be 0.14 and 0.05 mol% for the EISA and sol-gel-prepared samples, respectively. Systematic studies of the post-thermal treatment step for both samples show that Zr inhibits an anatase-to-rutile phase transition only up to 600 °C, at higher temperature phase separation occurs. Samples synthesized by EISA method showed enhanced degradation activity than sol-gel-synthesized samples.
[en] This study investigates the relationship between financial expenditure and carbon emission reduction using provincial-level dynamic panel data from 1996 to 2010. A positive correlation exists between the scale of financial expenditure and per capita carbon emissions, whereas a negative correlation exists between the composition of financial expenditure and per capita carbon emissions. The effects of subentry spending on the carbon emission reduction differ. An improvement in the relief structure of social security increases per capita carbon emissions, whereas an improvement in the composition of medical treatment and public health has no effect on per capita carbon emissions. Other forms of “pro-carbon emission reduction” spending lead to a reduction in per capita carbon emissions. An improvement in the composition of financial expenditure leads to a reduction in the carbon emissions of the second and third industries only. Meanwhile, the effect of the scale of financial expenditure is widespread across all industries.
[en] Great efforts have been devoted to assessing the effects of straw managements on greenhouse gas (GHG) emissions, global warming potential (GWP), and net economic budget in rice monoculture (RM). However, few studies have evaluated the effects of straw managements on GHG emissions and net ecosystem economic budget (NEEB) in integrated rice-crayfish farming (RC). Here, a randomized block field experiment was performed to comprehensively evaluate the effects of aquatic breeding practices (feeding or no feeding of forage) and straw managements (rice straw returning or removal) on soil NH4+–N and NO−3–N contents, redox potential (Eh), CH4 and N2O emissions, GWP, and NEEB of fluvo-aquic paddy soil in a rice-crayfish co-culture system in Jianghan Plain of China. We also compared the differences in CH4 and N2O emissions, GWP, and NEEB between RM and RC. Straw returning significantly increased CH4 and N2O emissions by 34.9–46.1% and 6.2–23.1% respectively compared with straw removal. Feeding of forage decreased CH4 emissions by 13.9–18.7% but enhanced N2O emissions by 24.4–33.2% relative to no feeding. Compared with RM treatment, RC treatment decreased CH4 emissions by 18.1–19.6% but increased N2O emissions by 16.8–21.0%. Moreover, RC treatment decreased GWP by 16.8–22.0% while increased NEEB by 26.9–75.6% relative to RM treatment, suggesting that the RC model may be a promising option for mitigating GWP and increasing economic benefits of paddy fields. However, the RC model resulted in a lower grain yield compared with the RM model, indicating that more efforts are needed to simultaneously increase grain yield and NEEB and decrease GWP under RC model.
[en] The Brazilian legislation does not establish limits or methodology for the measurement of aldehydes in the exhaust of heavy diesel engines. No conclusive studies on aldehyde emissions by such engines have been found in the literature available. This work measured the aldehyde emissions from a P7 diesel cycle engine (EURO V), which was tested on an engine test bench according to ETC (European Transient Cycle) and ESC (European Stationary Cycle) cycles using fuels with 5, 7 and 20% v/v of biodiesel and 10 and 500 ppm of sulphur. The results showed that biodiesel participation in the mixture did not significantly affect the aldehyde emissions of the tested engine and that the emission level generated in the ETC cycle is higher than that obtained with the ESC cycle. The diesel content in the blend was weakly and negatively correlated with the pollutant emissions, and the inverse pattern was observed for biodiesel. This finding indicates that an increase in biodiesel content causes a slight increase in pollutant emissions. Regarding the sulphur content, positive correlations between the sulphur content and particulate matter, NOx, CO and total hydrocarbon emissions were observed. When comparing the test cycles, the results were significantly different, with higher values for the ETC cycle.