خيارات البحث
النتائج 5671 - 5680 من 6,560
Response surface methodology and artificial neural network for remediation of acid orange 7 using TiO2-P25: optimization and modeling approach النص الكامل
2020
Zulfiqar, Muhammad | Chowdhury, Sujan | Omar, Abdul Aziz | Siyal, Ahmer Ali | Sufian, Suriati
The primary responsibility for continuously discharging toxic organic pollutants into water bodies and open environments is the increase in industrial and agricultural activities. Developing economical and suitable methods to continuously remove organic pollutants from wastewater is highly essential. The aim of the present research was to apply response surface methodology (RSM) and artificial neural networks (ANNs) for optimization and modeling of photocatalytic degradation of acid orange 7 (AO7) by commercial TiO₂-P25 nanoparticles (TNPs). Dose of TNPs, pH, and AO7 concentration were selected as investigated parameters. RSM results reveal the reflective rate of AO7 removal of ~ 94.974% was obtained at pH 7.599, TNP dose of 0.748 g/L, and AO7 concentration of 28.483 mg/L. The resulting quadratic model is satisfactory with the highest coefficient of determination (R²) between the predicted and experimental data (R² = 0.98 and adjusted R² = 0.954). On the other hand, ANNs were successfully employed for modeling of AO7 degradation process. The proposed ANN model was absolutely fitted with experimental results producing the highest R². Furthermore, root mean square error (RMSE), mean average deviation (MAD), absolute average relative error (AARE), and mean square error (MSE) were examined more to compare the predictive capabilities of ANN and RSM models. The experimental data was well fitted into pseudo-first-order and pseudo-second-order kinetics with more accuracy. Thermodynamic parameters, namely enthalpy, entropy, Gibbs’ free energy, and activation energy, were also evaluated to suggest the nature of the degradation process. The increase of temperature was analyzed to be more suitable for the fast removal of AO7 over TNPs. Graphical abstract
اظهر المزيد [+] اقل [-]Effect of controlled-release urea fertilizers for oilseed rape (Brassica napus L.) on soil carbon storage and CO2 emission النص الكامل
2020
Zhang, Kangping | Wang, Zhiyuan | Xu, Qiwen | Liu, Bangyan | Duan, Meichun | Wang, Longchang
Fertilizer-induced CO₂ emission is a primary driver of global warming. The experiment was used to study whether controlled-release urea (CRU) application in winter oilseed rape can play a positive role in mitigating CO₂ emission and promoting C utilization by soil microorganisms. Five fertilizer types consisted of N0 (0 g N plant⁻¹), conventional CRU application (CRU100%), monotypic CRU at the 80% of conventional rate (CRU80%), co-application of CRU with uncoated urea (CRC), and organic fertilizer (CRO). Results showed that soil CO₂ fluxes were significantly affected by N fertilizer types after the start of the stem growing (P < 0.05). CO₂ emissions typically peaked during the seed filling period, with the highest emission of 1.99 μmol m⁻² s⁻¹ being registered for CRU100%. CRU100% had 25.00%, 30.60%, and 4.17% greater CO₂ emissions than CRU80%, CRC, and CRO practices by harvest, respectively. Compared to the conventional CRU treatment, CRU80% led to a lower root volume and root mass ratio than CRU100%, which could partly contribute to the reduced CO₂ emission. Conversely, CRU80% performed better in N agronomic efficiency than that of CRU100% treatment. Also, C source utilization by soil microbiomes as well as microbial diversity indices following CRU80% along with CRO applications was substantially higher than that under the conventional CRU supply. These observations suggest that opportunity exists to maintain N balance by N fertilization practices to mitigate CO₂ emission from cropland. Further, a close and positive relationship between soil total nitrogen and CO₂ emission also supports this. CRO-treated soils substantially elevated the contents of total carbon and readily oxidation carbon over CK. Moreover, the enzyme activity of β-glucosidase in CRO soil was about twice as high as the CRU100%. Consequently, CRU amendments by decreasing CRU rate application and the incorporation of organic fertilizer into CRU have the potential for mitigating of CO₂ emission and positive effect on the soil microbial functional diversity to improve nitrogen use efficiency of rapeseed.
اظهر المزيد [+] اقل [-]A review of the application of sea material shells as low cost and effective bio-adsorbent for removal of heavy metals from wastewater النص الكامل
2020
Tamjidi, Sajad | Ameri, Abolhasan
The pollution caused by heavy metal ions in industrial wastewater is of a great concern. Applying effective and low-cost methods is an urgent need for treatment of polluted water and aqueous solutions. Biosorption have received the most attention among the various methods. It has become an alternative technique to conventional technologies due to low cost, simple operation and treatment for heavy metal recovery, and high selectivity. In recent years, sea material shells have been applied as one of the most cost-effective bio-adsorbents due to their special properties. They are environmentally friendly, low cost, and easy to access and have high adsorption capacity. The purpose of this review is to present the application of oyster shell, snail shell, and shrimp shell as low-cost and effective biosorbents for removal of noxious heavy metals from aqueous solutions. In addition, heavy metals, their sources, and ways to remediate them from waste streams and various factors affecting the biosorption process with sea materials shells are also reviewed. Moreover, a brief description and literature review of the equilibrium, kinetic, and thermodynamic behaviors of the heavy metal ion adsorption process on sea material shells have been studied. Finally, further applications of sea materials shell for waste effluents treatment are specially focused.
اظهر المزيد [+] اقل [-]Embryonic gene expression altered by maternal exposure to air pollution in rats النص الكامل
2020
Li, Zheng | Ma, Jianqing | Lin, Youxi | Shen, Jianxiong | Wu, Zhanyong | Chan, Matthew T. V. | Wu, William K. K.
Exposure to air pollution is known to increase the risks for cardiovascular, pulmonary and metabolic diseases. Growing evidences also indicated that air pollution exposure during pregnancy could negatively impact on early embryonic development and children’s health. We performed RNA sequencing to identify deregulated mRNAs in air pollution-exposed rat embryos. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were used to analyse the potential cellular functions of deregulated mRNAs. Our analysis indicated that a total of 1678 mRNAs were differentially expressed on gestation day 9 upon in utero exposure to fine particulate matter of > 200 μg/m³, among which 1098 mRNAs were downregulated and 580 mRNAs were upregulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed gap junction, cell adhesion, axon guidance and the neurotrophin signalling pathway as key biological processes perturbed by air pollution exposure. Furthermore, reconstruction of the mRNA regulatory network highlighted the central roles of Tbx4, Bmp4, Sox10, Wnt9b, Bmp7 and Foxc2. These data suggested that embryonic mRNA deregulation may underlie the formation of air pollution-associated congenital defects.
اظهر المزيد [+] اقل [-]Cross-Strait climate change and agricultural product loss النص الكامل
2020
Lin, Hsing-Chun | Chou, Li-Chen | Zhang, Wan-Hao
The structure of agricultural industries at Cross-Strait differs as climate change is considered. In fact, its influence on their agriculture and other industries vary when the impact produced by natural disasters due to climate change are faced. To estimate direct and indirect losses caused by natural disasters, this study applies Inter-Country Input-Output (ICIO) analysis developed by Miller and Blair (2009) to discuss the development among Cross-Strait industries as they face disaster losses. The data sources used in this article are from Lin (2013), Cross-Strait ICIO table, and the statistics of agriculture in the periods 2005–2017 for Taiwan and Mainland China. The main results from our ICIO analysis are as follows: the value-added losses caused by natural disasters mainly involve agriculture, forestry, fishery, wholesale and retail trade, animal feed, and chemical fertilizer industries. These sectors account for 87.4% in Mainland China and 94.6% in Taiwan of total separately.
اظهر المزيد [+] اقل [-]Improvement of the sorption behavior of aluminum silicate composite toward 134Cs and 60Co radionuclides by non-living biomass of Chlorella vulgaris النص الكامل
2020
Dakroury, Gehan Abdel Rahman | Abo-Zahra, Shereen Fathy | Hassan, Hisham Soliman | Ali, Hamdy Elsayed Ahmed
Cesium and cobalt radioactive isotopes (¹³⁴Cs and ⁶⁰Co) are dangerous to human health due to their long half-life about 2.1 and 5.3 year, respectively. Developing a new composite used as an efficient sorbent for these is an urgent requirement for radioactive waste management. Herein, preparation of different materials such as aluminum silicate (AS), cultured of Chlorella vulgaris (NCV) alga, and aluminum silicate/Chlorella vulgaris (AS/NCV) composite 3:1 were prepared by wet chemical technique and used to remove the ¹³⁴Cs and ⁶⁰Co radionuclides. Different analytical techniques were used to characterize the prepared sorbents as SEM, TEM, XRD, BET, TGA/DTA, FTIR particle size analyzer, and pore size distribution. The factors affecting the sorption process as pH, temperature, contact time, and weight of adsorbent were studied. The sorption process was found to follow a pseudo-second-order mechanism. The monolayer capacity for ¹³⁴Cs radionuclide onto the aluminum silicate, non-living Chlorella vulgaris biomass, and aluminum silicate/Chlorella vulgaris composites are 66.67, 83.54, and 90.11 mg/g, respectively, and for ⁶⁰Co radionuclide are 59.31, 91.99, and 99.24 mg/g, respectively. The values of thermodynamic parameters indicate that the sorption process is endothermic and spontaneous.
اظهر المزيد [+] اقل [-]Reply to the rebuttal to: Li et al. “Dynamic analysis of international green behavior from the perspective of the mapping knowledge domain,” Environmental Science and Pollution Research, vol. 26, pp. 6087–6098 النص الكامل
2020
Li, Xingwei | Du, Jianguo | Long, Hongyu
Recently, Dr. Yuh-shan Ho discussed the search methods of the paper “Dynamic analysis of international green behavior from the perspective of the mapping knowledge domain” Li et al. (Environ Sci Pollut Res 26:6087–6098, 2019a). In fact, Ho and co-workers have used the search methods in several papers Ivanović et al. (Scientometrics, 105:145–160, 2015); Monge-Nájera & Ho (Rev Biol Trop 63:1255–1266, 2015); Ho & Hartley (Br J Psychol, 107:768–780, 2016). In order to reply to the comments, this letter supplementarily explains the characteristics, scope, and limitations of search methods. In addition, the letter states that researchers can use improved methods suggested by Dr. Ho in future studies.
اظهر المزيد [+] اقل [-]Convergence of renewable energy consumption in the EU-15: evidence from stochastic and club convergence tests النص الكامل
2020
Kasman, Adnan | Kasman, Saadet
This paper investigates the convergence of per capita renewable energy consumption across 15 core EU member countries over the period 1990–2018. In addition to the traditional convergence tests, this paper employs a Lagrange multiplier (LM)–based panel unit root test that allows for two endogenously determined structural breaks to test for the stochastic convergence. Given the shortcomings of stochastic convergence tests in light of the possibility of multiple equilibria associated with groups of countries following different convergence paths, the club convergence algorithm is also employed. Traditional cross-sectional tests indicate that both β- and σ-convergence of per capita renewable energy consumption exist across the EU-15 countries. Moreover, the results of stochastic convergence tests reveal that relative per capita renewable energy consumption is converging across the sampled countries over the sample period. However, the club convergence test results suggest the rejection of full panel club convergence and the presence of a certain number of clubs for the variable of interest.
اظهر المزيد [+] اقل [-]Technical efficiency estimation of China’s environmental protection enterprises and its heterogeneity النص الكامل
2020
Wang, Ren | Wang, Rui | He, Xiaobo
The status of technical efficiency (TE) of environmental protection enterprises is crucial to the sustainable economic development. Based on the micro-survey data of China’s environmental protection enterprises from 2003 to 2013, through a systematic calculation and comparison about TE level under stochastic frontier analysis, this article investigated the distribution characteristics and heterogeneous sources of them comprehensively and found that first, there are wide-ranging technical efficiency differences among sub-sectors, ownership, and regions within China’s environmental protection industry, and this type of heterogeneity was significantly interfered by the institution and policy environment. Second, there is obvious scale economy effect and no scope economy effect in the TE distribution of China’s environmental protection enterprises, and their TE level has a positive response to management improvement and competition enhancement, but has a negative feedback on heavy asset expansion and debt-driven growth mode. Third, the overall TE levels of non-state-owned enterprises are higher than that of state-owned enterprises; the overall TE levels of enterprises located in the eastern provinces are higher than those of enterprises located in the central and western provinces. Fourth, reducing tax burdens of environmental protection enterprises is more effective to promote their TE level than providing governmental subsidies directly. Therefore, to promote the quality of the development for China’s environmental protection industry, it is necessary to emphasize the market mechanism. Based on the market power, we should accelerate the industry integration, cultivate the market demand, and promote market competition. Furthermore, the government should also need to design a targeted support system and differentiated policy arrangements for the development of environmental protection enterprises.
اظهر المزيد [+] اقل [-]Acute toxicity of chlorpyrifos and its metabolite 3,5,6-trichloro-2-pyridinol alone and in combination using a battery of bioassays النص الكامل
2020
Echeverri-Jaramillo, Gustavo | Jaramillo-Colorado, Beatriz | Sabater-Marco, Consuelo | Castillo-López, María Ángeles
Acute toxicity of chlorpyrifos (CP) and its principal metabolite 3,5,6-trichloro-2-pyridinol (TCP) alone and in combination have been evaluated using a test battery comprising aquatic organisms from different trophic levels: luminescent marine bacteria Aliivibrio fischeri, freshwater unicellular alga Pseudokirchneriella subcapitata, and cladoceran Daphnia magna. As expected, D. magna was the more sensitive organism to the compounds tested, being CP more toxic than its metabolite. On the contrary, TCP was found to be more toxic than its parental compound to A. fischeri and P. subcapitata. In all cases, the mixture of CP and its metabolite was more toxic than the compounds tested separately, multiplying between 5 and 200 times CP toxicity level and up to 15 times TCP toxicity level. These results indicate that the co-existence of parent chemical and its degradation product in the environment can result in a synergic interaction involving high risk to the aquatic ecosystems. Graphical abstract
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