Уточнить поиск
Результаты 4921-4930 из 6,441
Year-to-year climate variability affects methane emission from paddy fields under irrigated conditions Полный текст
2020
Sun, Huifeng | Zhou, Sheng | Zhang, Jining | Zhang, Xianxian | Wang, Cong
A field experiment in Yangtze River delta of China was conducted to investigate the effects of four treatments (conventional chemical fertilizers (CF), chemical fertilizers incorporated with wheat straw (CF-WS), slow-release urea fertilizer incorporated with wheat straw (SCF-WS), and no fertilizers (Non-F)) on methane emission, rice grain yield, and straw biomass in three (2013, 2014, and 2015) consecutive growing seasons. Similar air temperature and precipitation were recorded in 2014 and 2015 normal seasons; however, the 2013 season with a 2.1–2.3 °C higher mean air temperature and a 61–64% lower precipitation than the normal seasons was considered as a warm-and-dry season.No significant differences in seasonal total methane emissions across all treatments were observed in 2014 and 2015 seasons. Seasonal total methane emissions were 58–294% higher in 2013 season compared to 2014 and 2015 seasons, which suggests that higher ambient temperatures increase methane emissions from paddy fields. The enhanced methane emission was seen mainly during the mid-to-late growth stages after mid-season drainage. CF-WS and SCF-WS significantly increased methane emissions before mid-season drainage relative to CF, and thereby enhanced methane emissions in both normal and warm-and-dry seasons in a seasonal scale.While rice grain yield in each treatment in 2013 season was close to or lower than that in 2014 and 2015 seasons, straw biomass in CF, CF-WS, and SCF-WS in 2013 season were significantly higher than those in 2014 and 2015 seasons, by both 29%, 33–41%, and 15–16%, respectively. Enhancements in methane emissions at higher air temperatures were significantly correlated to its greater straw biomass. Furthermore, combination of slow-release urea fertilizer and straw by ploughing can significantly increase above-ground biomass yields and nitrogen use efficiency in both normal and warm-and-dry seasons.
Показать больше [+] Меньше [-]Physiological and biochemical responses of Amaranthus cruentus to polycyclic aromatic hydrocarbon pollution caused by thermal power units Полный текст
2020
Tandey, Roshni | Chouhan, Kavi Bhushan Singh | Sen, Kamal Kumar | Mahetā, Rājendra | Dubey, Amit | Das, Rajdeep | Saha, Pratip | Mandal, Vivekananda
Pollution due to release of polycyclic aromatic hydrocarbons from thermal power plants is a major global issue as the same is highly toxic and carcinogenic. The current research aims to investigate the responses of a dietary plant Amaranthus cruentus towards PAH pollution. For the said purpose, the plant was collected from agricultural land in close vicinity to thermal power units and the effects of PAH pollution on its chlorophyll and various nutraceutical content was evaluated. Oxidative stress biomarkers and antioxidant defense enzymes status and PAH accumulation was quantified as well. Real-time evidence of cell death, depletion of nutraceutical resources, and stomata configuration was generated through various histochemical studies and SEM analysis. Results indicated significant decline of chlorophyll a to the extent of 77% when compared to control. Oxidative stress markers, namely, superoxide radical, H₂O₂, and hydroxyl radical in pollution exposed plants were 12.7, 2.2, and 2.4 times respectively higher over the control which eventually resulted in 35% more cell death for the pollution exposed group. Total phenolics and flavonoids showed a decline of 57.6% and 41.3% respectively in the group exposed to PAH pollution. Similar decreasing trend was also observed for ascorbic acid, α-tocopherol, β-carotene, total proteins, and carbohydrate contents as well. PAH-induced stress also resulted in complete imbalance in the redox homeostasis of the plant which was evident from increase in super oxide dismutase, catalase, and peroxidase antioxidant enzymes by more than 2-fold when compared to control. PAH accumulation in sample group was 10–20 times more when compared to control. Proteomic analysis also indicated upregulation of some proteins related to stress situation. Results are evident of the fact that severe depletion of nutraceutical resources of dietary plants can take place if subjected to oxidative stress arising from PAH pollution.
Показать больше [+] Меньше [-]The effect of environmental regulation on capacity utilization in China’s manufacturing industry Полный текст
2020
Cheng, Zhonghua | Liu, Jun | Li, Lianshui | Gu, Xinbei
How environmental regulations are used to improve manufacturing capacity is crucial to the future development of China’s manufacturing industry from a quality point of view. This paper adopts a dynamic spatial panel model to empirically analyze both the effects of different types of environmental regulation policies on capacity utilization in China’s manufacturing industry and their mechanisms. The results show that China’s manufacturing capacity utilization varies a great deal, with improvements in technical efficiency playing the main role, although with significant regional differences. Both command-and-control and market-incentive environmental regulation are conducive to improvements in manufacturing capacity utilization; market-incentive environmental regulation, however, plays the stronger role. The above mechanisms have certain differences though. Both types of environmental regulations are able to improve manufacturing capacity utilization by improving technical efficiency and equipment utilization but the command-and-control policy tool exerts a greater effect in improving technical efficiency while the market-incentive mechanism has a greater effect in improving equipment utilization.
Показать больше [+] Меньше [-]Microplastics in aquatic environment: characterization, ecotoxicological effect, implications for ecosystems and developments in South Africa Полный текст
2020
Pereao, Omoniyi | Opeolu, Beatrice | Fatoki, Olalekan
Microplastics are small-size plastic piece scales (particles < 5 mm) in sediments and waters which interact with environment and organisms by various means. Microplastics are becoming a universal ecological concern since they may be a source of hazardous chemicals to marine organisms and environments. Recent research suggests microplastics could enable the transfer of hydrophobic aquatic pollutants or chemical additives to biota. Even though microplastic presence and interactions are recently being detected in marine and freshwater systems, the fate of microplastics is still very poorly understood. This literature review is a summary of the sources and transport of microplastics, their interactions with toxic chemicals and the methodologies for chemical quantification and characterization of microplastics. The environmental outcome and impact of microplastics in wastewater treatment plants were assessed as well as the trends and update on microplastic research in the South African aquatic ecosystem.
Показать больше [+] Меньше [-]Novel eco-friendly amino-modified nanoparticles for phenol removal from aqueous solution Полный текст
2020
Younis, Alaa M. | Elkady, Eman M. | Saleh, Sayed M.
Herein, the impact of using dried Caulerpa prolifera nanoparticles and silica-coated Caulerpa prolifera nanoparticles for the removal of phenol from aqueous solution has been investigated. The chemical structure and morphology of both dried Caulerpa prolifera nanoparticles and silica-coated Caulerpa prolifera nanoparticles were characterized by using Fourier-transform infrared spectroscopy (FTIR), Brunauer Emmett Teller (BET), scanning electron microscopy (SEM), and transmission electron microscope (TEM). Batch mode experiments were conducted depending on adsorbent dosage, pH, contact time, and initial phenol concentration. In order to investigate the adsorption mechanism of the phenol molecules to the surface of the nanoparticles, kinetic models including pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were executed. To describe the equilibrium isotherms, Langmuir and Freundlich isotherms were analyzed. However, the Langmuir isotherm model was agreed to be more significant with the obtained experimental data.
Показать больше [+] Меньше [-]Efficient removal of tylosin by nitrogen-doped mesoporous carbon nanospheres with tunable pore sizes Полный текст
2020
Hu, Xingru | Qi, Junwen | Lu, Rui | Sun, Xiuyun | Shen, Jinyou | Han, Weiqing | Wang, Lianjun | Li, Jiansheng
Efficient and selective removal of antibiotics from wastewater is quite important but challenging. In this work, the nitrogen-doped mesoporous carbon nanospheres (NMCN) with different pore size (from 2.67 to 4.62 nm) were successfully prepared by changing the hydrothermal condition, and their removal performance on tylosin was evaluated. The adsorption experimental data were fitted well with the pseudo-second-order kinetic model. Besides, Langmuir isotherm model could better describe the adsorption process. Notably, the NMCN with medium pore size (3.36 nm) exhibited the highest adsorption capacity (1333 mg g⁻¹), which was 24% and 14% higher than that of NMCNs with smaller and larger pore size, respectively. In order to study the adsorption mechanism, the mesoporous carbon nanospheres without N-doped was prepared, and the comparison of nitrogen adsorption-desorption isotherms was conducted. The result proved that in addition to the modified surface property, large specific surface area, and high pore volume, the pore size could precisely influence the adsorption performance of the proposed adsorbent. Furthermore, the proposed NMCN material possessed a selective adsorbing ability toward tylosin in the presence of tetracycline. Clearly, the NMCN was a promising alternative to be used as high efficient and selective adsorbent in practical environment pollution treatment, especially in large-size molecule adsorption.
Показать больше [+] Меньше [-]Experimental simulation of somatic and germ cell genotoxicity in male Mus musculus fed extracts of lead contaminated Pleurotus ostreatus (white rot fungi) Полный текст
2020
Olatunji-Ojo, Adetola M. | Alimba, Chibuisi G. | Adenipekun, Clementina O. | Bakare, Adekunle A.
Exposure to lead (Pb) is a major risk factor in reproductive toxicity, somatic, and germ cell genotoxicity. Exposure via deteriorating Pb paints and contaminated air, soil, and water had been the primary routes. However, with increasing reports of Pb accumulation in mushrooms and other food items may increase the etiology of Pb poisoning. The study herein investigated somatic genotoxicity and reproductive abnormalities in mice fed extracts of Pb-contaminated Pleurotus ostreatus. Male mice were fed aqueous extracts of P. ostreatus cultivated in 0, 10, 20, 100, 200, 500, and 1000 mg/L of Pb-contaminated rice straw for 35 days. Testes were analyzed for Pb accumulation, histopathology and relative weight gain, caudal epididymis for abnormal sperm morphology, and bone marrow for micronucleus test. Concentration-related significant increase in Pb accumulation was observed in P. ostreatus and testes of exposed mice. Decrease testicular weight, congestion of blood vessels, necrosis, and disorganization of the seminiferous tubules were observed in treated mice. In addition, fold increase of 2.78, 3.39, 6.67, 7.21, 9.63, and 9.70 in abnormal sperm morphology in accordance with the Pb concentrations respectively, confirmed reproductive toxicity. Significant increase in micronucleated polychromatic (PCE) and normochromatic (NCE) erythrocytes and concentration-related decrease PCE-NCE ratio in the bone marrow of treated mice suggest genome instability. Pb-contaminated P. ostreatus increased somatic and germ cell genotoxicity in mice. This may predispose the mice to genetic related syndromes and reproductive syndromes. It further suggests caution in the consumption of metal laden wild mushrooms and crop plants.
Показать больше [+] Меньше [-]Assessment and source quantification of heavy metal(loid)s in surface water using multivariate analyses from the Saigon River, Vietnam Полный текст
2020
Nguyen, Binh Thanh | Nguyen, Vinh Ngoc | Truong, Huong Thu Thi | Do, Dung Doan | Nguyen, Tong Xuan | Nguyen, Duong Thuy Phuc | Nguyen, My Hoang | Dong, Hao Phu | Le, Anh Hung | Bach, Quang-Vu
The metal concentration in surface water of a river could be affected by season, position, and oceanic process such as tide. The current study aimed to (1) examine the heavy metal(loid) concentration in surface water from the Saigon River as affected by the combination of season, tide, and position and (2) apportion and quantify pollution sources. Ninety-six surface water samples were collected from 13 sites on the River in four campaigns (rainy season + ebb tide, rainy season + flood tide, dry season + ebb tide, and dry season + flood tide). Eight heavy metal(loid)s (Al, B, Bi, Fe, Mn, Pb, Sr, and Zn) were measured and subjected to multivariate analyses. Three-way ANOVA showed that in the rainy season, the total concentration of the metal(loid)s (TCM) in two tides was not clearly different from each other while in the dry season the TCM was significantly higher during the ebb tide than during the flood tide. Principal component analysis/factor analysis and Pearson correlation matrix showed that the TCM could be derived from three main sources, grouped into anthropogenic activities such as industrial, agricultural, and domestic wastes from inside Ho Chi Minh city, and natural origins from lowland area and acid sulfate soil. Three pollution sources explained 70% and 68% of the total variance of TCM in the rainy and dry seasons, respectively. In brief, the metal(loid) concentration was significantly affected by the season and tide and the pollution sources could be derived from inside Ho Chi Minh City and from lowland areas beyond the river estuary.
Показать больше [+] Меньше [-]Renewable energy, urbanization, and ecological footprint linkage in CIVETS Полный текст
2020
Nathaniel, Solomon | Nwodo, Ozoemena | Sharma, Gagan | Shah, Muhammad
Emerging economies are mostly plague by a massive consumption of non-renewable energy amidst an ever inceasing urbanization rate with little or no attention to the quality of the environmental. As such, this paper investigates the relationship between renewable energy, urbanization, economic growth, trade openness, and ecological footprint in CIVETS countries, namely, Colombia, Indonesia, Vietnam, Egypt, Turkey, and South Africa. The study employs augmented mean group estimator, panel cointegration, and causality tests. The findings reveal that renewable energy improves environmental quality, and trade is not particularly harmful to the environment. However, non-renewable energy consumption and urbanization are the chief contributors to environmental degradation in the CIVETS countries. Economic expansion mitigates environmental deterioration in Colombia, South Africa, and Turkey, but contributes to pollution in Egypt, Indonesia, and Vietnam. Finally, the causality test suggests that urbanization drives environmental degradation. Policy directions are discussed.
Показать больше [+] Меньше [-]Rapid immobilization of viable Bacillus pseudomycoides in polyvinyl alcohol/glutaraldehyde hydrogel for biological treatment of municipal wastewater Полный текст
2020
Mehrotra, Tithi | Zaman, Mohammad Nawaid | Prasad, Bhim Bali | Shukla, Anuradha | Aggarwal, Srijan | Singh, Rachana
A new approach for easy synthesis of Bacillus pseudomycoides immobilized polyvinyl alcohol (PVA)/glutaraldehyde (GA) hydrogel for application in a wastewater treatment system is reported. Optimization studies revealed that GA/PVA mass ratio of 0.03 and acidic pH of 2 were required for hydrogel synthesis and eventually for bacterial cell immobilization. The synthesized crosslinked matrix possessed a pore size suitable for microbial cell entrapment while maintaining cell accessibility to external environment for bioremediation. Possible crosslinking and bacterial cell immobilization in the hydrogel were evidenced by FTIR, XRD, and SEM studies, respectively. Further, the extent of crosslinking of GA with PVA was investigated and confirmed by transmittance and permeability experiments. The viability and proliferation of hydrogel embedded cells (after 25 days) was confirmed by confocal fluorescence microscopy which also indicated that acidic pH of polymer solution did not affect the immobilized live cells. B. pseudomycoides immobilized hydrogel were demonstrated to be effective for treatment of municipal wastewater and reduced biochemical oxygen demand (BOD), chemical oxygen demand (COD), and protein content below the recommended levels. Overall, the results from this bench-scale work show that employing bacteria-embedded PVA/GA hydrogel for the treatment of municipal wastewater yield promising results which should be further explored in pilot/field-scale studies.
Показать больше [+] Меньше [-]