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Результаты 3291-3300 из 4,924
The dispersion, stability, and resuspension of C60 in environmental water matrices
2019
Ding, Guanghui | Li, Xueyao | Zhang, Jing | Zhang, Nannan | Li, Ruijuan | Wang, Yingying | Yang, Zhanning | Peijnenburg, Willie J. G. M.
Environmental waters cover a range of water quality characteristics which could greatly affect the behavior and fate of C₆₀ in the aquatic environment. In this study, the dispersion and stability of C₆₀ in several environmental water matrices during a 70-day extended mixing period were investigated to better understand its environmental behavior and fate in environmental waters. Relatively stable nanoscale aggregates in water (aqu/nC₆₀) could be formed in wastewater influent, while unstable suspensions were obtained in river water, wastewater effluent, seawater, and estuarine water. During the extended mixing under sunlight, oxygen-containing moieties were produced on the surface of the C₆₀ aggregates, independent of the kind of environmental water matrices. Once the mixed system went under quiescent condition, aggregation and sedimentation of aqu/nC₆₀ occurred. However, an extremely short-time disturbance could easily resuspend the C₆₀ aggregates deposited and increase the concentration of aqu/nC₆₀ in the overlying water column. Therefore, the effects of resuspension should be considered when investigating the environmental behavior and fate of C₆₀.
Показать больше [+] Меньше [-]Electro-transformation of mefenamic acid drug: a case study of kinetics, transformation products, and toxicity
2019
Mussa, Zainab Haider | Al-Qaim, Fouad Fadhil | Yuzir, Ali | Latip, Jalifah
Poor removal of many pharmaceuticals and personal care products in sewage treatment plants leads to their discharge into the receiving waters, where they may cause negative effects for aquatic environment and organisms. In this study, electrochemical removal process has been used as alternative method for removal of mefenamic acid (MEF). For our knowledge, removal of MEF using electrochemical process has not been reported yet. Effects of initial concentration of mefenamic acid, sodium chloride (NaCl), and applied voltage were evaluated for improvement of the efficiency of electrochemical treatment process and to understand how much electric energy was consumed in this process. Removal percentage (R%) was ranged between 44 and 97%, depending on the operating parameters except for 0.1 g NaCl which was 9.1%. Consumption energy was 0.224 Wh/mg after 50 min at 2 mg/L of mefenamic acid, 0.5 g NaCl, and 5 V. High consumption energy (0.433 Wh/mg) was observed using high applied voltage of 7 V. Investigation and elucidation of the transformation products were provided by Bruker software dataAnalysis using liquid chromatography-time of flight mass spectrometry. Seven chlorinated and two non-chlorinated transformation products were investigated after 20 min of electrochemical treatment. However, all transformation products (TPs) were eliminated after 140 min. For the assessment of the toxicity, it was impacted by the formation of transformation products especially between 20 and 60 min then the inhibition percentage of E. coli bacteria was decreased after 80 min to be the lowest value.
Показать больше [+] Меньше [-]Characterizations and mechanisms for synthesis of chitosan-coated Na–X zeolite from fly ash and As(V) adsorption study
2019
Han, Caiyun | Yang, Ting | Liu, Hang | Yang, Liu | Luo, Yongming
Solid waste fly ash with low aluminum of Yunnan Province in China was used as pristine material to prepared chitosan-coated Na–X zeolite, and the obtained composite material was employed as As(V) adsorbent. Then, the prepared materials were characterized by XRD, FT-IR, and XPS. And the results suggested that the low aluminum fly ash was successfully convert into Na–X zeolite, and the mineralization between Si–OH of the obtained Na–X zeolite and C–OH of chitosan was the dominated mechanism for coated chitosan over the surface of Na–X zeolite. From the batch experiments of As(V) removal, it has been found that the coated chitosan could significantly improve As(V) performance of Na–X zeolite. The optimal working pH for removal As(V) by chitosan-coated Na–X zeolite was attained at pH 2.1 ± 0.1, and the maximum adsorption capacity was 63.23 mg/g. And the adsorption data at different interval time was excellent fitted by pseudo-second-order kinetic model. From the analyze of XPS, the results suggested that As(V) uptake over adsorbent by the bond of As–N and As–O and the surface hydroxyl group of Al–OH and –NH₂ were involved in uptake As(V) from acid wastewater.
Показать больше [+] Меньше [-]Effect of ethylenediaminetetraacetic acid and biochar on Cu accumulation and subcellular partitioning in Amaranthus retroflexus L
2019
Liu, Na | Dai, Jiulan | Tian, Haoqi | He, Huan | Zhu, Yuen
Phytoremediation combined with amendments and stabilization technologies are two crucial methods to deal with soil contaminated with heavy metals. Copper (Cu) contamination in soil near Cu mines poses a serious threat to ecosystems and human health. This study investigated the effect of ethylenediaminetetraacetic acid (EDTA) and biochar (BC) on the accumulation and subcellular distribution of Cu in Amaranthus retroflexus L. to demonstrate the remediation mechanism of EDTA and BC at the cellular level. The role of calcium (Ca) in response to Cu stress in A. retroflexus was also elucidated. We designed a pot experiment with a randomized block of four Cu levels (0, 100, 200, 400 mg kg⁻¹) and three treatments (control, amendment with EDTA, and amendment with BC). The subcellular components were divided into three parts (cell walls, organelles, and soluble fraction) by differential centrifugation. The results showed that EDTA amendment significantly increased (p < 0.05) the concentrations of Cu in root cell walls and all subcellular components of stems and leaves (cell walls, organelles, and the soluble fraction). EDTA amendment significantly increased (p < 0.05) the proportion of exchangeable fraction and carbonate fraction in the soil. While BC amendment significantly decreased (p < 0.05) the concentrations of Cu in root cell walls and the root soluble fraction, it had no significant effects on Cu concentrations in the subcellular components of stems and leaves. The results revealed that EDTA mainly promoted the transfer of Cu to aboveground parts and accumulation in subcellular components of stems and leaves, while BC mainly limited Cu accumulation in root cell walls and the root soluble fraction. Ca concentrations in cell walls of roots, stems, and leaves increased as the Cu stress increased in all treatment groups, indicating that Ca plays an important role in relieving Cu toxicity in Amaranthus retroflexus L.
Показать больше [+] Меньше [-]Efficient removal of dyes from dyeing wastewater by powder activated charcoal/titanate nanotube nanocomposites: adsorption and photoregeneration
2019
Lin, Yingchao | Ma, Jun | Liu, Wen | Li, Zeyu | He, Kai
Effective removal of dyes has been widely investigated by the adsorption of powder activated carbon and photodegradation by titanate nanotubes (TNTs). In this study, a facile one-step alkaline-hydrothermal method was applied to synthesize powder activated charcoal–supported TNTs (TNTs@PAC). Adsorption of three representative dyes, i.e., cationic methylene blue (MB), cationic rhodamine B (RhB), and anionic methyl orange (MO), onto TNTs@PAC was evaluated by the adsorption kinetic experiments and adsorption isotherms. The first 30 min is the main time phase of adsorption, and MB, RhB, and MO obtained the experimental equilibrium uptake of 173.30, 115.06, and 106.85 mg/g, respectively, indicating their final removal efficiencies of 100%, 69.36%, and 64.11%, respectively. The increase of pH value reduced adsorption capacity of MO (from 149.35 mg/g at pH of 2 to 96.99 mg/g at pH of 10), but facilitated MB adsorption, which was attributed to the charge distribution on the surface of TNTs@PAC and the charge of dyes at different pH. Furthermore, good capacity recoveries of MB by TNTs@PAC (> 99%) were observed after UV irradiation treatment, indicating the used TNTs@PAC can be easily recycled for the adsorption of MB by UV irradiation. Overall, TNTs@PAC is an effective process for remediation of dye-contaminated water because of its adsorption performance for all selected dyes and good regeneration capacity for MB.
Показать больше [+] Меньше [-]Quantitative source apportionment of water solutes and CO2 consumption of the whole Yarlung Tsangpo River basin in Tibet, China
2019
Liu, Jiaju | Zhao, Yunpeng | Li, Zheng | Guo, Huaicheng
The Tibetan Plateau is known as the “Asian water tower,” and the Yarlung Tsangpo (YT) River is the largest river that originates in and flows across the southern Tibetan Plateau. Although the solute source of YT River has been extensively and qualitatively analyzed, there is a lack of the quantitative analysis for the whole basin and seasonal variation of hydrochemical characteristics. Here, 212 samples obtained in the mainstream and tributary of YT River in different (wet, normal, and dry) periods were used for the solute apportionment using the mass balance model. The results showed that the solutes in YT River water were mainly derived from the carbonate and silicate rock weathering that accounts 42.2% and 26.9% in the total solute source, respectively, as the complex geological conditions in the basin. A part of the ions (7.5%) was also originated from the atmospheric precipitation as the abundant rainfall in the wet period. Meanwhile, the contribution of solute sources had no significantly seasonal variation in the upstream, whereas it had significantly seasonal variation in the downstream with the tropical climate and heavy rainfall. Importantly, the rock weathering of the basin could consume so much atmospheric CO₂ (0.54% of the consumption at global with the only 0.16% of the global surface area) that could mitigate the global warming, which followed an increasing trend from upstream to downstream. The quantitative analysis of the solute source for YT River fills in the gaps in the chemically characteristic cognition of the basin. It is beneficial for the water resource management for the Asian. The proportion of solute sources in the YT River and its tributaries for wet (W), normal (N), and dry (D) periods
Показать больше [+] Меньше [-]Exploring regional differences in the impact of high energy-intensive industries on CO2 emissions: Evidence from a panel analysis in China
2019
Liu, Hanchu | Fan, Jie | Zhou, Gan | Wang, Qiang
China is currently the largest CO₂ emitter in the world. Within China, more than 60% of CO₂ emissions originate from high energy-intensive (HEI) industries. Therefore, controlling and reducing CO₂ emissions from HEI industries is crucial if China is to achieve its 2030 emission reduction targets. This study aims to investigate regional differences in the impact of HEI industries on CO₂ emissions in China. This paper presents an analysis of the impact of HEI industries on CO₂ emissions at the national and regional levels using a modified STIRPAT model and provincial panel data from 2000 to 2015 in China. The results show that HEI industries are significant contributors to China’s CO₂ emissions owing to the growth in industries, coal-based energy structure, low level of technology, and outstanding conduction effects. The impact intensity of HEI industries on CO₂ emissions decreases from the western to the central and eastern regions in China because of a huge regional difference in industrial structure, energy structure, R&D investment, and industrial transfer. Our findings have important implications for policymakers in China by indicating that regional policies concerning HEI industries should be differentiated to successfully reduce CO₂ emissions and meet national targets.
Показать больше [+] Меньше [-]Performance evaluation of a decentralized wastewater treatment system in India
2019
Singh, Anju | Sawant, Megha | Kamble, Sheetal Jaisingh | Herlekar, Mihir | Starkl, Markus | Aymerich, Enrique | Kazmi, Absar
A Decentralized Wastewater Treatment System (DEWATS) provides an economically feasible and efficient wastewater treatment solution especially in developing countries. It has an enormous potential for developing a sustainable environmental sanitation system. In this study, the treatment efficiency of eight DEWATS plants was evaluated in the state of Maharashtra, India, for their performance in terms of selected physico-chemical parameters of the wastewater. Although the efficiency of some of the plants was lower than that reported in literature, the effluent quality of all the plants was within the permissible discharge limits of the Central Pollution Control Board for all the parameters. Comprehensive assessment of Plant I was carried in terms of its technical and socio-economic aspects. Moreover, LCA tool has been utilized to evaluate the environmental impacts of the operation stage of DEWATS. The midpoint, CML 2001 (April 2015) methodology was adopted, in which 11 impact categories were considered. From the life cycle impact assessment and interpretation, the main impacts are identified as releases of COD, P-PO₄³⁻, and N-NH₄⁺ to water bodies and disposal of sludge. Due to negligible energy consumption, the operation stage was found to be less damaging to the environment. It was concluded that DEWATS can be a good alternative for treating wastewater with negligible energy and chemical consumption.
Показать больше [+] Меньше [-]Thermotolerance of camel (Camelus dromedarius) somatic cells affected by the cell type and the dissociation method
2019
Saadeldin, Islam M. | Swelum, Ayman Abdel-Aziz | Tukur, Hammed A. | Alowaimer, Abdullah N.
Researchers dealing with heat stress experiments use different cell kinds and use trypsin that has been reported to affect the cellular proteins of cultured cells. Therefore, we compared the effects of acute and chronic exposures to high temperature (45 °C) on camel skin fibroblast and granulosa cells. Primary culture of fibroblasts and granulosa cells tolerated the acute heat shock for 2 h; however, granulosa cells cultured for long duration (20 h) showed thermotolerance when compared with the fibroblasts. Moreover, the effect of cell dispersion method (trypsin and mechanical dissociation) on the thermotolerance of sub-cultured cells was examined. Trypsin altered the morphology of fibroblasts and granulosa cells exposed to 45 °C for 4 h. Moreover, trypsin significantly reduced the fibroblast and granulosa cell migration in the wound healing assay. The current results demonstrate that cell passaging and cell type can affect the thermotolerance of the cells; it also revealed that trypsin could alter the cellular response to the heat shock. We raise the demand for another alternative method for cell dispersion in experiments dealing with cellular responses to the heat shock.
Показать больше [+] Меньше [-]Biochar can improve the soil quality of new creation farmland on the Loess Plateau
2019
Su, Cui-Cui | Ma, Ji-Fu | Chen, Yiping
The Loess Plateau is the most severely degraded soil area worldwide and represents one of the lowest areas of soil productivity. To solve the conundrum between increasing populations and decreasing agricultural acreage, enhancing the quantity of cultivated land, gully land consolidation projects has been implemented. However, the new creation farmland soil is not enough to satisfy the demand of agricultural production. An incubation experiment was conducted to determine the effects of biochar on the new creation farmland soil. Five levels of amendments (0, 1%, 2%, 5%, and 10% (wt%) biochar soil) were used, and the soil columns remained in the laboratory for approximately 2 months. The results show that biochar proportion was a more important factor than incubation time across all soils tested. The soil moisture content and particle size clearly increased as the amendment level increased; however, the soil pH decreased gradually with incubation time and tended to slow soil salinization. These findings will have to be verified under field conditions.
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