خيارات البحث
النتائج 1771 - 1780 من 1,956
Gas/particle partitioning of polycyclic aromatic hydrocarbons in coastal atmosphere of the north Yellow Sea, China النص الكامل
2013
Wang, Zhen | Ren, Peifang | Sun, Yan | Ma, Xindong | Liu, Xing | Na, Guangshui | Yao, Ziwei
Samples of gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs) were collected at three sampling stations (Xiaomai Island, Laohutan, and Zhangzi Island) in the north Yellow Sea, China during November 2008 and September 2009 to study their atmospheric transport potential and the gas/particle distributions. The composition of PAHs was dominated by gaseous compounds. The percentages of the particle-phase PAHs to the total concentrations were found to be higher during the heating period than the non-heating period. The ratios of naphthalene and acenaphthene to phenanthrene, chrysene and dibenzo(a,h)anthracene showed an increasing trend from Xiaomai Island to Zhangzi Island, which can be called as the local atmospheric distillation of PAHs. Gas/particle partitioning coefficients (K ₚ) and their relationship with the sub-cooled liquid vapor pressures (pºL) of PAHs were investigated. The regressions of logK ₚ versus logpºL gave significant correlations for all samples of the three sites with r ² values in the range 0.56–0.66 (p < 0.01). Both Junge–Pankow adsorption model and octanol–air partition coefficient absorption model tended to underestimate the sorption for most PAHs, but the absorption model appeared to be more suitable for predicting the particle fraction of PAHs than the Junge–Pankow model.
اظهر المزيد [+] اقل [-]An early warning and control system for urban, drinking water quality protection: China’s experience النص الكامل
2013
Hou, Dibo | Song, Xiaoxuan | Zhang, Guangxin | Zhang, Hongjian | Loaiciga, Hugo
An event-driven, urban, drinking water quality early warning and control system (DEWS) is proposed to cope with China’s urgent need for protecting its urban drinking water. The DEWS has a web service structure and provides users with water quality monitoring functions, water quality early warning functions, and water quality accident decision-making functions. The DEWS functionality is guided by the principles of control theory and risk assessment as applied to the feedback control of urban water supply systems. The DEWS has been deployed in several large Chinese cities and found to perform well insofar as water quality early warning and emergency decision-making is concerned. This paper describes a DEWS for urban water quality protection that has been developed in China.
اظهر المزيد [+] اقل [-]Pharmaceutical residues in tidal surface sediments of three rivers in southeastern China at detectable and measurable levels النص الكامل
2013
Chen, Yongshan S. | Yu, Shen | Hong, Youwei W. | Lin, Qiaoying Y. | Li, Hongbo B.
Pharmaceutical compounds were increasingly detected in environmental matrices but little is known whether these compounds would transport to coastal zones via watersheds. Three typical tidal rivers in southeastern China were selected and 15 surface sediment samples (0-10 cm) were collected along a 50-km tidal section of each river. Surface sediment samples were frozen-drying and then extracted for pharmaceutical compounds by an accelerated solvent extraction system. The pharmaceutical compounds in extracts were scanned using a high-performance liquid chromatography/tandern mass spectrometry (HPLC-MS/MS). Three hundred and thirty compounds from nine pharmaceutical groups were detected with signal-to-noise above three (detectable level) in the surface sediments, of which 186 compounds were with a signal-to-noise above ten (measurable level). Of all, 291 and 80 compounds were detectable and measurable in all the three rivers, respectively. The Jiulong River showed a high load of pharmaceutical compounds in surface sediment than other two rivers. Of the nine pharmaceutical groups, the antihistamines and detoxification group and anti-infective drug group contributed five dominant compounds in the surface sediments in all the three rivers. Natures of pharmaceutical compounds rather than the sediment properties (pH, EC, and total carbon content) might influence their residues. The incredible number and intensity of pharmaceutical residues were detected in tidal surface sediments of the three rivers indicating that the pharmaceutical contamination should be strongly considered in China. Source identification and eco-toxicity assessment should be taken into account in the future study. Therapeutic medicine managements need to be strictly improved at a watershed scale to reduce loads of pharmaceuticals into aquatic ecosystems.
اظهر المزيد [+] اقل [-]Environmental–sanitary risk analysis procedure applied to artificial turf sports fields النص الكامل
2013
Ruffino, Barbara | Fiore, Silvia | Zanetti, Maria Chiara
Owing to the extensive use of artificial turfs worldwide, over the past 10 years there has been much discussion about the possible health and environmental problems originating from styrene-butadiene recycled rubber. In this paper, the authors performed a Tier 2 environmental-sanitary risk analysis on five artificial turf sports fields located in the city of Turin (Italy) with the aid of RISC4 software. Two receptors (adult player and child player) and three routes of exposure (direct contact with crumb rubber, contact with rainwater soaking the rubber mat, inhalation of dusts and gases from the artificial turf fields) were considered in the conceptual model. For all the fields and for all the routes, the cumulative carcinogenic risk proved to be lower than 10(-6) and the cumulative non-carcinogenic risk lower than 1. The outdoor inhalation of dusts and gases was the main route of exposure for both carcinogenic and non-carcinogenic substances. The results given by the inhalation pathway were compared with those of a risk assessment carried out on citizens breathing gases and dusts from traffic emissions every day in Turin. For both classes of substances and for both receptors, the inhalation of atmospheric dusts and gases from vehicular traffic gave risk values of one order of magnitude higher than those due to playing soccer on an artificial field.
اظهر المزيد [+] اقل [-]Nitrogen impacts on atrazine-degrading Arthrobacter strain and bacterial community structure in soil microcosms النص الكامل
2013
Zhou, Xiaode | Wang, Qingfeng | Wang, Zhao | Xie, Shuguang
The objective of this study was to investigate the impacts of exogenous nitrogen on a microbial community inoculated with the atrazine-degrading Arthrobacter sp. in soil amended with a high concentration of atrazine. Inoculated and uninoculated microcosms for biodegradation tests were constructed. Atrazine degradation capacity of the strain DAT1 and the strain's atrazine-metabolic potential and survival were assessed. The relative abundance of the strain DAT1 and the bacterial community structure in soils were characterized using quantitative PCR in combination with terminal restriction fragment length polymorphism. Atrazine degradation by the strain DAT1 and the strain's atrazine-metabolic potential and survival were not affected by addition of a medium level of nitrate, but these processes were inhibited by addition of a high level of nitrate. Microbial community structure changed in both inoculated and uninoculated microcosms, dependent on the level of added nitrate. Bioaugmentation with the strain DAT1 could be a very efficient biotechnology for bioremediation of soils with high concentrations of atrazine.
اظهر المزيد [+] اقل [-]Solid-state fermentation: tool for bioremediation of adsorbed textile dyestuff on distillery industry waste-yeast biomass using isolated Bacillus cereus strain EBT1 النص الكامل
2013
Kadam, Avinash A. | Kamatkar, Jeevan D. | Khandare, Rahul V. | Jadhav, Jyoti P. | Govindwar, Sanjay P.
Bioremediation of textile dyestuffs under solid-state fermentation (SSF) using industrial wastes as substrate pose an economically feasible, promising, and eco-friendly alternative. The purpose of this study was to adsorb Red M5B dye, a sample of dyes mixture and a real textile effluent on distillery industry waste-yeast biomass (DIW-YB) and its further bioremediation using Bacillus cereus EBT1 under SSF. Textile dyestuffs were allowed to adsorb on DIW-YB. DIW-YB adsorbed dyestuffs were decolorized under SSF by using B. cereus. Enzyme analysis was carried out to ensure decolorization of Red M5B. Metabolites after dye degradation were analyzed using UV–Vis spectroscopy, FTIR, HPLC, and GC-MS. DIW-YB showed adsorption of Red M5B, dyes mixture and a textile wastewater sample up to 87, 70, and 81 %, respectively. DIW-YB adsorbed Red M5B was decolorized up to 98 % by B. cereus in 36 h. Whereas B. cereus could effectively reduce American Dye Manufacture Institute value from DIW-YB adsorbed mixture of textile dyes and textile wastewater up to 70 and 100 %, respectively. Induction of extracellular enzymes such as laccase and azoreductase suggests their involvement in dye degradation. Repeated utilization of DIW-YB showed consistent adsorption and ADMI removal from textile wastewater up to seven cycles. HPLC and FTIR analysis confirms the biodegradation of Red M5B. GC-MS analysis revealed the formation of new metabolites. B. cereus has potential to bioremediate adsorbed textile dyestuffs on DIW-YB. B. cereus along with DIW-YB showed enhanced decolorization performance in tray bioreactor which suggests its potential for large-scale treatment procedures.
اظهر المزيد [+] اقل [-]Spatial distribution and source apportionment of water pollution in different administrative zones of Wen-Rui-Tang (WRT) river watershed, China النص الكامل
2013
Yang, Liping | Mei, Kun | Liu, Xingmei | Wu, Laosheng | Zhang, Minghua | Xu, Jianming | Wang, Fan
Water quality degradation in river systems has caused great concerns all over the world. Identifying the spatial distribution and sources of water pollutants is the very first step for efficient water quality management. A set of water samples collected bimonthly at 12 monitoring sites in 2009 and 2010 were analyzed to determine the spatial distribution of critical parameters and to apportion the sources of pollutants in Wen-Rui-Tang (WRT) river watershed, near the East China Sea. The 12 monitoring sites were divided into three administrative zones of urban, suburban, and rural zones considering differences in land use and population density. Multivariate statistical methods [one-way analysis of variance, principal component analysis (PCA), and absolute principal component score—multiple linear regression (APCS-MLR) methods] were used to investigate the spatial distribution of water quality and to apportion the pollution sources. Results showed that most water quality parameters had no significant difference between the urban and suburban zones, whereas these two zones showed worse water quality than the rural zone. Based on PCA and APCS-MLR analysis, urban domestic sewage and commercial/service pollution, suburban domestic sewage along with fluorine point source pollution, and agricultural nonpoint source pollution with rural domestic sewage pollution were identified to the main pollution sources in urban, suburban, and rural zones, respectively. Understanding the water pollution characteristics of different administrative zones could put insights into effective water management policy-making especially in the area across various administrative zones.
اظهر المزيد [+] اقل [-]Hydrothermal synthesis of meso/macroporous BiVO₄ hierarchical particles and their photocatalytic degradation properties under visible light irradiation النص الكامل
2013
Madhusudan, Puttaswamy | Kumar, Malahalli Vijaya | Ishigaki, Tadashi | Toda, Kenji | Uematsu, Kazuyoshi | Satō, Mineo
An ordered hierarchical meso/macroporous monoclinic bismuth vanadate (BiVO₄) particle was fabricated for the first time by a simple two-step melamine template hydrothermal method followed by calcination. The physiochemical parameters of as-prepared porous materials were characterized by means of X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Raman, Barrett–Emmett–Teller, and UV–vis techniques. The nitrogen adsorption–desorption measurement and pore size distribution curve suggest that meso/macropores exist in these hierarchical microarchitectures. Further, it is found that melamine plays a significant role in the formation of porous BiVO₄ particles, and when a known amount of melamine was added, the surface area and pore size of such porous BiVO₄ particles were increased. The photocatalytic activities of the as-prepared hierarchical BiVO₄ samples were measured for the photodegradation of Congo red aqueous dye solution under visible light irradiation. Surprisingly, the porous BiVO₄ particles showed outstanding photocatalytic activities than polycrystalline BiVO₄ sample. The possible enhancement of such catalytic performance has also been further discussed.
اظهر المزيد [+] اقل [-]Graphene—a promising material for removal of perchlorate (ClO₄ ⁻) from water النص الكامل
2013
Lakshmi, Jothinathan | Vasudevan, Subramanyan
A batch adsorption process was applied to investigate the removal of perchlorate (ClO) from water by graphene. In doing so, the thermodynamic adsorption isotherm and kinetic studies were also carried out. Graphene was prepared by a facile liquid-phase exfoliation. Graphene was characterized by Raman spectroscopy, Fourier-transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscope, and zeta potential measurements. A systematic study of the adsorption process was performed by varying pH, ionic strength, and temperature. The adsorption efficiency of graphene was 99.2 %, suggesting that graphene is an excellent adsorbent for ClO removal from water. The rate constants for all these kinetic models were calculated, and the results indicate that second-order kinetics model was well suitable to model the kinetic adsorption of ClO. Equilibrium data were well described by the typical Langmuir adsorption isotherm. The experimental results showed that graphene is an excellent perchlorate adsorbent with an adsorbent capacity of up to 0.024 mg/g at initial perchlorate concentration of 2 mg/L and temperature of 298 K. Thermodynamic studies revealed that the adsorption reaction was a spontaneous and endothermic process. Graphene removed the perchlorate present in the water and reduced it to a permissible level making it drinkable.
اظهر المزيد [+] اقل [-]Evaluation of the individuality of white rot macro fungus for the decolorization of synthetic dye النص الكامل
2013
Pandey, Priyanka | Singh, Ram Praksh | Singh, Kailash Nath | Manisankar, Paramasivam
INTRODUCTION: A biosorbent was developed by simple dried Agaricus bisporus (SDAB) and effectively used for the biosorption of cationic dyes, Crystal Violet and Brilliant Green. MATERIALS AND METHODS: For the evaluation of the biosorbent system, all the batch equilibrium parameters like pH, biomass dose, contact time, and temperature were optimized to determine the decolorization efficiency of the biosorbent. The maximum yields of dye removal were achieved at pH 4.0 for Crystal Violet (CV) and pH 5.0 for Brilliant Green (BG), which are closer to their natural pH also. RESULT AND DISCUSSION: Equilibrium was established at 60 and 40 min for CV and BG, respectively. Pseudo first-order, pseudo second-order, and intraparticle-diffusion kinetic models were studied at different temperatures. Isotherm models such as Freundlich, Langmuir, and Dubinin–Radushkevich were also studied. Biosorption processes were successfully described by Langmuir isotherm model and the pseudo second-order kinetic model. CONCLUSIONS: The biosorption capacity of A. bisporus over CV and BG were found as 21.74 and 12.16 mg gm⁻¹. Thermodynamic parameters indicated that the CV and BG dye adsorption onto A. bisporus is spontaneous and exothermic in the single and ternary systems. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used for the surface morphology, crystalline structure of biosorbent, and dye–biosorbent interaction, respectively. This analysis of the biosorption data confirmed that these biosorption processes are ecofriendly and economical. Thus, this biomass system may be useful for the removal of contaminating cationic dyes.
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