خيارات البحث
النتائج 2101 - 2110 من 2,512
A robust simulation–optimization modeling system for effluent trading—a case study of nonpoint source pollution control النص الكامل
2014
Zhang, J. L. | Li, Y. P. | Huang, G. H.
In this study, a robust simulation–optimization modeling system (RSOMS) is developed for supporting agricultural nonpoint source (NPS) effluent trading planning. The RSOMS can enhance effluent trading through incorporation of a distributed simulation model and an optimization model within its framework. The modeling system not only can handle uncertainties expressed as probability density functions and interval values but also deal with the variability of the second-stage costs that are above the expected level as well as capture the notion of risk under high-variability situations. A case study is conducted for mitigating agricultural NPS pollution with an effluent trading program in Xiangxi watershed. Compared with non-trading policy, trading scheme can successfully mitigate agricultural NPS pollution with an increased system benefit. Through trading scheme, [213.7, 288.8] × 10³ kg of TN and [11.8, 30.2] × 10³ kg of TP emissions from cropped area can be cut down during the planning horizon. The results can help identify desired effluent trading schemes for water quality management with the tradeoff between the system benefit and reliability being balanced and risk aversion being considered.
اظهر المزيد [+] اقل [-]Enhanced adsorptive removal of naphthalene intermediates from aqueous solution by introducing reed straw into sewage sludge-based activated carbon النص الكامل
2014
Gu, Lin | Guo, Huaqing | Zhou, Pin | Zhu, Nanwen | Zhang, Daofang | Yuan, Haiping | Lou, Ziyang
The disposal of sewage sludge (SS) and reed straw (RS) has becoming a critical issue due to their rapid production. In this study, the SS-based activated carbon (SSC) was produced by introducing the RS as a component material. Properties including BET surface area, pore volume, surface chemical groups, and morphologies were characterized. The adsorption of 1-diazo-2-naphthol-4-sulfonic acid (1,2,4-Acid) and 2-Naphthol (2-Nap), which differs in their physicochemical properties, on as-prepared carbons were investigated. The overall adsorption was found to be jointly controlled by external mass transfer and intraparticle diffusion, and the optimal pH was found to be 5 due to their electrostatic attraction. Further study revealed that the SS- and RS-based carbons (SC and RSC, respectively) exhibited different adsorption behavior toward 1,2,4-Acid and 2-Nap. The calculated adsorption capacity from Langmuir–Freundlich model of SC and RSC for the two intermediates was 141.0, 84.6 mg g⁻¹and 48.2, 110.2 mg g⁻¹, respectively, whereas their hybrid product (SSC) showed comparable capacity for 1,2,4-Acid (117.8 mg g⁻¹), as well as higher capacity for 2-Nap (157.5 mg g⁻¹). It was found that the presence of meso- or macropores facilitates the precipitation of mineral phases of inorganic substances during carbonization, attracting the molecules with polar functional groups, while the introduction of C-rich RS to SS enhances the adsorption of hydrophobic molecules.
اظهر المزيد [+] اقل [-]Enhanced removal of arsenic from a highly laden industrial effluent using a combined coprecipitation/nano-adsorption process النص الكامل
2014
Jiang, Yingnan | Hua, Ming | Wu, Bian | Ma, Hongrui | Pan, Bingcai | Zhang, Quanxing
Effective arsenic removal from highly laden industrial wastewater is an important but challenging task. Here, a combined coprecipitation/nano-adsorption process, with ferric chloride and calcium chloride as coprecipitation agents and polymer-based nanocomposite as selective adsorbent, has been validated for arsenic removal from tungsten-smelting wastewater. On the basis of operating optimization, a binary FeCl₃(520 mg/L)–CaCl₂(300 mg/L) coprecipitation agent could remove more than 93 % arsenic from the wastewater. The resulting precipitate has proved environmental safety based on leaching toxicity test. Fixed-bed column packed with zirconium or ferric-oxide-loaded nanocomposite was employed for further elimination of arsenic in coprecipitated effluent, resulting in a significant decrease of arsenic (from 0.96 to less than 0.5 mg/L). The working capacity of zirconium-loaded nanocomposite was 220 bed volumes per run, much higher than that of ferric-loaded nanocomposite (40 bed volumes per run). The exhausted zirconium-loaded nanocomposite could be efficiently in situ regenerated with a binary NaOH–NaCl solution for reuse without any significant capacity loss. The results validated the combinational coprecipitation/nano-adsorption process to be a potential alternative for effective arsenic removal from highly laden industrial effluent.
اظهر المزيد [+] اقل [-]Detection of feral GT73 transgenic oilseed rape (Brassica napus) along railway lines on entry routes to oilseed factories in Switzerland النص الكامل
2014
Hecht, Mirco | Oehen, Bernadette | Schulze, Jürg | Brodmann-Kron, Peter | Bagutti, Claudia
Detection of feral GT73 transgenic oilseed rape (Brassica napus) along railway lines on entry routes to oilseed factories in Switzerland النص الكامل
2014
Hecht, Mirco | Oehen, Bernadette | Schulze, Jürg | Brodmann-Kron, Peter | Bagutti, Claudia
To obtain a reference status prior to cultivation of genetically modified oilseed rape (OSR, Brassica napus L.) in Switzerland, the occurrence of feral OSR was monitored along transportation routes and at processing sites. The focus was set on the detection of (transgenic) OSR along railway lines from the Swiss borders with Italy and France to the respective oilseed processing factories in Southern and Northern Switzerland (Ticino and region of Basel). A monitoring concept was developed to identify sites of largest risk of escape of genetically modified plants into the environment in Switzerland. Transport spillage of OSR seeds from railway goods cars particularly at risk hot spots such as switch yards and (un)loading points but also incidental and continuous spillage were considered. All OSR plants, including their hybridization partners which were collected at the respective monitoring sites were analyzed for the presence of transgenes by real-time PCR. On sampling lengths each of 4.2 and 5.7 km, respectively, 461 and 1,574 plants were sampled in Ticino and the region of Basel. OSR plants were found most frequently along the routes to the oilseed facilities, and in larger amounts on risk hot spots compared to sites of random sampling. At three locations in both monitored regions, transgenic B. napus line GT73 carrying the glyphosate resistance transgenes gox and CP4 epsps were detected (Ticino, 22 plants; in the region of Basel, 159).
اظهر المزيد [+] اقل [-]Detection of feral GT73 transgenic oilseed rape (Brassica napus) along railway lines on entry routes to oilseed factories in Switzerland النص الكامل
2014
Hecht, Mirco | Oehen, Bernadette | Schulze, Jürg | Brodmann, Peter | Bagutti, Claudia
To obtain a reference status prior to cultivation of genetically modified oilseed rape (OSR, Brassica napus L.) in Switzerland, the occurrence of feral OSR was monitored along transportation routes and at processing sites. The focus was set on the detection of (transgenic) OSR along railway lines from the Swiss borders with Italy and France to the respective oilseed processing factories in Southern and Northern Switzerland (Ticino and region of Basel). A monitoring concept was developed to identify sites of largest risk of escape of genetically modified plants into the environment in Switzerland. Transport spillage of OSR seeds from railway goods cars particularly at risk hot spots such as switch yards and (un)loading points but also incidental and continuous spillage were considered. All OSR plants, including their hybridization partners which were collected at the respective monitoring sites were analyzed for the presence of transgenes by real-time PCR. On sampling lengths each of 4.2 and 5.7 km, respectively, 461 and 1,574 plants were sampled in Ticino and the region of Basel. OSR plants were found most frequently along the routes to the oilseed facilities, and in larger amounts on risk hot spots compared to sites of random sampling. At three locations in both monitored regions, transgenic B. napus line GT73 carrying the glyphosate resistance transgenes gox and CP4 epsps were detected (Ticino, 22 plants; in the region of Basel, 159).
اظهر المزيد [+] اقل [-]Aerosol and ozone observations during six cruise campaigns across the Mediterranean basin: temporal, spatial, and seasonal variability النص الكامل
2014
Bencardino, Mariantonia M. | Pirrone, Nicola N. | Sprovieri, Francesca F.
The Mediterranean basin, because of its semi-enclosed configuration, is one of the areas heavily affected by air pollutants. Despite implications on both human health and radiative budget involving an increasing interest, monitoring databases measuring air pollution directly over this area are yet relatively limited. Owing to this context, concentrations of fine (PM₂.₅) and coarse (PM₂.₅–₁₀) particles along with other ancillary data, such as ozone levels and meteorological parameters, were measured during six cruise campaigns covering almost the whole Mediterranean basin. Elemental composition of both PM₂.₅and PM₂.₅–₁₀was also determined to identify specific tracers for different classes of particles that can be found in the Mediterranean atmosphere. Outcomes resulting from the integration of a preliminary qualitative examination with a more quantitative analysis, based on receptor modelling, suggested that European continental influence, Saharan dust outbreaks, wildfire events, sea spray and fossil fuel combustion were the leading causes of the aerosol-ozone variations within the Mediterranean basin. Shipping emissions, consisting in both local harbours and maritime traffic across the basin, were also tested using the marker ratio of V/Ni. Peak values observed for coarse fraction have shown to be driven by the occurrence of African dust events. Considering the major influence of Continental pollution and wildfire events, the spatial variability resulted in larger fine particle concentrations and higher ozone levels over the Eastern Mediterranean side in comparison to the Western one.
اظهر المزيد [+] اقل [-]Characterization of the interactions between tetracycline antibiotics and microbial extracellular polymeric substances with spectroscopic approaches النص الكامل
2014
Song, Chao | Sun, Xue-Fei | Xing, Su-Fang | Xia, Peng-Fei | Shi, Yi-Jing | Wang, Shu-Guang
The antibiotics have attracted global attentions for their impact on aquatic ecosystem. The knowledge about the fate of antibiotics encountering extracellular polymeric substances (EPS) is, however, limited. In this study, we investigated the interacting mechanisms of tetracycline (TC) to EPS extracted from aerobic activated sludge. The contributions of the main components of EPS, extracellular proteins, and polysaccharides were evaluated using bovine serum albumin and alginate sodium, respectively. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance indicated that hydroxyl, carboxyl, and amino groups were the domain chemical groups involved in the interaction between TC and EPS, and the binding of TC onto EPS changed the structure of these chemical groups, thus causing shifts in their UV–visible absorption spectra. In addition, we found that extracellular proteins, rather than polysaccharides, were the major active contents involved in the interaction. Three-dimensional excitation–emission matrix fluorescence spectroscopy showed that the fluorophores in EPS were clearly quenched by TC and the static quenching process was observed, implying the complex formation of TC and EPS. Furthermore, thermodynamic analysis indicated that the binding of TC with EPS is spontaneous and dominated by electrostatic forces.
اظهر المزيد [+] اقل [-]Effects of multigenerational exposures of D. magna to environmentally relevant concentrations of pentachlorophenol النص الكامل
2014
Chen, Yi | Huang, Jin | Xing, Liqun | Liu, Hongling | Giesy, John P. | Yu, Hongxia | Zhang, Xiaowei
The re-emergence of schistosomiasis has given rise to ubiquitous concentrations of the primary control agent pentachlorophenol (PCP) in the environment, especially in the surface waters of China. In this study, the effects of environmentally relevant concentrations of PCP, namely, 0.0002, 0.002, 0.02, 0.2, and 2 μmol/L on survival, age at first reproduction, fecundity, length of mothers, and number of molts of Daphnia magna were studied over three generations. The survival of D. magna exposed to 2 μmol/L was significantly affected in the three generations. Toxic effects were enhanced in later generations. Age at first reproduction of F₁and F₂D. magna was significantly slower than that of the controls. The total number of offspring per female exposed to concentrations of 0.002 μmol/L or greater was less (23.5 to 67.6, 9.4 to 73.7, and 3.6 to 83.7 %) than that of the controls in the F₀, F₁, and F₂generations, respectively. The body length of mothers significantly decreased (4.7 to 6.8, 9.6 to 15.1, and 13.3 to 23.2 %) after exposure to 0.002 μmol/L or greater than those of unexposed individuals in the F₀, F₁, and F₂generations, respectively. Dose–response relationships between concentrations of PCP and length and number of molts of D. magna were observed in the F₀to F₂generations. PCP concentrations on the surface waters of China caused adverse effects to D. magna, which increased over successive generations. Significant effects were observed in the third generation. The multigenerational studies were more sensitive than the single-generation experiments. Thus, multigenerational exposure may be more predictive of chronic exposure under field conditions.
اظهر المزيد [+] اقل [-]Air pollution control equipment selection guide النص الكامل
2014
Schifftner, Kenneth C.
This book is a good discussion of various air pollution control equipment. It covers a wide range of equipment and gives a good overview of the principles and applications. Very valuable is the practical experiences that are not commonly available in a typical textbook. The language is easy to understand, especially for those who do not have formal training in air pollution control. It provides hybrid systems such as those applied to biomass gasification, odor control using biological technology, plasma arc waste reduction, and more.
اظهر المزيد [+] اقل [-]Reduction of DNA mismatch repair protein expression in airway epithelial cells of premenopausal women chronically exposed to biomass smoke النص الكامل
2014
Mukherjee, Bidisha | Dutta, Anindita | Chowdhury, Saswati | Roychoudhury, Sanghita | Ray, Manas Ranjan
Biomass burning is a major source of indoor air pollution in rural India. This study examined whether chronic inhalation of biomass smoke causes change in the DNA mismatch repair (MMR) pathway in the airway cells. For this, airway cells exfoliated in sputum were collected from 72 premenopausal nonsmoking rural women (median age 34 years) who cooked with biomass (wood, dung, crop residues) and 68 control women who cooked with cleaner fuel liquefied petroleum gas (LPG) for the past 5 years or more. The levels of particulate matters with diameters less than 10 and 2.5 μm (PM₁₀and PM₂.₅) in indoor air were measured by real-time aerosol monitor. Benzene exposure was monitored by measuring trans,trans-muconic acid (t,t-MA) in urine by high-performance liquid chromatography with ultraviolet detector. Generation of reactive oxygen species (ROS) and level of superoxide dismutase (SOD) in airway cells were measured by flow cytometry and spectrophotometry, respectively. Immunocytochemical assay revealed lower percentage of airway epithelial cells expressing MMR proteins mutL homolog 1 (MLH1) and mutS homolog 2 (MSH2) in biomass-using women compared to LPG-using controls. Women who cooked with biomass had 6.7 times higher level of urinary t,t-MA, twofold increase in ROS generation, and 31 % depletion of SOD. Indoor air of biomass-using households had three times more particulate matters than that of controls. ROS, urinary t,t-MA, and particulate pollution in biomass-using kitchen had negative correlation, while SOD showed positive correlation with MSH2 and MLH1 expression. It appears that chronic exposure to biomass smoke reduces MMR response in airway epithelial cells, and oxidative stress plays an important role in the process.
اظهر المزيد [+] اقل [-]Hexavalent chromium removal by a novel Serratia proteamaculans isolated from the bank of Sebou River (Morocco) النص الكامل
2014
Tahri Joutey, Nezha | Bahafid, Wifak | Sayel, Hanane | Ananou, Samir | El Ghachtouli, Naïma
The novel Serratia proteamaculans isolated from a chromium-contaminated site was tolerant to a concentration of 500 mg Cr(VI)/l. The optimum pH and temperature for reduction of Cr(VI) by S. proteamaculans were found to be 7.0 and 30 °C, respectively. The Cr(VI) reduction rate decreased with the increase in Cr(VI) concentration from 100 to 400 mg/l, suggesting the enzymatic chromium reduction. Resting and permeabilised cell assays provided the better evidence that chromate reduction in S. proteamaculans is enzymatic. Reduction by cell-free filtrate shows no extracellular chromate-reducing activity, revealing that this activity may be associated to membrane fraction and/or cytosolic fraction. Assays conducted with cytosolic and particulate fraction of S. proteamaculans confirmed the role of membrane-bound proteins in Cr(VI) reduction. Furthermore, chromium reduced by heat-treated cells suggests that membrane-associated chromate reductase activity of S. proteamaculans is preceded by its adsorption on the cell surface.
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