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Résultats 2761-2770 de 4,033
Screening of pollution control and clean-up materials for river chemical spills using the multiple case-based reasoning method with a difference-driven revision strategy
2016
Liu, Rentao | Jiang, Jiping | Guo, Liang | Shi, Bin | Liu, Jie | Du, Zhaolin | Wang, Peng
In-depth filtering of emergency disposal technology (EDT) and materials has been required in the process of environmental pollution emergency disposal. However, an urgent problem that must be solved is how to quickly and accurately select the most appropriate materials for treating a pollution event from the existing spill control and clean-up materials (SCCM). To meet this need, the following objectives were addressed in this study. First, the material base and a case base for environment pollution emergency disposal were established to build a foundation and provide material for SCCM screening. Second, the multiple case-based reasoning model method with a difference-driven revision strategy (DDRS-MCBR) was applied to improve the original dual case-based reasoning model method system, and screening and decision-making was performed for SCCM using this model. Third, an actual environmental pollution accident from 2012 was used as a case study to verify the material base, case base, and screening model. The results demonstrated that the DDRS-MCBR method was fast, efficient, and practical. The DDRS-MCBR method changes the passive situation in which the choice of SCCM screening depends only on the subjective experience of the decision maker and offers a new approach to screening SCCM.
Afficher plus [+] Moins [-]Distribution, fate, and risk assessment of antibiotics in five wastewater treatment plants in Shanghai, China
2016
Wu, Minghong | Que, Chenjing | Tang, Liang | Xu, Hui | Xiang, Jiajia | Wang, Jiajun | Shi, Wenyan | Xu, Gang
The project studied the occurrence, fate, and seasonal variation of 14 antibiotics, from five wastewater treatment plants (WWTPs) in Shanghai. The results indicated that ofloxacin, sulfamethoxazole, and oxytetracycline were the predominant antibiotics, with maximum concentrations of 1208.20, 959.13, and 564.30 ng/L in influents, while 916.88, 106.60, and 337.81 ng/L in effluents, respectively. The level of antibiotics in WWTPs obviously varied with seasonal changes, and higher detectable frequencies and concentrations were found in winter. The daily mass loads per capita of amoxicillin, enrofloxacin, and oxytetracycline in the study were all higher than those in other regions/countries, such as Hong Kong, Australia, and Italy. The elimination of antibiotics through these WWTPs was incomplete, and a wide range of removal efficiencies during the different treatment process and seasons were observed (−500.56 to 100 % in winter and −124.24 to 94.21 % in summer). Sulfonamides were relatively easy to be removed in WWTPs and the ultraviolet (UV) process can effectively improve the removal efficiency. Risk assessment of antibiotics in effluents was estimated. Only AMOX’s hazard quotient (HQ) was higher than 0.01. Even though the environmental risks in the study were estimated to be low, the potential negative effects on aquatic ecosystems should call our attention as continually discharge in the long term.
Afficher plus [+] Moins [-]Fate and transport of perfluoro- and polyfluoroalkyl substances including perfluorooctane sulfonamides in a managed urban water body
2016
Nguyen, Tung V. | Reinhard, Martin | Chen, Huiting | Gin, Karina Y.-H.
Transport and fate of perfluoro- and polyfluoroalkyl substances (PFASs) in an urban water body that receives mainly urban runoff was investigated. Water, suspended solids, and sediment samples were collected during the monsoon (wet) and inter-monsoon (dry) season at different sites and depths. Samples were analyzed for C7 to C12 perfluoroalkyl carboxylate homologues (PFCAs) (PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA), perfluorohexane, perfluorooctane, and 6:2-fluorotelomer sulfonate (PFHxS, PFOS, and 6:2FtS, respectively), perfluorooctane sulfonamide (FOSA), N-ethyl FOSA (sulfluramid), N-ethyl sulfonamidoethanol (N-EtFOSE), and N-methyl and N-ethyl sulfonamidoacetic acid (N-EtFOSAA and N-MeFOSAA, respectively). Concentrations in wet samples were only slightly higher. The sum total PFAS (ΣPFAS) concentrations dissolved in the aqueous phase and sorbed to suspended solids (SS) ranged from 107 to 253 ng/L and 11 to 158 ng/L, respectively. PFOA, PFOS, PFNA, PFHxS, and PFDA contributed most (approximately 90 %) to the dissolved ΣPFASs. N-EtFOSA dominated the particulate PFAS burden in wet samples. K D values of PFOA and PFOS calculated from paired SS and water concentrations varied widely (1.4 to 13.7 and 1.9 to 98.9 for PFOA and PFOS, respectively). Field derived K D was significantly higher than laboratory K D suggesting hydrophobic PFASs sorbed to SS resist desorption. The ΣPFAS concentrations in the top sedimentary layer ranged from 8 to 42 μg/kg and indicated preferential accumulation of the strongly sorbing long-chain PFASs. The occurrence of the metabolites N-MeFOSAA, N-EtFOSAA and FOSA in the water column and sediments may have resulted from biological or photochemical transformations of perfluorooctane sulfonamide precursors while the absence of FOSA, N-EtFOSA and 6:2FtS in sediments was consistent with biotransformation.
Afficher plus [+] Moins [-]Water-soluble ionic species of coarse and fine particulate matter and gas precursor characteristics at urban and rural sites of central Taiwan
2016
Tsai, Jiun-Horng | Tsai, Su-Mei | Wang, Wei-Chi | Chiang, Hung-Lung
Coarse and fine particulate matter (PM) were taken by a dichotomous sampler, and gas precursors were determined by a denuder sampler at two stations in central Taiwan. Water-soluble ionic constituents of PM and their precursor gases were analyzed by ionic chromatograph. In summer, the daytime/nighttime PM₁₀ concentrations were 37 ± 10/41 ± 18 μg m⁻³ and 36 ± 14/34 ± 18 μg m⁻³ for Xitun and Jhushan, respectively. Average PM₁₀ concentration in winter was 1.55 and 1.76 times that of summer for Xitun and Jhushan, respectively. PM mass concentrations were similar for both stations, although one station is located in the downtown area of Taichung, and the other is in a rural area with no heavy pollution sources. Water-soluble ionic species content was 38–53 % of PM₂.₅ and 43–48 % of PM₁₀ mass concentration. HNO₃, HCl, and SO₂ were high in the daytime; the daytime-to-nighttime concentration ratio was 3.75–6.88 for HNO₃,1.7–7.8 for HCl, and 1.45–2.77 for SO₂. High NH₃ levels were determined in the area, especially in winter, which could be a precursor of NH₄ ⁺ to form particulate matter. In Xitun, motor vehicles downtown and in the industrial district could be sources of air pollution. In contrast, there are few industrial sources at Jhushan; therefore, the transport of air pollutants from upwind of other regions and the accumulation of pollutants could be important PM sources at Jhushan.
Afficher plus [+] Moins [-]Accumulation of metals relevant for agricultural contamination in gills of European chub (Squalius cephalus)
2016
Dragun, Zrinka | Tepić, Nataša | Krasnići, Nesrete | Teskeredžić, Emin
The study of metal bioaccumulation in the gills of European chub (Squalius cephalus) was conducted in September 2009 at the medium-sized rural river Sutla, characterized by agricultural and municipal type of water contamination. The concentration ranges were established for the first time in the soluble, metabolically available fractions of chub gills for 12 metals, which are environmentally extremely relevant and yet only seldom studied, as follows in a decreasing order: K, 225–895 mg L⁻¹; Na, 78–366 mg L⁻¹; Ca, 19–62 mg L⁻¹; Mg, 13–47 mg L⁻¹; Rb, 164–1762 μg L⁻¹; Sr, 24–81 μg L⁻¹; Ba, 13–67 μg L⁻¹; Mo, 1.3–16 μg L⁻¹; Co, 0.7–2.7 μg L⁻¹; Li, 0.4–2.2 μg L⁻¹; Cs, 0.2–1.9 μg L⁻¹; and V, 0.1–1.8 μg L⁻¹. The concentrations of Fe (1.6–6.4 mg L⁻¹) and Mn (16–69 μg L⁻¹) were also determined and were in agreement with previous reports. By application of general linear modelling, the influence of different abiotic (metal exposure level) and biotic parameters (fish sex, age, size and condition) on metal bioaccumulation was tested. It was established that bioaccumulation of many metals in fish depended on various physiological conditions, wherein Ba could be singled out as metal exhibiting the strongest association with one of biotic parameters, being significantly higher in smaller fish. However, it was also undoubtedly demonstrated that the concentrations of three metals can be applied as reliable indicators of metal exposure even in the conditions of low or moderate water contamination, such as observed in the Sutla River, and those were nonessential elements Li and Cs and essential element Fe. The results of our study present an important contribution to maintenance of high ecological status of European freshwaters, through enrichment of knowledge on the bioaccumulation of various metals in gills of European chub as frequently applied bioindicator species in monitoring of water pollution.
Afficher plus [+] Moins [-]N-fixing trees in wetland restoration plantings: effects on nitrogensupply and soil microbial communities
2016
Chen, Xueping | Yang, JunNa | Zhu, XiE | Liang, Xia | Lei, YanRu | He, ChiQuan
To investigate the impact of an exotic Frankia nodulated tree (Alnus trabeculosa) on soil nitrogen content, soil microbial composition, and the abundance of N turnover-related functional microorganism community, we compared the community structure and abundance of key functional genes (nifH, bacterial/archaeal amoA, and nosZ) in the rhizosphere and nonrhizosphere of monoculture of Phragmites australis and A.trabeculosa–P.australis mixed communities by MiSeq Illumina sequencing and real-time PCR, respectively. The introduction of Frankia nodulated tree to recover degraded wetland was effective in the accumulation of soil organic carbon and nitrogen, which was the key factor to impact on the bacterial community composition revealed by canonical correspondence analysis. Acidobacteria and Proteobacteria were the dominant bacterial phylums while seven rare phyla appeared the most phylogenetically different among the investigated soil of two vegetations, including Chlorobi, Cyanobacteria, OD1, OP11, TM6, TM7, and GN02. The gene copy numbers of nifH were ranged from 2.28 × 10⁸ to 2.96 × 10⁹ copies g⁻¹ dry soil in the wetland, and which were significantly higher in soil samples from P. australis than that from A.trabeculosa. While the abundance of nosZ in both rhizosphere and nonrhizosphere soils of A.trabeculosa–P.australis mixed communities was significantly lower compared with P.australis monoculture. The potential nitrification (PNA) (0.15–0.41 mg NOx-N kg⁻¹ dry soil d⁻¹) in the rhizosphere of A. trabeculosa was significantly higher than that of P. australis, and the soil denitrification enzyme activity (DEA) (0.42–0.90 nmol N₂O-N g⁻¹ dry soil h⁻¹) was lower in the mixed community compared with monoculture of P. australis. The introduced planting of Frankia nodulated tree effectively accumulated soil organic carbon and nitrogen and reduce the relative abundance and activity of nitrogen-fixing bacteria and denitrification bacteria.
Afficher plus [+] Moins [-]Carbon emissions, logistics volume and GDP in China: empirical analysis based on panel data model
2016
Guo, Xiaopeng | Ren, Dongfang | Shi, Jiaxing
This paper studies the relationship among carbon emissions, GDP, and logistics by using a panel data model and a combination of statistics and econometrics theory. The model is based on the historical data of 10 typical provinces and cities in China during 2005–2014. The model in this paper adds the variability of logistics on the basis of previous studies, and this variable is replaced by the freight turnover of the provinces. Carbon emissions are calculated by using the annual consumption of coal, oil, and natural gas. GDP is the gross domestic product. The results showed that the amount of logistics and GDP have a contribution to carbon emissions and the long-term relationships are different between different cities in China, mainly influenced by the difference among development mode, economic structure, and level of logistic development. After the testing of panel model setting, this paper established a variable coefficient model of the panel. The influence of GDP and logistics on carbon emissions is obtained according to the influence factors among the variables. The paper concludes with main findings and provides recommendations toward rational planning of urban sustainable development and environmental protection for China.
Afficher plus [+] Moins [-]Sewage sludge hazardous assessment: chemical evaluation and cytological effects in CHO-k1 cells
2016
Bonomo, M. M. | Morozesk, M. | Duarte, I. D. | Rocha, L. D. | Fernandes, M. N. | Matsumoto, S. T.
Application of sewage sludge in agricultural lands is a growing practice in several countries due to its numerous benefits to soil and crops, where chemical and pathogen levels are determined by corresponding legislation. However, the presence of contaminants in residues must always be controlled before application due to their dangerous effects over the ecosystem and potential risks to human health. The main objective of this study was to integrate biological and chemical analysis in order to help elucidating the residue potential toxic, cytotoxic, and mutagenic effects. We evaluate samples of sewage sludge before and after the sanitizing treatment with lime in cytokinesis-block assay using CHO-k1 culture cells. The sanitizing treatment promoted a decrease in pathogen levels, which is the main purpose of this process. Even with chemical levels below the established by environmental agencies, results showed sewage sludge ability to enhance genotoxic and mutagenic effects, proving that residue should be handled with caution in order to minimize its environmental and human risk.
Afficher plus [+] Moins [-]Assessing toxic effects of [Omim]Cl and [Omim]BF4 in zebrafish adults using a biomarker approach
2016
Liu, Tong | Guo, Yingying | Wang, Jinhua | Wang, Jun | Zhu, Lusheng | Zhang, Jun | Zhang, Cheng
In the present study, the toxic effects of 1-octyl-3-methylimidazolium chloride ([Omim]Cl) and 1-octyl-3-methylimidazolium tetrafluoroborate ([Omim]BF₄) on the zebrafish livers were studied at 0, 5, 10, 20, and 40 mg L⁻¹ on the 7th and 14th days. In addition, the concentrations of [Omim]Cl and [Omim]BF₄ in the test water, the acute toxicity of the two ionic liquids (ILs), and the influence of anions on the toxicity of the ILs were evaluated. The acute toxicity test results showed 50 % lethal concentration (LC₅₀) values of 152.3 ± 12.1 mg L⁻¹ for [Omim]Cl and 144.0 ± 11.4 mg L⁻¹ for [Omim]BF₄. At the lowest concentration investigated (5 mg L⁻¹), [Omim]Cl and [Omim]BF₄ did not significantly affect zebrafish during the exposure period. However, the toxic effects of these substances were enhanced as dosing concentrations and exposure times were increased. Levels of reactive oxygen species (ROS) were significantly enhanced on the 7th day after 20 mg L⁻¹ and on the 14th day after 10 mg L⁻¹ of either substance was applied, resulting in oxidative damage, such as lipid peroxidation and DNA damage. The experimental results also indicated little effect of the anions on the toxicity of ILs and consistent toxic effects of [Omim]Cl and [Omim]BF₄. Graphical Abstract The graphical abstract for the present study after exposure to [Omim]Cl and [Omim]BF₄. The letter R represents the anions Cl⁻ and BF₄ ⁻
Afficher plus [+] Moins [-]Comparison of UV/hydrogen peroxide and UV/peroxydisulfate processes for the degradation of humic acid in the presence of halide ions
2016
Lou, Xiaoyi | Xiao, Dongxue | Fang, Changling | Wang, Zhaohui | Liu, Jianshe | Guo, Yaoguang | Lü, Shuyu
This study compared the behaviors of two classic advanced oxidation processes (AOPs), hydroxyl radical-based AOPs (•OH-based AOPs) and sulfate radical-based AOPs (SO₄ •⁻-based AOPs), represented by UV/ hydrogen peroxide (H₂O₂) and UV/peroxydisulfate (PDS) systems, respectively, to degrade humic acid (HA) in the presence of halide ions (Cl⁻ and Br⁻). The effects of different operational parameters, such as oxidant dosages, halide ions concentration, and pH on HA degradation were investigated in UV/H₂O₂/Cl⁻, UV/PDS/Cl⁻, UV/H₂O₂/Br⁻, and UV/PDS/Br⁻ processes. It was found that the oxidation capacity of H₂O₂ and PDS to HA degradation in the presence of halides was nearly in the same order. High dosage of peroxides would lead to an increase in HA removal while excess dosage would slightly inhibit the efficiency. Both Cl⁻ and Br⁻ would have depressing impact on the two AOPs, but the inhibiting effect of Br⁻ was more obvious than that of Cl⁻, even the concentration of Cl⁻ was far above that of Br⁻. The increasing pH would have an adverse effect on HA decomposition in UV/H₂O₂ system, whereas there was no significant impact of pH in UV/PDS process. Furthermore, infrared spectrometer was used to provide the information of degraded HA in UV/H₂O₂/Cl⁻, UV/PDS/Cl⁻, UV/H₂O₂/Br⁻, and UV/PDS/Br⁻ processes, and halogenated byproducts were identified in using GC-MS analysis in the four processes. The present research might have significant technical implications on water treatment using advanced oxidation technologies.
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