خيارات البحث
النتائج 2531 - 2540 من 4,309
Fate of antimicrobial resistance genes in response to application of poultry and swine manure in simulated manure-soil microcosms and manure-pond microcosms النص الكامل
2017
Wang, Mianzhi | Sun, Yongxue | Liu, Peng | Sun, Jing | Zhou, Qin | Xiong, Wenguang | Zeng, Zhenling
This study aimed to determine the occurrence, abundance, and fate of nine important antimicrobial resistance genes (ARGs) (sul1, sul2, tetB, tetM, ermB, ermF, fexA, cfr, and Intl1) in the simulated soil and pond microcosms following poultry and swine manure application. Absolute quantitative PCR method was used to determine the gene copies. The results were modeled as a logarithmic regression (N = mlnt + b) to explore the fate of target genes. Genes sul1, Intl1, sul2, and tetM had the highest abundance following the application of the two manure types. The logarithmic regression model fitted the results well (R ² values up to 0.99). The reduction rate of all genes (except for the genes fexA and cfr) in manure-pond microcosms was faster than those in manure-soil microcosms. Importantly, sul1, intl1, sul2, and tetM had the lowest reduction rates in all the samples and the low reduction rates of tetM was the first time to be reported. These results indicated that ARG management should focus on using technologies for the ARG elimination before the manure applications rather than waiting for subsequent attenuation in soil or water, particularly the ARGs (such as sul1, intl1, sul2, and tetM investigated in this study) that had high abundance and low reduction rate in the soil and water after application of manure.
اظهر المزيد [+] اقل [-]Photodegradation applied to the treatment of phenol and derived substances catalyzed by TiO2/BiPO4 and biological toxicity analysis النص الكامل
2017
Zaidan, Léa Elias Mendes Carneiro | de Lima Sales, Renata Vitória | de Almeida Salgado, Júlia Barbosa | da Silva, Ana Maria Ribeiro Bastos | Napoleão, Daniella Carla | Rodríguez-Díaz, Joan Manuel | Marques, Olga Martins | Benachour, Mohand | da Silva, Valdinete Lins
For this work, a phenol solution model was treated by an advanced oxidation process (AOPs), using the heterogeneous catalyst TiO₂/BiPO₄ and hydrogen peroxide combined with UVA for 240 min. An annular reactor containing a UVA lamp (80 W) was employed. A central composite rotacional design was developed employing a TiO₂/BiPO₄ concentration of 87 mg L⁻¹ and a hydrogen peroxide concentration of 1800 mg L⁻¹, being evaluated by the degradation percentage and phenol mineralization percentage as responses; 94.30 and 67.00 % were obtained for the phenol degradation and total organic carbon (TOC) conversion, respectively. The lumped kinetic model (LKM) was applied and a satisfactory profile of the residual fractions of the organic compounds present in the liquid phase as a time function with a determination coefficient (R ² = 0.9945). The toxicity tests employing microbiological species indicated that the organisms tested for the evaluation of the toxic compounds present in the contaminated samples presented a practical low cost test, rapid execution, and high sensibility as an indicator of the presence of toxic substances in liquid effluents.
اظهر المزيد [+] اقل [-]A combined NMR- and HPLC-MS/MS-based metabolomics to evaluate the metabolic perturbations and subacute toxic effects of endosulfan on mice النص الكامل
2017
Zhang, Ping | Zhu, Wentao | Wang, Dezhen | Yan, Jin | Wang, Yao | Zhou, Zhiqiang | He, Lin
Endosulfan is the newly persistent organic pollutants (POPs) added to the Stockholm Convention as its widespread use, persistence, bioaccumulation, long-range transport, endocrine disruption, and toxicity related to various adverse effects. In the present study, male mice were administrated endosulfan at 0, 0.5, and 3.5 mg/kg by gavage for 2 weeks. ¹H-NMR-based urinary metabolomics, HPLC-MS/MS-based targeted serum metabolomics, clinical analysis, and histopathology techniques were employed to evaluate the metabolic perturbations of subacute endosulfan exposure. Endosulfan exposures resulted in weight loss, liver inflammation and necrosis, and alterations in serum amino acids and urine metabolomics. Based on altered metabolites, several significantly perturbed pathways were identified including glycine, serine, and threonine metabolism; TCA cycle; pyruvate metabolism; glycolysis or gluconeogenesis; glycerophospholipid metabolism; and glyoxylate and dicarboxylate metabolism. Such pathways were highly related to amino acid metabolism, energy metabolism, and lipid metabolism. In addition, metabolomic results also demonstrated that gut microbiota was remarkably altered after endosulfan exposure. These observations may provide novel insight into revealing the potential toxic mechanism and evaluating the health risk of endosulfan exposure at metabolomic level.
اظهر المزيد [+] اقل [-]Maternal-embryonic metabolic and antioxidant response of Chapalichthys pardalis (Teleostei: Goodeidae) induced by exposure to 3,4-dichloroaniline النص الكامل
2017
Carbajal-Hernández, Ana Laura | Valerio-García, Roberto Carlos | Martínez-Ruíz, Erika Berenice | Jarquín-Díaz, Víctor Hugo | Martínez-Jerónimo, Fernando
Chapalichthys pardalis is a viviparous fish, microendemic to the Tocumbo Region in the state of Michoacán, Mexico. Despite the peculiar type of reproduction of goodeid fish and their mother-embryo interaction, the effects on embryos induced by maternal exposure to aquatic xenobiotics are still unknown. The objective of the present work was to determine the maternal-embryonic metabolic and antioxidant response of C. pardalis exposed to 3,4-dichloroaniline (3,4-DCA), a compound considered highly noxious to the environment because of its high toxicity and persistence, which has been used as reference toxicant in toxicological bioassays. We determined the median lethal concentration (LC₅₀, 96 h) and then exposed pregnant females to 3.3, 2.5, and 0.5 mg L⁻¹ of 3,4-DCA (equivalent to LC₁, LC₀.₀₁, and LC₅₀/₁₀, respectively) during 21 days. We assessed the activity of antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), macromolecules content (proteins, lipids, carbohydrates), glucose, and lactate concentration, as well as the oxidative damage, by measuring thiobarbituric acid reactive substances, and protein oxidation. To interpret results, we used the integrated biomarker response (IBRv2). The average LC₅₀ was of 5.18 mg L⁻¹ (4.8–5.5 mg L⁻¹; p = 0.05). All females exposed to concentrations of 3.3 and 2.5 mg L⁻¹ lost 100% of the embryos during the bioassay, whereas those exposed to 0.5 mg L⁻¹ showed alterations in the antioxidant activity and oxidative damage, being the embryos and the maternal liver the most affected, with IBRv2 values of 10.09 and 9.21, respectively. Damage to macromolecules was greater in embryos and the maternal liver, with IBRv2 of 16.14 and 8.40, respectively. We conclude that exposure to xenobiotics, like 3,4-DCA, in species with a marked maternal-embryonic interaction represents a potential risk for the development and survival of the descendants, thereby, potentially affecting the future of the population.
اظهر المزيد [+] اقل [-]Emergency material allocation and scheduling for the application to chemical contingency spills under multiple scenarios النص الكامل
2017
Liu, Jie | Guo, Liang | Jiang, Jiping | Jiang, Dexun | Wang, Peng
In the emergency management relevant to chemical contingency spills, efficiency emergency rescue can be deeply influenced by a reasonable assignment of the available emergency materials to the related risk sources. In this study, an emergency material scheduling model (EMSM) with time-effective and cost-effective objectives is developed to coordinate both allocation and scheduling of the emergency materials. Meanwhile, an improved genetic algorithm (IGA) which includes a revision operation for EMSM is proposed to identify the emergency material scheduling schemes. Then, scenario analysis is used to evaluate optimal emergency rescue scheme under different emergency pollution conditions associated with different threat degrees based on analytic hierarchy process (AHP) method. The whole framework is then applied to a computational experiment based on south-to-north water transfer project in China. The results demonstrate that the developed method not only could guarantee the implementation of the emergency rescue to satisfy the requirements of chemical contingency spills but also help decision makers identify appropriate emergency material scheduling schemes in a balance between time-effective and cost-effective objectives.
اظهر المزيد [+] اقل [-]An overview of municipal solid waste management and landfill leachate treatment: Malaysia and Asian perspectives النص الكامل
2017
Kamaruddin, Mohamad Anuar | Yusoff, Mohd Suffian | Rui, Lo Ming | Isa, Awatif Md | Zawawi, Mohd Hafiz | Alrozi, Rasyidah
Currently, generation of solid waste per capita in Malaysia is about 1.1 kg/day. Over 26,500 t of solid waste is disposed almost solely through 166 operating landfills in the country every day. Despite the availability of other disposal methods, landfill is the most widely accepted and prevalent method for municipal solid waste (MSW) disposal in developing countries, including Malaysia. This is mainly ascribed to its inherent forte in terms cost saving and simpler operational mechanism. However, there is a downside. Environmental pollution caused by the landfill leachate has been one of the typical dilemmas of landfilling method. Leachate is the liquid produced when water percolates through solid waste and contains dissolved or suspended materials from various disposed materials and biodecomposition processes. It is often a high-strength wastewater with extreme pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD), inorganic salts and toxicity. Its composition differs over the time and space within a particular landfill, influenced by a broad spectrum of factors, namely waste composition, landfilling practice (solid waste contouring and compacting), local climatic conditions, landfill’s physico-chemical conditions, biogeochemistry and landfill age. This paper summarises an overview of landfill operation and leachate treatment availability reported in literature: a broad spectrum of landfill management opportunity, leachate parameter discussions and the way forward of landfill leachate treatment applicability.
اظهر المزيد [+] اقل [-]Optimized treatment conditions for textile wastewater reuse using photocatalytic processes under UV and visible light sources النص الكامل
2017
Starling, Maria Clara V. M. | Castro, Luiz Augusto S. | Marcelino, Rafaela B. P. | Leão, Mônica M. D. | Amorim, Camila C.
In this study, photo-Fenton systems using visible light sources with iron and ferrioxalate were tested for the DOC degradation and decolorization of textile wastewater. Textile wastewaters originated after the dyeing stage of dark-colored tissue in the textile industry, and the optimization of treatment processes was studied to produce water suitable for reuse. Dissolved organic carbon, absorbance, turbidity, anionic concentrations, carboxylic acids, and preliminary cost analysis were performed for the proposed treatments. Conventional photo-Fenton process achieved near 99 % DOC degradation rates and complete absorbance removal, and no carboxylic acids were found as products of degradation. Ferrioxalate photo-Fenton system achieved 82 % of DOC degradation and showed complete absorbance removal, and oxalic acid has been detected through HPLC analysis in the treated sample. In contrast, photo-peroxidation with UV light was proved effective only for absorbance removal, with DOC degradation efficiency near 50 %. Treated wastewater was compared with reclaimed water and had a similar quality, indicating that these processes can be effectively applied for textile wastewater reuse. The results of the preliminary cost analysis indicated costs of 0.91 to 1.07 US$ m⁻³ for the conventional and ferrioxalate photo-Fenton systems, respectively. Graphical Abstract ᅟ
اظهر المزيد [+] اقل [-]Use of phytoproductivity data in the choice of native plant species to restore a degraded coal mining site amended with a stabilized industrial organic sludge النص الكامل
2017
Chiochetta, Claudete G. | Toumi, Hela | Böhm, Renata F. S. | Engel, Fernanda | Poyer-Radetski, Gabriel | Rörig, Leonardo R. | Adani, Fabrizio | Radetski, Claudemir M.
Coal mining-related activities result in a degraded landscape and sites associated with large amounts of dumped waste material. The arid soil resulting from acid mine drainage affects terrestrial and aquatic ecosystems, and thus, site remediation programs must be implemented to mitigate this sequential deleterious processes. A low-cost alternative material to counterbalance the affected physico-chemical-microbiological aspects of the degraded soil is the amendment with low contaminated and stabilized industrial organic sludge. The content of nutrients P and N, together with stabilized organic matter, makes this material an excellent fertilizer and soil conditioner, fostering biota colonization and succession in the degraded site. However, choice of native plant species to restore a degraded site must be guided by some minimal criteria, such as plant survival/adaptation and plant biomass productivity. Thus, in this 3-month study under environmental conditions, phytoproductivity tests with five native plant species (Surinam cherry Eugenia uniflora L., C. myrianthum–Citharexylum myrianthum, Inga–Inga spp., Brazilian peppertree Schinus terebinthifolius, and Sour cherry Prunus cerasus) were performed to assess these criteria, and additional biochemical parameters were measured in plant tissues (i.e., protein content and peroxidase activity) exposed to different soil/sludge mixture proportions. The results show that three native plants were more adequate to restore vegetation on degraded sites: Surinam cherry, C. myrianthum, and Brazilian peppertree. Thus, this study demonstrates that phytoproductivity tests associated with biochemical endpoint measurements can help in the choice of native plant species, as well as aiding in the choice of the most appropriate soil/stabilized sludge proportion in order to optimize biomass production.
اظهر المزيد [+] اقل [-]Effects of sublethal Abamectin exposure on some hormonal profiles and testicular histopathology in male albino rats and the possible ameliorative role of Eruca sativa النص الكامل
2017
Hassan, Hanaa Fawzy | Meligi, Noha M.
The ameliorative role of Eruca sativa on some hormonal profile and testicular histopathology in male albino rats exposed to a sublethal dose of 1 mg/kg body weight (b.wt). Abamectin (Crater 3.37% EC) was evaluated. Eighteen male albino rats were divided into three groups: control group, Abamectin-treated group, and Abamectin + E. sativa-treated group. Rats of the second group were orally administrated 1 mg/kg b.wt. of Abamectin, the third group received a mixture of sublethal oral dose of Abamectin (1 mg/kg b.wt.) and E. sativa suspension (5 g/kg b.wt.) every 48 h for 28 days. At the end of the study, blood samples were collected from all groups to measure some hormonal parameters; also, rats were dissected and tissue sections from the testes were prepared and stained with hematoxylin and eosin for examination under light microscope. The results of the present study revealed a disturbance in the hormonal parameters and some testicular histopathological changes. In addition, administration of E. sativa might have a promising effect against Abamectin toxicity-induced disorders of thyroid hormones and impaired testicular functions, which were correlated with histopathological changes in the testes of male rats.
اظهر المزيد [+] اقل [-]Investigations into Salmonella contamination in feed production chain in Karst rural areas of China النص الكامل
2017
Yang, Shenglin | Wu, Zongfen | Lin, Wei | Xu, Longxin | Cheng, Long | Zhou, Lin
In order to understand the status of Salmonella contamination of feed production chain in Karst rural areas, southwest of China, a total of 1077 feed samples including animal feed materials and feed products were randomly collected from different sectors of feed chain covering feed mills, farms, and feed sales in nine regions of Karst rural areas between 2009 and 2012, to conduct Salmonella test. The different positive rates with Salmonella contamination were detected, the highest was 4.7 % in 2009, the lowest was 0.66 % in 2011, while 4.3 % in 2010, 2.8 % in 2012, respectively. Twelve types of feed including concentrate, complete, self-made, and feed ingredients were inspected. Salmonella contamination mainly concentrated on animal protein material such as meat meal, meat and bone meal, feather meal, blood meal, and fish meal. No Salmonella contamination was detected in feed yeast, microbial protein, rapeseed, and soybean meal. Salmonella contamination existed in each sector of feed production chain. This investigation provided a basic reference for feed production management and quality control in feed production chain in Karst rural areas of China.
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