خيارات البحث
النتائج 3221 - 3230 من 5,151
Mixed strategy to allocate resources with air pollution treatment in China: based on the analytic network process and large-group decision-making method النص الكامل
2018
Chen, Xi | Zhao, Liu | Özdemir, Mujgan Sagir | Leung, Raymond H. M. (Raymond Hai Ming)
The resource allocation of air pollution treatment in China is a complex problem, since many alternatives are available and many criteria influence mutually. A number of stakeholders participate in this issue holding different opinions because of the benefits they value. So a method is needed, based on the analytic network process (ANP) and large-group decision-making (LGDM), to rank the alternatives considering interdependent criteria and stakeholders’ opinions. In this method, the criteria related to air pollution treatment are examined by experts. Then, the network structure of the problem is constructed based on the relationships between the criteria. Further, every participant in each group provide comparison matrices by judging the importance between criteria according to dominance, regarding a certain criteria (or goal), and the geometric average comparison matrix of each group is obtained. The decision weight of each group is derived by combining the subjective weight and the objective weight, in which the subjective weight is provided by organizers, while the objective weight is determined by considering the consensus levels of groups. The final comparison matrices are obtained by the geometric average of comparison matrices and the decision weights. Next, the resource allocation is made according to the priorities of the alternatives using the super decision software. Finally, an example is given to illustrate the use of the proposed method.
اظهر المزيد [+] اقل [-]Hydrologic monitoring tools for freshwater municipal planning in the Arctic: the case of Iqaluit, Nunavut, Canada النص الكامل
2018
Bakaic, Michael | Medeiros, Andrew Scott | Peters, Jessica F. | Wolfe, Brent B.
Freshwater and the services it provides are vital to both natural ecosystems and human needs; however, extreme climates and their influence on freshwater availability can be challenging for municipal planners and engineers to manage these resources effectively. In Arctic Canada, financial and human capital limitations have left a legacy of freshwater systems that underserve current communities and may be inadequate in the near future under a warming climate, growing population, and increasing demand. We address this challenge to community water resource planning by applying several novel water supply forecasting methods to evaluate the Apex River as an alternative freshwater source for Iqaluit, Nunavut (Canada). Surveys of water isotope composition of the Apex River and tributaries indicated that rainfall is the main source of water replenishment. This information was utilized to calibrate a water resource assessment that considered climate forecasting scenarios and their influence on supply, and alternative scenarios for freshwater management to better adapt to a changing climate. We found that under current climate and demand conditions, the freshwater supply of Iqaluit would be in a perpetual state of drawdown by 2024. Analysis of current infrastructure proposals revealed significant deficiencies in the supply extensions proposed whereby the Apex replenishment pipeline would only provide a 2-year extension to current municipal supply. Our heuristic supply forecast methods allowed for several alternative supply strategies to be rapidly evaluated, which will aid the community planning process by specifically quantifying the service life of the city’s current and future primary water supply.
اظهر المزيد [+] اقل [-]Does biochar affect the availability and chemical fractionation of phosphate in soils? النص الكامل
2018
Hong, Can | Lu, Shenggao
Biochar as a soil amendment has been reported to affect the content and availability of soil nutrients. In this study, we aimed to test whether the biochar addition to soils would change the availability and chemical fractionation of phosphate in soils. Two soils (Ultisol and Alfisol) were amended with five kinds of biochars at application rate of 0, 1, and 2% (w/w). After 3-month incubation, availability and chemical forms of P were measured to investigate the potential effect and role of biochar in improving P availability in soils. The biochars used here had a lager variation of P content, depending on their feedstocks. Compared to the untreated soils, application of biochars derived from deciduous tree leaves (DLB), reed (RB), and rice straw (RSB) significantly increased the pH of two soils. The total P content of biochar-amended soils was increased with the addition of biochars. However, only RSB exhibited a significant increase (p < 0.05) of total P content. Application of biochars significantly increased the NH₄Cl-extractable P content of two soils, indicating that biochars were able to increase the availability of phosphate in soils, but the amount of available P was dependent on biochar types. Ultisol and Alfisol amended with RSB (2% w/w) showed an increase in the P availability (0.5 M NaHCO₃-extractable P) by 46 and 39%, respectively. For strongly acidic Ultisol, addition of biochar significantly increased Al-P and Ca-P content, as well as decreased Fe-P content. The P desorption test indicated the release of P from soils increased with the addition of biochar. Results suggested that biochar would change the P sorption affinity of the soil and help to increase the availability of fixed P. The increase of P availability with biochar application was due to the pH change and direct P contribution from biochar. Our results concluded that biochar affected the availability, chemical forms, and sorption capability of phosphate in soil. The extent of biochar effects on soil P varied greatly with the type of feedstock of biochar and soil type.
اظهر المزيد [+] اقل [-]Differential transcriptional changes in human alveolar epithelial A549 cells exposed to airborne PM2.5 collected from Shanghai, China النص الكامل
2018
Lei, Xiaoning | Muscat, Joshua E. | Huang, Zhongsi | Chen, Chao | Xiu, Guangli | Chen, Jiahui
Fine particulate matters (PM₂.₅) are the core pollutants of haze episode, which pose a serious threat to the human health of developing countries. However, the mechanisms involved in PM₂.₅-induced hazard influence are not to fully elucidated. In the present study, human lung epithelial cells (A549) were exposed to various concentrations of PM₂.₅ samples collected from Shanghai, China. Illumina RNA-Seq method with transcriptome, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were further employed to identify the detrimental effects of PM₂.₅ on A549 cells in vitro. A total of 712 differentially expressed genes were obtained from global transcriptome profiling of A549 cells after PM₂.₅ exposure. In addition, GO function enrichment analysis revealed that major differentially expressed genes (DEGs) involved in the biological process of the immune system and the response to the stress. KEGG pathway analysis further proposes that infectious disease, cancers, cardiovascular disease, and immune disease pathway were the key human disease events that occur in A549 cells under PM₂.₅ stress. The data obtained here shed light on the related biological process and gene signaling pathways affected by PM₂.₅ exposure. This study aids our understanding of the complicated mechanisms related to PM₂.₅-induced health effects and is informative for the prevention and treatment of PM₂.₅-induced systemic diseases.
اظهر المزيد [+] اقل [-]Identification of phytotoxins in different plant parts of Brassica napus and their influence on mung bean النص الكامل
2018
Mehmood, Azhar | Naeem, Muhammad | Khalid, Farhan | Saeed, Yousaf | Abbas, Tasawer | Jabran, Khawar | Sarwar, Muhammad Aqeel | Tanveer, Asif | Javaid, Muhammad Mansoor
Plants in Brassica genus have been found to possess strong allelopathic potential. They may inhibit seed germination and emergence of subsequent crops following them in a rotation system. Series of laboratory and greenhouse experiments were conducted to determine the allelopathic impacts of Brassica napus L. against mung bean. We studied (1) the effects of aqueous extract (5%) of different plant parts (root, stem, leaf, flower, and whole plant) of B. napus, (2) the effects of leaf and flower extracts of B. napus at 0, 1, 2, 3, and 4% concentrations, and (3) the effect of residues of different B. napus plant parts and decomposition periods (0, 7, 14, and 21 days) on germination and seedling growth of mung bean. Various types of phenolics including quercitin, chlorogenic acid, p-coumeric acid, m-coumaric acid, benzoic acid, caffeic acid, syringic acid, vanillic acid, ferulic acid, cinamic acid, and gallic acid were identified in plant parts of B. napus. Among aqueous extracts of various plant parts, leaf and flower were found to have stronger inhibitory effects on germination and seedling growth traits of mung bean, higher concentrations were more toxic. The decomposition period changed the phtotoxic effect of residues, more inhibitory effect was shown at 14 days decomposition while decomposition for 21 days reduced inhibitory effect. The more total water-soluble phenolic was found in 5% (w/v) aqueous extract and 5% (w/w) residues of B. napus flowers at 14 days of decomposition (89.80 and 10.47 mg L⁻¹), respectively. The strong inhibitory effects of B. napus should be managed when followed in rotation.
اظهر المزيد [+] اقل [-]In situ phytoremediation characterization of heavy metals promoted by Hydrocotyle ranunculoides at Santa Bárbara stream, an anthropogenic polluted site in southern of Brazil النص الكامل
2018
Demarco, Carolina F. | Afonso, Thays F. | Pieniz, Simone | Quadro, Maurízio S. | Camargo, Flávio A. O. | Andreazza, Robson
Aquatic environments are widely affected by anthropogenic activities and efficient remediation of these areas requires detailed studies for each natural ecosystem. This research aimed to evaluate the natural phytoremediation potential of Hydrocotyle ranunculoides L., a floating aquatic macrophyte located in a polluted aquatic environment in South of the Rio Grande do Sul, Brazil. Nutrients such as P, K, Ca, Mg, and S and heavy metals such as Cu, Zn, Fe, Mn, Na, Cd, Cr, Ni, Pb, Al, As, Co, and V content in the roots and shoots of the plants were evaluated through nitric perchloric acid digestion (HNO₃-HClO₄) methods and quantified by ICP-OES. Bioconcentration factor (BCF), translocation factor (TF), plant effective number (PEN), and potential phytoremoval (mg m⁻²) were carried out. H. ranunculoides showed a substantial ability for phytoextracting P, Na, and As, since showed ability of uptake these elements from the water and translocate them to the shoots of the plants. H. ranunculoides also showed potential for application in rhizofiltration of Mg, S, Cu, Zn, Fe, Mn, Cd, Cr, Ni, Pb, Al, and V, since exhibited high potential to uptake higher levels in the roots. The highest potential for bioremoval (mg m⁻²) of the H. ranunculoides was detected for K, Ca, P (recommending thus the use for phytoextraction), Fe, and Al (highly recommended for rhizofiltration). Therefore, this species under study showed high potential for in situ phytoremediation at Santa Bárbara stream, and as a widespread species, it might be tested for phytoremediation in other sites.
اظهر المزيد [+] اقل [-]Assessment of legacy and emerging contaminants in an introduced catfish and implications for the fishery النص الكامل
2018
Luellen, Drew R. | LaGuardia, Mark J. | Tuckey, Troy D. | Fabrizio, Mary C. | Rice, Gary W. | Hale, Robert C.
Since introduction into the Chesapeake Bay watershed in the 1970s, blue catfish (Ictalurus furcatus) populations have increased, impacting native species. One strategy suggested to limit their growing numbers is to expand the existing commercial fishery. However, the promotion of human consumption of this large, omnivorous fish may increase exposure to contaminants of concern (COC). However, there are few published data on contaminants in blue catfish. To evaluate this possibility, we measured COC (PCBs, PBDEs, OCs, Hg) in individual fillets and compared levels to established consumption advisory limits. James River (near Richmond, Virginia) and Upper Potomac River (downstream of Washington DC) fish exhibited higher burdens of most COC than those from the lower James and rural Rappahannock rivers. Fish sex and δ¹⁵N values (surrogate for trophic position) did not correlate with COC concentrations. Potomac River fish exhibited greatest δ¹⁵N, perhaps related to local wastewater inputs. Despite differences in human population densities among watersheds, fish mercury (Hg) levels were similar. Most fillets surpassed US EPA advisory limits for unrestricted consumption (> 16 meals/month) for Hg and PCBs. Hg and PCB advisories in the region typically restrict consumption to two 220 g meals/month. Hence, individuals who rely on fish for a large portion of their diet may be exposed to unacceptable Hg and PCB concentrations. COC levels typically increased with fish length; in particular, fish > 550 mm often exceeded unrestricted consumption limits for chlordanes and DDTs. PBDEs, pentachloroanisole, hexachlorobenzene, and mirex levels were generally below established advisories. However, because fish advisories are based on the expected consequences from single contaminants and a single or limited number of toxicological endpoints, consumers face greater risks due to cumulative effects from all coincident COCs, as well as additional exposure pathways, such as other food and air. The additional data on contaminant levels reported here will increase the accuracy of forecasted risks. However, it also illustrates the complexity in communicating the risks from multi-contaminant exposure.
اظهر المزيد [+] اقل [-]Valorisation of tuna processing waste biomass: isolation, purification and characterisation of four novel antioxidant peptides from tuna by-product hydrolysate النص الكامل
2018
Saidi, Sami | Saoudi, Mongi | Ben Amar, Raja
Tuna protein hydrolysate (TPH) was prepared by hydrolysis with Prolyve BS and fractionated by membranes process. The antioxidant activities of recovered peptide fractions were evaluated. Four novel antioxidant peptides that were isolated from nanofiltration retentate exhibited the highest antioxidant activity, using gel chromatography and reversed phase high-performance liquid chromatography. The amino acid sequences of isolated peptides were identified as Tyr-Glu-Asn-Gly-Gly (P2), Glu-Gly-Tyr-Pro-Trp-Asn (P4), Tyr-Ile-Val-Tyr-Pro-Gly (P7) and Trp-Gly-Asp-Ala-Gly-Gly-Tyr-Tyr (P8) with molecular weights of 538.46, 764.75, 710.78 and 887.85 Da, respectively. P2, P4, P7 and P8 exhibited good scavenging activities on hydroxyl radical (IC₅₀ 0.41, 0.327, 0.17 and 0.042 mg/ml), DPPH radical (IC₅₀ 0.666, 0.326, 0.451 and 0.377 mg/ml) and superoxide radical (IC₅₀ 0.536, 0.307, 0.357 and 0.115 mg/ml). P7 was effective against lipid peroxidation in the model system. The isolated peptides might be useful used as natural food additive in food industry and formulation of nutritional products.
اظهر المزيد [+] اقل [-]Biodegradation of CuTETA, an effluent by-product in mineral processing النص الكامل
2018
Cushing, Alexander M. L. | Kelebek, Sadan | Yue, Siqing | Ramsay, Juliana A.
Polyamines such as triethylenetetramine (TETA) and other amine chelators are used in mineral processing applications. Formation of heavy metal complexes of these reagents as a by-product in effluent water is a recent environmental concern. In this study, Paecilomyces sp. was enriched from soil on TETA as the sole source of carbon and nitrogen and was found to degrade > 96 and 90% CuTETA complexes at initial concentrations of 0.32 and 0.79 mM respectively, following 96-h incubation. After destabilization, most of the copper (> 78%) was complexed extracellularly and the rest was associated with the cell. Mass spectroscopy results provided confirmation that copper re-complexed with small, extracellular, and organic molecules. There are no reports in the literature that Paecilomyces or any other organism can grow on TETA or CuTETA. This study is the first to show that biological destabilization of CuTETA complexes in mineral processing effluents is feasible.
اظهر المزيد [+] اقل [-]Polycyclic aromatic hydrocarbon (PAH) levels in environmental media potentially impacted by reused or stored creosote-treated railway ties النص الكامل
2018
Cargouët, Maëlle | Jeannee, Nicolas | Vidart, Bertrand | Gregori, Patrizia
Disused creosote-treated railway ties are reused in France and many other countries and, in particular, for landscaping and other residential uses. Given the lack of data on the environmental fate of creosote-derived compounds released from used railway ties, a survey of different environmental media (i.e. soil, sediment, surface water, plants and outdoor air) was carried out at six sites located in France where old creosote-treated railway ties are stored or reused for different purposes. Maximum total polycyclic aromatic hydrocarbon (PAH) concentrations measured in soils ranged from 2 to 140 mg/kg dry weight. PAH impacts were limited both vertically and horizontally to several centimetres from the railway ties. At two sites, PAH levels in plants (up to 140 μg/kg fresh weight) appeared correlated to the levels measured in soils, suggesting a transfer from soils to the plants. PAHs in sediment were measured at concentrations of up to 280 mg/kg dry weight. As observed in soil, PAH concentrations decreased rapidly further away from the railway ties. Principal component analysis and hierarchical clustering on principal components indicate that PAHs detected in soils and sediments originated from unweathered to severely weathered creosote and could be strongly influenced by urban background. Results on outdoor air measurements show a degradation of air quality above old and fresh railway tie storage areas at a railway station and to a lesser extent in their vicinity. However, this degradation was low to moderate when compared to French regulatory values, ambient background levels reported in France, as well as health-based air comparison values.
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