خيارات البحث
النتائج 1851 - 1860 من 2,512
Phytoremediation potential of Pteris vittata L. under the combined contamination of As and Pb: beneficial interaction between As and Pb النص الكامل
2014
Wan, Xiao-ming | Lei, Mei | Chen, Tong-bin | Zhou, Guang-dong | Yang, Jun | Zhou, Xiao-yong | Zhang, Xi | Xu, Rui-xiang
The frequent co-existence of arsenic (As) and lead (Pb) necessitates the investigation of clean-up technologies for multi-metal(loid)s. Field survey and hydroponic experiments were conducted to elucidate the co-accumulation of As and Pb in Pteris vittata L. The P. vittata population isolated from a Pb–Zn mine in Yunnan province, China is a potential extractor of As and Pb co-contamination. Hydroponic experiment found that the highest frond As and Pb concentrations in mining population of P. vittata reached 12.2 and 0.99 g kg⁻¹, respectively. The interaction between As and Pb in P. vittata was further more disclosed. Pb (2 mg L⁻¹) improved the frond As concentration by 60 to 150 % in mining populations of P. vittata. Micro-X-ray absorption spectroscopy indicated that under the combined exposure of As and Pb, the As content in the rhizoid epidermis increased by about 10-fold, and the As(V) percentage increased in each rhizoid tissue, as compared with that under As exposure alone. The co-absorption of As and Pb on the epidermis and the enhanced transportation of As(V) from epidermis into the rhizoid were suggested to contribute to the increased As accumulation.
اظهر المزيد [+] اقل [-]Impact of dispersed fuel oil on cardiac mitochondrial function in polar cod Boreogadus saida النص الكامل
2014
Dussauze, Matthieu | Camus, Lionel | Le Floch, Stéphane | Pichavant-Rafini, Karine | Geraudie, Perrine | Coquillé, Nathalie | Amérand, Aline | Lemaire, Philippe | Theron, Michael
In this study, impact of dispersed oil on cardiac mitochondrial function was assessed in a key species of Arctic marine ecosystem, the polar cod Boreogadus saida. Mature polar cod were exposed during 48 h to dispersed oil (mechanically and chemically) and dispersants alone. The increase observed in ethoxyresorufin-O-deethylase activity and polycyclic aromatic hydrocarbon metabolites in bile indicated no difference in contamination level between fish exposed to chemical or mechanical dispersion of oil. Oil induced alterations of O₂consumption of permeabilised cardiac fibres showing inhibitions of complexes I and IV of the respiratory chain. Oil did not induce any modification of mitochondrial proton leak. Dispersants did not induce alteration of mitochondrial activity and did not increase oil toxicity. These data suggest that oil exposure may limit the fitness of polar cod and consequently could lead to major disruption in the energy flow of polar ecosystem.
اظهر المزيد [+] اقل [-]A new method for modelling roofing materials emissions on the city scale: Application for zinc in the City of Créteil (France) النص الكامل
2014
Sellami-Kaaniche, Emna | Gouvello, Bernard de | Gromaire, Marie-Christine | Chebbo, G. (Ghassan)
A new method for modelling roofing materials emissions on the city scale: Application for zinc in the City of Créteil (France) النص الكامل
2014
Sellami-Kaaniche, Emna | Gouvello, Bernard de | Gromaire, Marie-Christine | Chebbo, G. (Ghassan)
Today, urban runoff is considered as an important source of environmental pollution. Roofing materials, in particular, the metallic ones, are considered as a major source of urban runoff metal contaminations. In the context of the European Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required on the city scale, and therefore the development of assessment tools is needed. However, on this scale, there is an important diversity of roofing materials. In addition, given the size of a city, a complete census of the materials of the different roofing elements represents a difficult task. Information relating roofing materials and their surfaces on an urban district do not currently exist in urban databases. The objective of this paper is to develop a new method of evaluating annual contaminant flow emissions from the different roofing material elements (e.g., gutter, rooftop) on the city scale. This method is based on using and adapting existing urban databases combined with a statistical approach. Different rules for identifying the materials of the different roofing elements on the city scale have been defined. The methodology is explained through its application to the evaluation of zinc emissions on the scale of the city of Créteil.
اظهر المزيد [+] اقل [-]A new method for modelling roofing materials emissions on the city scale: Application for zinc in the City of Créteil (France) النص الكامل
2014
Sellami-Kaaniche, Emna | de Gouvello, Bernard | Gromaire, Marie-Christine | Chebbo, Ghassan | Laboratoire Eau, Environnement et Systèmes Urbains (LEESU) ; AgroParisTech-Université Paris-Est Marne-la-Vallée (UPEM)-École nationale des ponts et chaussées (ENPC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12) | Centre Scientifique et Technique du Bâtiment (CSTB)
International audience | Today, urban runoff is considered as an important source of environmental pollution. Roofing materials, in particular, the metallic ones, are considered as a major source of urban runoff metal contaminations. In the context of theEuropean Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required on thecity scale, and therefore the development of assessment tools is needed. However, on this scale, there is an important diversity of roofing materials. In addition, given the size of a city, a complete census of the materials of the different roofing elements represents a difficult task. Information relating roofing materials and their surfaces on an urban district do not currently exist in urban databases. The objective of this paper is to develop a new method of evaluating annual contaminant flow emissions from the different roofing material elements (e.g., gutter, rooftop) on the city scale. This method is based on using and adapting existing urban databases combined with a statistical approach. Different rules for identifying the materials of the different roofing elements on the city scale have been defined. The methodology is explained through its application to the evaluation of zinc emissions on the scale of the city of Créteil.
اظهر المزيد [+] اقل [-]Weighted species sensitivity distribution method to derive site-specific quality criteria for copper in Tai Lake, China النص الكامل
2014
Shi, Rui | Yang, Chunhui | Su, Runhua | Jin, Jiarui | Chen, Yi | Liu, Hongling | Giesy, John P. | Yu, Hongxia
Tai Lake (Ch: Taihu), which is the largest lake in Jiangsu province, China, has been affected by human activities. As part of a concerted effort to improve water quality to protect the integrity of the Tai Lake ecosystem, a water quality criterion (WQC) was developed for copper (Cu) II. The acute WQC was based on 440 values for acute toxicity of Cu to 24 species from 6 phyla, 16 families, and 20 genera. In addition, 255 values for chronic toxicity of Cu to 10 species from 5 phyla, 8 families, and 9 genera were used to derive chronic WQC. Instead of using a traditional approach based species sensitivity distributions (SSD), a weighted species sensitivity distribution (WSSD) approach was used to calculate the cumulative probability based on endemic species to Tai Lake. Acute and chronic WQC developed by use of the WSSD were 5.3 and 3.7 μg Cu/L, respectively. While the WQC values were comparable to those of other countries, there were slight differences due to variability in species composition of different regions. The site-specific criteria indicated that the current standard set for surface water by the Chinese government might not be protective of aquatic organisms in Tai Lake.
اظهر المزيد [+] اقل [-]Ecological risks and potential sources of heavy metals in agricultural soils from Huanghuai Plain, China النص الكامل
2014
Zhou, Lingli | Yang, Bing | Xue, Nandong | Li, Fasheng | Seip, Hans Martin | Cong, Xin | Yan, Yunzhong | Liu, Bo | Han, Baolu | Li, Huiying
A total of 224 agricultural soil samples from Huanghuai Plain in China were investigated for the concentrations of seven heavy metals (As, Cd, Cr, Hg, Ni, Pb, and Zn). The mean concentrations of the metals were 12, 0.17, 79, 0.04, 35, 25, and 74 mg/kg, respectively. These values are similar or slightly higher than background values in this region, except for Cd with a mean nearly twice the background value. The estimated ecological risks based on contamination factors and potential ecological risk indexes are also mostly low, but considerable for Cd and Hg. Multivariate analysis (including Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) clearly revealed three distinct metal groups, i.e., Cr/Ni/Zn, As/Cd/Pb, and Hg, whose concentrations were closely associated with the distribution and pollution characteristics of industries in and around the plain. The main anthropogenic sources for the three metal groups were identified as atmospheric deposition, sewage irrigation/fertilizers usage, and atmospheric deposition/irrigation water, respectively. The present results are well suited for planning, risk assessment, and decision making by environmental managers of this region.
اظهر المزيد [+] اقل [-]Toxicity assessment through multiple endpoint bioassays in soils posing environmental risk according to regulatory screening values النص الكامل
2014
Rodriguez-Ruiz, A. | Asensio, V. | Zaldibar, B. | Soto, M. | Marigómez, I.
Toxicity profiles of two soils (a brownfield in Legazpi and an abandoned iron mine in Zugaztieta; Basque Country) contaminated with several metals (As, Zn, Pb and Cu in Legazpi; Zn, Pb, Cd and Cu in Zugaztieta) and petroleum hydrocarbons (in Legazpi) were determined using a multi-endpoint bioassay approach. Investigated soils exceeded screening values (SVs) of regulatory policies in force (Basque Country; Europe). Acute and chronic toxicity bioassays were conducted with a selected set of test species (Vibrio fischeri, Dictyostelium discoideum, Lactuca sativa, Raphanus sativus and Eisenia fetida) in combination with chemical analysis of soils and elutriates, as well as with bioaccumulation studies in earthworms. The sensitivity of the test species and the toxicity endpoints varied depending on the soil. It was concluded that whilst Zugaztieta soil showed very little or no toxicity, Legazpi soil was toxic according to almost all the toxicity tests (solid phase Microtox®, D. discoideum inhibition of fruiting body formation and developmental cycle solid phase assays, lettuce seed germination and root elongation test, earthworm acute toxicity and reproduction tests, D. discoideum cell viability and replication elutriate assays). Thus, albeit both soils had similar SVs, their ecotoxicological risk, and therefore the need for intervening, was different for each soil as unveiled after toxicity profiling based on multiple endpoint bioassays. Such a toxicity profiling approach is suitable to be applied for scenario-targeted soil risk assessment in those cases where applicable national/regional soil legislation based on SVs demands further toxicity assessment.
اظهر المزيد [+] اقل [-]Biodegradation of polystyrene-graft-starch copolymers in three different types of soil النص الكامل
2014
Nikolic, Vladimir | Velickovic, Sava | Popović, Alexandre
Materials based on polystyrene and starch copolymers are used in food packaging, water pollution treatment, and textile industry, and their biodegradability is a desired characteristic. In order to examine the degradation patterns of modified, biodegradable derivates of polystyrene, which may keep its excellent technical features but be more environmentally friendly at the same time, polystyrene-graft-starch biomaterials obtained by emulsion polymerization in the presence of new type of initiator/activator pair (potassium persulfate/different amines) were subjected to 6-month biodegradation by burial method in three different types of commercially available soils: soil rich in humus and soil for cactus and orchid growing. Biodegradation was monitored by mass decrease, and the highest degradation rate was achieved in soil for cactus growing (81.30 %). Statistical analysis proved that microorganisms in different soil samples have different ability of biodegradation, and there is a significant negative correlation between the share of polystyrene in copolymer and degree of biodegradation. Grafting of polystyrene on starch on one hand prevents complete degradation of starch that is present (with maximal percentage of degraded starch ranging from 55 to 93 %), while on the other hand there is an upper limit of share of polystyrene in the copolymer (ranging from 37 to 77 %) that is preventing biodegradation of degradable part of copolymers.
اظهر المزيد [+] اقل [-]Sorption of cyromazine on humic acid: Effects of pH, ionic strength and foreign ions النص الكامل
2014
Zhao, Ling | Lin, Zhi-rong | Dong, Yuan-hua
Cyromazine (CY) is a triazine pesticide used as an insect growth inhibitor for fly control in cattle manure, field crops, vegetables, and fruits. Sorption of CY onto humic acid (HA) may affect its environmental fate. In this study, HA was used to investigate the sorption of CY at different solution chemistry conditions (pH, ionic strength) and in the presence of foreign ions and norfloxacin. All sorption isotherms fitted well with the Freundlich and Langmuir models. The sorption reached a maximum at initial pH 4.0 over the initial pH range of 3.0–7.0, implying that the primary sorption mechanism was cation exchange interaction between CY⁺species and the negatively charged functional groups of HA. Increasing Ca²⁺concentration resulted in a considerable reduction in the Kdvalues of CY, hinting that Ca²⁺had probably competed with CY⁺for the cation exchange sites on the surfaces of HA. The sorption of CY on HA in different ionic media followed the order of NH₄Cl ≈ KCl > K₂SO₄> ZnCl₂≈ CaCl₂at pH 5.0. Spectroscopic evidence demonstrated that the amino groups and triazine ring of CY was responsible for sorption onto HA, while the carboxyl group and the O-alkyl structure of HA participated in adsorbing CY.
اظهر المزيد [+] اقل [-]Biological control of plant pathogens: advantages and limitations seen through the case study of Pythium oligandrum النص الكامل
2014
Gerbore, J. | Benhamou, N. | Vallance, J. | Le Floch, G. | Grizard, D. | Regnault-Roger, C. | Rey, P.
The management of certain plant beneficial microorganisms [biological control agents (BCAs)] seems to be a promising and environmental friendly method to control plant pathogens. However, applications are still limited because of the lack of consistency of BCAs when they are applied in the field. In the present paper, the advantages and limitations of BCAs are seen through the example of Pythium oligandrum, an oomycete that has received much attention in the last decade. The biological control exerted by P. oligandrum is the result of a complex process, which includes direct effects through the control of pathogens and/or indirect effects mediated by P. oligandrum, i.e. induction of resistance and growth promotion. P. oligandrum antagonism is a multifaceted and target fungus-dependent process. Interestingly, it does not seem to disrupt microflora biodiversity on the roots. P. oligandrum has an atypical relationship with the plant because it rapidly penetrates into the root tissues but it cannot stay alive in planta. After root colonisation, because of the elicitation by P. oligandrum of the plant-defence system, plants are protected from a range of pathogens. The management of BCAs, here P. oligandrum, is discussed with regard to its interactions with the incredibly complex agrosystems.
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.
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