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Resultados 1891-1900 de 1,956
Quantitative and qualitative characteristics of dissolved organic matter from eight dominant aquatic macrophytes in Lake Dianchi, China Texto completo
2013
Qu, Xiaoxia | Xie, Li | Lin, Ying | Bai, Yingchen | Zhu, Yuanrong | Xie, Fazhi | Giesy, John P. | Wu, Fengchang
The aim of this research was to determine and compare the quantitative and qualitative characteristics of dissolved organic matters (DOM) from eight aquatic macrophytes in a eutrophic lake. C, H, N, and P in ground dry leaves and C, N, and P in DOM of the species were determined, and C/N, C/P, C/H, DOC/C, TDN/N, TDP/P, DOC/TDN, and DOC/TDP were calculated. Chemical structures of the DOM were characterized by the use of multiple techniques including UV-visible, FT-IR, and (13)C CP/MAS spectra. The results showed subtle differences in quantity and quality of DOM among species and life-forms. Except oriental pepper which had a C/H of 0.7, C/H of all the other species was 0.6. C/N and C/P of ground leaves was 10.5-17.3 and 79.4-225.3, respectively, which were greater in floating and submerged species than in the others. Parrot feather also had a small C/P (102.8). DOC/C, TDN/N, and TDP/P were 7.6-16.8, 5.5-22.6, and 22.9-45.6 %, respectively. Except C/N in emergent and riparian species, C/N in the other species and C/P in all the species were lower in their DOM than in the ground leaves. DOM of the macrophytes had a SUVA254 value of 0.83-1.80. The FT-IR and (13)C NMR spectra indicated that the DOM mainly contained polysaccharides and/or amino acids/proteins. Percent of carbohydrates in the DOM was 37.3-66.5 % and was highest in parrot feather (66.5 %) and crofton weed (61.5 %). DOM of water hyacinth, water lettuce, and sago pondweed may have the greatest content of proteins. Aromaticity of the DOM was from 6.9 % in water lettuce to 17.8 % in oriental pepper. DOM of the macrophytes was also different in polarity and percent of Ar-OH. Distinguished characteristics in quantity and quality of the macrophyte-derived DOM may induce unique environmental consequences in the lake systems.
Mostrar más [+] Menos [-]Acetylcholinesterase in honey bees (Apis mellifera) exposed to neonicotinoids, atrazine and glyphosate: laboratory and field experiments Texto completo
2013
Boily, Monique | Sarrasin, Benoit | DeBlois, Christian | Aras, Philippe | Chagnon, Madeleine
In Québec, as observed globally, abnormally high honey bee mortality rates have been reported recently. Several potential contributing factors have been identified, and exposure to pesticides is of increasing concern. In maize fields, foraging bees are exposed to residual concentrations of insecticides such as neonicotinoids used for seed coating. Highly toxic to bees, neonicotinoids are also reported to increase AChE activity in other invertebrates exposed to sub-lethal doses. The purpose of this study was therefore to test if the honey bee’s AChE activity could be altered by neonicotinoid compounds and to explore possible effects of other common products used in maize fields: atrazine and glyphosate. One week prior to pollen shedding, beehives were placed near three different field types: certified organically grown maize, conventionally grown maize or non-cultivated. At the same time, caged bees were exposed to increasing sub-lethal doses of neonicotinoid insecticides (imidacloprid and clothianidin) and herbicides (atrazine and glyphosate) under controlled conditions. While increased AChE activity was found in all fields after 2 weeks of exposure, bees close to conventional maize crops showed values higher than those in both organic maize fields and non-cultivated areas. In caged bees, AChE activity increased in response to neonicotinoids, and a slight decrease was observed by glyphosate. These results are discussed with regard to AChE activity as a potential biomarker of exposure for neonicotinoids.
Mostrar más [+] Menos [-]The porifera Hymeniacidon perlevis (Montagu, 1818) as a bioindicator for water quality monitoring Texto completo
2013
Mahaut, Marie-Laure | Basuyaux, Olivier | Baudinière, Estelle | Chataignier, Claire | Pain, Julien | Caplat, Christelle
Because sponges are promising bioindicators, we present here a multispecies comparison of the bioconcentration capacity for copper, zinc and the hydrocarbon fluoranthene. The spatial distribution of sponge populations was studied in 17 areas in intertidal zones on the Lower Normandy coast (France) to determine the most common species with the highest bioaccumulation capacity. Results are compared with published data on blue mussels Mytilus edulis from the Réseau d'Observation de la Contamination Chimique biomonitoring network. A total of 720 sponge samples were collected to assess species richness. Samples were analysed for metal concentrations by flame-mode atomic absorption spectrometry. Analyses of polycyclic aromatic hydrocarbon were sub-contracted. Species richness varies according to the water mass concerned. The most common species in the study area showing the highest bioconcentration in its soft tissues is Hymeniacidon perlevis, which contains about 20 times the zinc, 44 times the copper and 16 times the fluoranthene levels found in mussels. The variability of contaminant concentrations in H. perlevis is also systematically higher than those in mussels. The results obtained for this sponge closely reflect the heterogeneous distribution of contaminants. This study demonstrates that H. perlevis has a much higher capacity to accumulate in situ contaminants than the blue mussel M. edulis. H. perlevis meets all the requirements of a good bioindicator suitable for use in an integrated monitoring programme. In the near future, controlled cultivation of H. perlevis will allow us to produce sufficient quantities of this species to carry out ecotoxicological tests and in situ biomonitoring by caging.
Mostrar más [+] Menos [-]Impact of sewage sludge spreading on nickel mobility in a calcareous soil: adsorption–desorption through column experiments Texto completo
2013
Mamindy-Pajany, Yannick | Sayen, Stéphanie | Guillon, Emmanuel
A soil column adsorption–desorption study was performed on an agricultural calcareous soil to determine the impact of sewage sludge spreading on nickel mobility. Ni adsorption experiments were followed by desorption tests involving the following liquid extractants: water, calcium (100 mg/L), oxalic acid (525 mg/L equivalent to 100 mg carbon/L), and sludge extracts (0.5 and 2.5 g/L). Desorption tests were also conducted after sewage sludge spreading at three application rates (30, 75, and 150 t/ha). According to the breakthrough curve, Ni adsorption was irreversible and occurred mainly through interactions with calcite surface sites. Nickel desorption from the soil column was promoted in presence of significant dissolved organic carbon (DOC) concentration as observed with oxalic acid elution and sludge extract at 2.5 g/L. In sludge-amended soil columns, the maximum Ni levels occurred in first pore volumes, and they were positively correlated to the sludge application rate. The presence of DOC in leaching waters was the main factor controlling Ni desorption from the sludge-amended soil columns. This finding implies that DOC generated by sludge applied on calcareous soils might facilitate the leaching of Ni due to the formation of soluble Ni–organic complexes. Thus, sludge application can have potential environmental impacts in calcareous soils, since it promotes nickel transport by decreasing Ni retention by soil components.
Mostrar más [+] Menos [-]A novel source of biofertilizer from feather biomass for banana cultivation Texto completo
2013
Gurav, Ranjit G. | Jadhav, Jyoti P.
Feather waste is a promising protein biomass available as by-product from poultry processing was found to be rich in peptides, amino acids, and minerals like nitrogen, phosphorus, potassium, calcium, magnesium, iron, manganese, zinc, and copper. Soil and foliar application of these products, besides representing a sustainable solution to the problem of feather disposal, may also represent an effective strategy to tackle the environmental effluence. As a consequence, they were also found to be very attractive in elevating the protein, amino acids, reducing sugar, total chlorophyll, and proline content of plants. On the other side, fertilizing effect enhanced the antioxidant potential of banana fruit which was assessed using 2, 2-diphenyl-1-picrylhydrazyl, ferric reducing/antioxidant power, and N, N-dimethyl-p-phenylendiamine. This was associated with considerably higher antioxidant contents like total phenolics and flavonoids. Therefore, the application of this organic amendment could promote and improve the agro-ecosystem, human health; soil biological activities, and at the same time enhance the production of plant or products rich in bioactive substances.
Mostrar más [+] Menos [-]Remediation of polycyclic aromatic hydrocarbon and metal-contaminated soil by successive methyl-β-cyclodextrin-enhanced soil washing–microbial augmentation: a laboratory evaluation Texto completo
2013
Sun, Mingming | Luo, Yongming | Teng, Ying | Jia, Zhongjun | Li, Zhengao | Deng, Shiping
Polycyclic aromatic hydrocarbon (PAH) and metal-polluted sites caused by abandoned coking plants are receiving wide attention. To address the associated environmental concerns, innovative remediation technologies are urgently needed. This study was initiated to investigate the feasibility of a cleanup strategy that employed an initial phase, using methyl-β-cyclodextrin (MCD) solution to enhance ex situ soil washing for extracting PAHs and metals simultaneously, followed by the addition of PAH-degrading bacteria (Paracoccus sp. strain HPD-2) and supplemental nutrients to treat the residual soil-bound PAHs. Elevated temperature (50 °C) in combination with ultrasonication (35 kHz, 30 min) at 100 g MCD L⁻¹ was effective in extracting PAHs and metals to assist soil washing; 93 % of total PAHs, 72 % of Cd, 78 % of Ni, 93 % of Zn, 84 % of Cr, and 68 % of Pb were removed from soil after three successive washing cycles. Treating the residual soil-bound PAHs for 20 weeks led to maximum biodegradation rates of 34, 45, 36, and 32 % of the remaining total PAHs, 3-ring PAHs, 4-ring PAHs, and 5(+6)-ring PAHs after washing procedure, respectively. Based on BIOLOG Ecoplate assay, the combined treatment at least partially restored microbiological functions in the contaminated soil. The ex situ cleanup strategy through MCD-enhanced soil washing followed by microbial augmentation can be effective in remediating PAH and metal-contaminated soil.
Mostrar más [+] Menos [-]Effects of a constructional intervention on airborne and deposited particulate matter in the Portuguese National Tile Museum, Lisbon Texto completo
2013
Anaf, Willemien | Horemans, Benjamin | Madeira, Teresa I. | Carvalho, M Luisa | De Wael, Karolien | Van Grieken, René
In the 1970s, a large ambulatory of the National Tile Museum, Lisbon, was closed with glass panes on both ground and first floor. Although this design was meant to protect the museum collection from ambient air pollutants, small openings between the glass panes remain, creating a semi-enclosed corridor. The effects of the glass panes on the indoor air quality were evaluated in a comparative study by monitoring the airborne particle concentration and the extent of particle deposition at the enclosed corridor as well as inside the museum building. Comparison of the indoor/outdoor ratio of airborne particle concentration demonstrated a high natural ventilation rate in the enclosed corridor as well as inside the museum building. PM₁₀ deposition velocities on vertical surfaces were estimated in the order of 3 × 10⁻⁴ m s⁻¹ for both indoor locations. Also, the deposition rates of dark-coloured and black particles in specific were very similar at both indoor locations, causing visual degradation. The effectiveness of the glass panes in protecting the museum collection is discussed.
Mostrar más [+] Menos [-]Preliminaries on pollution risk factors related to mining and ore processing in the Cu-rich pollymetallic belt of Eastern Carpathians, Romania Texto completo
2013
Stumbea, Dan
The present study focuses on the mineralogical and geochemical patterns of mining and ore-processing wastes from some occurrences in the Eastern Carpathians; its aim is to identify the main factors and processes that could lead to the pollution of the environment. In this respect, the following types of solid waste were investigated: efflorescent salts developed on the surface of rock blocks from a quarry, ore-processing waste from two tailings ponds, and salt crusts developed at the surface of a tailings pond. The potential risks emphasized by these preliminary investigations are the following: (1) the risk of wind-driven removal and transport of the waste from the surface of tailings ponds, given that fine grains prevail (up to 80 %); (2) the risk of tailings removal through mechanical transport by water, during heavy rainfall; (3) the appearance of hydrated sulfates on the rock fragments from the mining waste, sulfates which are highly susceptible to the generation of acid mine drainage (pH < 4); (4) the high amount of toxic elements (Pb, Cd, Cu, Zn, As, etc.) that acid mine drainage leachates contain; and (5) the development of a salt crust on the flat, horizontal surfaces of the waste deposit, due to this very shape. Statistical data regarding the amount of both major and minor elements in the tailings have revealed two statistical populations for nearly all the toxic metals. This suggests that, beyond the effect that the tailings have upon the environment through their mere presence in a given area, there are alleged additional factors and processes which intensify the pollution: the location of the waste deposit relative to the topography of the area; the shape of the waste deposit; the development of low areas on the surface of the deposit, areas which favor the appearance of salt crusts; and the mineralogy of efflorescent aggregates.
Mostrar más [+] Menos [-]Sources of fluorescent dissolved organic matter in high salinity seawater (Bohai Bay, China) Texto completo
2013
Chen, Hao | Zheng, Binghui
Fluorescent dissolved organic matter (FDOM) identified in coastal waters within a large salinity range had been widely reported in previous studies, which stated that conservative mixing of terrestrially derived and river-transported FDOM by clear seawaters could account for the relatively low FDOM fluorescence signals in high salinity seawaters. This study aimed at testing the conservative mixing model in high salinity seawaters in a shallow bay (Bohai Bay, China) with low river flow in a dry season. The water showed high salinities varying in a narrow range (30.52 − 2.07), and salinity effects on fluorescence quantum yields therefore less likely introduced complications to fluorescence data analyses. By applying a parallel factor analysis to fluorescence excitation emission matrices of the water samples, we identified a tyrosine-like FDOM component, a tryptophan-like FDOM component, and two humic substances-like FDOM components. Based on a theoretical analysis, we found that dissolved organic carbon concentrations and suspended solid concentrations of the bulk-water samples as well as the maximum fluorescence signals of each identified FDOM component showed spatial distributions that could not be accounted for by the conservative mixing model. Marine autochthonous processes including microbial activities and FDOM releasing from resuspended sediment were likely to be invoked.
Mostrar más [+] Menos [-]A study on influential factors of high-phosphorus wastewater treated by electrocoagulation–ultrasound Texto completo
2013
Li, Jiangping | Song, Chen | Su, Yixin | Long, Hai | Huang, Da | Yeabah, Trokon Omarley | Wu, Wei
A combined treatment of electrocoagulation and ultrasound was proposed to solve some problems which exist in the phosphorus removal processes in fine chemical industry. The intermittently discharged wastewater has the features of high initial phosphorus concentration and wide initial pH variation. The electrocoagulation-ultrasound effective performance for the removal of phosphorus was investigated. The results obtained from synthetic wastewater showed that the total phosphorus (TP) decreased from 86 to about 0.4 mg/L, and the removal efficiency reached about 99.6 %, when ultrasound was applied to the electrocoagulation cell under the optimum working conditions in 10 min. Comparatively, the TP removal efficiency of electrocoagulation group was 81.3 % and the ultrasound group has almost no change. Therefore, we can conclude that the electrocoagulation and ultrasound synergistic effect can effectively degrade high-phosphorus wastewater. We have discussed the impact of various parameters on the electrocoagulation-ultrasound based on the phosphorus removal efficiency. The results obtained from synthetic wastewater showed that the optimum working pH was found to be 6, allowing the effluent to be met the emission standards without pH adjustment. An increased current enhanced the speed of treatment significance, but higher current (>40 mA/cm(2)) enhanced ultrasonic cavitation effect causing flocculation ineffective. In addition, it was found that the optimum ultrasonic power was 4 W/cm(2) and the frequency was 20 kHz. The best ultrasound intervention and ultrasonic irradiation time were processed with electrocoagulation simultaneously. The results indicated that the electrocoagulation-ultrasound could be utilized as an attractive technique for removal of phosphate in the real wastewater.
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