خيارات البحث
النتائج 3121 - 3130 من 4,043
Absorption and translocation of copper and arsenic in an aquatic macrophyte Myriophyllum alterniflorum DC. in oligotrophic and eutrophic conditions النص الكامل
2016
Krayem, Maha | Baydoun, Mohamad | Deluchat, Véronique | Lenain, Jean-Francois | Kazpard, Véronique | Labrousse, Pascal
The aim of this study is to evaluate copper and arsenic accumulation and translocation at a concentration of 100 μg/L of a submersed macrophyte Myriophyllum alterniflorum. The trophic level (eutrophic and oligotrophic conditions) of the medium was also considered. To achieve this goal, plants were incubated for 21 days in the presence of 100 μg/L of Cu or AsV. The heavy metal transfers from the contaminated medium to plants and into plant tissues was discussed in terms of the bioconcentration factor (BCF) and the translocation factor (TF). Malondialdehyde (MDA) content in tissues was analyzed in order to study the toxicity of these two contaminants. Our results show that copper was more accumulated in shoots, than roots, whereas the opposite trend was observed for arsenic. In addition, the two contaminants were more accumulated in oligotrophic than eutrophic medium. The BCF of copper in shoots was 1356 in oligotrophic condition, while that of arsenic was higher in roots about 620 in the same condition. The TF was less than 1 for arsenic, and higher than 1 for copper, indicating that watermilfoil restrains the translocation of arsenic to shoots, while it has a low capacity to control the translocation of an essential micronutrient like copper. An increase in MDA content was observed under Cu and As stress. On the basis of this experiment, M. alterniflorum has a higher accumulation potential of copper and arsenic, and therefore, it can be a good candidate for the phytofiltration of these two contaminants from water.
اظهر المزيد [+] اقل [-]Culturable endophytic bacteria from the salt marsh plant Halimione portulacoides: phylogenetic diversity, functional characterization, and influence of metal(loid) contamination النص الكامل
2016
Fidalgo, Cátia | Henriques, Isabel | Rocha, Jaqueline | Tacão, Marta | Alves, Arthur
Halimione portulacoides is abundant in salt marshes, accumulates mercury (Hg), and was proposed as useful for phytoremediation and pollution biomonitoring. Endophytic bacteria promote plant growth and provide compounds with industrial applications. Nevertheless, information about endophytic bacteria from H. portulacoides is scarce. Endophytic isolates (n = 665) were obtained from aboveground and belowground plant tissues, from two Hg-contaminated sites (sites E and B) and a noncontaminated site (site C), in the estuary Ria de Aveiro. Representative isolates (n = 467) were identified by 16S rRNA gene sequencing and subjected to functional assays. Isolates affiliated with Proteobacteria (64 %), Actinobacteria (23 %), Firmicutes (10 %), and Bacteroidetes (3 %). Altererythrobacter (7.4 %), Marinilactibacillus (6.4 %), Microbacterium (10.2 %), Salinicola (8.8 %), and Vibrio (7.8 %) were the most abundant genera. Notably, Salinicola (n = 58) were only isolated from site C; Hoeflea (17), Labrenzia (22), and Microbacterium (67) only from belowground tissues. This is the first report of Marinilactibacillus in the endosphere. Principal coordinate analysis showed that community composition changes with the contamination gradient and tissue. Our results suggest that the endosphere of H. portulacoides represents a diverse bacterial hotspot including putative novel species. Many isolates, particularly those affiliated to Altererythrobacter, Marinilactibacillus, Microbacterium, and Vibrio, tested positive for enzymatic activities and plant growth promoters, exposing H. portulacoides as a source of bacteria and compounds with biotechnological applications.
اظهر المزيد [+] اقل [-]Development of magnetic graphene oxide adsorbent for the removal and preconcentration of As(III) and As(V) species from environmental water samples النص الكامل
2016
Rashidi Nodeh, Hamid | Wan Ibrahim, Wan Aini | Ali, Imran | Sanagi, Mohd Marsin
New-generation adsorbent, Fe₃O₄@SiO₂/GO, was developed by modification of graphene oxide (GO) with silica-coated (SiO₂) magnetic nanoparticles (Fe₃O₄). The synthesized adsorbent was characterized using Fourier transform infrared spectroscopy, X-ray diffractometry, energy-dispersive X-ray spectroscopy, and field emission scanning electron microscopy. The developed adsorbent was used for the removal and simultaneous preconcentration of As(III) and As(V) from environmental waters prior to ICP-MS analysis. Fe₃O₄@SiO₂/GO provided high adsorption capacities, i.e., 7.51 and 11.46 mg g⁻¹ for As(III) and As(V), respectively, at pH 4.0. Adsorption isotherm, kinetic, and thermodynamic were investigated for As(III) and As(V) adsorption. Preconcentration of As(III) and As(V) were studied using magnetic solid-phase extraction (MSPE) method at pH 9.0 as the adsorbent showed selective adsorption for As(III) only in pH range 7–10. MSPE using Fe₃O₄@SiO₂/GO was developed with good linearities (0.05–2.0 ng mL⁻¹) and high coefficient of determination (R ² = 0.9992 and 0.9985) for As(III) and As(V), respectively. The limits of detection (LODs) (3× SD/m, n = 3) obtained were 7.9 pg mL⁻¹ for As(III) and 28.0 pg mL⁻¹ for As(V). The LOD obtained is 357–1265× lower than the WHO maximum permissible limit of 10.0 ng mL⁻¹. The developed MSPE method showed good relative recoveries (72.55–109.71 %) and good RSDs (0.1–4.3 %, n = 3) for spring water, lake, river, and tap water samples. The new-generation adsorbent can be used for the removal and simultaneous preconcentration of As(III) and As(V) from water samples successfully. The adsorbent removal for As(III) is better than As(V).
اظهر المزيد [+] اقل [-]Exercise protects against PCB-induced inflammation and associated cardiovascular risk factors النص الكامل
2016
Murphy, Margaret O. | Petriello, Michael C. | Han, Sung Gu | Sunkara, Manjula | Morris, Andrew J. | Esser, Karyn | Hennig, Bernhard
Polychlorinated biphenyls (PCBs) are persistent environmental pollutants that contribute to the initiation of cardiovascular disease. Exercise has been shown to reduce the risk of cardiovascular disease; however, whether exercise can modulate PCB-induced vascular endothelial dysfunction and associated cardiovascular risk factors is unknown. We examined the effects of exercise on coplanar PCB-induced cardiovascular risk factors including oxidative stress, inflammation, impaired glucose tolerance, hypercholesteremia, and endothelium-dependent relaxation. Male ApoE⁻/⁻ mice were divided into sedentary and exercise groups (voluntary wheel running) over a 12-week period. Half of each group was exposed to vehicle or PCB 77 at weeks 1, 2, 9, and 10. For ex vivo studies, male C57BL/6 mice exercised via voluntary wheel training for 5 weeks and then were administered with vehicle or PCB 77 24 h before vascular reactivity studies were performed. Exposure to coplanar PCB increased risk factors associated with cardiovascular disease, including oxidative stress and systemic inflammation, glucose intolerance, and hypercholesteremia. The 12-week exercise intervention significantly reduced these proatherogenic parameters. Exercise also upregulated antioxidant enzymes including phase II detoxification enzymes. Sedentary animals exposed to PCB 77 exhibited endothelial dysfunction as demonstrated by significant impairment of endothelium-dependent relaxation, which was prevented by exercise. Lifestyle modifications such as aerobic exercise could be utilized as a therapeutic approach for the prevention of adverse cardiovascular health effects induced by environmental pollutants such as PCBs.
اظهر المزيد [+] اقل [-]Hydroponic root mats for wastewater treatment—a review النص الكامل
2016
Chen, Zhongbing | Cuervo, Diego Paredes | Müller, Jochen A. | Wiessner, Arndt | Köser, Heinz | Vymazal, Jan | Kästner, Matthias | Kuschk, Peter
Hydroponic root mats (HRMs) are ecotechnological wastewater treatment systems where aquatic vegetation forms buoyant filters by their dense interwoven roots and rhizomes, sometimes supported by rafts or other floating materials. A preferential hydraulic flow is created in the water zone between the plant root mat and the bottom of the treatment system. When the mat touches the bottom of the water body, such systems can also function as HRM filter; i.e. the hydraulic flow passes directly through the root zone. HRMs have been used for the treatment of various types of polluted water, including domestic wastewater; agricultural effluents; and polluted river, lake, stormwater and groundwater and even acid mine drainage. This article provides an overview on the concept of applying floating HRM and non-floating HRM filters for wastewater treatment. Exemplary performance data are presented, and the advantages and disadvantages of this technology are discussed in comparison to those of ponds, free-floating plant and soil-based constructed wetlands. Finally, suggestions are provided on the preferred scope of application of HRMs.
اظهر المزيد [+] اقل [-]Modeling the temporal variability of zinc concentrations in zinc roof runoff—experimental study and uncertainty analysis النص الكامل
2016
Sage, Jérémie | El Oreibi, Elissar | Saad, Mohamed | Gromaire, Marie-Christine
Modeling the temporal variability of zinc concentrations in zinc roof runoff—experimental study and uncertainty analysis النص الكامل
2016
Sage, Jérémie | El Oreibi, Elissar | Saad, Mohamed | Gromaire, Marie-Christine
This study investigates the temporal variability of zinc concentrations from zinc roof runoff. The influence of rainfall characteristics and dry period duration is evaluated by combining laboratory experiment on small zinc sheets and in situ measurements under real weather conditions from a 1.6-m² zinc panel. A reformulation of a commonly used conceptual runoff quality model is introduced and its ability to simulate the evolution of zinc concentrations is evaluated. A systematic and sharp decrease from initially high to relatively low and stable zinc concentrations after 0.5 to 2 mm of rainfall is observed for both experiments, suggesting that highly soluble corrosion products are removed at early stages of runoff. A moderate dependence between antecedent dry period duration and the magnitude of zinc concentrations at the beginning of a rain event is evidenced. Contrariwise, results indicate that concentrations are not significantly influenced by rainfall intensities. Simulated rainfall experiment nonetheless suggests that a slight effect of rainfall intensities may be expected after the initial decrease of concentrations. Finally, this study shows that relatively simple conceptual runoff quality models may be adopted to simulate the variability of zinc concentrations during a rain event and from a rain event to another.
اظهر المزيد [+] اقل [-]Modeling the temporal variability of zinc concentrations in zinc roof runoff—experimental study and uncertainty analysis النص الكامل
2016
Sage, Jérémie | El Oreibi, E. | Saad, M. | Gromaire, Marie-Christine | Laboratoire Eau Environnement et Systèmes Urbains (LEESU) ; AgroParisTech-École nationale des ponts et chaussées (ENPC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)
International audience | Jérémie Sage, Elissar El Oreibi, Mohamed Saad, Marie-Christine Gromaire (2016). Modelling the temporal variability of zinc concentrations in zinc roof runoff – Experimental study and uncertainty analysis, Environmental Science and Pollution Research, pp. 1-15. The final publication is available at Springer via http://dx. ABSTRACT This study investigates the temporal variability of zinc concentrations from zinc roof runoff. The influence of rainfall characteristics and dry period duration is evaluated by combining laboratory experiment on small zinc sheets and in-situ measurements under real weather conditions from a 1.6 m² zinc panel. A reformulation of a commonly used conceptual runoff quality model is introduced and its ability to simulate the evolution of zinc concentrations is evaluated. A systematic and sharp decrease from initially high to relatively low and stable zinc concentrations after 0.5 to 2 millimetres of rainfall is observed for both experiments, suggesting that highly soluble corrosion products are removed at early stages of runoff. A moderate dependence between antecedent dry period duration and the magnitude of zinc concentrations at the beginning of a rain event is evidenced. Contrariwise, results indicate that concentrations are not significantly influenced by rainfall intensities. Simulated rainfall experiment nonetheless suggests that a slight effect of rainfall intensities may be expected after the initial decrease of concentrations. Finally, this study shows that relatively simple conceptual runoff quality models may be adopted to simulate the variability of zinc concentrations during a rain event and from a rain event to another.
اظهر المزيد [+] اقل [-]Estrogenic effects in the influents and effluents of the drinking water treatment plants النص الكامل
2016
Gou, Yan-You | Lin, Susana | Que, Danielle E. | Tayo, Lemmuel L. | Lin, Ding-Yan | Chen, Kuan-Chung | Chen, Fu-An | Chiang, Pen-Chi | Wang, Gen-Shuh | Hsu, Yi-Chyuan | Zhuang, Guobin | Chuang, Chun-Yu | Tsou, Tsui-Chun | Chao, How-Ran
Estrogen-like endocrine disrupting compounds (EEDC) such as bisphenol A, nonylphenol, and phthalic acid esters are toxic compounds that may occur in both raw- and drinking water. The aim of this study was to combine chemical- and bioassay to evaluate the risk of EEDCs in the drinking water treatment plants (DWTPs). Fifty-six samples were collected from seven DWTPs located in northern-, central-, and southern Taiwan from 2011 to 2012 and subjected to chemical analyses and two bioassay methods for total estrogenic activity (E-Screen and T47D-KBluc assay). Among of the considered EEDCs, only dibutyl phthalate (DBP) and di (2-ethylhexyl) phthalate (DEHP) were detected in both drinking and raw water samples. DBP levels in drinking water ranged from <MDL to 0.840 μg/L and from <MDL to 0.760 μg/L in raw water. DEHP had higher detection rate (82.1 %) than other compounds and was present in both drinking water and raw water from all the DWTPs. The highest daily drinking water intake calculated for male and female were 0.0823 and 0.115 μg/kg per day. The two selected bioassays were conducted for the first batch of 56 samples and a detection rate of 23 % for estradiol equivalent (EEQ) lower than the LOQ to 1.3 and 15 % for EEQ lower than LOQ to 0.757 for the second 53 samples. Our results showed a good correlation between E-screen and chemical assay which indicates that a combination of both can be used in detecting EEDCs in environmental samples.
اظهر المزيد [+] اقل [-]Efficient biodegradation of phenanthrene by a novel strain Massilia sp. WF1 isolated from a PAH-contaminated soil النص الكامل
2016
Wang, Haizhen | Lou, Jun | Gu, Haiping | Luo, Xiaoyan | Yang, Li | Wu, Laosheng | Liu, Yong | Wu, Jianjun | Xu, Jianming
A novel phenanthrene (PHE)-degrading strain Massilia sp. WF1, isolated from PAH-contaminated soil, was capable of degrading PHE by using it as the sole carbon source and energy in a range of pH (5.0–8.0), temperatures (20–35 °C), and PHE concentrations (25–400 mg L⁻¹). Massilia sp. WF1 exhibited highly effective PHE-degrading ability that completely degraded 100 mg L⁻¹ of PHE over 2 days at optimal conditions (pH 6.0, 28 °C). The kinetics of PHE biodegradation by Massilia sp. WF1 was well represented by the Gompertz model. Results indicated that PHE biodegradation was inhibited by the supplied lactic acid but was promoted by the supplied carbon sources of glucose, citric acid, and succinic acid. Salicylic acid (SALA) and phthalic acid (PHTA) were not utilized by Massilia sp. WF1 and had no obvious effect on PHE biodegradation. Only two metabolites, 1-hydroxy-2-naphthoic acid (1H2N) and PHTA, were identified in PHE biodegradation process. Quantitatively, nearly 27.7 % of PHE was converted to 1H2N and 30.3 % of 1H2N was further metabolized to PHTA. However, the PHTA pathway was broken and the SALA pathway was ruled out in PHE biodegradation process by Massilia sp. WF1.
اظهر المزيد [+] اقل [-]Mercury in forest mushrooms and topsoil from the Yunnan highlands and the subalpine region of the Minya Konka summit in the Eastern Tibetan Plateau النص الكامل
2016
Falandysz, Jerzy | Saba, Martyna | Liu, Hong-Gao | Li, Tao | Wang, Ji-Peng | Wiejak, Anna | Zhang, Ji | Wang, Yuan-Zhong | Zhang, Dan
This study aimed to investigate and discuss the occurrence and accumulation of mercury in the fruiting bodies of wild-growing fungi (Macromycetes) collected from montane forests in two regions of southwestern China with differences in soil geochemistry, climate and geographical conditions. Fungal mycelia in soils of the subalpine region of the Minya Konka (Gongga Mountain) in Sichuan and in the highlands of Yunnan efficiently accumulated mercury in fruiting bodies (mushrooms). The examined sites in Yunnan with highly mineralized red and yellow soils showed Hg contents ranging from 0.066 to 0.28 mg kg⁻¹ dry biomass (db) which is roughly similar to the results obtained for samples collected from sites with dark soils relatively rich in organic matter from a remote, the subalpine region of Minya Konka. Due to the remoteness of the subalpine section of Minya Konka, as well as its elevation and climate, airborne mercury from long-range transport could be deposited preferentially on the topsoil and the Hg levels determined in soil samples taken beneath the fruiting bodies were up to 0.48 mg kg⁻¹ dry matter. In Yunnan, with polymetallic soils (Circum-Pacific Mercuriferous Belt), Amanita mushrooms showed mercury in caps of fruiting bodies of up to 7.3 mg kg⁻¹ dry biomass. Geogenic Hg from the mercuriferous belt seems to be the overriding source of mercury accumulated in mushrooms foraged in the regions of Yunnan, while long-range atmospheric transport and subsequent deposition are the mercury sources for specimens foraged in the region of Minya Konka.
اظهر المزيد [+] اقل [-]Simultaneous removal of ammonia and hydrogen sulfide gases using biofilter media from the biodehydration stage and curing stage of composting النص الكامل
2016
Hou, Jiaqi | Li, Mingxiao | Xia, Tianming | Hao, Yan | Ding, Jie | Liu, Dongming | Xi, Beidou | Liu, Hongliang
Biofiltration of NH₃ and H₂S with different packing media, biodehydration stage compost (BSC), and curing stage compost (CSC) was studied. Meanwhile, fluorescence excitation–emission matrix (EEM) spectroscopy was used to characterize the conversion mechanisms of organic matter during these biofiltration processes. Both biofilters were effective for the simultaneous removal of NH₃ and H₂S when inlet concentrations of NH₃ and H₂S were 0–50 and 50–250 mg/m³, respectively. An abrupt increase in the inlet gas concentrations of NH₃ and H₂S to 100–150 and 200–250 mg/m³, respectively, caused the decrease in the removal efficiencies (REs) of NH₃ and H₂S in the BSC biofilter, followed by a slow upturn. By contrast, relatively steady REs of both NH₃ and H₂S were observed in the CSC biofilter. After 60 days of operation, the average REs of NH₃ and H₂S were more than 95 % in the CSC biofilter. During the operation of CSC, nitrate and nitrite peaked around the 30th day, whereas sulfate showed a steady increase. The excitation–emission matrix fluorescence and parallel factor analysis (EEM-PARAFAC) indicated that the simultaneous inlet of NH₃ and H₂S facilitated the degradation of protein-like substances, whereas humic-like substances played an important role in the packing filters for the treatment of the two odorous pollutants.
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