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Phytoremediation: role of terrestrial plants and aquatic macrophytes in the remediation of radionuclides and heavy metal contaminated soil and water Полный текст
2015
Sharma, Sunita | Singh, Bikram | Manchanda, V. K.
Nuclear power reactors are operating in 31 countries around the world. Along with reactor operations, activities like mining, fuel fabrication, fuel reprocessing and military operations are the major contributors to the nuclear waste. The presence of a large number of fission products along with multiple oxidation state long-lived radionuclides such as neptunium (²³⁷Np), plutonium (²³⁹Pu), americium (²⁴¹/²⁴³Am) and curium (²⁴⁵Cm) make the waste streams a potential radiological threat to the environment. Commonly high concentrations of cesium (¹³⁷Cs) and strontium (⁹⁰Sr) are found in a nuclear waste. These radionuclides are capable enough to produce potential health threat due to their long half-lives and effortless translocation into the human body. Besides the radionuclides, heavy metal contamination is also a serious issue. Heavy metals occur naturally in the earth crust and in low concentration, are also essential for the metabolism of living beings. Bioaccumulation of these heavy metals causes hazardous effects. These pollutants enter the human body directly via contaminated drinking water or through the food chain. This issue has drawn the attention of scientists throughout the world to device eco-friendly treatments to remediate the soil and water resources. Various physical and chemical treatments are being applied to clean the waste, but these techniques are quite expensive, complicated and comprise various side effects. One of the promising techniques, which has been pursued vigorously to overcome these demerits, is phytoremediation. The process is very effective, eco-friendly, easy and affordable. This technique utilizes the plants and its associated microbes to decontaminate the low and moderately contaminated sites efficiently. Many plant species are successfully used for remediation of contaminated soil and water systems. Remediation of these systems turns into a serious problem due to various anthropogenic activities that have significantly raised the amount of heavy metals and radionuclides in it. Also, these activities are continuously increasing the area of the contaminated sites. In this context, an attempt has been made to review different modes of the phytoremediation and various terrestrial and aquatic plants which are being used to remediate the heavy metals and radionuclide-contaminated soil and aquatic systems. Natural and synthetic enhancers, those hasten the process of metal adsorption/absorption by plants, are also discussed. The article includes 216 references.
Показать больше [+] Меньше [-]Evaluating and validating abundance monitoring methods in the absence of populations of known size: review and application to a passive tracking index Полный текст
2015
Allen, Lee R. | Engeman, Richard M.
Evaluating and validating abundance monitoring methods in the absence of populations of known size: review and application to a passive tracking index Полный текст
2015
Allen, Lee R. | Engeman, Richard M.
Rarely is it possible to obtain absolute numbers in free-ranging populations and although various direct and indirect methods are used to estimate abundance, few are validated against populations of known size. In this paper, we apply grounding, calibration and verification methods, used to validate mathematical models, to methods of estimating relative abundance. To illustrate how this might be done, we consider and evaluate the widely applied passive tracking index (PTI) methodology. Using published data, we examine the rationality of PTI methodology, how conceptually animal activity and abundance are related and how alternative methods are subject to similar biases or produce similar abundance estimates and trends. We then attune the method against populations representing a range of densities likely to be encountered in the field. Finally, we compare PTI trends against a prediction that adjacent populations of the same species will have similar abundance values and trends in activity. We show that while PTI abundance estimates are subject to environmental and behavioural stochasticity peculiar to each species, the PTI method and associated variance estimate showed high probability of detection, high precision of abundance values and, generally, low variability between surveys, and suggest that the PTI method applied using this procedure and for these species provides a sensitive and credible index of abundance. This same or similar validation approach can and should be applied to alternative relative abundance methods in order to demonstrate their credibility and justify their use.
Показать больше [+] Меньше [-]Evaluating and validating abundance monitoring methods in the absence of populations of known size: review and application to a passive tracking index Полный текст
2015
Allen, Lee R. | Engeman, Richard M.
Rarely is it possible to obtain absolute numbers in free-ranging populations and although various direct and indirect methods are used to estimate abundance, few are validated against populations of known size. In this paper, we apply grounding, calibration and verification methods, used to validate mathematical models, to methods of estimating relative abundance. To illustrate how this might be done, we consider and evaluate the widely applied passive tracking index (PTI) methodology. Using published data, we examine the rationality of PTI methodology, how conceptually animal activity and abundance are related and how alternative methods are subject to similar biases or produce similar abundance estimates and trends. We then attune the method against populations representing a range of densities likely to be encountered in the field. Finally, we compare PTI trends against a prediction that adjacent populations of the same species will have similar abundance values and trends in activity. We show that while PTI abundance estimates are subject to environmental and behavioural stochasticity peculiar to each species, the PTI method and associated variance estimate showed high probability of detection, high precision of abundance values and, generally, low variability between surveys, and suggest that the PTI method applied using this procedure and for these species provides a sensitive and credible index of abundance. This same or similar validation approach can and should be applied to alternative relative abundance methods in order to demonstrate their credibility and justify their use.
Показать больше [+] Меньше [-]Investigations on sediment toxicity of German rivers applying a standardized bioassay battery Полный текст
2015
Hafner, Christoph | Gartiser, Stefan | Garcia-Käufer, Manuel | Schiwy, Sabrina | Hercher, Christoph | Meyer, Wiebke | Achten, Christine | Larsson, Maria | Engwall, Magnus | Keiter, Steffen | Hollert, Henner
River sediments may contain a huge variety of environmental contaminants and play a key role in the ecological status of aquatic ecosystems. Contaminants adsorbed to sediments and suspended solids may contribute directly or after remobilization to an adverse ecological and chemical status of surface water. In this subproject of the joint research project DanTox, acetonic Soxhlet extracts from three German river sediments from the River Rhine (Altrip and Ehrenbreitstein with moderate contamination) and River Elbe (Veringkanal Hamburg heavily contaminated) were prepared and redissolved in dimethyl sulfoxide (DMSO). These extracts were analyzed with a standard bioassay battery with organisms from different trophic levels (bacteria, algae, Daphnia, fish) as well as in the Ames test and the umuC test for bacterial mutagenicity and genotoxicity according to the respective OECD and ISO guidelines. In total, 0.01 % (standard) up to 0.25 % (only fish embryo test) of the DMSO sediment extract was dosed to the test systems resulting in maximum sediment equivalent concentrations (SEQ) of 2 up to 50 g l⁻¹. The sediment of Veringkanal near Hamburg harbor was significantly more toxic in most tests compared to the sediment extracts from Altrip and Ehrenbreitstein from the River Rhine. The most toxic effect found for Veringkanal was in the algae test with an EᵣC₅₀ (72 h) of 0.00226 g l⁻¹ SEQ. Ehrenbreitstein and Altrip samples were about factor 1,000 less toxic. In the Daphnia, Lemna, and acute fish toxicity tests, no toxicity at all was found at 2 g l⁻¹ SEQ. corresponding to 0.01 % DMSO. Only when increasing the DMSO concentration the fish embryo test showed a 22-fold higher toxicity for Veringkanal than for Ehrenbreitstein and Altrip samples, while the toxicity difference was less evident for the Daphnia test due to the overlaying solvent toxicity above 0.05 % dimethyl sulfoxide (DMSO). The higher toxicities observed with the Veringkanal sample are supported by the PAH and PCB concentrations analyzed in the sediments. The sediment extracts of Altrip and Veringkanal were mutagenic in the Ames tester strain TA98 with metabolic activation (S9-mix). The findings allow a better ecotoxicological characterization of the sediments extensively analyzed in all subprojects of the DanTox project (e.g., Garcia-Kaeufer et al. Environ Sci Pollut Res. doi: 10.1007/s11356-014-3894-4 , 2014; Schiwy et al. Environ Sci Pollut Res. doi: 10.1007/s11356-014-3185-0 , 2014; Hollert and Keiter 2015). In the absence of agreed limit values for sediment extracts in standard tests, further data with unpolluted reference sediments are required for a quantitative risk assessment of the investigated polluted sediments.
Показать больше [+] Меньше [-]Biodecolorization of recalcitrant dye as the sole sourceof nutrition using Curvularia clavata NZ2 and decolorization ability of its crude enzymes Полный текст
2015
Neoh, Chin Hong | Lam, Chi Yong | Lim, Chi Kim | Yahya, Adibah | Bay, Hui Han | Ibrahim, Zaharah | Noor, Zainura Zainon
Extensive use of recalcitrant azo dyes in textile and paper industries poses a direct threat to the environment due to the carcinogenicity of their degradation products. The aim of this study was to investigate the efficiency of Curvularia clavata NZ2 in decolorization of azo dyes. The ability of the fungus to decolorize azo dyes can be evaluated as an important outcome as existing effluent treatment is unable to remove the dyes effectively. C. clavata has the ability to decolorize Reactive Black 5 (RB5), Acid Orange 7 (AO7), and Congo Red azo dyes, utilizing these as sole sources of carbon and nitrogen. Ultraviolet–visible (UV–vis) spectroscopy and Fourier infrared spectroscopy (FTIR) analysis of the extracted RB5’s metabolites along with desorption tests confirmed that the decolorization process occurred due to degradation and not merely by adsorption. Enzyme activities of extracellular enzymes such as carboxymethylcellulase (CMCase), xylanase, laccase, and manganese peroxidase (MnP) were also detected during the decolorization process. Toxicity expressed as inhibition of germination was reduced significantly in fungal-treated azo dye solution when compared with the control. The cultivation of C. clavata under sequential batch system also recorded a decolorization efficiency of above 90 %. The crude enzyme secreted by C. clavata also showed excellent ability to decolorize RB5 solutions with concentrations of 100 ppm (88–92 %) and 1000 ppm (70–77 %) without redox mediator. This proved that extracellular enzymes produced by C. clavata played a major role in decolorization of RB5.
Показать больше [+] Меньше [-]Prevalence and characteristics of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae isolated from rural well water in Taian, China, 2014 Полный текст
2015
Zhang, Hongna | Zhou, Yufa | Guo, Shuyuan | Chang, Weishan
The production of extended-spectrum beta-lactamase (ESBL) is one of the major antimicrobial resistance mechanisms in Enterobacteriaceae, and the increasing number of ESBL-producing Enterobacteriaceae isolated from water environments has posed a serious threat to the public health. The study aimed to analyze prevalence and characterization of ESBL-producing Enterobacteriaceae from rural well waters in Taian, China. A total of 10 isolates expressing an ESBL phenotype, including 9 Escherichia coli (E. coli) and 1 Klebsiella pneumoniae (K. pneumoniae) was obtained from 4 (4 %) out of the 100 sampled wells. ESBL genotype revealed that 9 expressed CTX-M-15 and 1 produced CTX-M-27. Five out of 8 ESBL-producing E. coli expressing CTX-M-15 belonged to ST10, which are mostly detected from human feces in China. Importantly, the only strain of CTX-M-27-producing E. coli belonged to multi-locus sequence type B2:131 (ST131), which may be related with severe infection in humans and animals.
Показать больше [+] Меньше [-]Modeling and optimization of the flocculation processes for removal of cationic and anionic dyes from water by an amphoteric grafting chitosan-based flocculant using response surface methodology Полный текст
2015
Wu, Hu | Yang, Ran | Li, Ruihua | Long, Chao | Yang, Hu | Li, Aimin
In this study, an amphoteric grafting chitosan-based flocculant (carboxymethyl chitosan-graft-poly(2-methacryloyloxyethyl) trimethyl ammonium chloride, denoted as CMC-g-PDMC) was applied to removal of the anionic and cationic dyes, acid Green 25 (AG25) and Basic Bright Yellow (7GL), from water. Flocculation conditions have been optimized by response surface methodology (RSM) on the basis of central composite design (CCD) using flocculant dosage, initial solution pH and temperature as input variables. The second-order and cubic regression models, which have been both tested by the analysis of variance (ANOVA), were constructed to link the output response (the dye removal factor) with the aforementioned input variables, respectively. The second-order regression model well described the process of AG25 removal, whereas the cubic one is more suitable for that of 7GL. The effects of those variables on the flocculation performance of CMC-g-PDMC for removal of the two dyes containing opposite charges from aqueous solutions have been studied, and the flocculation mechanisms including the interactive effects between various influencing factors have been discussed in detail also.
Показать больше [+] Меньше [-]Comparative sensitivity of the cnidarian Exaiptasia pallida and a standard toxicity test suite: testing whole effluents intended for ocean disposal Полный текст
2015
Howe, P. L. | Reichelt-Brushett, A. J. | Krassoi, R. | Micevska, T.
The sea anemone Exaiptasia pallida (formally Aiptasia pulchella) has been identified as a valuable test species for tropical marine ecotoxicology. Here, the sensitivities of newly developed endpoints for E. pallida to two unidentified whole effluents were compared to a standard suite of temperate toxicity test species and endpoints that are commonly used in toxicological risk assessments for tropical marine environments. For whole effluent 1 (WE1), a 96-h lethal concentration 50 % (LC50) of 40 (95 % confidence intervals, 30–54) % v/v and a 12-day LC50 of 12 (9–15) % v/v were estimated for E. pallida, exhibiting a significantly higher sensitivity than standard sub-lethal endpoints in Allorchestes compressa (96-h effective concentration 50 % (EC50) of >100 % v/v for immobilisation) and Hormosira banksii (72-h EC50 of >100 % v/v for germination), and a similar sensitivity to Mytilus edulis galloprovincialis larval development with a 48-h LC50 of 29 (28–30) % v/v. Sub-lethal effects of whole effluent 2 (WE2) on E. pallida pedal lacerate development resulted in an 8-day EC50 of 7 (3–11) % v/v, demonstrating comparable sensitivity of this endpoint to standardised sub-lethal endpoints in H. banksii (72-h EC50 of 11 (10–11) % v/v for germination), M. edulis galloprovincialis (48-h EC50 for larval development of 12 (9–14) % v/v) and Heliocidaris tuberculata (1-h EC50 of 13 (12–14) % v/v for fertilisation; 72-h EC50 of 26 (25–27) % v/v for larval development) and a significantly higher sensitivity than A. compressa immobilisation (96-h EC50 of >100 % v/v). The sensitivity of E. pallida compared to a standard test species suite highlights the value in standardising the newly developed toxicity test methods for inclusion in routine toxicological risk assessment of complex whole effluents. Importantly, this species provides an additional taxonomic group to the test species that are currently available for tropical marine ecotoxicology and, being a cnidarian, may represent important tropical marine environments including coral reefs.
Показать больше [+] Меньше [-]Effect of pyoverdine supply on cadmium and nickel complexation and phytoavailability in hydroponics Полный текст
2015
Ferret, C. | Cornu, J. Y. | Elhabiri, M. | Sterckeman, T. | Braud, A. | Jezequel, K. | Lollier, M. | Lebeau, T. | Schalk, I. J. | Geoffroy, V. A.
Effect of pyoverdine supply on cadmium and nickel complexation and phytoavailability in hydroponics Полный текст
2015
Ferret, C. | Cornu, J. Y. | Elhabiri, M. | Sterckeman, T. | Braud, A. | Jezequel, K. | Lollier, M. | Lebeau, T. | Schalk, I. J. | Geoffroy, V. A.
Siderophores are chelators with a high selectivity for Fe(III) and a good affinity for divalent metals, including Cd(II) and Ni(II). Inoculation with siderophore-producing bacteria (SPB) has thus been proposed as an alternative to chelator supply in phytoremediation. Accurate assessments of the potential of this association require a dissection of the interaction of siderophores with metals at the soil–root interface. This study focuses on pyoverdine (Pvd), the main siderophore produced by Pseudomonas aeruginosa. We first assessed the ability of Pvd to coordinate Ni(II). The stability constant of Pvd–Ni(II) (log K ᴸ′ᴺⁱ = 10.9) was found to be higher than that of Pvd–Cd(II) (log K ᴸ′Cᵈ = 8.2). We then investigated the effect of a direct supply of Pvd on the mobilization, speciation, and phytoavailability of Cd and Ni in hydroponics. When supplied at a concentration of 50 μM, Pvd selectively promoted Ni mobilization from smectite. It decreased plant Ni and Cd contents and the free ionic fractions of these two metals, consistent with the free ion activity model. Pvd had a more pronounced effect for Ni than for Cd, as predicted from its coordination properties. Inoculation with P. aeruginosa had a similar effect on Ni phytoavailability to the direct supply of Pvd.
Показать больше [+] Меньше [-]Effect of pyoverdine supply on cadmium and nickel complexation and phytoavailability in hydroponics Полный текст
2015
Ferret, C. | Cornu, J. | Elhabiri, M. | Sterckeman, Thibault | Braud, A. | Jezequel, K. | Lollier, M. | Lebeau, T. | Schalk, I. | Geoffroy, V. | Service d'Hépato-gastro-entérologie et Nutrition [CHU Dupuytren 1, Limoges] ; CHU Limoges-Hôpital Dupuytren [CHU Limoges] | Laboratoire de chimie moléculaire (LCM) ; Université de Strasbourg (UNISTRA)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS) | Laboratoire Sols et Environnement (LSE) ; Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL) | Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG) ; Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST) ; Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) | Laboratoire Vigne Biotechnologie et Environnement (LVBE) ; Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA)) | Equipe Dépollution Biologique des Sols ; Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))
International audience | Siderophores are chelators with a high selectivity for Fe(III) and a good affinity for divalent metals, including Cd(II) and Ni(II). Inoculation with siderophore-producing bacteria (SPB) has thus been proposed as an alternative to chelator supply in phytoremediation. Accurate assessments of the potential of this association require a dissection of the interaction of siderophores with metals at the soil–root interface. This study focuses on pyoverdine (Pvd), the main siderophore produced by Pseudomonas aeruginosa. We first assessed the ability of Pvd to coordinate Ni(II). The stability constant of Pvd–Ni(II) (log K L′Ni = 10.9) was found to be higher than that of Pvd–Cd(II) (log K L′Cd = 8.2). We then investigated the effect of a direct supply of Pvd on the mobilization, speciation, and phytoavailability of Cd and Ni in hydroponics. When supplied at a concentration of 50 μM, Pvd selectively promoted Ni mobilization from smectite. It decreased plant Ni and Cd contents and the free ionic fractions of these two metals, consistent with the free ion activity model. Pvd had a more pronounced effect for Ni than for Cd, as predicted from its coordination properties. Inoculation with P. aeruginosa had a similar effect on Ni phytoavailability to the direct supply of Pvd.
Показать больше [+] Меньше [-]Winter time chemical characteristics of aerosols over the Bay of Bengal: continental influence Полный текст
2015
Aryasree, S. | Nair, Prabha R. | Girach, I. A. | Jacob, Salu
As part of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) conducted under the Geosphere Biosphere Programme of Indian Space Research Organisation, ship-based aerosol sampling was carried out over the marine environment of Bay of Bengal (BoB) during the northern winter months of December 2008 to January 2009. About 101 aerosol samples were collected, covering the region from 3.4° to 21° N latitude and 76° to 98° E longitude—the largest area covered—including the south east (SE) BoB for the first time. These samples were subjected to gravimetric and chemical analysis and the total aerosol loading as well the mass concentration of the ionic species namely F⁻, Cl⁻, Br⁻, NO₂ ⁻, NO₃ ⁻, PO₄ ²⁻, SO₄ ²⁻, NH₄ ⁺, etc. and the metallic species, Na, Mg, Ca, K, Al, Fe, Mn, Zn, and Pb were estimated for each sample. Based on the spatial distribution of individual chemical species, the air flow pattern, and airmass back trajectory analysis, the source characteristics of aerosols for different regions of BoB were identified. Significant level of continental pollution was noticed over BoB during winter. While transport of pollution from Indo-Gangetic Plain (IGP) contributed to aerosols over north BoB, those over SE BoB were influenced by SE Asia. A quantitative study on the wind-induced production of sea salt aerosols and a case study on the species dependent effect of rainfall are also presented in this paper.
Показать больше [+] Меньше [-]Effect of Zn stresses on physiology, growth, Zn accumulation, and chlorophyll of Phyllostachys pubescen s Полный текст
2015
Peng, Danli | Shafi, Mian M. | Wang, Ying | Li, Song | Yan, Wenbo | Chen, Junren | Ye, Zhengqian | Liu, Dan
The effects of Zinc (Zn) on lipid peroxidation, antioxidative enzymes, growth, Zn accumulation, and leaf chlorophyll of Phyllostachys pubescens (Pradelle) Mazel ex J.Houz. were investigated in two greenhouse experiments. Hydroponics experiment with Zn application of 0, 20, 100, and 400 μM revealed that lower concentration of Zn in solution led to increased malondialdehyde (MDA) and proline contents but inhibited SOD activity in all treatments. P. pubescens had showed strong ability to accumulate Zn in stems and reached maximum level at 100 μM with 7.91-fold increase compared with control. In pot experiment, treatment with Zn ranged from 0, 200, 400, 800, 1,600, to 3,200 mg kg⁻¹. Application of 800 mg kg⁻¹ revealed 116, 24.6, and 28.3 times increase in Zn concentration of roots, stems, and leaves, respectively. Growth and chlorophyll contents of plants in pots were better promoted at 400 mg kg⁻¹ Zn, with 60.5 and 30.9 % enhanced roots and shoot compared with control. The bioaccumulation factor (BAF) was in the sequence of stem > roots > leaves. The translocation factor (TF) of stem was higher than leaves.
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