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النتائج 1691 - 1700 من 1,955
Differences between 4-fluoroaniline degradation and autoinducer release by Acinetobacter sp. TW: implications for operating conditions in bacterial bioaugmentation النص الكامل
2013
Wang, Meizhen | Xu, Junjie | Wang, Juehua | Wang, Shuo | Feng, Huajun | Shentu, Jiali | Shen, Dongsheng
To develop a bacterial bioaugmentation system for fluorine-containing industrial wastewater treatment, optimal conditions for 4-fluoroaniline (4-FA) degradation and autoinducer release in Acinetobacter sp. TW were determined. Quorum sensing in biofilms of strain TW was also investigated. Different optimal conditions exist for 4-FA degradation and autoinducer release, particularly with regard to pH. Quorum sensing modulates extracellular polymeric substance (EPS) secretion and biofilm formation in the strain but plays no role in 4-FA degradation. Under optimal conditions for 4-FA degradation, the release of N-3-oxo-hexanoyl-homoserine lactone (3-oxo-C6-HSL) and N-hexanoyl-homoserine lactone (C6-HSL) in strain TW was significantly lower than required for quorum sensing. Under optimal conditions for autoinducer release, on the other hand, 3-oxo-C6-HSL and C6-HSL levels exceeded the quorum sensing thresholds, thereby inducing EPS secretion and biofilm formation. We conclude that the optimal conditions for autoinducer release (25 °C, pH 5, 800 mg L(-1) 4-FA, and 0 % NaCl) are suitable for bacterial colonization in bioaugmentation, while those for 4-FA degradation (25-30 °C, pH 8 and 800 mg L(-1) 4-FA) maximize the system performance after colonization.
اظهر المزيد [+] اقل [-]Spatial distribution of polychlorinated biphenyls in High Tatras lake sediments النص الكامل
2013
van Drooge, Barend L. | Grimalt, Joan O. | Stuchlík, Evzen
The objective of the present study was to gain insight on the spatial distribution of seven polychlorinated biphenyl (PCB) congeners in the High Tatras mountain range in Eastern Europe. Twenty high mountain lakes were sampled on their top-core sediment. Despite the relative uniform composition of PCB congeners among the lakes, there are important differences in the observed concentrations. Moderate top-core sediment concentrations of PCB congeners were observed (1.9 to 38 ng/g dw for ∑PCB) in comparison to other high mountain or Arctic areas. The variation in PCB concentrations can partly be explained by a possible altitudinal effect, resulting in higher PCB concentrations at higher (colder) altitudes. Part of this enhanced accumulation of PCBs could be caused by external factors (topography and meteorology) and internal lake factors (sediment dynamics). Many of these factors were not quantified for all individual lakes and their influence could, therefore, only be studied for some.
اظهر المزيد [+] اقل [-]Size mass distribution of water-soluble ionic species and gas conversion to sulfate and nitrate in particulate matter in southern Taiwan النص الكامل
2013
Tsai, Jiun-Horng | Chang, Li-Peng | Chiang, Hung-Lung
A Micro-Orifice Uniform Deposition Impactor (MOUDI) and a Nano-MOUDI were employed to determine the size-segregated mass distributions of ambient particulate matter (PM) and water-soluble ionic species for particulate constituents. In addition, gas precursors, including HCl, HONO, HNO₃, SO₂, and NH₃gases, were analyzed by an annular denuder system. PM size mass distribution, mass concentration, and ionic species concentration were measured during the day and at night during episode and non-episode periods in winter and summer. Average total suspended particle (TSP) concentrations during episode days in winter were as high as 153 ± 33 μg/m³, and PM mass concentrations in summer were as low as one-third of that in winter. Generally, PM concentration at night was higher than that in the daytime in southern Taiwan during the sampling periods. In winter during the episode periods, the size-segregated mass distribution of PM mass concentration was mostly in the 0.32–3.2-μm range, and the PM concentration increased significantly in the range of 0.32–3.2 μm at night. Ammonium, nitrate, and sulfate were the dominant water-soluble ionic species in PM, contributing 34–48 % of TSP mass. High concentrations of ammonia (12.9–49 μg/m³) and SO₂(2.6–27 μg/m³) were observed in the gas precursors. The conversion ratio was high in the PM size range of 0.18–3.2 μm both during the day and at night in winter, and the conversion ratio of episode days was 20 % higher than that of non-episode days. The conversion factor was high for both nitrogen and sulfur species at nighttime, especially on episode days.
اظهر المزيد [+] اقل [-]Continuous automated imaging-in-flow cytometry for detection and early warning of Karenia brevis blooms in the Gulf of Mexico النص الكامل
2013
Campbell, Lisa | Henrichs, Darren W. | Olson, Robert J. | Sosik, Heidi M.
Monitoring programs for harmful algal blooms (HABs) typically rely on time-consuming manual methods for identification and enumeration of phytoplankton, which make it difficult to obtain results with sufficient temporal resolution for early warning. Continuous automated imaging-in-flow by the Imaging FlowCytobot (IFCB) deployed at Port Aransas, TX has provided early warnings of six HAB events. Here we describe the progress in automating this early warning system for blooms of Karenia brevis. In 2009, manual inspection of IFCB images in mid-August 2009 provided early warning for a Karenia bloom that developed in mid-September. Images from 2009 were used to develop an automated classifier that was employed in 2011. Successful implementation of automated file downloading, processing and image classification allowed results to be available within 4 h after collection and to be sent to state agency representatives by email for early warning of HABs. No human illness (neurotoxic shellfish poisoning) has resulted from these events. In contrast to the common assumption that Karenia blooms are near monospecific, post-bloom analysis of the time series revealed that Karenia cells comprised at most 60-75 % of the total microplankton.
اظهر المزيد [+] اقل [-]Response of microcrustacean communities from the surface—groundwater interface to water contamination in urban river system of the Jarama basin (central Spain) النص الكامل
2013
Iepure, Sanda | Martinez-Hernandez, Virtudes | Herrera, Sonia | Rasines-Ladero, Ruben | de Bustamante, Irene
In order to evaluate the water quality at the surface/groundwater interface (hyporheic zone), the pattern of microcrustacean assemblages in response to environmental stress caused by urban industrial contamination was studied in the Jarama River basin (central Spain) during high water discharges (March and April 2011). The clustering of biological variables and the concentration of urban contaminants in hyporheic waters showed that pristine hyporheic waters have moderate species diversity (two to seven species) and dominance of k strategist stygobites, whereas excessively contaminated sites are devoid by crustaceans. An intermediate level of disturbance in hyporheic waters is associated with a peak of species taxonomic diversity (four to nine species) and proliferation of r strategist more tolerant species. Typical species found in hyporheic zone, e.g., Paracyclops imminutus (Copepoda, Cyclopoida), Cryptocandona vavrai (Ostracoda) and Herpetocypris chevreuxi (Ostracoda), were good indicators of high concentrations of Cr, Mn, Ni, Cd, Pb and VOCs; whereas the stygobites do not show any significant correlation. The effectiveness of hyporheic crustaceans as efficient bioindicators for assessing the current ecological status of river ecosystems is emphasised.
اظهر المزيد [+] اقل [-]The role of transboundary air pollution over Galicia and North Portugal area النص الكامل
2013
Borrego, C. | Souto, J. A. | Monteiro, A. | Dios, M. | Fernandez, Aurelio Rodriguez | Ferreira, J. | Saavedra, S. | Casares, J. J. | Miranda, A. I.
The role of transboundary air pollution over Galicia and North Portugal area النص الكامل
2013
Borrego, C. | Souto, J. A. | Monteiro, A. | Dios, M. | Fernandez, Aurelio Rodriguez | Ferreira, J. | Saavedra, S. | Casares, J. J. | Miranda, A. I.
In summer, high levels of ozone (O₃) are frequently measured at both Galicia and Northern Portugal air quality monitoring stations, even exceeding the limit values imposed by legislation. This work aims to investigate the origin of these high O₃ concentrations by the application of a chemical transport modelling system over the northwestern area of the Iberian Peninsula. The WRF–CHIMERE modelling system was applied with high resolution to simulate the selected air pollution episodes that occurred simultaneously in Galicia and North Portugal and in order to study both the contribution of local emission sources and the influence of transboundary pollution. Emission inputs have been prepared based on the development of the Portuguese and Galician emission inventories. The obtained results for O₃ have been evaluated and validated against observations. Modelling results show possible contribution of the transboundary transport over the border of two neighbour regions/countries, indicating that the O₃ episode starts over the urban and industrialised area of North coast of Portugal, reaching the maximum peaks over this region; at the same time, O₃ levels increased over Galicia region, where lower concentrations, but still high, were observed. These results pointed out that air quality management should not be driven by political boundaries and highlight the importance of joining efforts between neighbouring countries.
اظهر المزيد [+] اقل [-]The role of transboundary air pollution over Galicia and North Portugal area النص الكامل
2013
Borrego, C. | Souto, J. A. | Monteiro, A. | Dios, M. | Rodríguez, A. | Ferreira, J. | Saavedra, S. | Casares, J. J. | Miranda, A. I.
Insummer,highlevelsofozone(O3)arefrequently measured at both Galicia and Northern Portugal air quality monitoring stations, even exceeding the limit values imposed by legislation. This work aims to investigate the origin of these high O3 concentrations by the application of a chemical transport modelling system over the northwestern area of the Iberian Peninsula. The WRF–CHIMERE modelling system was applied with high resolution to simulate the selected air pollutionepisodesthatoccurredsimultaneouslyinGaliciaand North Portugal and in order to study both the contribution of local emission sources and the influence of transboundary pollution. Emission inputs have been prepared based on the development of the Portuguese and Galician emission inventories. The obtained results for O3 have been evaluated and validated against observations. Modelling results show possiblecontributionofthetransboundarytransportovertheborder of two neighbour regions/countries, indicating that the O3 episode starts over the urban and industrialised area of North coast of Portugal, reaching the maximum peaks over this region; at the same time, O3 levels increased over Galicia region, where lower concentrations, but still high, were observed. These results pointed out that air quality management should not be driven by political boundaries and high light the importance of joining efforts between neigh bouring countries. | TheauthorsacknowledgethePortugueseEnvironmental Protection Agency, MeteoGalicia, Laboratorio de Medio Ambiente de Galicia (Xunta de Galicia) and As Pontes Power Plant (Endesa) for the observational dataset support. The authors gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model and/or READY website (http://www.arl. noaa.gov/ready.php) used in this publication. Thanks are extended to the Portuguese Ministério da Ciência, da Tecnologia e do Ensino Superior for the post-doctoral grants of A. Monteiro (SFRH/BPD/63796/2009) and J. Ferreira (SFRH/BPD/40620/2007). PhD grants of A. Rodríguez and M. Dios (‘María Barbeito’ Programme) and the research stay abroad grant of M.Dios(09.02.561B.444.0) at the University of Aveiro were supported by Xunta de Galicia regional government. This work was developed as part of the project ‘XIMERE/FUXIMERE’ (10MDS009E), also with support of Endesa Generación, S.A. (‘Characterization of ozone episodes’) and Troposfera S.C. (‘Collaboration in air quality modeling over Galicia’). | published
اظهر المزيد [+] اقل [-]Biofilm comprising phototrophic, diazotrophic, and hydrocarbon-utilizing bacteria: a promising consortium in the bioremediation of aquatic hydrocarbon pollutants النص الكامل
2013
Al-Bader, Dhia | Kansour, Mayada K. | Rayan, Rehab | Radwan, Samir S.
Biofilms harboring simultaneously anoxygenic and oxygenic phototrophic bacteria, diazotrophic bacteria, and hydrocarbon-utilizing bacteria were established on glass slides suspended in pristine and oily seawater. Via denaturing gradient gel electrophoresis analysis on PCR-amplified rRNA gene sequence fragments from the extracted DNA from biofilms, followed by band amplification, biofilm composition was determined. The biofilms contained anoxygenic phototrophs belonging to alphaproteobacteria; pico- and filamentous cyanobacteria (oxygenic phototrophs); two species of the diazotroph Azospirillum; and two hydrocarbon-utilizing gammaproteobacterial genera, Cycloclasticus and Oleibacter. The coexistence of all these microbial taxa with different physiologies in the biofilm makes the whole community nutritionally self-sufficient and adequately aerated, a condition quite suitable for the microbial biodegradation of aquatic pollutant hydrocarbons.
اظهر المزيد [+] اقل [-]Sublethal detergent concentrations increase metabolization of recalcitrant polyphosphonates by the cyanobacterium Spirulina platensis النص الكامل
2013
Forlani, Giuseppe | Bertazzini, Michele | Giberti, Samuele | Wieczorek, Dorota | Kafarski, Paweł | Lipok, Jacek
As a consequence of increasing industrial applications, thousand tons of polyphosphonates are introduced every year into the environment. The inherent stability of the C–P bond results in a prolonged half-life. Moreover, low uptake rates limit further their microbial metabolization. To assess whether low detergent concentrations were able to increase polyphosphonate utilization by the cyanobacterium Spirulina platensis, tolerance limits to the exposure to various detergents were determined by measuring the growth rate in the presence of graded levels below the critical micellar concentration. Then, the amount of hexamethylenediamine-N,N,N′,N′-tetrakis(methylphosphonic acid) that is metabolized in the absence or in the presence of sublethal detergent concentrations was quantified by ³¹P NMR analysis on either P-starved or P-fed cyanobacterial cultures. The strain tolerated the presence of detergents in the order: nonionic > anionic > cationic. When added to the culture medium at the highest concentrations showing no detrimental effects upon cell viability, detergents either improved or decreased polyphosphonate utilization, the anionic sodium dodecyl sulfate being the most beneficial. Metabolization was not lower in P-fed cells—a result that strengthens the possibility of using, in the future, this strain for bioremediation purposes.
اظهر المزيد [+] اقل [-]The reciprocal relation between lightning and pollution and their impact over Kolkata, India النص الكامل
2013
Middey, Anirban | Chaudhuri, Sutapa
Aerosol loading in the atmosphere can cause increased lightning flashes, and those lightning flashes produce NO X , which reacts in sun light to produce surface ozone. The present study deals with the effect of surface pollutants on premonsoon (April–May) lightning activity over the station Kolkata (22.65° N, 88.45° E). Seven-year (2004–2010) premonsoon thunderstorms data are taken for the study. Different parameters like aerosol optical depth and cloud top temperature from the Moderate Resolution Imaging Spectroradiometer satellite products along with lightning flash data from Tropical Rainfall Measuring Mission’s (TRMM) Lightning Imaging Sensor are analyzed. Some surface pollution parameters like suspended particulate matter, particulate matter 10, nitrogen oxides (NO X), and surface ozone (O₃) data during the same period are taken account for clear understanding of their association with lightning activity. Heights of convective condensation level and lifting condensation level are collected from radiosonde observations to anticipate about cloud base. It is found that increased surface pollution in a near storm environment is related to increased lightning flash rate, which results in increased surface NO X and consequently increased surface ozone concentration over the station Kolkata.
اظهر المزيد [+] اقل [-]PFOS and PFC releases and associated pollution from a PFC production plant in Minnesota (USA) النص الكامل
2013
Oliaei, Fardin | Kriens, Don | Weber, Roland | Watson, Alan
Perfluorooctane sulfonate (PFOS) and PFOS-related substances have been listed as persistent organic pollutants in the Stockholm Convention. From August 2012, Parties to the Convention needed to address the use, storage, and disposal of PFOS—including production sites and sites where PFOS wastes have been deposited—in their national implementation plans. The paper describes the pollution in Minnesota (USA) caused by the 3M Company at one of the largest per/polyfluorinated chemical (PFC) production facilities. From early 1950s until the end of 2002, when 3M terminated PFOS and perfluorooctanoic acid (PFOA) production, PFOS, PFOA, and other PFC production wastes were disposed around the plant and in local disposal sites. Discharges from the site and releases from deposits caused widespread contamination of ground and surface waters including local drinking water wells. Fish in the river downstream were contaminated with PFOS to levels that led to fish consumption advisories. Human exposures resulted from ingesting contaminated drinking water, requiring installation of water treatment facilities and alternate water supplies. The critical evaluation of the assessments done revealed a range of gaps in particular of human exposure where relevant exposure pathways including the entire exposure via food have not been taken into consideration. Currently, the exposure assessment of vulnerable groups such as children or Hmong minorities is inadequate and needs to be improved/validated by epidemiological studies. The assessment methodology described for this site may serve—with highlighted improvements—as a model for assessment of other PFOS/PFC production sites in the Stockholm Convention implementation.
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