21,382 research outputs found

    Biodiversity of Cyanobacteria in industrial effluents

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    Biodiversity of cyanobacteria in industrial effluents. In order to study the biodiversity of cyanobacteria in industrial effluents, four different effluents such as dye, paper mill, pharmaceutical and sugar were selected. The hysicochemical characteristics of all the effluents studied were more or less similar. Totally 59 species of cyanobacteria distributed in four different effluents were recorded. Among the effluents, sugar mill recorded the maximum number of species (55) followed by dye (54), paper mill (45) and pharmaceutical (30). Except pharmaceutical effluent, others recorded heterocystous cyanobacteria. In total 26 species of cyanobacteria were recorded in common to all the effluents analysed. Of them, Oscillatoria with 13 species was the dominant genus which was followed by Phormidium (8), Lyngbya (2), Microcystis (2) and Synechococcus with single species. The abundance of cyanobacteria in these effluents was due to favourable contents of oxidizable organic matter, rich calcium and abundant nutrients such as nitrates and phosphates with less dissolved oxygen. Indicator species from each effluent and their immense value for the future pollution abatement programmes have also been discussed.Biodiversidad de cianobacterias en vertidos industriales. Se ha estudiado la biodiversidad de cianobacterias presente en vertidos industriales de diferente naturaleza (colorantes, fabricación de papel, sector farmacéutico y azúcar). Las características físico-químicas de los vertidos fueron más o menos similares. Se han identificado un total de 59 especies de cianobacterias en los cuatro tipos de vertidos. La mayor riqueza específica se encontró en el vertido de la industria azucarera (55 especies), seguida luego por la industria de colorantes, papel y productos farmacéuticos (54, 45 y 30 especies, respectivamente). Con la excepción del vertido de la industria farmacéutica, en los restantes vertidos se detectaron cianobacterias heterocistadas. El número de especies comunes a los cuatro vertidos ascendió a 26. Entre éstas, Oscillatoria, con 13 especies, fue el género dominante, seguido por Phormidium (8), Lyngbya y Microcystis (ambas con 2) y Synechococcus (1). La abundancia de cianobacterias en estos vertidos se debió al contenido en materia orgánica oxidable, altos niveles de calcio y nutrientes inorgánicos (nitratos y fosfatos) y bajos niveles de oxígeno disuelto. Se discuten el valor del indicador de especies de cada vertido y su importancia para los programas de reducción de la contaminación

    Three-dimensional Evolution of Solar Wind during Solar Cycles 22-24

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    This paper presents the analysis of 3D evolution of solar wind density turbulence and speed at various levels of solar activity between solar cycles 22 and 24. The solar wind data has been obtained from interplanetary scintillation (IPS) measurements made at the Ooty Radio Telescope. Results show that (i) on the average, there was a downward trend in density turbulence from the maximum of cycle 22 to the deep minimum phase of cycle 23; (2) the scattering diameter of the corona around the Sun shrunk steadily towards the Sun, starting from 2003 to the smallest size at the deepest minimum, and it corresponded to a reduction of ~50% in density turbulence between maximum and minimum phases of cycle 23; (3) The latitudinal distribution of solar wind speed was significantly different between minima of cycles 22 and 23. At the minimum phase of solar cycle 22, when the underlying solar magnetic field was simple and nearly dipole in nature, the high-speed streams were observed from poles to ~30 deg. latitudes in both hemispheres. In contrast, in the long-decay phase of cycle 23, the sources of high-speed wind at both poles, in accordance with the weak polar fields, occupied narrow latitude belts from poles to ~60 deg. latitudes. Moreover, in agreement with the large amplitude of heliospheric current sheet, the low-speed wind prevailed the low- and mid-latitude regions of the heliosphere. (4) At the transition phase between cycles 23 and 24, the high levels of density and density turbulence were observed close to the heliospheric equator and the low-speed speed wind extended from equatorial- to mid-latitude regions. Results are consistent with the onset of the current cycle 24, from middle of 2009 and it has almost reached near to the maximum phase at the northern hemisphere of the Sun, but activity not yet developed in the southern hemisphere.Comment: 14 pages, 9 figures, Accepted for Publication in The Astrophysical Journa

    Coronal Mass Ejections - Propagation Time and Associated Internal Energy

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    In this paper, we analyze 91 coronal mass ejection (CME) events studied by Manoharan et al. (2004) and Gopalswamy and Xie (2008). These earth-directed CMEs are large (width >>160∘^\circ) and cover a wide range of speeds (∼\sim120--2400 {\kmps}) in the LASCO field of view. This set of events also includes interacting CMEs and some of them take longer time to reach 1 AU than the travel time inferred from their speeds at 1 AU. We study the link between the travel time of the CME to 1 AU (combined with its final speed at the Earth) and the effective acceleration in the Sun-Earth distance. Results indicate that (1) for almost all the events (85 out of 91 events), the speed of the CME at 1 AU is always less than or equal to its initial speed measured at the near-Sun region, (2) the distributions of initial speeds, CME-driven shock and CME speeds at 1 AU clearly show the effects of aero-dynamical drag between the CME and the solar wind and in consequence, the speed of the CME tends to equalize to that of the background solar wind, (3) for a large fraction of CMEs (for ∼\sim50% of the events), the inferred effective acceleration along the Sun-Earth line dominates the above drag force. The net acceleration suggests an average dissipation of energy ∼\sim1031−32^{31-32} ergs, which is likely provided by the Lorentz force associated with the internal magnetic energy carried by the CME.Comment: 18 pages, 6 figure

    Observation of Interplanetary Scintillation with Single-Station Mode at Urumqi

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    The Sun affects the Earth's physical phenomena in multiple ways, in particular the material in interplanetary space comes from coronal expansion in the form of inhomogeneous plasma flow (solar wind), which is the primary source of the interplanetary medium. Ground-based Interplanetary Scintillation (IPS) observations are an important and effective method for measuring solar wind speed and the structures of small diameter radio sources. We discuss one mode of ground-based single-station observations: Single-Station Single-Frequency (SSSF) mode. To realize the SSSF mode, a new system has been established at Urumqi Astronomical Observatory (UAO), China, and a series of experimental observations were carried out successfully from May to December, 2008

    Eruption of a plasma blob, associated M-class flare, and large-scale EUV wave observed by SDO

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    We present a multiwavelength study of the formation and ejection of a plasma blob and associated EUV waves in AR NOAA 11176, observed by SDO/AIA and STEREO on 25 March 2011. SDO/AIA images clearly show the formation and ejection of a plasma blob from the lower solar atmosphere at ~9 min prior to the onset of the M1.0 flare. This onset of the M-class flare happened at the site of the blob formation, while the blob was rising in a parabolic path with an average speed of ~300 km/s. The blob also showed twisting and de-twisting motion in the lower corona, and the blob speed varied from ~10-540 km/s. The faster and slower EUV wavefronts were observed in front of the plasma blob during its impulsive acceleration phase. The faster EUV wave propagated with a speed of ~785 to 1020 km/s, whereas the slower wavefront speed varied in between ~245 and 465 km/s. The timing and speed of the faster wave match the shock speed estimated from the drift rate of the associated type II radio burst. The faster wave experiences a reflection by the nearby AR NOAA 11177. In addition, secondary waves were observed (only in the 171 \AA channel), when the primary fast wave and plasma blob impacted the funnel-shaped coronal loops. The HMI magnetograms revealed the continuous emergence of new magnetic flux along with shear flows at the site of the blob formation. It is inferred that the emergence of twisted magnetic fields in the form of arch-filaments/"anemone-type" loops is the likely cause for the plasma blob formation and associated eruption along with the triggering of M-class flare. Furthermore, the faster EUV wave formed ahead of the blob shows the signature of fast-mode MHD wave, whereas the slower wave seems to be generated by the field line compression by the plasma blob. The secondary wave trains originated from the funnel-shaped loops are probably the fast magnetoacoustic waves.Comment: A&A (in press), 22 pages, 13 figure

    Evolution of Solar Magnetic Field and Associated Multi-wavelength Phenomena: Flare events on 20 November 2003

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    We analyze H-alpha images, soft X-ray profiles, magnetograms, extreme ultra-violet images and radio observations of two homologous flare events (M1.4/1N and M9.6/2B) on 20 November 2003 in the active region NOAA 10501 and study properties of reconnection between twisted filament systems, energy release and associated launch of coronal mass ejections (CMEs). During both events twisted filaments observed in H-alpha approached each other and initiated the flare processes. However, the second event showed the formation of cusp as the filaments interacted. The rotation of sunspots of opposite polarities, inferred from magnetograms likely powered the twisted filaments and injection of helicity. Along the current sheet between these two opposite polarity sunspots, the shear was maximum, which could have caused the twist in the filament. At the time of interaction between filaments, the reconnection took place and flare emission in thermal and non-thermal energy ranges attained the maximum. The radio signatures revealed the opening of field lines resulting from reconnection. The H-alpha images and radio data provide the inflow speed leading to reconnection and the scale size of particle acceleration region. The first event produced a narrow and slow CME, whereas the later one was associated with a fast full halo CME. The halo CME signatures observed between Sun and Earth using white-light and scintillation images and in-situ measurements indicated the magnetic energy utilized in the expansion and propagation. The magnetic cloud signature at the Earth confirmed the flux rope ejected at the time of filament interaction and reconnection.Comment: 22 pages, 16 figures, Accepted for the publication in Astrophysical Journal (APJ
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