Blind Stereoscopy of the Coronal Magnetic Field     

Markus J. Aschwanden  Carolus J. Schrijver  Anna Malanushenko 《Solar physics》2015,290(10):2765-2789

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Short-term effects of changes in water management on the limnological characteristics and zooplankton of a eutrophic Mediterranean coastal lagoon (NE Iberian Peninsula)     

Badosa A  Boix D  Brucet S  López-Flores R  Quintana XD 《Marine pollution bulletin》2007,54(8):1273-1284

The Ter Vell (NE Iberian Peninsula) is a eutrophic coastal lagoon which has been flooded by the excess irrigation water and the agricultural runoff during the last decades. Between 1999 and 2003, restoration measures were applied to improve its water quality. At the same time, but independently, agricultural water management drastically reduced the freshwater inflow. The short-term effects of these management actions on the limnological characteristics of the lagoon were analysed by comparing two hydrological cycles, one before (1999/2000) and the other one after (2002/2003) the actions. The two cycles are illustrative of opposite situations in the hydrological functioning of coastal wetlands. In the first, the lagoon was exorheic, with prolonged flooding periods and a low residence time; in the second, it had a more endorheic character, with scarce water inputs and prolonged periods of confinement. Consequently, nitrogen inputs diminished and organic load and salinity increased as the internal loading and the accumulation effects became more relevant. These effects were actually caused by the drastic reduction in the freshwater inflow which prevented, in turn, the success of the restoration measures. The zooplankton community of the Ter Vell lagoon was not significantly altered by the hydrological change, at least in the short-term, and rotifers and cladocerans, mainly those species indicative of eutrophy, dominated the community.  相似文献   

Dioxins and PCBs in Greenland shark (Somniosus microcephalus) from the North-East Atlantic     

Strid A  Jörundsdóttir H  Päpke O  Svavarsson J  Bergman A 《Marine pollution bulletin》2007,54(9):1514-1522

The Greenland shark (Somniosus microcephalus) is a high-trophic fish species present in Arctic waters. The present study aimed to determine concentrations of polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs), dioxin-like (DL) PCBs and six non-dioxin-like (NDL) PCBs in muscle and liver from 10 female Greenland sharks collected between 2001 and 2003 from Icelandic waters. The mean total concentrations of PCDDs/Fs were 13 and 530pg/g fat for muscle and liver, respectively, and show enrichment in the liver. Concentrations of DL-non-ortho PCBs were also higher in liver compared to muscle with mean concentrations of 7.8 and 0.36ng/g fat, respectively. No enrichment in the liver was found for DL-mono-ortho- and NDL-PCBs. No correlation was found between the size range studied and total concentrations of the compounds analyzed. Total WHO-TEQs (PCDDs/Fs and DL-PCBs) ranged between 7.1-70 and 54-1500pg/g fat in muscle and liver, respectively.  相似文献   

Filter-feeder macroinvertebrates as key players in culturable bacteria biodiversity control: a case of study with Sabella spallanzanii (Polychaeta: Sabellidae)     

Licciano M  Terlizzi A  Giangrande A  Cavallo RA  Stabili L 《Marine environmental research》2007,64(4):504-513

The present study investigates the effect of the filtering activity of Sabella spallanzanii on the culturable heterotrophic bacterial community through the comparison of the bacterial diversity in transplanted polychaetes and the surrounding seawater. For isolation of culturable heterotrophic bacteria, seawater samples as well as polychaete homogenates were plated in triplicates onto Bacto Marine Agar 2216 (Difco). All the colonies grown were isolated, subcultured and identified by several morphological, biochemical and cultural methods. Some bacterial genera showed higher average abundances in polychaetes than in seawater (i.e. Lucibacterium and Photobacterium). Aeromonas represented a conspicuous component of the bacterial community both in S. spallanzanii and seawater. The presence of Cytophaga and Pseudomonas was also relevant in the examined seawater samples. The selective concentrations of some bacterial genera inside S. spallanzanii either by grazing on bacteria or their capability as bacterial reservoirs, provides evidence for the role of macrobenthic invertebrates as key determinants for microbial diversity.  相似文献   

The correlation of star formation quenching with internal galaxy properties and environment     

Taysun Kimm  Rachel S. Somerville  Sukyoung K. Yi  Frank C. van den Bosch  Samir Salim  Fabio Fontanot  Pierluigi Monaco  Houjun Mo  Anna Pasquali  R. M. Rich  Xiaohu Yang 《Monthly notices of the Royal Astronomical Society》2009,394(3):1131-1147

We investigate the correlation of star formation quenching with internal galaxy properties and large-scale environment (halo mass) in empirical data and theoretical models. We make use of the halo-based group catalogue of Yang and collaborators, which is based on the Sloan Digital Sky Survey. Data from the Galaxy evolution explorer are also used to extract the recent star formation rate. In order to investigate the environmental effects, we examine the properties of 'central' and 'satellite' galaxies separately. For central galaxies, we are unable to conclude whether star formation quenching is primarily connected with halo mass or stellar mass, because these two quantities are themselves strongly correlated. For satellite galaxies, a nearly equally strong dependence on halo mass and stellar mass is seen. We make the same comparison for five different semi-analytic models based on three independently developed codes. We find that the models with active galactic nuclei feedback reproduce reasonably well the dependence of the fraction of central red and passive galaxies on halo mass and stellar mass. However, for satellite galaxies, the same models badly overproduce the fraction of red/passive galaxies and do not reproduce the empirical trends with stellar mass or halo mass. This satellite overquenching problem is caused by the too-rapid stripping of the satellites' hot gas haloes, which leads to rapid strangulation of star formation.  相似文献   

Clustering of luminous red galaxies – II. Small-scale redshift-space distortions     

Anna Cabré  Enrique Gaztañaga 《Monthly notices of the Royal Astronomical Society》2009,396(2):1119-1131

This is the second paper of a series where we study the clustering of luminous red galaxies (LRG) in the recent spectroscopic Sloan Digital Sky Survey (SDSS) data release, DR6, which has 75 000 LRG covering over  1 Gpc³  h ⁻³  for  0.15 < z < 0.47  . Here, we focus on modelling redshift-space distortions in  ξ(σ, π)  , the two-point correlation in separate line-of-sight and perpendicular directions, at small scales and in the line-of-sight. We show that a simple Kaiser model for the anisotropic two-point correlation function in redshift space, convolved with a distribution of random peculiar velocities with an exponential form, can describe well the correlation of LRG on all scales. We show that to describe with accuracy the so-called 'fingers-of-God' (FOG) elongations in the radial direction, it is necessary to model the scale dependence of both bias b and the pairwise rms peculiar velocity σ₁₂ with the distance. We show how both quantities can be inferred from the  ξ(σ, π)  data. From   r ≃ 10 Mpc  h ⁻¹  to   r ≃ 1 Mpc  h ⁻¹  , both the bias and σ₁₂ are shown to increase by a factor of 2: from   b = 2  to 4 and from  σ₁₂= 400  to  800 km s⁻¹  . The latter is in good agreement, within a 5 per cent accuracy in the recovered velocities, with direct velocity measurements in dark matter simulations with  Ω_m= 0.25  and  σ₈= 0.85  .  相似文献   

Clustering of luminous red galaxies – III. Baryon acoustic peak in the three-point correlation     

Enrique Gaztañaga  Anna Cabré  Francisco Castander  Martin Crocce  Pablo Fosalba 《Monthly notices of the Royal Astronomical Society》2009,399(2):801-811

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Clustering of luminous red galaxies – IV. Baryon acoustic peak in the line-of-sight direction and a direct measurement of H(z)     

Enrique Gaztañaga  Anna Cabré  Lam Hui 《Monthly notices of the Royal Astronomical Society》2009,399(3):1663-1680

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A Comparison Between Modelled and Measured Mixing-Layer Height Over Munich   总被引：1，自引：0，他引：1  

Aggeliki Dandou  Maria Tombrou  Klaus Schäfer  Stefan Emeis  Anna P. Protonotariou  Elissavet Bossioli  Nikolaos Soulakellis  Peter Suppan 《Boundary-Layer Meteorology》2009,131(3):425-440

An attempt is made to correlate the mixing heights, derived from ceilometer and Sodar measurements, to those simulated by different atmospheric boundary-layer parameterization schemes. The comparison is performed at two sites (one suburban and one rural) close to Munich, Germany for two spring and two winter days. It is found that, under convective conditions, the mixing height determined, by both Sodar and ceilometer, corresponds to the middle or the top of the entrainment zone, respectively, as calculated from the eddy-viscosity profiles. Under stable conditions, the measured mixing height is related to the height where eddy viscosities attain their minimum values (Sodar) or to the height of residual mechanical turbulence (ceilometer). During a foehn case with weak turbulence, the measured mixing height from both Sodar and ceilometer is better inferred by considering the eddy-viscosity profiles during daytime and the height of the low-level jet during nighttime.  相似文献   

Newania carbonatites, Western India: example of mantle derived magnesium carbonatites     

Anna Gennad’evna Doroshkevich  German Ripp  Shrinivas Viladkar 《Mineralogy and Petrology》2010,98(1-4):283-295

The key mineralogical features of the Newania carbonatites, that illustrate their derivation from primary mantle melts (Gruau et al. Terra Nova, Abstract Suppl 1:336, 1995; Viladkar Petrology 6(3):272–283, 1998; Basu and Murty Abstracts of Goldschmidt Conference A40, 2006), are the presence of magnesite, graphite and Cr-rich magnetite. Magnesite is an early crystallizing phase. Cr-rich magnetite and graphite coexist with carbonatite minerals and precipitated from carbonate magma. Graphite, as well as gaseous CO₂ and carbonate minerals such as dolomite and magnesite, can be stable in peridotite mantle. Coexistence of these minerals is controlled by fO ₂ and PT-conditions. Mineral geothermometers for the Newania carbonatite give temperatures from 463 to 950°C. The parental source for Newania carbonatites was characterized by a relatively high log (fHF/fH₂O) level which increased during the crystallization history of Newania. The estimated oxygen fugacity (for ilmenite–magnetite pairs) varies from ?1.5 to +3.5 (log-bar unit deviation from FMQ buffer), which is supported by the presence of Fe-columbite, and the composition of phlogopite, amphibole and pyroxene that have an elevated concentration of Fe³⁺. However, the oxygen fugacity range represented by co-existing early-crystallized graphite and magnesite is below that of the FMQ buffer and lies on the CCO buffer.  相似文献