Polycyclic aromatic hydrocarbons in surface sediments of Binacional Itaipu Lake,Brazil: characteristics,sources and toxicity evaluation     

Miguel Kalwa  Sueli P. Quináia  Adelmo L. Pletsch  Yohandra R. Torres  Daiane Finger 《Environmental Earth Sciences》2014,72(11):4473-4481

Itaipu Lake, which includes the Itaipu hydroelectric power plant, is one of the largest dams in the world and has a strong relationship with its surroundings. The flooded area has multiple uses such as navigation, recreation, water abstraction for industrial, urban and agricultural irrigation. The lake is located at the frontier between Brazil, Argentina and Paraguay. In this study, superficial sediments collected from nine sampling sites were analysed for grain size, organic matter and 16 priority polycyclic aromatic hydrocarbons (PAHs) using high-performance liquid chromatography (HPLC) with fluorescence detector. The total concentration of PAHs in the dry sediment ranged from 35.21 to 685.37 µg kg^?1. Diagnostic ratios showed that the possible source of PAHs in the Itaipu Lake could be pyrolitic and petrogenic. The potential toxicity of sediment of PAHs varied from not detected to 127.70 µg g^?1, suggesting that some adverse ecological effects would arise due to PAHs in these sediments.  相似文献   

The stellar content of the young open cluster Trumpler 37     

R. Errmann  R. Neuhuser  L. Marschall  G. Torres  M. Mugrauer  W.P. Chen  S.C.‐L. Hu  C. Briceno  R. Chini  &#x;. Bukowiecki  D.P. Dimitrov  D. Kjurkchieva  E.L.N. Jensen  D.H. Cohen  Z.‐Y. Wu  T. Pribulla  M. Va&#x;ko  V. Krushevska  J. Budaj  Y. Oasa  A.K. Pandey  M. Fernandez  A. Kellerer  C. Marka 《Astronomische Nachrichten》2013,334(7):673-681

With an apparent cluster diameter of 1.5° and an age of 4 Myr, Trumpler 37 is an ideal target for photometric monitoring of young stars as well as for the search of planetary transits, eclipsing binaries and other sources of variability. The YETI consortium has monitored Trumpler 37 throughout 2010 and 2011 to obtain a comprehensive view of variable phenomena in this region. In this first paper we present the cluster properties and membership determination as derived from an extensive investigation of the literature. We also compared the coordinate list to some YETI images. For 1872 stars we found literature data. Among them 774 have high probability of being member and 125 a medium probability. Based on infrared data we re‐calculate a cluster extinction of 0.9–1.2 mag. We can confirm the age and distance to be 3–5 Myr and870 pc. Stellar masses are determined from theoretical models and the mass function is fitted with a power‐law index of α = 1.90 (0.1–0.4 M_⊙) and α = 1.12 (1–10 M_⊙). (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

GRIS: The GREGOR Infrared Spectrograph     

M. Collados  R. Lpez  E. Pez  E. Hernndez  M. Reyes  A. Calcines  E. Ballesteros  J.J. Díaz  C. Denker  A. Lagg  R. Schlichenmaier  W. Schmidt  S.K. Solanki  K.G. Strassmeier  O. von der Lühe  R. Volkmer 《Astronomische Nachrichten》2012,333(9):872-879

This paper describes the main characteristics of GRIS (GREGOR Infrared Spectrograph), the grating spectrograph installed in the recently inaugurated (May 2012) 1.5‐meter GREGOR telescope located at the Observatorio del Teide in Tenerife. The spectrograph has a standard Czerny‐Turner configuration with parabolic collimator and camera mirrors that belong to the same conic surface. Although nothing prevents its use at visible wavelengths, the spectrograph will be initially used in combination with the infrared detector of the Tenerife Infrared Polarimeter (TIP‐II) in standard spectroscopic mode as well as for spectropolarimetric measurements (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Periodic motions in a gravitational central field with a rotating external force     

Alessandro Fonda  Rodica Toader  Pedro J. Torres 《Celestial Mechanics and Dynamical Astronomy》2012,113(3):335-342

We consider a Kepler problem, with an additional rotating external force, and study the existence of periodic solutions when a small perturbative term is introduced. Surprisingly enough, we always get at least one of such solutions. Moreover, if a nonresonance assumption is added, then the existence of a second solution is also proved.  相似文献   

Thermal Drying and Alkaline Treatment of Biosolids: Effects on Nitrogen Mineralization     

Jorge Silva‐Leal  Patricia Torres‐Lozada  Yasmin J. Cardoza 《洁净——土壤、空气、水》2013,41(3):298-303

Biosolids from the Cañeveralejo WWTP were dehydrated by filter press and then applied two processes to reduce pathogens (PRP): thermally dried biosolid (TDB) and alkalinized biosolid (AB). Untreated, dehydrated biosolid (DB) was used as a control. We evaluated the impact of thermal drying and alkaline treatments on nitrogen mineralization in these substrates. Moreover, agronomic rates for biosolid applications to sugarcane were estimated for each of the treatments leading to application rates of 35.8, 36.4, and 54.5 t/ha for DB, TDB, and AB, respectively, to meet the nitrogen requirement (200 kg N/ha) for sugarcane cultivation (Saccharum officinarum). The results showed that the biosolid rates used increased the mineral nitrogen content of soils by an average of 93.8 and 439.8 mg/kg for all biosolids and the PRP (thermal drying and alkaline treatment) in biosolids had significant effects on mineralization rate, showing better results for the TDBs.  相似文献   

Refining the estimation of metal loads dissolved in acid mine drainage by continuous monitoring of specific conductivity and water level     

Laura Galván  Manuel Olías  Carlos Ruiz Cánovas  Ester Torres  Carlos Ayora  José Miguel Nieto  Aguasanta Miguel Sarmiento 《Applied Geochemistry》2012

The accurate estimation of metal loads transported by streams is necessary to calculate reliable mass transfers of metals between compartments, both at local and global scales. This estimation is particularly relevant in the case of the Tinto and Odiel Rivers (SW Spain) due to their significant contribution to the total metal transfer from continents to the ocean. At a local scale, the metal load transported by streams plays a key role in predicting the biogeochemical evolution of water reservoirs affected by Acid Mine Drainage (AMD). This work uses the relationships between specific conductivity (SC) and dissolved elements to calculate the metal load of the River Meca, a tributary of the Odiel. The SC and the water level were continuously monitored from April 2009 to June 2010. Water samples were also collected and measurements of the discharge were carried out manually once a month. The relationships between the SC and the concentration of dissolved elements are, in general, very good (R² > 0.90). However, some key elements such as Fe show a very poor correlation. A simple methodology based on the MIX code (a maximum likelihood method to estimate mixing ratios) was used to elucidate their different behaviours. During the dry period (April–December, 2009) the Fe concentration was lower than that deduced from the SC recorded value due to the precipitation of Fe-oxihydroxides, which also reduced the concentrations of As, Cr, Pb and, to a lesser extent, Cu. At the same time Na, Sr, Ca and Li were enriched because of the higher interaction with the riverbed materials. Correlations between the SC and the metal concentration improved significantly when each period was considered separately. A second dry period (April–June 2010) shows high SC values, although no dissolution/precipitation of solid phases is evidenced. This indicates that SC alone is not enough to predict the dissolved metal loads in Mediterranean AMD streams. The metal load transported by the River Meca was determined for the hydrological year 2009/10 as 1933 ± 129 tonnes of Fe, 990 ± 155 of Al and 378 ± 41 of Zn.  相似文献   

Inversion of ambient seismic noise HVSR to evaluate velocity and structural models of the Lower Tagus Basin,Portugal     

J. F. Borges  H. G. Silva  R. J. G. Torres  B. Caldeira  M. Bezzeghoud  J. A. Furtado  J. Carvalho 《Journal of Seismology》2016,20(3):875-887

During its history, several significant earthquakes have shaken the Lower Tagus Valley (Portugal). These earthquakes were destructive; some strong earthquakes were produced by large ruptures in offshore structures located southwest of the Portuguese coastline, and other moderate earthquakes were produced by local faults. In recent years, several studies have successfully obtained strong-ground motion syntheses for the Lower Tagus Valley using the finite difference method. To confirm the velocity model of this sedimentary basin obtained from geophysical and geological data, we analysed the ambient seismic noise measurements by applying the horizontal to vertical spectral ratio (HVSR) method. This study reveals the dependence of the frequency and amplitude of the low-frequency (HVSR) peaks (0.2–2 Hz) on the sediment thickness. We have obtained the depth of the Cenozoic basement along a profile transversal to the basin by the inversion of these ratios, imposing constraints from seismic reflection, boreholes, seismic sounding and gravimetric and magnetic potentials. This technique enables us to improve the existing three-dimensional model of the Lower Tagus Valley structure. The improved model will be decisive for the improvement of strong motion predictions in the earthquake hazard analysis of this highly populated basin. The methodology discussed can be applied to any other sedimentary basin.  相似文献   

A first approach to earthquake damage estimation in Haiti: advices to minimize the seismic risk     

Y. Torres  S. Molina  S. Martínez-Cuevas  M. Navarro  J. J. Martínez-Díaz  B. Benito  J. J. Galiana-Merino  D. Belizaire 《Bulletin of Earthquake Engineering》2016,14(1):39-58

  相似文献   

Rare earth element geochemistry in cold-seep pore waters of Hydrate Ridge, northeast Pacific Ocean   总被引：2，自引：1，他引：1  

Tobias Himmler  Brian A. Haley  Marta E. Torres  Gary P. Klinkhammer  Gerhard Bohrmann  Jörn Peckmann 《Geo-Marine Letters》2013,33(5):369-379

The concentrations of rare earth elements (REEs), sulphate, hydrogen sulphide, total alkalinity, calcium, magnesium and phosphate were measured in shallow (<12 cm below seafloor) pore waters from cold-seep sediments on the northern and southern summits of Hydrate Ridge, offshore Oregon. Downward-decreasing sulphate and coevally increasing sulphide concentrations reveal sulphate reduction as dominant early diagenetic process from ~2 cm depth downwards. A strong increase of total dissolved REE (∑REE) concentrations is evident immediately below the sediment–water interface, which can be related to early diagenetic release of REEs into pore water resulting from the re-mineralization of particulate organic matter. The highest pore water ∑REE concentrations were measured close to the sediment–water interface at ~2 cm depth. Distinct shale-normalized REE patterns point to particulate organic matter and iron oxides as main REE sources in the upper ~2-cm depth interval. In general, the pore waters have shale-normalized patterns reflecting heavy REE (HREE) enrichment, which suggests preferential complexation of HREEs with carbonate ions. Below ~2 cm depth, a downward decrease in ∑REE correlates with a decrease in pore water calcium concentrations. At this depth, the anaerobic oxidation of methane (AOM) coupled to sulphate reduction increases carbonate alkalinity through the production of bicarbonate, which results in the precipitation of carbonate minerals. It seems therefore likely that the REEs and calcium are consumed during vast AOM-induced precipitation of carbonate in shallow Hydrate Ridge sediments. The analysis of pore waters from Hydrate Ridge shed new light on early diagenetic processes at cold seeps, corroborating the great potential of REEs to identify geochemical processes and to constrain environmental conditions.  相似文献   

A parsimonious crop-water productivity index: an application to Brazil     

Marco P Maneta  Purnendu N Singh  Marcelo Torres  Wesley W Wallender  Stephen A Vosti  Lineu N Rodrigues  Luis H Bassoi  Julie A Young 《Area》2009,41(1):94-106

Reducing poverty in rural areas of developing countries requires sustained and sustainable increases in agricultural water productivity. However, aside from traditional measures of precipitation, little is known about water available to farmers or how productively they use it. We present a crop-water productivity index (a ratio of the value of annual crop production to a dimensionless potential water availability index) for large water basins using readily available low-resolution data. The index is transferable, permits direct inter-basin comparisons, and is simple to calculate. We calculate the index for each municipality in the São Francisco river basin in Brazil. No clear patterns linking water availability and value of agricultural output are evident, even though clusters of municípios with high- and low-crop-water productivity emerge, and the former may be useful in guiding policies aimed at increasing water productivity. Finally, analyses of the effects of information uncertainty on the crop-water productivity index suggest that the returns to agricultural investments in certain places in the São Francisco river basin are more risky than others. Improvements in data quality and quantity can help refine estimates of the index and reduce their uncertainty.  相似文献