Phenanthrene Biodegradation by Pseudomonas xanthomarina Isolated from an Aged Contaminated Soil          下载免费PDF全文

Fatima Sopeña  Leonila Laiz  Esmeralda Morillo  Maria Antonia Sanchez‐Trujillo  Jaime Villaverde  Valme Jurado  Cesareo Saiz‐Jimenez 《洁净——土壤、空气、水》2014,42(6):785-790

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Comparison of Recharge Estimation Methods During a Wet Period in a Karst Aquifer          下载免费PDF全文

Carolina Guardiola‐Albert  Sergio Martos‐Rosillo  Eulogio Pardo‐Igúzquiza  Juan José Durán Valsero  Antonio Pedrera  Pablo Jiménez‐Gavilán  Cristina Liñán Baena 《Ground water》2015,53(6):885-895

Management of water resources, implying their appropriate protection, calls for a sound evaluation of recharge. Such assessment is very complex in karst aquifers. Most methods are developed for application to detrital aquifers, without taking into account the extraordinary heterogeneity of porosity and permeability of karst systems. It is commonly recommended to estimate recharge using multiple methods; however, differences inherent to the diverse methods make it difficult to clarify the accuracy of each result. In this study, recharge was estimated in a karst aquifer working in a natural regime, in a Mediterranean‐type climate, in the western part of the Sierra de las Nieves (southern Spain). Mediterranean climate regions are characterized by high inter‐annual rainfall variability featuring long dry periods and short intense wet periods, the latter constituting the most important contribution to aquifer water input. This paper aims to identify the methods that provide the most plausible range of recharge rate during wet periods. Six methods were tested: the classical method of Thornthwaite‐Mather, the Visual Balan code, the chloride balance method, and spatially distributed methods such as APLIS, a novel spatiotemporal estimation of recharge, and ZOODRM. The results help determine valid methods for application in the rest of the unit of study and in similar karst aquifers.  相似文献   

3D Attenuation Tomography of the Volcanic Island of Tenerife (Canary Islands)   总被引：1，自引：1，他引：0  

J. Prudencio  J. M. Ibáñez  E. Del Pezzo  J. Martí  A. García-Yeguas  L. De Siena 《Surveys in Geophysics》2015,36(5):693-716

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Anomalous Diffuse CO2 Emissions at the Masaya Volcano (Nicaragua) Related to Seismic-Volcanic Unrest     

Germán D. Padilla  Pedro A. Hernández  Nemesio M. Pérez  Ernesto Pereda  Eleazar Padrón  Gladys Melián  José Barrancos  Fátima Rodríguez  Samara Dionis  David Calvo  Martha Herrera  Wilfried Strauch  Angélica Muñoz 《Pure and Applied Geophysics》2014,171(8):1791-1804

Anomalous changes in the diffuse emission of carbon dioxide within the Masaya caldera have been observed before two seismic events that occurred at 10 and 30 km from the observation site. Their epicenters are located, respectively, south of Managua in Las Colinas (4.3 magnitude) and the Xiloa caldera (3.6 magnitude), in 2002 and 2003, recorded by the geochemical station located at El Comalito, Masaya volcano (Nicaragua). Anomalous increases were observed, which occurred around 50 and 8 days before the main seismic event that took place in Las Colinas, and 4 days before the seismic swarm at the Xiloa caldera, with a maximum CO₂ efflux of 9.3 and 10.7 kg m^?2 day^?1, respectively. The anomalous CO₂ efflux increases remained after filtering with multiple regression analysis was applied to the CO₂ efflux time series, which indicated that atmospheric variables, during the first 4 months, explained 23 % CO₂ variability, whereas, during the rest of the time series, CO₂ efflux values are poorly controlled with only 6 %. The observed anomalies of the diffuse CO₂ emission rate might be related to pressure changes within the volcanic–hydrothermal system and/or to geostructural changes in the crust due to stress/strain changes caused before and during the earthquakes’ formation, and seem not to be related to the activity of the main crater of Masaya volcano.  相似文献   

Initialisation of Land Surface Variables for Numerical Weather Prediction     

Patricia de Rosnay  Gianpaolo Balsamo  Clément Albergel  Joaquín Muñoz-Sabater  Lars Isaksen 《Surveys in Geophysics》2014,35(3):607-621

Land surface processes and their initialisation are of crucial importance for Numerical Weather Prediction (NWP). Current land data assimilation systems used to initialise NWP models include snow depth analysis, soil moisture analysis, soil temperature and snow temperature analysis. This paper gives a review of different approaches used in NWP to initialise land surface variables. It discusses the observation availability and quality, and it addresses the combined use of conventional observations and satellite data. Based on results from the European Centre for Medium-Range Weather Forecasts (ECMWF), results from different soil moisture and snow depth data assimilation schemes are shown. Both surface fields and low-level atmospheric variables are highly sensitive to the soil moisture and snow initialisation methods. Recent developments of ECMWF in soil moisture and snow data assimilation improved surface and atmospheric forecast performance.  相似文献   

Using OSL to assess hypotheses related to the impacts of land use change with the early nineteenth century arrival of Europeans in south‐eastern Australia: an exploratory case study from Grabben Gullen Creek,New South Wales          下载免费PDF全文

Esperanza Muñoz‐Salinas  Paul Bishop  David Sanderson  Tim Kinnaird 《地球表面变化过程与地形》2014,39(12):1576-1586

A common explanation for intense soil erosion and gullying in SE Australia is the introduction by Europeans of new land use practices following their arrival in Australia in the late 18th century. Eucalyptus woodlands were cleared to introduce farming, and valley bottoms, characterized by chains of ponds with organic‐rich swampy meadow (SM) soils, were subsequently buried by thick deposits of ‘post‐settlement alluvium’ (PSA) generated by erosion in the catchment. In this study, optically stimulated luminescence (OSL) is used to evaluate the source(s) of the PSA in Grabben Gullen Creek (GGC), Australia. We use a portable OSL reader to measure total photon counts on bulk polymineral and polygrain‐size samples from nine profiles along the Creek. We use these luminescence signals as geotracers of sediment source(s) and transport pathways. We obtained higher luminescence signals in the PSA than in the SM sediments, suggesting different sources and fluvial transport conditions for these two widespread sedimentary units. Portable OSL reader data from soils in the GGC catchment that are potential sources for the SM sediments and PSA show that the high luminescence signals recorded in the PSA are similar to those from subsoil samples in granite soils, suggesting that the PSA was derived by gullying of granite subsoils. In the SM sediments, luminescence signals decrease upwards from the base of the profile, as expected in well‐reset fluvial deposits, but with one or more changes in gradient in the profile of photon counts with depth, most likely indicating changes in sediment deposition rates. To calculate deposition rates in the SM sediments, several samples were dated using OSL. The OSL ages produced low scatter in the equivalent doses, confirming the well‐reset nature of the grains composing the SM and indicating a process of sediment transport in dilute flows, as is interpreted from the portable OSL signals. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Star formation in NGC5471     

Rubén García-Benito  Enrique Pérez  Ángeles I. Díaz  Jesús Maíz Apellániz  Miguel Cerviño 《Astrophysics and Space Science》2009,324(2-4):337-340

We present a study of the star formation in the giant Hii region NGC5471 in the outskirts of M101. We have performed integrated photometry of the mean emission knots. Stellar population analysis with the code chorizos is compatible with the hypothesis that these regions have at least two different populations. The color–magnitude diagram of the region as derived from Hubble Space Telescope/WPFC2 stellar photometry shows that star formation has been going on for the last 70 Myr.  相似文献   

The starburst-AGN connection: the role of stellar clusters in AGNs     

R. M. González Delgado  V. M. Muñoz Marín  E. Pérez  H. R. Schmitt  R. Cid Fernandes 《Astrophysics and Space Science》2009,320(1-3):61-67

Nuclear stellar clusters are a common phenomenon in spirals and in starburst galaxies, and they may be a natural consequence of the star formation processes in the central regions of galaxies. HST UV imaging of a few Seyfert 2 galaxies have resolved nuclear starbursts in Seyfert 2 revealing stellar clusters as the main components of the extended emission. However, we do not know whether stellar clusters are always associated with all types of nuclear activity. We present HST NUV and optical images to study the role that stellar clusters play in different types of AGNs. Also with these images, we study the circumnuclear dust morphology as a probe of the circumnuclear environment of AGNs.  相似文献   

Cyclical Behavior of Coronal Mass Ejections     

K. J. Li  P. X. Gao  Q. X. Li  J. Mu  T. W. Su 《Solar physics》2009,257(1):149-154

With the use of coronal mass ejections (CMEs) observed by the Large Angle and Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) from January 1996 through December 2005, it is found that, for the cyclical activity of CMEs, there is surprisingly no equatorward drift at low latitudes (thus, no “butterfly diagram”) and no poleward drift at high latitudes, and no antiphase relationship between CME activity at low and high latitudes. The cyclical behaviors of CMEs differ in a significant way from that of the small-scale solar photospherical and chromospherical phenomena. Thus, our analysis leads to results that are inconsistent with a close, physical relationship with small-scale aspects of solar activity, and it is suggested that there is possibly a single so-called large-scale activity cycle in CMEs.  相似文献   

The Near-Surface Stress Profile and Conditional Averaging of Turbulence     

George Treviño  Edgar L. Andreas 《Boundary-Layer Meteorology》2009,132(3):475-481

Using the conditional average formulation, we suggest a new explanation for why the stress in the atmospheric surface layer is often observed to vary with height. In essence, because turbulence series are always correlated for small lags, the steady-state equations of motion with negligible viscous terms that traditionally require vertical fluxes to be constant with height accordingly now require the vertical fluxes to vary with height. This result has implications for interpreting and validating Monin–Obukhov similarity theory.  相似文献