Throughfall enrichment and stream nutrient chemistry in small headwater catchments with different land cover in southern Chile          下载免费PDF全文

Pedro Hervé‐Fernandez  Carlos E. Oyarzún  Stefan Woelfl 《水文研究》2016,30(26):4944-4955

Land cover changes have a great impact on nitrogen (N) and phosphorous (P) fluxes catchments. In this study, we wanted to compare different land covers: deciduous (D), evergreen (E) (both native forests), and exotic Eucalyptus globulus plantation (EP), affected precipitation, and stream discharge on N and P species concentrations and fluxes, under a low deposition climate in south‐central Chile. For this, we collected bulk precipitation, throughfall, and stream water samples after 41 rainfall events in E and EP, during the period June 2009–March 2011, and 31 rainfall events in D, during the period October 2009–March 2011. The highest canopy enrichment of N and P species for throughfall was observed in deciduous forest, while E. globulus showed the minimum enrichment. Total nitrogen (total‐N) discharge in EP was about 8.6 times higher than that of E and D catchments. Total‐N annual retention was positive only in E and D catchments. However, EP catchment showed a net loss (?4.79 kg N ha/year). The biggest difference was observed in nitrate stream concentrations, which showed low values for E (3.4 ± 1.3 μg/L), while EP and D showed higher nitrate concentrations (84.9 ± 16.7 and 134.7 ± 36.7 μg/L, for EP and D, respectively). Total phosphorous (total‐P) discharge flux was low in EP (0.4 kg P ha/year), and negligible in E and D forests (<0.1 kg P ha/year). Total‐P annual retention was near to 1.0 kg N ha/year (on E and D), while a net loss (?1.5 kg N ha/year) was observed for EP. We attribute the observed differences in nutrient throughfall enrichment due to high multi‐stratified canopies in the native forests. Both deciduous and evergreen native forest‐covered catchments showed the highest retention of total‐N and total‐P, in contrast to Eucalyptus‐covered plantation.  相似文献   

Effects of the inclusion of bending-to-stretching transitions in the non-LTE modeling of ozone vibrational temperatures     

Rafael P. Fernandez  Martin Kaufmann  Beatriz M. Toselli 《Journal of Atmospheric and Solar》2010,72(11-12):890-899

  相似文献   

Composition,pre-eruptive zonation,and geochronologic significance of the ∼450 ka Diamante Tuff,Andean Cordillera (34°S), Argentina     

Scott A. Hynek  David W. Marchetti  Diego P. Fernandez  Thure E. Cerling 《Quaternary Geochronology》2010,5(5):591-601

Vertical geochemical sampling through the Diamante Tuff establishes patterns of zonation in the pre-eruption magma. Volcanic glass demonstrates a roofward increase in Fe and Cl, and a roofward decrease in Ca. Trace elements have no measurable zonation. Welded volcanic glass shows post-eruption loss of Fe, Mg and Cl as well as K gain. Our reported glass chemistry provides robust criteria for correlation to other localities. The Diamante Tuff is an important stratigraphic marker and recognition of this unit provides age control on Quaternary deposits, allowing determination of process rates and elucidating timing of tectonic and geomorphic activity.  相似文献   

Assessing aeolian beach‐surface dynamics using a remote sensing approach     

Irene Delgado‐Fernandez  Robin Davidson‐Arnott  Bernard O. Bauer  Ian J. Walker  Jeff Ollerhead  Hosahng Rhew 《地球表面变化过程与地形》2012,37(15):1651-1660

A remote sensing technique for assessing beach surface moisture was used to provide insight into beach‐surface evolution during an aeolian event. An experiment was carried out on 21 October 2007 at Greenwich Dunes, Prince Edward Island National Park, Canada, during which cameras were mounted on a mast on the foredune crest at a height of about 14 m above the beach. Maps of beach surface moisture were created based on a calibrated relationship between surface brightness from the photographs and surface moisture content measured in situ at points spaced every 2.5 m along a transect using a Delta‐T moisture probe. A time sequence of maps of surface moisture content captured beach surface evolution through the transport event at a spatial and temporal resolution that would be difficult to achieve with other sampling techniques such as impedance probes. Erosion of the foreshore and berm crest resulted in an increase in surface moisture content in these areas as the wetter underlying sediments were exposed. Flow expansion downwind of the berm crest led to sand deposition and a consequent decrease in surface moisture content. Remote sensing systems such as the one presented here allow observations of the combined evolution of beach surface moisture, shoreline position, and fetch distances during short‐term experiments and hence provide a comprehensive rendering of sediment erosion and transport processes. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Mass-to-light ratio of Lyα emitters: implications of Lyα surveys at redshifts z= 5.7, 6.5, 7 and 8.8     

Elizabeth R. Fernandez  Eiichiro Komatsu 《Monthly notices of the Royal Astronomical Society》2008,384(4):1363-1376

  相似文献   

Binarity and multiperiodicity in high-amplitude δ Scuti stars     

A. Derekas  L. L. Kiss  T. R. Bedding  M. C. B. Ashley  B. Csák  A. Danos  J. M. Fernandez  G. F&#;rész  Sz. Mészáros  Gy. M. Szabó  R. Szakáts  P. Székely  K. Szatmáry 《Monthly notices of the Royal Astronomical Society》2009,394(2):995-1008

We have carried out a photometric and spectroscopic survey of bright high-amplitude δ Scuti (HADS) stars. The aim was to detect binarity and multiperiodicity (or both) in order to explore the possibility of combining binary star astrophysics with stellar oscillations. Here, we present the first results for 10, predominantly southern, HADS variables. We detected the orbital motion of RS Gru with a semi-amplitude of ∼6.5 km s⁻¹ and 11.5 d period. The companion is inferred to be a low-mass dwarf star in a close orbit around RS Gru. We found multiperiodicity in RY Lep from both photometric and radial velocity data and detected orbital motion in the radial velocities with hints of a possible period of 500–700 d. The data also revealed that the amplitude of the secondary frequency is variable on the time-scale of a few years, whereas the dominant mode is stable. Radial velocities of AD CMi revealed cycle-to-cycle variations, which might be due to non-radial pulsations. We confirmed the multiperiodic nature of BQ Ind, while we obtained the first radial velocity curves of ZZ Mic and BE Lyn. The radial velocity curve and the O–C diagram of CY Aqr are consistent with the long-period binary hypothesis. We took new time series photometry on XX Cyg, DY Her and DY Peg, with which we updated their O–C diagrams.  相似文献   

Low Perihelion Near-Earth Asteroids     

Humberto Campins  Michael S. Kelley  Yanga Fernández  Javier Licandro  Kelsey Hargrove 《Earth, Moon, and Planets》2009,105(2-4):159-165

We present initial results from a study of a sample of low-perihelion near-Earth asteroids (NEAs) using the Infrared Spectrograph (IRS) on NASA’s Spitzer Space Telescope. The 7–14 μm thermal emission spectra have been fitted with models of the thermal continuum to derive the asteroid’s effective diameter, geometric albedo and beaming parameter η. In this work, we concentrate on the thermal behavior and we find a trend of increasing η (lower thermal fluxes and cooler color temperatures) with increasing solar phase angle. The slope of this trend is somewhat different from that reported for other NEAs (e.g., Delbó 2004); if confirmed, this result would indicate that the thermal behavior of low-perihelion asteroids is different from that of other members of the NEA population. In addition, deviations of the observed continuum from the thermal model, which can be diagnostic of composition, are apparent in a few of our targets. A complete characterization of these intrinsically faint objects will benefit from the large ground based facilities described elsewhere in these proceedings.  相似文献   

Geological and Geochemical Characteristics of the Intrusion‐Related Vein‐Type Gold Deposits in the El Morado District,Coastal Cordillera,Northern Chile          下载免费PDF全文

Shoji Kojima  Iván Soto  Milenka Quiroz  Paulina Valencia  Iván Fernandez 《Resource Geology》2017,67(2):197-206

  相似文献   

Trace elements in high-S subbituminous coals from the teruel Mining District, northeast Spain     

X. Querol  J.L. Fernandez Turiel  A. Lopez Soler  M.E. Duran 《Applied Geochemistry》1992,7(6)

The elemental composition of high temperature ash (750°C) and forms of S were studied in 25 coal seams from the Escucha Formation (Middle Albian) in the Teruel Mining District, northeast Spain. The principal analytical method was ICP-MS, but ICP-ES was also used in the determination of some trace elements. The analytical data show wide ranges of trace element cotnents among the coal seams studied, even in the vertical profile of a single coal seam. These wide ranges of the trace element concentrations are attributed to both syngenetic and epigenetic processes.When a comparison was made between the average trace element contents of the Teruel Mining District coals, and those of the average content in worldwide coals, the Teruel coals show slightly higher concentrations of Be and U, and lower concentrations of Ba, Cd, Mn, Pb, Sr and Zr. Further, three main groups of trace elements were differentiated on the basis of the inorganic/organic association: (1) trace elements with inorganic affinity; Ba, Ce, Co, Cr, La, Mn, Ni, Rb and Zr. Between these, Ba, Ce, Cr and Rb show a well defined correlation with the clay mineral content, and Co and Ni with pyritic-S content; (2) trace elements with an intermediate (mixed) affinity; As, Cd, Cu, Dy, Er, Eu, Gd, Ge, Ho, Lu, Mo, Nd, Pb, Pr, Sb, Sm, Sr, Tb, Th, Tm, U, Yb and Zn. In this group, As, Cd, Cu, Ge, Mo, Th, U and Zn show a weak trend associated with the mineral matter and Sr with the organic matter; and (3) Be shows an organic affinity. The high mineral matter content (21.3% HTA) of the Teruel coals may account for the great number of elements with inorganic affinity. This classification represents a general trend, but the results show that the affinities of some trace elements (e.g. As, Sb and Zn) may vary from one coal seam to another in the Teruel Mining District.  相似文献   

The Western Mediterranean extensional basins and the Alpine orogen   总被引：1，自引：0，他引：1  

Carlo Doglioni  Erwan Gueguen  Francesc Sàbat  & Manuel Fernandez 《地学学报》1997,9(3):109-112

The western Mediterranean late Oligocene–Miocene basins (Alboran, Valencia and Provençal basins) are a coherent system of interrelated troughs. In all basins normal faults and thermal subsidence migrated toward the east progressively moving to the Miocene-to-Pleistocene Algerian and Tyrrhenian basins. All those troughs appear elements of the back-arc opening related to the eastward roll-back of the W-directed Apennines–Maghrebides subduction zone, similarly to western Pacific back-arc settings.
These late Oligocene–early Miocene basins nucleated both within the Betic cordillera (e.g. Alboran sea) and in its foreland (Valencia and Provençal troughs). The N40–70° direction of grabens is oblique to the coexisting N60–80°-trending orogen and shows its structural independence from the orogenic roots. Thus, as the extension cross-cuts the orogen and developed also well outside the thrust belt front, the westernmost basins of the Mediterranean had to develop independently from the Alps-Betics orogen. Therefore, the Alboran extension, considered a classic example of a basin generated by the collapse of an orogen, cannot be ascribed to the detachment or annihilation of the lithospheric root. In contrast with the eastward migrating extensional basins, the Betic-Balearic thrust front was migrating westward producing interference or inversion structures.  相似文献