Seasonal changes in the daily emission rates of terpenes by Quercus ilex and the atmospheric concentrations of terpenes in the natural park of Montseny, NE Spain     

Joan Llusia  Josep Pe?uelas  Roger Seco  Iolanda Filella 《Journal of Atmospheric Chemistry》2012,69(3):215-230

We studied the daily patterns in the rates of terpene emissions by the montane holm oak, Quercus ilex, in three typical days of winter and three typical days of summer in Montseny, a natural park near Barcelona, and related them to the air concentrations of terpenes, ozone and NO₂. Terpene emission rates were about 10 times higher in summer than in winter. Emissions virtually stopped in the dark. In both seasons, rates of terpene emissions were well correlated with light, air temperature and relative humidity. Rates of emissions were also correlated with stomatal conductance and the rates of transpiration and photosynthesis. Almost all the individual terpenes identified followed the same pattern as total terpenes. The most abundant terpene was ??-pinene, followed by sabinene + ??-pinene, limonene, myrcene, camphene and ??-phellandrene. Atmospheric terpene concentrations were also about 10 times higher in summer than in winter. A significant diurnal pattern with maxima at midday was observed, especially in summer. The increase by one order of magnitude in the concentrations of these volatile isoprenoids highlights the importance of local biogenic summer emissions in these Mediterranean forested areas which also receive polluted air masses from nearby or distant anthropic sources. Atmospheric concentrations of O₃ and NO₂ were also significantly higher in summer and at midday hours. In both seasons, concentrations of O₃ were significantly correlated with concentrations of terpenes and NO₂ in the air and with rates of terpene emission.  相似文献   

A simultaneous X-ray and optical study of TT Arietis     

R. Hudec  B. Valnícek  R. Peřesty  W. Wenzel  G. A. Richter  W. Goetz  G. Hacke  H. Hutch  R. Schult  W. Pfau  G. -H. Reimann  B. Stecklum  J. Tremko  A. Mrkos  I. V. Schpitshka  V. P. Kojevnikov  M. I. Kumshiashvili  G. Oprescu  A. Dumitrescu  C. Cristescu  W. Bojack  L. Patkós  I. Toth  K. Olah 《Astrophysics and Space Science》1987,130(1-2):255-260

Prelimary results of an extended program of coordinated X-ray and optical observations of TT Ari are presented. The object was observed on August 21/22 1985 both in X-rays (EXOSAT) and optical range, about 100 days after the return to the active state. The first detailed simultaneous study of TT Ari in active state indicates the presence of strongly absorbing structure in the system.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.  相似文献   

Recent observations of the WR central star of the planetary nebula LMC-N66     

Miriam Peña  Manuel Peimbert  Silvia Torres-Peimbert  Maria Teresa Ruiz  Jose Maza 《Astrophysics and Space Science》1996,238(1):55-58

The recent evolution of the central star of the planetary nebula LMC-N66 is presented. Before 1987, it showed a weak continuum with aT _eff120 000 K andL _bol25 000L and in a few years it developed strong WR features (P Cygni line profiles in N v at 124.0 nm and C IV at 155.0 nm, wide Heii emission, etc.) typical of a WN 4.5. Additionally the stellar continuum increased by a large factor and the absolute visual magnitude of the star changed from + 1.24 in 1987 to–2.57 in January, 1995. The WR features and enhanced continuum, evidencing a powerful mass-loss event remained with small variations for more than 5 years. Recent ultraviolet and optical data shows that the mass-loss seems to have diminished abruptly in the last three months.  相似文献   

塔里木盆地奥陶系生物礁露头的地球物理特征   总被引：8，自引：0，他引：8  

罗平  张兴阳  顾家裕  汪圣国  林鹏 《沉积学报》2003,21(3):423-427

奥陶系生物礁为塔里木盆地重要的储集层,明确露头上生物礁的内部结构及发育规模,探索露头和井下生物礁对比研究的新手段有重要意义。应用探地雷达及自然伽马能谱仪对塔里木盆地巴楚达吾孜塔格奥陶系露头进行了探测。研究表明,探地雷达剖面上多数生物礁为扁平透镜状或层状,这与露头上观察的结果有所差别;高分辨率雷达剖面揭示出较出露生物礁发育程度更大、个体更小的疙瘩状礁体或礁团块;礁体内部的分层性及礁体内部水道充填体的斜层理在雷达剖面上反映明显,雷达分辨率可达到分米级别。礁灰岩的自然伽马值高于亮晶砂、砾屑灰岩,而低于泥晶灰岩、棘屑灰岩、泥晶生屑灰岩、泥灰岩的放射性。生物礁在自然伽马曲线上表现为漏斗形、钟形或箱形;自然伽马曲线也反映出礁体内部的分层性。露头和轮南井下奥陶系生物礁的自然伽马放射性特征有一定的相似性,这为露头和井下生物礁的对比研究提供了有力的辅助手段.  相似文献   

Induction vector estimates in the Polish-Czechoslovak part of the Carpathians     

Jerzy Jankowski  Václav Petr  Jana Pečová  Oldřich Praus  Reviewer A. Janáčková 《Studia Geophysica et Geodaetica》1979,23(1):89-93

u¶rt;um ¶rt;a ma ua m u¶rt;uu n mam amu n aum auau ¶rt;a a n -a am anam.  相似文献   

A new potassium-iron-nickel sulphide from a nodule in kimberlite     

D.B. Clarke  G.G. Pe  R.M. Mackay  K.R. Gill  M.J. O&#x;Hara  J.A. Gard 《Earth and Planetary Science Letters》1977,35(3):421-428

A new K-rich sulphide phase is described from a clinopyroxene-ilmenite intergrowth from the Frank Smith kimberlite diatremes. The mineral occurs as ovoid blebs, which also contain pyrrhotite and pentlandite, in close spatial association with the ilmenite lamellae, and as individual grains in cracks in the clinopyroxene host. Chemical analyses from twelve grains show the following ranges of composition (wt.%): K, 8.12–13.01; Cu, 1.24–2.99; Fe, 38.47–41.76; Ni, 11.65–15.04; S, 32.09–34.34. Electron diffraction data indicate a primitive cubic unit cell,a = 10.29 ± 0.03Å, with no systematically absent reflections. Three models for the origin of this sulphide, liquid immiscibility, multiple exsolution, and metasomatism, are considered. The discovery of potassic sulphide in a kimberlite nodule has important implications, not only as a potential source of K in the upper mantle, but also for those models which propose removal of K and S from the lower mantle into the core.  相似文献   

Relating Hyperspectral Airborne Data to Ground Measurements in a Complex and Discontinuous Canopy     

Javier F. Calleja  Christine Hellmann  Gorka Mendiguren  Suvarna Punalekar  Juanjo Peón  Alasdair MacArthur  Luis Alonso 《Acta Geophysica》2015,63(6):1499-1515

The work described in this paper is aimed at validating hyperspectral airborne reflectance data collected during the Regional Experiments For Land-atmosphere EXchanges (REFLEX) campaign. Ground reflectance data measured in a vineyard were compared with airborne reflectance data. A sampling strategy and subsequent ground data processing had to be devised so as to capture a representative spectral sample of this complex crop. A linear model between airborne and ground data was tried and statistically tested. Results reveal a sound correspondence between ground and airborne reflectance data (R2 > 0.97), validating the atmospheric correction of the latter.  相似文献   

First Results of DSD Measurement by Videodistrometer in the Czech Republic in 1998-1999     

Fišer  Ondřej  Schönhuber  Michael  Pešice  Petr 《Studia Geophysica et Geodaetica》2002,46(3):485-505

The first results of the almost one year drop size distribution (DSD) measurement in the Czech Republic are summarised in this study. The ESA-ESTEC 2D videodistrometer was used to measure the rain drop parameters. The average DSD is shown to be of the gamma type. One minute DSDs were evaluated to test the accuracy of analytical DSD models. Parameters of gamma distribution and exponential distribution functions were evaluated for the whole data set as well as for the various rain rate intervals. Regression technique and the method of moments were applied to estimate the parameters of DSD. It is shown that the parameter value strongly depends on the method of computation as well as on the rain type. Its average value is about 0.59 for the average (smooth) one minute DSD while an average value of un-smoothed DSD is 11.0 (moment method) or 5.4 (regression technique). The Joss's shape parameter and the Tokay-Short's parameter CS estimating roughly the rain type are also discussed (if CS>1, the event should be convective). The tendency of increasing numerical value of the CS parameter with the increasing rain rate was observed (the DSDs were distributed into classes respecting the rain rate value) and thus the idea of the convectivity occurrence bounded with the higher CS parameter value was supported. The study also compares the parameters of the average DSD with the averages of parameter values of all 4 183 one minute DSDs.  相似文献   

Analysis of the mobilization of solid loads and heavy metals in runoff waters from granite quarries     

Enrique Peña González  Joaquín Suárez López  Jordi Delgado Martín  Alfredo Jácome Burgos  Jerónimo Puertas Agudo 《Environmental Geology》2006,50(6):823-834

The cutting operations of dimension stone at quarries produce a large amount of fines that, in turn, cause a negative environmental impact over local surface waters. This article presents a detailed analysis of the mobilized contamination associated with runoff waters in a large granite quarry (～200 ha) which is located in Porriño (Galicia, NW Spain), the most important production centre of dimension stone in Spain. There, an intensive monitoring survey was developed in order to characterize the hydrology of the system as well as the release and transport of pollutants. This was accomplished by means of different control sections for the flow and by the collection of 52 random water samples. Automatic samplers were also used to collect 192 water samples associated with runoff generated by significant rain events. For each of the samples collected, a wide battery of analytic determinations was performed, including solid loads, turbidity, organic pollution, nutrient and selected metals. Upon careful examination it has been possible to obtain different parameters related to the contamination control, like the “event mean concentration” (EMC), maximum concentrations and specific sediment loads. Moreover, a comprehensive statistical study including parameter correlation and cumulative probability analyses helped to understand the pollutant mobilization behaviour within the quarry system. It can be concluded that mobilized contamination shows the anomalous presence of some metals, whose concentrations are in excess when compared to the natural rock. This excess metal amount must be attributed to an anthropogenic source associated to mining and cutting operations.  相似文献   

Extra-tropical atmospheric response to ENSO in the CMIP5 models     

Margaret M. Hurwitz  Natalia Calvo  Chaim I. Garfinkel  Amy H. Butler  Sarah Ineson  Chiara Cagnazzo  Elisa Manzini  Cristina Peña-Ortiz 《Climate Dynamics》2014,43(12):3367-3376

The seasonal mean extra-tropical atmospheric response to El Niño/Southern Oscillation (ENSO) is assessed in the historical and pre-industrial control CMIP5 simulations. This analysis considers two types of El Niño events, characterized by positive sea surface temperature (SST) anomalies in either the central equatorial Pacific (CP) or eastern equatorial Pacific (EP), as well as EP and CP La Niña events, characterized by negative SST anomalies in the same two regions. Seasonal mean geopotential height anomalies in key regions typify the magnitude and structure of the disruption of the Walker circulation cell in the tropical Pacific, upper tropospheric ENSO teleconnections and the polar stratospheric response. In the CMIP5 ensembles, the magnitude of the Walker cell disruption is correlated with the strength of the mid-latitude responses in the upper troposphere i.e., the North Pacific and South Pacific lows strengthen during El Niño events. The simulated responses to El Niño and La Niña have opposite sign. The seasonal mean extra-tropical, upper tropospheric responses to EP and CP events are indistinguishable. The ENSO responses in the MERRA reanalysis lie within the model scatter of the historical simulations. Similar responses are simulated in the pre-industrial and historical CMIP5 simulations. Overall, there is a weak correlation between the strength of the tropical response to ENSO and the strength of the polar stratospheric response. ENSO-related polar stratospheric variability is best simulated in the “high-top” subset of models with a well-resolved stratosphere.  相似文献