Dynamics of Stream Water Quality during Snowmelt and Rainfall – Runoff Events in a Small Agricultural Catchment     

Petr Fučík  Markéta Kaplická  Tomáš Kvítek  Jana Peterková 《洁净——土壤、空气、水》2012,40(2):154-163

Surface water quality can vary a lot with fluctuating discharge during a Rainfall – runoff event. This paper uses a set of hydrological and hydrochemical variables to explain concentration–discharge loops and hysteresis of ${\rm NO}_{3}^{- } $ , ${\rm NH}_{4}^{ + } $ and total suspended solids in a brook dewatering a small upland agricultural catchment in the Czech Republic. Our study is based on data collected by a continuous monitoring approach provided by an automatic ISCO sampler both from snow thawing and rainfall – runoff events. Methods of correlation, regression and principal component analysis (PCA) were employed to reveal possible relationships among the variables. For ${\rm NO}_{3}^{- } $ and ${\rm NH}_{4}^{ + } $ , we found several types of concentration–discharge loops due to the loop rotation direction and also the loop curvature shape, in mutual combinations, no matter which type of a hydrological event it was related to. PCA indicated that ${\rm NO}_{3}^{- } $ loops correlated mostly with the length of a rising hydrograph limb and with the slope of the initial phase of a falling hydrograph limb, 5‐day amount of precipitation and runoff coefficient. In case of ${\rm NH}_{4}^{ + } $ , the concentrations usually increased with elevated discharge, whereas PCA did not detect any closer linkages. For suspended solids, an unambiguous positive monotonic relationship was discovered. Although no definite pattern was found, this study showed the necessity of a continuous water quality monitoring system as an approach for capturing and understanding relationships between solute concentrations and runoff formation for tracing and modelling catchment pollution sources and describing transport processes.  相似文献   

A radar survey of M- and X-class asteroids     

Michael K. Shepard  Beth Ellen Clark  Ellen S. Howell  Jon D. Giorgini  Steven J. Ostro  Brian Warner  Petr Pravec  Thomas Bennett  Raoul Behrend  Josep Coloma  Andrew Rivkin 《Icarus》2008,195(1):184-205

We observed ten M- and X-class main-belt asteroids with the Arecibo Observatory's S-band (12.6 cm) radar. The X-class asteroids were targeted based on their albedos or other properties which suggested they might be M-class. This work brings the total number of main-belt M-class asteroids observed with radar to 14. We find that three of these asteroids have rotation rates significantly different from what was previously reported. Based on their high radar albedo, we find that only four of the fourteen—16 Psyche, 216 Kleopatra, 758 Mancunia, and 785 Zwetana—are almost certainly metallic. 129 Antigone has a moderately high radar albedo and we suggest it may be a CH/CB/Bencubbinite parent body. Three other asteroids, 97 Klotho, 224 Oceana, and 796 Sarita have radar albedos significantly higher than the average main belt asteroid and we cannot rule out a significant metal content for them. Five of our target asteroids, 16 Psyche, 129 Antigone, 135 Hertha, 758 Mancunia, and 785 Zwetana, show variations in their radar albedo with rotation. We can rule out shape and composition in most cases, leaving variations in thickness, porosity, or surface roughness of the regolith to be the most likely causes. With the exception of 129 Antigone, we find no hydrated M-class asteroids (W-class; Rivkin, A.S., Howell, E.S., Lebofsky, L.A., Clark, B.E., Britt, D.T., 2000. Icarus 145, 351-368) to have high radar albedos.  相似文献   

On 17 – 22 January 2005 Events in Space Weather     

I. Dorotovič  K. Kudela  M. Lorenc  M. Rybanský 《Solar physics》2008,250(2):339-346

This contribution is a follow-up to the recent paper of Kuznetsov et al. (Contrib. Astron. Obs. Skalnaté Pleso 36, 85, 2006) on the ground level enhancement (GLE) on 20 January 2005. We focused on a study of Forbush decrease (FD) of 17 – 18 and 21 – 22 January 2005, respectively. The data from the neutron monitor at Lomnicky Štít (1 min counts) and from the Geomagnetic Observatory in Hurbanovo, both in Slovakia, were used as the basis for our investigation. The data on magnetic field and solar wind from GOES 10 and 12, SOHO-CELIAS, ACE and WIND satellites were used for better understanding of the global evolution of the event. The magnetic field is transformed to the RTN (Radial – Tangential – Normal) system where only the disturbed part of the field is compared, i.e., daily variations and a constant part are subtracted. The field reduction method is described. Our results are temporal vector diagrams of variation of all parameters at all positions from where we used the data. The amplitudes of |B| exceed 100 nT and variations during the arrival of the wavefront of CME take place simultaneously at the ground-based station and at GOES satellites. The character of the variations is as if there would be regions with the dominant electric charge of opposite signs, or electric currents with different orientations in the CME. On the basis of the values v _p and n _p and using certain assumptions we determined the mass of CME on 17 January and 21 January, respectively, of 10¹² kg. A decrease of the cosmic ray level runs suddenly (during 10 minutes), starting, however, about two hours after a sudden change of the magnetic field.  相似文献   

Estimation of finite seismic source parameters for selected events of the West Bohemia year 2008 seismic swarm     

Petr Kolář  Bohuslav Růžek 《Journal of Seismology》2015,19(2):403-421

  相似文献   

Estimation of parameters of finite seismic source model for selected event of West Bohemia year 2008 seismic swarm—methodology improvement and data extension     

Petr Kolář 《Journal of Seismology》2015,19(4):935-947

  相似文献   

Ground-air temperature tracking and multi-year cycles in the subsurface temperature time series at geothermal climate-change observatory     

Vladimír Čermák  Louise Bodri  Jan Šafanda  Milan Krešl  Petr Dědeček 《Studia Geophysica et Geodaetica》2014,58(3):403-424

Long-term observations of air, near-surface (soil) and ground temperatures, collected between 1994 and 2011, monitored in the Geothermal Climate Change Observatory at Spo?ilov, Prague (GCCO) are analyzed to better understand the relationship between these quantities and to describe the mechanism of heat transport at the land-atmosphere boundary layer. The 17 years long monitoring series provided a surprisingly small mean ground-air temperature offset of only 0.31 K with no clear annual course and with the offset value changing irregularly even on a daily scale. Such value is substantially lower than similar values (1–2 K and more) found elsewhere, but it may be well characteristic for a mild temperate zones, when all so far available information referred rather to more southern locations. As many other observed geophysical data, temperature time series consist of a systematic pattern (usually a set of identifiable components) contaminated by random noise, which makes the identification of the proper pattern difficult. To identify the existing systematic patterns (cycles) of the temperature-time series at several depth levels in the investigated depth interval 0–40 m, the observed data were processed with the help of the Fast Fourier Transform (FFT) and Recurrence Quantification Interval (RQI) analysis. The latter represents recently developed powerful technique to uncover hidden periodicities in a noisy time environment. At low frequency band the RQI may provide far finer resolution than the conventional FFT technique. The results proved considerable similarity for all investigated depth levels. In addition to the annual wave all measured series proved to have a more complex pattern including predominantly 8-year and 11 years long periodicities. The results were compared with similar analysis of the meteorological air temperature series as well as with the results of other similar studies. The potential dynamics explaining the occurrence of the 8-year wave is briefly discussed.  相似文献   

Analysis of uncertainties in regional climate model outputs over the Czech Republic     

Eva Holtanová  Jaroslava Kalvová  Jiří Mikšovský  Petr Pišoft  Martin Motl 《Studia Geophysica et Geodaetica》2010,54(3):513-528

In this study we present results of uncertainty analysis in eight regional climate model (RCM) outputs over the area of the Czech Republic. The RCM simulations come from the EU 5th Framework program project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects). Using the analysis of variance we have found that the main source of uncertainty in projected changes of mean seasonal air temperature is the driving global climate model. In case of precipitation changes, the RCM is the largest source of uncertainty in all seasons except for the spring. With the second method, the Reliability Averaging method, we have focused on the uncertainty coming from the RCM itself. The results of both methods showed that the relative contribution of the regional climate model to the uncertainty of simulated mean seasonal air temperature and precipitation changes is largest in summer and smallest in winter.  相似文献   

Magnetostratigraphy and fold tests from Račiška pečina and Pečina v Borštu caves (Classical Karst,Slovenia)     

Petr Pruner  Nadja Zupan Hajna  Andrej Mihevc  Pavel Bosák  Otakar Man  Petr Schnabl  Daniela Venhodová 《Studia Geophysica et Geodaetica》2010,54(1):27-48

Clastic and chemogenic cave sediments were sampled and analyzed from Račiška pečina and Pečina v Borštu caves of southwestern Slovenia. Samples were subjected to both thermal and alternating field demagnetization; specimens belonging to the same sample of the same layer produce identical results. Unblocking temperatures of 540 to 560°C on average suggests magnetite as the principal carrier of magnetization. These directions also pass a reversals test indicating the demagnetization results are free of secondary overprints and have adequately averaged out paleosecular variation. Normally magnetized clays containing fauna belonging to the MN17 mammal biozone at a depth of ∼ 4 m in Račiška pecina cave indicate these clays were deposited at the beginning of the Olduvai subchron (1.95 Ma). Correlation with the Geomagnetic Polarity Time Scale (GPTS) indicates the base of the speleothems in Račiška pečina terminate in the upper part of subchron C2An.3n with numerous breaks in deposition, lasting up to 250 ka and more. Therefore rates of speleothem growth cannot be calculated. Fold tests on dome-like stalagmites of differing sizes and ages (Pleistocene, Pliocene) from the two caves indicate the domelike structures are primary.  相似文献   

Seismic Structures in the Earth’s Inner Core Below Southeastern Asia     

Dmitry Krasnoshchekov  Petr Kaazik  Elena Kozlovskaya  Vladimir Ovtchinnikov 《Pure and Applied Geophysics》2016,173(5):1575-1591

  相似文献   

Sediment lithology and stable isotope composition of organic matter in a core from a cirque in the Krkonoše Mountains,Czech Republic     

Zbyněk Engel  Grzegorz Skrzypek  Debajyoti Paul  Wojciech Drzewicki  Daniel Nývlt 《Journal of Paleolimnology》2010,43(4):609-624

This study presents detailed lithostratigraphy and stable carbon and nitrogen isotopic variations in a 520-cm-long sediment core from a cirque basin in the Labsky důl Valley, Krkonoše Mountains, Czech Republic. Detailed study of the core reveals five major periods of sedimentation during the last 7600 years: silt and sand deposition during ~7.6–5.1 ka cal BP, Sphagnum peat accumulation during ~5.1–4.0 ka cal BP, sandy silt and sand during ~4.0–2.8 ka cal BP, raised peat bog during ~2.8–2.0 ka cal BP (Sphagnum peat), and sedimentation of sandy silt since ~2.0 ka cal BP. The δ¹³C values of the organic matter in the core vary in the range typical for C3 plants, from −24.35 to −27.68‰, whereas the δ¹⁵N values vary from −2.65 to +4.35‰. Core sections having ash contents ≥70% have δ¹⁵N > 1‰ and δ¹³C < −26‰, whereas those having ≤70% ash content have δ¹⁵N < 1‰ and δ¹³C > −26‰. Strong linear correlations are observed between δ¹³C and δ¹⁵N values as well as between C:N ratios and δ¹⁵N values in the horizons with ash content >10%, primarily for sand and silt horizons. On the other hand, poor correlations between δ¹³C and C:N ratio, as well as δ¹⁵N and C:N ratio, were observed in Sphagnum peat layers (45–125 and 185–265 cm). We conclude that the primary stable isotope variations are not preserved in the layers where significant correlation between δ¹⁵N and C:N ratio is observed. The relatively small δ¹³C variation in the uppermost Sphagnum peat layer suggests stable temperature during ~2.8–2.0 ka cal BP.  相似文献