Time-series of δ26Mg values in a headwater catchment reveal decreasing magnesium isotope variability from precipitation to runoff     

Martin Novak  Alexandre Andronikov  Pavel Kram  Jan Curik  Frantisek Veselovsky  Marketa Stepanova  Eva Prechova  Ondrej Sebek  Leona Bohdalkova 《水文研究》2021,35(4):e14116

Data on temporal variability in Mg isotope ratios of atmospheric deposition and runoff are critical for decreasing the uncertainty associated with construction of isotope mass balances in headwater catchments, and statistical evaluation of isotope differences among Mg pools and fluxes. Such evaluations, in turn, are needed to distinguish between biotic and abiotic contributions to Mg²⁺ in catchment runoff. We report the first annual time-series of δ²⁶Mg values simultaneously determined for rainfall, canopy throughfall, soil water and runoff. The studied 55-ha catchment, situated in western Czech Republic, is underlain by Mg-rich amphibolite and covered by mature spruce stands. Between 1970 and 1996, the site received extremely high amounts of acid deposition and fly ash form nearby coal-burning power plants. The δ²⁶Mg values of open-area precipitation (median of −0.79‰) at our study site were statistically indistinguishable from the δ²⁶Mg values of throughfall (−0.73‰), but significantly different from the δ²⁶Mg values of soil water (−0.55‰) and runoff (−0.55‰). The range of δ²⁶Mg values during the observation period decreased in the order: open-area precipitation (0.57‰) > throughfall (0.27‰) > runoff (0.21‰) > soil water (0.16‰). The decreasing variability in δ²⁶Mg values of Mg²⁺ from precipitation to soil water and runoff reflected an increasing homogenization of atmospheric Mg in the catchment and its mixing with geogenic Mg. In addition to atmospheric Mg, runoff also contained Mg mobilized from the three major solid Mg pools, bedrock (δ²⁶Mg of −0.32‰), soil (−0.28‰), and vegetation (−0.31‰). The drought of summer 2019 did not affect the nearly constant δ²⁶Mg value of runoff. Collectively, our data show that within-catchment processes buffer the Mg isotope variability of the atmospheric input.  相似文献   

U‐Pb zircon dating of metaigneous rocks from the Nordbreen Nappe of Svalbard’s Ny‐Friesland suggests their affinity to Northeast Greenland     

Jakub Bazarnik  Jaros&#x;aw Majka  William C. McClelland  Justin V. Strauss  Karolina Komi&#x;ska  Karsten Piepjohn  Synnve Elvevold  Zbigniew Czupyt  Tom&#x; Miku&#x; 《地学学报》2019,31(6):518-526

SIMS U‐Pb zircon dating of metaigneous rocks of the Nordbreen Nappe from the West Ny‐Friesland terrane (Eastern Basement Province of Svalbard) yields crystallization ages of 1,761 ± 4 Ma for a felsic metatuff and 1,373 ± 4 Ma for a metagabbro dyke. The Palaeoproterozoic age of the metatuff is similar to previously obtained ages for various felsic rocks from the study area, whereas the Mesoproterozoic age of the metagabbro has not been thus far documented on Svalbard. However, a similar age pattern has been reported from Northeast Greenland. Therefore, we conclude that the West Ny‐Friesland terrane can be correlated with age equivalent units of Northeast Greenland. We also explore similarities and dissimilarities between the study area and other terranes of Svalbard and speculate on regional‐scale correlations. Together, the presented new ages provide critical piercing points in palaeogeographic reconstructions of the relatively poorly understood circum‐Arctic region.  相似文献   

Potentially Bioavailable Natural Organic Carbon and Hydrolyzable Amino Acids in Aquifer Sediments     

Lashun K. Thomas  Mark A. Widdowson  John T. Novak  Francis H. Chapelle  Ronald Benner  Karl Kaiser 《Ground Water Monitoring & Remediation》2012,32(4):92-95

This study evaluated the relationship between concentrations of operationally defined potentially bioavailable organic ‐carbon (PBOC) and hydrolyzable amino acids (HAAs) in sediments collected from a diverse range of chloroethene‐‐contaminated sites. Concentrations of PBOC and HAA were measured using aquifer sediment samples collected at six selected study sites. Average concentrations of total HAA and PBOC ranged from 1.96 ± 1.53 to 20.1 ± 25.6 mg/kg and 4.72 ± 0.72 to 443 ± 65.4 mg/kg, respectively. Results demonstrated a statistically significant positive relationship between concentrations of PBOC and total HAA present in the aquifer sediment (p < 0.05). Higher levels of HAA were consistently observed at sites with greater levels of PBOC and first‐order decay rates. Because amino acids are known to be readily biodegradable carbon compounds, this relationship suggests that the sequential chemical extraction procedure used to measure PBOC is a useful indicator of bioavailable carbon in aquifer sediments. This, in turn, is consistent with the interpretation that PBOC measurements can be used for estimating the amount of natural organic carbon available for driving the reductive dechlorination of chloroethenes in groundwater systems.  相似文献   

Floods at the northern foothills of the Tatra Mountains — A Polish-Swiss research project   总被引：1，自引：1，他引：0  

Zbigniew W. Kundzewicz  Markus Stoffel  Ryszard J. Kaczka  Bartłomiej Wyżga  Tadeusz Niedźwiedź  Iwona Pińskwar  Virginia Ruiz-Villanueva  Ewa Łupikasza  Barbara Czajka  Juan Antonio Ballesteros-Canovas  Łukasz Małarzewski  Adam Choryński  Karolina Janecka  Paweł Mikuś 《Acta Geophysica》2014,62(3):620-641

The present paper introduces the topical area of the Polish-Swiss research project FLORIST (Flood risk on the northern foothills of the Tatra Mountains), informs on its objectives, and reports on initial results. The Tatra Mountains are the area of the highest precipitation in Poland and largely contribute to flood generation. The project is focused around four competence clusters: observation-based climatology, model-based climate change projections and impact assessment, dendrogeomorphology, and impact of large wood debris on fluvial processes. The knowledge generated in the FLORIST project is likely to have impact on understanding and interpretation of flood risk on the northern foothills of the Tatra Mountains, in the past, present, and future. It can help solving important practical problems related to flood risk reduction strategies and flood preparedness.  相似文献   

Investigation of the 16-year and 18-year ZTD Time Series Derived from GPS Data Processing     

Zofia Bałdysz  Grzegorz Nykiel  Mariusz Figurski  Karolina Szafranek  Krzysztof KroszczyńSki 《Acta Geophysica》2015,63(4):1103-1125

The GPS system can play an important role in activities related to the monitoring of climate. Long time series, coherent strategy, and very high quality of tropospheric parameter Zenith Tropospheric Delay (ZTD) estimated on the basis of GPS data analysis allows to investigate its usefulness for climate research as a direct GPS product. This paper presents results of analysis of 16-year time series derived from EUREF Permanent Network (EPN) reprocessing performed by the Military University of Technology. For 58 stations Lomb-Scargle periodograms were performed in order to obtain information about the oscillations in ZTD time series. Seasonal components and linear trend were estimated using Least Square Estimation (LSE) and Mann—Kendall trend test was used to confirm the presence of a linear trend designated by LSE method. In order to verify the impact of the length of time series on trend value, comparison between 16 and 18 years were performed.  相似文献   

Response of pile foundations to rayleigh waves and obliquely incident body waves     

Amir M. Kaynia  Milos Novak 《地震工程与结构动力学》1992,21(4):303-318

The paper presents results of a study on the harmonic response of piles and pile groups embedded in a halfspace to various forms of seismic waves. These include the Rayleigh wave as well as obliquely incident P, SV and SH waves. The pertinent mixed boundary value problems of pile-soil-pile interaction are solved by a numerical model of the boundary integral nature. All modes of foundation vibrations, i.e. translational, rocking and torsional, are included in the model. The results presented are used to highlight the salient features of the seismic response of piles. In addition, the influence of certain pile-soil parameters, such as pile rigidity and pile spacing, on the seismic behaviour of pile foundations is investigated.  相似文献   

Soil-pile interaction in horizontal vibration     

M. Novak  T. Nogami 《地震工程与结构动力学》1977,5(3):263-281

Interaction between soil and an elastic pile vibrating horizontally is theoretically examined. The soil is modelled as a linear, viscoelastic layer overlying rigid bedrock. The pile is assumed to be vertical and point bearing. This study utilizes the definition of soil resistance presented in a preceding paper.¹ A direct solution is developed which yields closed form formulas for pile displacement, stiffness and damping. A parametric study clarifies the role of the parameters involved, illustrates the interaction between the soil and the pile and shows the stiffness and damping properties of the soil-pile system for typical values of the governing parameters.  相似文献   

Additional note on the effect of soil on structural response     

Milos Novak 《地震工程与结构动力学》1974,3(3):312-315

The previous paper on this subject, Reference 1, is complemented here to include one additional effect of soil on structural response. This effect is the modification of the original structural damping, estimated under the assumption of rigid foundation, due to foundation flexibility. This can be of practical importance, particularly with heavily damped structures vibrating in the fundamental mode. With lightly damped structures, such as those assumed in Reference 1, this effect diminishes.  相似文献   

Buchbesprechungen     

Peter Perret  P. Bossard  B. M. Novak dipl. Ing. 《Aquatic Sciences - Research Across Boundaries》1974,36(1):201-204

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Torsional and coupled vibrations of embedded footings     

M. Novak  K. Sachs 《地震工程与结构动力学》1973,2(1):11-33

An approximate analytical solution is presented for torsional vibrations of footings partially embedded into a semi-infinite medium or a stratum. Simple formulas derived for pure torsional motion make it possible to apply a correction for the effect of embedment to the known solutions of surface footings. The solution completes an approach to the analysis of all modes of footing vibrations, including the coupled modes. The approach to coupled modes is illustrated by the solution of coupled response involving horizontal translation, rocking and torsion. Formulas are presented for stiffness and damping coefficients that can be used in the analysis of embedded footings or structures supported by such footings Field experiments were conducted with concrete footings featuring circular, square and rectangular bases and variable embedment depths. The experimental results were compared with theoretical predictions of pure torsional vibrations.  相似文献