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11.
Xuechao Wu Qingzhen Hao B Marković Slobodan Yu Fu Namira Yang Song Zhengtang Guo 《地球科学进展》2020,35(4):363-377
Danube loess, located at the westernmost part of the widespread Eurasian loess belt, is one of the most well-preserved aeolian dust deposits in Europe with the basal age dating back over 1 Ma. Owing to its unique location and formation processes, Danube loess plays an important role in understanding the linkage of climate changes in different climate regimes over Eurasian continent and paleoclimatic changes in middle-high northern latitudes. Major research advances of the Danube loess, including compositions, provenance, chronology, stratigraphy and paleoenvironment changes were systematically reviewed and the focuses of future research were suggested. To better understand loess provenance, the compositions of sediments in all the potential source areas should be investigated, and methodological study of provenance indicators and application of multi-proxies approaches need to be carried out. Chronologically and stratigraphically, feldspar luminescence dating and tephrochronology methods should be widely used, and the establishment of a uniform stratigraphic framework and correlation scheme should be constrained by precise chronology. In terms of the paleoenvironment, it is necessary to conduct high-resolution multi-proxies reconstruction of paleoenviroment for the entire loess-paleosol sequence, extending from the last interglacial period (130 ka to present) to interval of last 1 Ma. The future progress in Danube loess is crucial to improving the study of continental paleoclimate comparison and paleoclimate dynamics over the Eurasian loess region. 相似文献
12.
Assessment on variability of extreme climate events for the Upper Thames River basin in Canada 总被引：1，自引：0，他引：1
Climate change may affect magnitude and frequency of regional extreme events with possibility of serious impacts on the existing infrastructure systems. This study investigates how the current spatial and temporal variations of extreme events are affected by climate change in the Upper Thames River basin, Ontario, Canada. A weather generator model is implemented to obtain daily time series of three climate variables for two future climate scenarios. The daily time series are disaggregated into hourly to capture characteristics of intense and rapidly changing storms. The maximum annual precipitation events for five short durations, 6‐, 12‐, 24‐, 48‐, and 72‐h durations, at each station are extracted from the generated hourly data. The frequency and seasonality analyses are conducted to investigate the temporal and spatial variability of extreme precipitation events corresponding to each duration. In addition, this study investigates the impacts of increase in temperature using reliability, resilience, and vulnerability. The results indicate that the extreme precipitation events under climate change will occur earlier than in the past. In addition, episodes of extremely high temperature may last longer up to 19·7% than under the no‐change climate scenario. This study points out that the revision of the design storms (e.g. 100‐ or 250‐year return period) is warranted for the west and the south east region of the basin. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
13.
Michael Zech Nikolai Pedentchouk Katharina Leiber Slobodan B. Markovi? 《Geochimica et cosmochimica acta》2011,75(17):4917-4928
During the last decade, compound-specific hydrogen isotope analysis of plant leaf-wax and sedimentary n-alkyl lipids has become a promising tool for paleohydrological reconstructions. However, with the exception of several previous studies, there is a lack of knowledge regarding possible effects of early diagenesis on the δD values of n-alkanes. We therefore investigated the n-alkane patterns and δD values of long-chain n-alkanes from three different C3 higher plant species (Acer pseudoplatanus L., Fagus sylvatica L. and Sorbus aucuparia L.) that have been degraded in a field leaf litterbag experiment for 27 months.We found that after an initial increase of long-chain n-alkane masses (up to ∼50%), decomposition took place with mean turnover times of 11.7 months. Intermittently, the masses of mid-chain n-alkanes increased significantly during periods of highest total mass losses. Furthermore, initially high odd-over-even predominances (OEP) declined and long-chain n-alkane ratios like n-C31/C27 and n-C31/C29 started to converge to the value of 1. While bulk leaf litter became systematically D-enriched especially during summer seasons (by ∼8‰ on average over 27 months), the δD values of long-chain n-alkanes reveal no systematic overall shifts, but seasonal variations of up to 25‰ (Fagus, n-C27, average ∼13‰).Although a partly contribution by leaf-wax n-alkanes by throughfall cannot be excluded, these findings suggest that a microbial n-alkane pool sensitive to seasonal variations of soil water δD rapidly builds up. We propose a conceptual model based on an isotope mass balance calculation that accounts for the decomposition of plant-derived n-alkanes and the build-up of microbial n-alkanes. Model results are in good agreement with measured n-alkane δD results. Since microbial ‘contamination’ is not necessarily discernible from n-alkane concentration patterns alone, care may have to be taken not to over-interpret δD values of sedimentary n-alkanes. Furthermore, since leaf-water is generally D-enriched compared to soil and lake waters, soil and water microbial n-alkane pools may help explain why soil and sediment n-alkanes are D-depleted compared to leaves. 相似文献
14.
Slobodan B. Marković Eric A. Oches Zoran M. Perić Tivadar Gaudenyi Mlađen Jovanović Györgi Sipos Christine Thiel Jan-Pieter Buylaert Stevan Savić William D. McCoy Milica G. Radaković Rastko S. Marković Milivoj B. Gavrilov 《第四纪科学杂志》2021,36(8):1436-1447
The loess sequence preserved in the Požarevac brickyard in north-eastern Serbia comprises eight loess units separated by seven paleosols. Geochronological investigation using amino acid racemization and luminescence dating support stratigraphic correlations of loess units L3, S2LL1 and L1 at the Požarevac section with loess of glacial cycles E [Marine Isotope Stage (MIS) 10], D (MIS 9–8), C (MIS 7–6) and B (MIS 5–2) across central Europe. Correlation with the marine oxygen-isotope stratigraphy and associated paleoclimatic inferences are further supported by magnetic susceptibility, particle size and carbonate content measured in Požarevac sediments. Malacological investigations at the Požarevac section reveal the continuous presence of the Chondrula tridens and Helicopsis striata faunal assemblages throughout the last 350 ka. The loess malacological fauna, which is characterized by the complete absence of cold-resistant and cold-preferring species, suggests a stable, dry and relatively warm glacial and interglacial climate, compared with other central European loess localities. Together these data suggest that the south-eastern part of the Carpathian (Pannonian, Middle Danube) Basin was a refugium for warm-preferring and xerophilous land-snails during the generally unfavorable glacial climates of the late Middle and Late Pleistocene. 相似文献
15.
Abhishek?GaurEmail authorView author&#;s OrcID profile Slobodan?P.?Simonovic 《Theoretical and Applied Climatology》2018,132(1-2):287-300
Physical scaling (SP) method downscales climate model data to local or regional scales taking into consideration physical characteristics of the area under analysis. In this study, multiple SP method based models are tested for their effectiveness towards downscaling North American regional reanalysis (NARR) daily precipitation data. Model performance is compared with two state-of-the-art downscaling methods: statistical downscaling model (SDSM) and generalized linear modeling (GLM). The downscaled precipitation is evaluated with reference to recorded precipitation at 57 gauging stations located within the study region. The spatial and temporal robustness of the downscaling methods is evaluated using seven precipitation based indices. Results indicate that SP method-based models perform best in downscaling precipitation followed by GLM, followed by the SDSM model. Best performing models are thereafter used to downscale future precipitations made by three global circulation models (GCMs) following two emission scenarios: representative concentration pathway (RCP) 2.6 and RCP 8.5 over the twenty-first century. The downscaled future precipitation projections indicate an increase in mean and maximum precipitation intensity as well as a decrease in the total number of dry days. Further an increase in the frequency of short (1-day), moderately long (2–4 day), and long (more than 5-day) precipitation events is projected. 相似文献
16.
Slobodan Ninković 《Astrophysics and Space Science》1987,136(2):299-314
An analysis of the data concerning high-velocity stars from Eggen's catalogue aimed at a determination of the approximate slope of the mass function for the spherical component of our Galaxy, and at estimating the local circular velocity, as well as the local rotation velocity, as by-products, has been performed. Our conclusions are that:
- A linear dependence of the mass on the radius is very likely;
- the value of the limiting radius is most likely equal to (40±10) kpc;
- the two local velocities are approximately equal to each other, being both equal to (230±30) km s?1;
- the local escape velocity appears to be most likely equal to (520±30) km s?1;
- the total mass of a corona, obtained in this way, is (5±1)×1011 M ⊙.
17.
Quantification of uncertainty in the assessment of future streamflow under changing climate conditions 
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下载免费PDF全文 Climate change has a significant influence on streamflow variation. The aim of this study is to quantify different sources of uncertainties in future streamflow projections due to climate change. For this purpose, 4 global climate models, 3 greenhouse gas emission scenarios (representative concentration pathways), 6 downscaling models, and a hydrologic model (UBCWM) are used. The assessment work is conducted for 2 different future time periods (2036 to 2065 and 2066 to 2095). Generalized extreme value distribution is used for the analysis of the flow frequency. Strathcona dam in the Campbell River basin, British Columbia, Canada, is used as a case study. The results show that the downscaling models contribute the highest amount of uncertainty to future streamflow predictions when compared to the contributions by global climate models or representative concentration pathways. It is also observed that the summer flows into Strathcona dam will decrease, and winter flows will increase in both future time periods. In addition to these, the flow magnitude becomes more uncertain for higher return periods in the Campbell River system under climate change. 相似文献
18.
在现代信息技术中，应用数据库进行交流存在着一个极为重要的问题，即用户的观点差异问题。为了能够应用信息系统进行交流，传统的系统要求用户具有专门的训练。这种专门训练往往是长期的，甚至必须具有良好的计算机基础知识和勤奋好学的性格。因此，无论这些信息系统多么先进和有益，上述原因足以使一些人望而却步，放弃使用计算机信息资源。基于这一问题，贝尔格莱德大学矿业和地质学院开发了一个连接软件，它可弥补上述传统用户交流手段的不足。本文介绍了这一软件的结构，即沉积学数据的录入方法和应用数据库进行图解式交流的连接软件的原理。 相似文献
19.
Flood of 1997 affected a large number of residents in the Red River Basin. Life disruption, economic damage, lengthy recovery process, physical and emotional trauma motivated a number of main initiatives to improve the level of preparedness in case of future floods. This review will focus on the involvement of the International Joint Commission (IJC). Personal experience is used in this review to emphasize a number of important lessons, of special relevance to Canadian portion of the basin, from the post flood activities. Level of preparedness for, and potential damage from future floods will benefit from focusing very serious effort on the improvement of the Canadian database, exchange of data with the U.S. and standardization of data collection, exchange and use. Tools for sustainable floodplain management are improving. However, the Red River Basin with its characteristics requires a special set of sophisticated tools that will enhance flood flow forecasting, planning of new flood control measures (structural and non-structural) and emergency operations of existing flood protection system. City of Winnipeg, being the largest population centre in the basin deserves a special attention. Additional protection of 670,000 people is required that will take into consideration temporal and spatial distribution of economic and social costs and benefits. 相似文献
20.
The comparison of two multiple regression models is based on the assumption that geochemical composition of the drainage basin
alluvial sediments is derived primarily from the underlying bedrock lithology. The parent material is integrated with both
stream sediment and overbank sediment geochemistry via the two essentially different approaches as regards the drainage basin
geomorphological data: (1) as the relative area of influence representing a portion of the catchment basin occupied by a specific
rock type and (2) as the relative “line” of influence representing a narrow zone of the underlying bedrock traversed by the
perennial streams which form the active stream network. The model comparison is established on the goodness-of-fit test for
both experimental designs and for the same set of data. Both experiments converge on the linear approach as the more appropriate
model in evaluating the lithologic influence on the analysed sample media in small mountainous watersheds. 相似文献