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1.
Sessionl:PhysicalandNumericalModelingofSedimentationMisganawDemissieandJenrenNiKeynotelecturebyBenC.Yen:FrommodelingtheYellowRivertorivermodelingProfessorYenprovidedahistoricalperspectiveonmodelingingeneralandapplicationtotheYellowRiverinparticular.ProfessorYentracedthestartofmodemriverhydraulicmodelingtoLoutsJeromeFarquesofFrancewhobuiltaifl00scalemodeloftheGarvonnein1875.However,itwasGermanhydraulicengineersthatdevelopedhydraulicmodelsfortheYellowRiverstartingwithHerbertEngles(18…  相似文献   

2.
The sorption of AuCl4 −,AuCl2 − and Au(S2O3)3- on δ-MnO2 was investigated at pH2–11.6, 0.01 mol/L and 0.1 mol/L NaNO3 solutions. At pH 4 in two electrolyte strength solutions, Au sorption densities on δ-MnO2 are 0.18–0.21 and 0.28μmoL/m2 for AuCl4 − and Au(S2O3)2 3-, respectively, and the Au surface coverage is approximate to or lower than 1%. This adsorption of the two Au complexes decreases as the solution pH increases, which conforms to the sorption regularity of the anion on δ-MnO2. The Au sorption decreases in the sequence of Au(S2O3)2 3- >AuCl4 − >AuC12 −. The intrinsic equilibrium constants (logK int) of the three Au complexes are 1.17–2.7, much higher than those of Cu and Cd. The hydrolysis products of AuCl4 - are preferentially adsorbed by δ-MnO2 and the inner-sphere Au-surface complexes are formed on the surface. Project supported by the National Studying-abroad Foundation, the National Natural Science Foundation of China (Grant No. 49573200) and the Australian Mining Industry.  相似文献   

3.
In recent years, a strong debate has emerged in the hydrologic literature regarding what constitutes an appropriate framework for uncertainty estimation. Particularly, there is strong disagreement whether an uncertainty framework should have its roots within a proper statistical (Bayesian) context, or whether such a framework should be based on a different philosophy and implement informal measures and weaker inference to summarize parameter and predictive distributions. In this paper, we compare a formal Bayesian approach using Markov Chain Monte Carlo (MCMC) with generalized likelihood uncertainty estimation (GLUE) for assessing uncertainty in conceptual watershed modeling. Our formal Bayesian approach is implemented using the recently developed differential evolution adaptive metropolis (DREAM) MCMC scheme with a likelihood function that explicitly considers model structural, input and parameter uncertainty. Our results demonstrate that DREAM and GLUE can generate very similar estimates of total streamflow uncertainty. This suggests that formal and informal Bayesian approaches have more common ground than the hydrologic literature and ongoing debate might suggest. The main advantage of formal approaches is, however, that they attempt to disentangle the effect of forcing, parameter and model structural error on total predictive uncertainty. This is key to improving hydrologic theory and to better understand and predict the flow of water through catchments.  相似文献   

4.
During the EU project BEEP a battery of biomarkers was applied in flounder (Platichthys flesus) and the blue mussel (Mytilus edulis) collected at three locations off the Lithuanian coast (Baltic Sea) in June and September 2001 and 2002. The elevated biomarker responses in specimens sampled in September 2001 were apparently related to the extensive dredging activities in the Klaipeda port area and subsequent dumping of contaminated sediments. High concentrations of organic pollutants (organochlorines and PBDEs) were also measured in the tissues of both indicator species. In addition, response levels of genotoxicity, cytotoxicity, immunotoxicity as well as concentrations of PAH metabolites in the bile of flounder showed elevations in 2002 after an oil spill in the Būtinge oil terminal in November 2001. In flounder, biomarker measurements 10 months after the spill indicated recovery processes but in mussels a high level of genotoxicity could still be observed 22 months later. The present study illustrates the usefulness of the multi-biomarker approach in the detection of biological effects of pollution in this region of the Baltic Sea.  相似文献   

5.
In the article the author looks back the hard development course and great progress in earth quake science and technology in China during the last near a half of century and expounds the following 3 aspects: (1) The strong desire of the whole society to mitigate seismic disasters and reduce the effect of earthquakes on social-economic live is a great driving force to push forward the development of earthquake science and technology in China; (2) To better ensure people‘ s life and property, sustainable economic development, and social stability is an essential purpose to drive the development of earthquake science and technology in China; and (3) To insist on the dialectical connection of setup of technical system for seismic monitoring with the scientific research of earthquakes and to better handle the relation between crucial task, current scientif ic level, and the feasibility are the important principles to advance the earthquake science and technology in China. Some success and many setbacks in earthquake disaster mitigation consistently enrich our knowledge regarding the complexity of the conditions for earthquake occurrence and the process of earthquake preparation, promote the reconstruction and modernization of technical system for earthquake monitoring, and deepen the scientific research of earthquakes. During the last 5 years, the improvement and modernization of technical system for earthquake monitoring have clearly provided the technical support to study and practice of earthquake prediction and pre caution, give prominence to key problems and broaden the field of scientific research of earth quakes. These have enabled us to get some new recognition of the conditions for earthquake oc currence and process of earthquake preparation, characteristics of seismic disaster, and mecha nism for earthquake generation in China‘s continent. The progress we have made not only en courages us to enhance the effectiveness of earthquake disaster mitigation, but also provides a basis for accelerating further development of earthquake science and technology in China in the new century, especially in the 10th five-year plan. Based on the history reviewed, the author sets forth a general requirement for develop ment of earthquake science and technology in China and brings out 10 aspects to be stressed and strengthened at present and in the future. These are: upgrade and setup of the network of digitized seismic observation; upgrade and setup of the network for observation of seismic pre cursors; setup of the network for observation of strong motion; setup of the laboratories for ex periment on seismic regime; establishment of technical system for seismic information, emer gency command and urgent rescue; research on short-term and imminent earthquake predic tion; research on intermediate- and long-term earthquake prediction; research on attenuation of seismic ground motion, mechanism for seismic disaster, and control on seismic disaster; ba sic research fields related to seismology and geoscience. We expect that these efforts will signifi cantly elevate the level of earthquake science and technology in China to the advanced interna tional level, improve theories, techniques, and methods for earthquake precaution and predic tion, and enhance the effectiveness of earthquake disaster mitigation.  相似文献   

6.
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7.
40Ar/39Ar method is a high precision dating means, of which the age is obtained by contrasting the un- known sample with those of standards. Usually the age of standard is determined by K-Ar method in which the 38Ar spike should be added for measurement. However, the absolute concentration of 38Ar spike is measured through the calibrated standards in turn, al- though occasionally the concentration of 38Ar spike is determined by other dating methods, such as Rb-Sr, U-Pb methods, which is kn…  相似文献   

8.
The article examines how heads of farmers’ households perceive the socioeconomic benefits of Lake Ziway (Ethiopia), the causes of its current degradation, and the state of land and water use management in its watershed. The investigation was based on in-depth empirical field work including a survey with 635 heads of smallholder farmers’ households via interview using semi-structured questionnaires. Further, water abstraction was estimated from three districts that border with the lake. Respondents believe that Lake Ziway provides a number of individual and collective benefits for local communities, private companies and public institution. They stated, however, that the lake is under pressure from the floriculture industry and other investment projects, high population growth and subsequent expansion of settlements and irrigation farms, high applications of agrochemicals, soil erosion, uncontrolled water abstraction, and deforestation in the watershed. The respondents further believe that these activities are degrading the lake water quality, shrinking its water volume and decreasing its fish population. After examining government’s efforts to address these activities, the majority of respondents believe that the government role in the whole watershed is weak. This study contributes to better understand the local socio-ecological coherences and the problems Lake Ziway and its watershed are facing. It also provides information regarding long-term sustainable land and water use planning strategies for the lake and management of its watershed, which could also be applied to other lakes in Ethiopia, and beyond.  相似文献   

9.
ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｉｓｋｎｏｗｎｔｈａｔＣｈｉｎａｉｓａｎｅａｒｔｈｑｕａｋｅ ｐｒｏｎｅｃｏｕｎｔｒｙｉｎｔｈｅｗｏｒｌｄａｎｄｉｓａｌｓｏａｃｏｕｎｔｒｙｓｕｆｆｅｒｉｎｇｍｏｓｔｓｅｖｅｒｅｓｅｉｓｍｉｃｃａｌａｍｉｔｉｅｓｉｎｔｈｅｗｏｒｌｄ .Ｃｈｉｎａ’ｓｔｅｒｒｉｔｏｒｙｏｃｃｕｐｉｅｓａｂｏｕｔ 1 1 4ｏｆｔｈｅｇｌｏｂａｌｃｏｎｔｉ ｎｅｎｔａｌａｒｅａ ,ｗｈｉｌｅａｂｏｕｔ 1 3ｏｆｇｌｏｂａｌＭ≥ 7.0ｃｏｎｔｉｎｅｎｔａｌｅａｒｔｈｑｕａｋｅｓｏｃｃｕｒｒｅｄｉｎＣｈ…  相似文献   

10.
Naturally occurring 210Po (half-life 138.4d) is the granddaughter of 210Pb (half-life 22.3a), both are members of 238U decay series and have been inten-sively utilized to study kinetic aspects of material cy-cling in the ocean[1]. Based on radioactive disequilibria in the 226Ra-210Pb-210Po system, oceanographical processes with different timescales have been widely studied. Rama et al.[2] first detected excess 210Pb rela-tive to its precursor 226Ra in surface waters, and considered this exc…  相似文献   

11.
《Journal of Atmospheric and Solar》2002,64(12-14):1371-1381
We review the observational evidence for describing the characteristics of the equatorial temperature and zonal wind anomaly (ETWA) in the low-latitude thermosphere in solar maximum and minimum periods. In spite of some new results on ETWA in the last decade, including its discovery, there is no satisfactory explanation in our understanding of the phenomenon. The two suggested mechanisms for heating at the crests of the equatorial ionization anomaly (EIA) to form the equatorial temperature anomaly (ETA) are due to (1) the ion-drag on the zonal winds resulting in the transfer of kinetic energy into heat energy and (2) the exothermic chemical reactions involved in the dominant O+ion re-combinations. To verify which of the two suggested mechanisms is the most effective in causing ETA, it is necessary to measure simultaneously a few parameters in situ by the satellite-borne instruments. They are (1) the electron density (Ne) and temperature (Te), (2) the molecular and atomic ion densities (Nij) and ion temperatures (Ti), (3) the gas temperatures (T) and densities of the gas constituents, (4) the vector winds or at least the zonal (Z) and vertical (V) wind components and (5) the drift velocities of the ionization. These together with the simultaneous ground-based measurements, will resolve identifying not only the dominant mechanism(s) for ETWA, but also the processes responsible for the enigmatic phenomena, such as the equatorial spread-F (ESF), the midnight temperature maximum (MTM) and the possible role of the EIA in their occurrences.  相似文献   

12.
—The Erzincan strike-slip earthquake of March 13, 1992 ruptured a section of the North Anatolian fault (NAF) at the northern margin of the Erzincan basin. The focal depth of about 10 km was less than given by ISC and NEIC. Erzincan and the surrounding villages were considerably damaged. In the Erzincan basin and in the neighbouring mountains a seismic network of ten stations was installed. It was operating continuously from March 21 through June 16, 1992. More than 3,000 aftershocks were recorded of which 505 could be located. The spectral parameters of 394 and the fault-plane solutions of 53 aftershocks were determined. For the given region the frequency dependent coda Q was derived as Q c = 122 f 0.68. The aftershock area increased with time, reflecting the process of stress redistribution. Some events clustered in the immediate vicinity of the town of Erzincan close to the epicentre of the main event and seem to trace the NAF. Their source mechanism is similar to that of the main event (strike slip). About 150 aftershocks clustered in the southeastern part of the Erzincan basin where a concentration of the events in a small volume of 5 × 5 × 3 km3 was observed. The majority of fault-plane solutions available for these aftershocks showed a normal faulting mechanism with an east-west directed extension. Most of the aftershocks southeast of the basin clustered between two lineaments that were mapped by satellite images. The P-wave velocity below the Erzincan basin, derived from travel-time residual analysis, is lower compared to areas NE and SW of the basin. Three-dimen sional stress modelling of the Erzincan region qualitatively explains the occurrence of the aftershocks southeast of the basin. The calculated displacement distribution which exhibits the north-westward motion of the basin and tension at its southeastern margin, caused by the Erzincan earthquake, is in agreement with derived fault-plane solutions.  相似文献   

13.
Geomagnetism and Aeronomy - Spectral observations of the mesopause airglow at the Zvenigorod Scientific Station have been used to obtain the midnight emission intensities of molecular oxygen...  相似文献   

14.
Ｔｈｅｃｒｕｓｔａｌｆｌｕｉｄｅｖｏｌｕｔｉｏｎａｎｄｔｈｅｃａｕｓｅｓｏｆｅａｒｔｈｑｕａｋｅｓ（Ⅲ）ＣＨＡＮＧ－ＦＡＮＧＸＵ（徐常芳）ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｌｏｇｙ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕ，Ｂｅｉｊｉｎｇ１０００...  相似文献   

15.
Stability of arsenopyrite and As(III) in low-temperature acidic solutions   总被引：1，自引：0，他引：1  
Arsenopyrite is one of the most important pri-mary arsenic mineral. In the Eh-pH diagram of the As-O2-S-H2O system, if the total arsenic concentration (TAs) is taken to be 0.75 mg/L, the total sulfur con-centration, 32 mg/L, the temperature, 25℃and the pressure, one atmosphere pressure for the discrimina-tion of arsenic species, it may be found that under hy-pergene conditions, arsenopyrite is a moderately stable mineral. Only in the strongly alkaline and reducing environment can arsenopy…  相似文献   

16.
The Seismic Intensity Zoning Map of China(1990)was based on the probabilistic method of seismic hazard analysis.In compiling the map,the characteristics of inhomogeneity of earthquake distribution both in space and time in China are considered sufficiently,and some necessary modifications in the model of seismic hazard analysis are carried out.Based on the analysis of the seismic activity and seismotectonic environment,26 seismic provinces are divided first as the statistical elements of the seismicity analysis; the seismic potential source areas are then divided in the seismic provinces.The 733 potential source areas with various upper limit magnitudes have been divided in the country.According to the reliable time domain of earthquake data with various magnitude intervals,the b values in magnitude-frequency relationship are calculated in the seismic provinces.According to the analysis of the inhomogeneity of seismicity distribution both in space and time,the annual average occurrence rates of the eart  相似文献   

17.
In recent years, locating total lightning at the VLF/LF band has become one of the most important directions in lightning detection. The Low-frequency E-field Detection Array(LFEDA) consisting of nine fast antennas was developed by the Chinese Academy of Meteorological Sciences in Guangzhou between 2014 and 2015. This paper documents the composition of the LFEDA and a lightning-locating algorithm that applies to the low-frequency electric field radiated by lightning pulse discharge events(LPDEs). Theoretical simulation and objective assessment of the accuracy and detection efficiency of LFEDA have been done using Monte Carlo simulation and artificial triggered lightning experiment, respectively. The former results show that having a station in the network with a comparatively long baseline improves both the horizontal location accuracy in the direction perpendicular to the baseline and the vertical location accuracy along the baseline. The latter results show that detection efficiencies for triggered lightning flashes and return strokes are 100% and 95%, respectively. The average planar location error for return strokes of triggered lightning flashes is 102 m. By locating LPDEs in thunderstorms, we find that LPDEs are consistent with convective regions as indicated by strong reflectivity columns, and present a reasonable distribution in the vertical direction.In addition, the LFEDA can reveal an image of lightning development through mapping the channels of lightning. Based on three-dimensional locations, the vertical propagation speed of the preliminary breakdown and the changing trend of the leader's speed in an intra-cloud and a cloud-to-ground flash are investigated. The research results show that the LFEDA has the capability for three-dimensional location of lightning, which provides a new technique for researching lightning development characteristics and thunderstorm electricity.  相似文献   

18.
The observation of oil inclusions trapped prior to 2.0 Ga in Palaeoproterozoic rocks and the ability to obtain detailed molecular geochemical information from them provide a robust way for understanding the early biogeochemical evolution of the Earth. Oil-bearing fluid inclusions (FI) in ca. 2.45 Ga fluvial metaconglomerate of the Matinenda Formation at Elliot Lake, Canada were trapped in quartz and feld-spar during diagenesis and early metamorphism of the host rock, probably before ca. 2.2 Ga. The 2.1 Ga FA Formation sandstone of the Franceville Basin in Gabon that hosts the Oklo natural fission reactors has also been discovered to contain abundant Palaeoproterozoic oil-bearing FIs. This oil occurs within H2O and CO2-dominated inclusions trapped in syntaxial quartz overgrowths and intragranular and transgranular microfractures in detrital quartz, and was most likely trapped 2.1–1.98 Ga. Molecular geochemical analyses of both FI oils reveal a wide range of compounds, including n-alkanes, isoprenoids, monomethylalkanes, aromatic hydrocarbons, and trace amounts of complex multi-ring biomarkers including terpanes, hopanes, methylhopanes, steranes and diasteranes. To ensure a reliable interpretation of oil inclusions, a comprehensive series of outside-rinse blanks and procedural system blanks was analysed by gas chromatography-mass spectrometry; quantitative amounts of the hydrocarbons in these blanks were compared to the FI extracts, so as to provide confidence limits on the experimental integrity of each compound class. Maturity ratios based on reliably detected compound classes show that the FI oils were generated in the oil window, with no evidence of extensive thermal cracking. The presence of biomarkers for cyanobacteria and eukaryotes derived from and trapped in rocks deposited prior to 2.0 Ga is consistent with early evolution of oxygenic photosynthesis and suggests that some aquatic settings had become sufficiently oxygenated for sterol biosynthesis by this time. The extraction of biomarker molecules from Palaeoproterozoic oil-bearing FIs thus establishes a new method, using low detection limits and system blank levels, to trace evolution through Earth’s early history that avoids the potential contamination problems affecting shale-hosted hydrocarbons. Supported by the ARC Discovery Grant, which includes a QEII Fellowship to A.D., the Natural Sciences and Engineering Research Grant to D.M., and by the National Aeronautics and Space Administration Astrobiology Institute (R.B.)  相似文献   

19.
In the framework of the EU funded BEEP project a set of biomarkers, gross morphometric indices and tissue concentrations of selected organic pollutants were measured in flounder (Platichthys flesus) and mussels (Mytilus trossulus) collected twice a year (April and October) from three sites in the inner Gulf of Gdańsk between autumn 2001 and spring 2003. In flounder, seasonal differences in most biomarkers were observed, but no correlations with tissue pollutant levels could be found. In mussels, highly variable levels in biomarker responses were seen, but no clear seasonal or spatial trends, directly related to tissue concentrations, could be established. The observed biomarkers distribution the study sites are probably mostly caused by interannual, seasonal and individual variability and, in case of flounder, possibly by exchange of stocks between the sampling sites.  相似文献   

20.
High εNd(t)-εHf(t) granites are robust evidence for crustal growth. In this paper we report results of petrologic, geochronological and geochemical investigations on the Huashiban granites from the Ailaoshan tectonic zone in western Yunnan(SW China). Zircon grains separated from the two samples(10HH-119 A and 10HH-120A) yield the weighted mean 206Pb/238 U ages of 229.9 ± 2.0 Ma and 229.3 ± 2.3 Ma, respectively, interpreted as the crystallization ages of the granites. Based on our results, in combination with the existing U-Pb geochronological data for the Ailaoshan metamorphic rocks, we propose that the Ailaoshan Group might be a rock complex composed of the Mesoproterozoic, Neoproterozoic, Hercynian, Indosinian and Himalayan components, rather than a part of the crystalline basement of the Yangtze block. The zircon grains show highly depleted Lu-Hf isotope compositions, with positive εHf(t) values ranging from 8.4 to 13.1. The Huashiban granites have high SiO2(72.66 wt%–73.70 wt%), low Mg#(0.28–0.34) with A/CNK=1.01–1.05, and can be classified as peralumious high-K calc-alkaline I-type granites. A synthesis of these data indicates that the Ailaoshan tectonic zone had evolved into a post-collisional setting by the Late-Triassic(229 Ma). Genesis of the Huashiban high εNd(t)-εHf(t) granites involved into two processes:(1) underplating of the sub-arc mantle into the lower crust, and(2) remelting of the juvenile crustal materials in response to the upwelling of the asthenospheric mantle in the post-collisional setting.  相似文献   

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