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1.
The results of studies of variations of δ18O values in river water in Crimea Peninsula in January–February 2015–2017 are given. The variation range of δ18О in river water over the three years of studies never exceeded 3‰. A tendency toward an increase in δ18О in the water of the Salgir, Kacha, Al’ma, Bel’bek, Biyuk-Karasu from their sources to mouths was identified and explained by a decrease in evaporation in the mouth areas of the rivers relative to their sources and upper reaches, and the inflow of isotopically light precipitation (rain and snow) into the rivers in their upper reaches. The values of δ18О in waters of the rivers with regulated stream were found to increase under the effect of the Simferopol Reservoir on the Salgir River and the Izobil’nenskoe Reservoir on the Ulu-Zen’ River. The values of δ18О in the upper reaches of the large rivers of Kacha and Bel’bek (the northwestern slope of the Crimean Mountains) vary from ?8.7 to ?9.7‰, except for the rivers of Al’ma (?7.7‰) and Kokozka (?10.2‰) because of the different shares of groundwater in the recharge of these rivers.  相似文献   

2.
A stochastic triggering (epidemic) model incorporating short-term clustering was fitted to the instrumental earthquake catalog of Italy for event with local magnitudes 2.6 and greater to optimize its ability to retrospectively forecast 33 target events of magnitude 5.0 and greater that occurred in the period 1990–2006. To obtain an unbiased evaluation of the information value of the model, forecasts of each event use parameter values obtained from data up to the end of the year preceding the target event. The results of the test are given in terms of the probability gain of the epidemic-type aftershock sequence (ETAS) model relative to a time-invariant Poisson model for each of the 33 target events. These probability gains range from 0.93 to 32000, with ten of the target events yielding a probability gain of at least 10. As the forecasting capability of the ETAS model is based on seismic activity recorded prior to the target earthquakes, the highest probability gains are associated with the occurrence of secondary mainshocks during seismic sequences. However, in nine of these cases, the largest mainshock of the sequence was marked by a probability gain larger than 50, having been preceded by previous smaller magnitude earthquakes. The overall evaluation of the performance of the epidemic model has been carried out by means of four popular statistical criteria: the relative operating characteristic diagram, the R score, the probability gain, and the log-likelihood ratio. These tests confirm the superior performance of the method with respect to a spatially varying, time-invariant Poisson model. Nevertheless, this method is characterized by a high false alarm rate, which would make its application in real circumstances problematic.  相似文献   

3.
The problem of systematic overestimation (20–50%) of the retrieved ozone concentrations in the altitude range of 60–80 km in the TIMED–SABER satellite experiment in the daytime has been solved. The reason for overestimation is the neglect of the electronic vibrational kinetics of photolysis products of ozone and molecular oxygen O2(b1Σg +, ν) and O2(a1Δg, ν). The IR emission band of O2(a1Δg, ν = 0) at 1.27 μm can be correctly used in remote sensing in order to obtain the ozone altitude profile in the altitude range of 50–88 km only with the use of a complete model of electronic vibrational kinetics of O2 and O3 photolysis products (YM2011) in the Earth’s mesosphere and lower thermosphere. Alternative ozone tracers have been considered, and an optimum tracer in the altitude range of 50–100 km such as O2(b1Σg +, ν = 1) molecule emissions has been proposed.  相似文献   

4.
El Chichón volcano (Chiapas, Mexico) erupted violently in March–April 1982, breaching through the former volcano–hydrothermal system. Since then, the 1982 crater has hosted a shallow (1–3.3 m, acidic (pH ∼ 2.2) and warm (∼ 30 °C) crater lake with a strongly varying chemistry (Cl/SO4 = 0–79 molar ratio). The changes in crater lake chemistry and volume are not systematically related to the seasonal variation of rainfall, but rather to the activity of near-neutral geyser-like springs in the crater (Soap Pool). These Soap Pool springs are the only sources of Cl for the lake. Their geyser-like behaviour with a long-term (months to years) periodicity is due to a specific geometry of the shallow boiling aquifer beneath the lake, which is the remnant of the 1983 Cl-rich (24,000 mg/l) crater lake water. The Soap Pool springs decreased in Cl content over time. The zero-time extrapolation (1982, year of the eruption) approaches the Cl content in the initial crater lake, meanwhile the extrapolation towards the future indicates a zero-Cl content by 2009 ± 1. This particular situation offers the opportunity to calculate mass balance and Cl budget to quantify the lake–spring system in the El Chichón crater. These calculations show that the water balance without the input of SP springs is negative, implying that the lake should disappear during the dry season. The isotopic composition of lake waters (δD and δ18O) coincide with this crater lake-SP dynamics, reflecting evaporation processes and mixing with SP geyser and meteoric water. Future dome growth, not observed yet in the post-1982 El Chichón crater, may be anticipated by changes in lake chemistry and dynamics.  相似文献   

5.
Application of Schmidt‐hammer exposure‐age dating (SHD) to landforms has substantially increased in recent years. The original mechanical Schmidt hammer records R‐(rebound) values. Although the newly introduced electronic Schmidt hammer (SilverSchmidt) facilitates greatly improved data processing, it measures surface hardness differently, recording Q‐(velocity) values that are not a priori interconvertible with R‐values. This study is the first to compare the performance of both instruments in the context of field‐based exposure‐age dating with a particular focus on the interconvertibility of R‐values and Q‐values. The study was conducted on glacially polished pyroxene‐granulite gneiss, Jotunheimen, southern Norway. Results indicate that mean Q‐values are consistently 8–10 units higher than mean R‐values over the range of values normally encountered in the application of SHD to glacial and periglacial landforms. A convenient conversion factor of ±10 units may, therefore, be appropriate for all but the softest rock types close to the technical resolution of the instruments. The electronic Schmidt hammer should therefore be regarded as a useful complement and potential replacement for the mechanical Schmidt hammer. Conversion of published R‐values data to Q‐values requires, however, careful control and documentation of instrument calibration. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

6.
Atmospheric particulate matter (PM) is one of the pollutants that may have a significant impact on human health. Data collected over 7 years from the air quality monitoring station at the LD-III steelworks, belonging to the Arcelor-Mittal Steel Company, located in the metropolitan area of Avilés (Principality of Asturias, Northern Spain), is analyzed using four different mathematical models: vector autoregressive moving-average, autoregressive integrated moving-average (ARIMA), multilayer perceptron neural networks and support vector machines with regression. Measured monthly, the average concentration of pollutants (SO2, NO and NO2) and PM10 (particles with a diameter less than ?10 μm) is used as input to forecast the monthly average concentration of PM10 from one to 7 months ahead. Simulations showed that the ARIMA model performs better than the other models when forecasting 1 month ahead, while in the forecast from one to 9 months ahead the best performance is given by the support vector regression.  相似文献   

7.
A growing body of field, theoretical and numerical modelling studies suggests that predicting river response to even major changes in input variables is difficult. Rivers are seen to adjust rapidly and variably through time and space as well as changing independently of major driving variables. Concepts such as Self‐Organized Criticality (SOC) are considered to better reflect the complex interactions and adjustments occurring in systems than traditional approaches of cause and effect. This study tests the hypothesis that riverbank mass failures which occurred both prior to, and during, an extreme flood event in southeast Queensland (SEQ) in 2011 are a manifestation of SOC. Each wet‐flow failure is somewhat analogous to the ‘avalanche’ described in the initial sand‐pile experiments of Bak et al. (Physical Review Letters, 1987, 59(4), 381–384) and, due to the use of multitemporal LiDAR, the time period of instability can be effectively constrained to that surrounding the flood event. The data is examined with respect to the key factors thought to be significant in evaluating the existence of SOC including; non‐linear temporal dynamics in the occurrence of disturbance events within the system; an inverse power‐law relation between the magnitude and frequency of the events; the existence of a critical state to which the system readjusts after a disturbance; the existence of a cascading processes mechanism by which the same process can initiate both low‐magnitude and high‐magnitude events. While there was a significant change in the frequency of mass failures pre‐ and post‐flood, suggesting non‐linear temporal dynamics in the occurrence of disturbance events, the data did not fit an inverse power‐law within acceptable probability and other models were found to fit the data better. Likewise, determining a single ‘critical’ state is problematic when a variety of feedbacks and multiple modes of adjustment are likely to have operated throughout this high magnitude event. Overall, the extent to which the data supports a self‐organized critical state is variable and highly dependent upon inferential arguments. Investigating the existence of SOC, however, provided results and insights that are useful to the management and future prediction of these features. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

8.
The Iranian Plateau does not appear to be a single crustal block, but an assemblage of zones comprising the Alborz—Azerbaijan, Zagros, Kopeh—Dagh, Makran, and Central and East Iran. The Gumbel’s III asymptotic distribution method (GIII) and maximum magnitude expected by Kijko—Sellevoll method is applied in order to check the potentiality of the each seismogenic zone in the Iranian Plateau for the future occurrence of maximum magnitude (Mmax). For this purpose, a homogeneous and complete seismicity database of the instrumental period during 1900–2012 is used in 29 seismogenic zones of the examined region. The spatial mapping of hazard parameters (upper bound magnitude (ω), most probable earthquake magnitude in next 100 years (M100) and maximum magnitude expected by maximum magnitude estimated by Kijko—Sellevoll method (max MK ? Smax) reveals that Central and East Iran, Alborz and Azerbaijan, Kopeh—Dagh and SE Zagros are a dangerous place for the next occurrence of a large earthquake.  相似文献   

9.
Based on cross-dating tree rings from the Tianmu Mountain, Zhejiang Province, the tree rings α-cellulose σ13C time series was measured. By spectrum analysis, the variation of tree-ring σ13C sequence shows a quasi periodicity of 4.4 years, which is coincident with the standard cycle of El Niño. After removing the long-term decrease trend of the σ13C variation related to atmospheric CO2 concentration, the response of the σ13C to climate elements was analyzed using meteorology data from a nearby weather station. The results suggest that there is a distinct relativity between high-frequency variation of tree ring σ13C series and seasonal climate parameters, e.g. temperature and precipitation, with a significant time-lag effect. In addition, the high frequency also reflects the strength change of the East Asian Monsoon. The multiple regression method was employed to reconstruct the historical climate, and to analyze the climate change and trend in the last 160 years in the northern Zhejiang Province.  相似文献   

10.
The average value of the intrinsic shear wave quality factor, Q β , for the 15 km of the upper crust in the NW Himalaya is estimated. Thirty-two teleseismic broadband SH and sSH waveforms of 8 October 2005 South Asian earthquake (Mw = 7.6), from sixteen Global Seismographic Network stations of the National Earthquake Information Center network have been used. The selected windows of the direct and depth phases have been Fourier transformed and smoothed using the Hamming and Tuckey technique. Ratio of the smoothed spectra of depth and direct phases are obtained in the frequency range 0.2–1.5 Hz. A straight line is fitted in the least-square sense to the spectral ratio versus frequency. The value of Q β is estimated from the slope of the line. The frequency independent average value of Q β is estimated to be 218±56.  相似文献   

11.
The assertion that the application of the USLE to predicting soil losses within a catchment or watershed is not sound because the USLE provides an estimate of erosion that would be measured if the entire area were divided up into 22·1 m long plots, and the output from them all added together, is incorrect. The slope length factor was derived from data obtained using a wide range of plot lengths and included the 22·1 m length simply to force it to take on a value of 1·0 when the slope length is 22·1 m. The 22·1 m length has no physical significance but the USLE slope length factor has a physical basis when applied to planar and convex hillslopes. The use of sediment delivery ratios when the USLE is applied to concave areas attempts to correct for applying the USLE beyond its design criteria. It fails because, in using the sediment delivery ratios in the prediction sediment delivery, it is incorrectly assumed that sediment delivery ratios de not vary with the amount of sediment entering a zone of deposition.  相似文献   

12.
Biogeomorphological processes are an important component of dynamic intertidal systems. On rocky shores, the direct contribution of microorganisms, plants and animals to weathering and erosion is well known. There is also increasing evidence that organisms can alter rock breakdown indirectly, by moderating temperature and moisture regimes at the rock–air interface. These influences have been purported to represent mechanisms of bioprotection, by buffering microclimatic fluctuations associated with weathering processes such as wetting and drying and salt crystallization. However, virtually nothing has been done to test whether microclimatic buffering translates to differences in actual rock breakdown rates. Here we report a preliminary laboratory experiment to assess how an artificial canopy (chosen to represent seaweed) affects mechanical rock breakdown. Using a simplified and accelerated thermal regime based on field data from a rocky shore platform in southern England, UK, we find that breakdown (mineral debris release) of mudstone covered with a canopy is reduced by as much as 79% relative to bare rock after around 100 thermal cycles. Reduction in rock surface hardness (measured using an Equotip device) was also greater for bare rock (17%) compared to covered rock (10%) over this period. Measurements of salt crystal formation indicate that the mechanism driving these differences was a reduction in the frequency of crystallization events, via moisture retention and shading of the rock surface. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

13.
The genus Vibrio, belonging to Gammaproteobacteria of the phylum Proteobacteria, is a genetically and ecologically diverse group of heterotrophic bacteria, that are ubiquitous in marine environments, especially in coastal areas. In particular, vibrios dominate, i.e. up to 10% of the readily culturable marine bacteria in these habitats. The distribution of Vibrio spp. is shaped by various environmental parameters, notably temperature, salinity and dissolved organic carbon. Vibriospp. may utilize a wide range of organic carbon compounds, including chitin (this may be metabolized by most Vibrio spp.), alginic acid and agar. Many Vibrio spp. have very short replication times (as short as ~10 min), which could facilitate them developing into high biomass content albeit for relatively short durations. Although Vibriospp. usually comprise a minor portion (typically ~1% of the total bacterioplankton in coastal waters) of the total microbial population, they have been shown to proliferate explosively in response to various nutrient pulses, e.g., organic nutrients from algae blooms and iron (Fe+) from Saharan dust. Thus, Vibrio spp. may exert large impacts on marine organic carbon cycling especially in marginal seas. Genomics and related areas of investigation will reveal more about the molecular components and mechanisms involved in Vibrio-mediated biotransformation and remineralization processes.  相似文献   

14.
The majority of the world's mangrove forests occur on mostly mineral sediments of fluvial origin. Two perspectives exist on the biogeomorphic development of these forests, i.e. that mangroves are opportunistic, with forest development primarily driven by physical processes, or alternatively that biophysical feedbacks strongly influence sedimentation and resulting geomorphology. On the Firth of Thames coast, New Zealand, we evaluate these two possible scenarios for sediment accumulation and forest development using high‐resolution sedimentary records and a detailed chronology of mangrove‐forest (Avicennia marina) development since the 1950s. Cores were collected along a shore‐normal transect of known elevation relative to mean sea level (MSL). Activities for lead‐210 (210Pb), caesium‐137 (137Cs) and beryllium‐7 (7Be), and sediment properties were analysed, with 210Pb sediment accumulation rates (SARs), compensated for deep subsidence (~8 mm yr?1) used as a proxy for elevation gain. At least four phases of forest development since the 1950s are recognized. An old‐growth forest developed by the late‐1970s with more recent seaward forest expansion thereafter. Excess 210Pb profiles from the old‐growth forest exhibit relatively low SARs near the top (7–12 mm yr?1) and bottom (10–22 mm yr?1) of cores, separated by an interval of higher SARs (33–100 mm yr?1). A general trend of increasing SAR over time characterizes the recent forest. Biogeomorphic evolution of the system is more complex than simple mudflat accretion/progradation and mangrove‐forest expansion. Surface‐elevation gain in the old‐growth forest displays an asymptotic trajectory, with a secondary depocentre developing on the seaward mudflat from the mid‐1970s. Two‐ to ten‐fold increases in 210Pb SARs are unambiguously large and occurred years to decades before seedling recruitment, demonstrating that mangroves do not measurably enhance sedimentation over annual to decadal timescales. This suggests that mangrove‐forest development is largely dependent on physical processes, with forests occupying mudflats once they reach a suitable elevation in the intertidal. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

15.
Based on the results from seismogeological study, aeromagnetic inversion and deep seismic sounding (DSS), it is found that the M≥8.0 earthquakes in North China have three common deep structural characteristics, i.e., they all took place above the ultra-crustal deep faults or on the edges of the tectonic blocks with higher intensity, and there are low-velocity, low-density and high-conductive layers deep in the epicentral regions. The origins of the earthquakes are also discussed and the two possibilities of seismogenesis are proposed, i.e., tectonic movement and intracrustal explosion.  相似文献   

16.
The results of the modeling the anomalous behavior of the F 1 layer characteristics are presented. The anomaly lies in the jump-like variations in the critical frequency of the layer f 0 F1 and an abnormally large f 0 F1 value for the considered season and time. The observed effect is simulated based on the propagation of a large-scale travelling ionospheric disturbance. The quantitative values of the disturbance parameter are obtained and some peculiarities of its propagation are analyzed. The investigation was carried out with the help of the software for automated processing of the vertical sounding ionograms. The experimental data were obtained during the Radar-Progress project.  相似文献   

17.
Summary A possible relation between the 10-day, 1-month, and 2-month geomagnetic as well as solar activity, characterized by Kp and Wolf's number R, and temperatures measured at the Prague-Klementinum meteorological station in January–February of the years 1932–1987 was sought. It was found that:1) Kp correlates with the temperature in Prague better than Wolf's number R.2) If the QBO phase is taken into account, the correlations improve.3) Even if the correlations improves with increasing length of the subintervals into which the individual winter periods (January-February) were derived, their statistical significance declines.  相似文献   

18.
This paper mainly observed and analyzed the character of shear-wave splitting in rock specimens while they were in the critical state of rupture. The rock specimens for study are made of Laizhou marble from Shandong, China. A series of records were obtained from two rock specimens when they were in the critical state of rupture. The result shows that, in the critical state just before rock rupture, there may be the phenomenon of rise and fall in the time delay of shear-wave splitting, even though the load was kept constant. That is to say, the time delay of shear-wave splitting may have a falling process before rock rupture.  相似文献   

19.
The deep information of the Turfan sag was extracted and analyzed through the re-processing of the magneto-gravitational data of the Turfan sag in the Turfan-Hami basin. It is considered that the basement faults have played an important role in the controlling of the framework, lithology and the distribution of volcanic rocks in the basement of the Turfan sag. The deep crystalline basement and the upper Hercynian folded basement were studied part by part in the sag through the combined data of aeromagnetic and electric methods. It is revealed that the Huoyanshan fault is steep in the upper and lower parts but gentle in the middle, displaying a “S” type texture, and discovered that there are at least a row of local structures in the down-thrown block of the Huoyanshan fault, through the CEMP prospecting in Huoyanshan. The result is very important for the studying of the Turfan sag as a whole.  相似文献   

20.
Li Gang 《中国地震研究》2007,21(1):110-120
1 SURVEY OF GLOBAL SEISMICITY IN 2006 A total of 15 strong earthquakes with Ms ≥ 7.0 occurred in the world according to the Chinese Seismic Station Network in 2006 （Table 1 ）. The strongest earthquakes were the Kamchatka earthquake with Ms8.0 on March 29 and the Kuril Islands earthquake with Ms8.0 on November 15 （Fig. 1）. The frequency was slightly lower, and the energy release of earthquakes reduced in 2006 compared with the seismicity in 2005. The seismicity last year had the following characteristics：  相似文献   

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