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1.
Changes in the chemical composition of the hot springs of Mendeleev Volcano (Kunashir Island) as for Cl?, SO 4 2? , CO2, NH 4 + and Cl?/SO 4 2? are given in function of the 1965–66 and 1973 (in part) seismic activity in the South Kurile islands.  相似文献   

2.
Dew samples were collected between October 2007 and February 2008 from a suburban site in Agra. pH, conductivity, major inorganic ions (F?, Cl?, NO 3 ? , SO 4 2? , Na+, K+, Ca2+, Mg2+, and NH 4 + ), and some trace metals (Cr, Sn, Zn, Pb, Cd, Ni, Mn, Fe, Si, Al, V, and Cu) were determined to study the chemistry of dew water. The mean pH was 7.3, and the samples exhibited high ionic concentrations. Dew chemistry suggested both natural and anthropogenic influences, with acidity being neutralized by atmospheric ammonia and soil constituents. Ion deposition flux varied from 0.25 to 3.0?neq?m?2?s?1, with maximum values for Ca2+ followed by NH 4 + , Mg2+, SO 4 2? , Cl?, NO 3 ? , Na+, K+, and F?. Concentrations of trace metals varied from 0.13 to 48?μg?l?1 with maximum concentrations of Si and minimum concentration of Cd. Correlation analysis suggested their contributions from both crustal and anthropogenic sources.  相似文献   

3.
The relative rate constants of O2(b1Σ g + , v= 1–4) production at an inelastic interaction between electronically excited N(2D) atoms and O2(X3Σ g ? , v = 0) oxygen molecules have been calculated. It was shown that an increase in equilibrium distances between oxygen atoms in NO2 quasi-molecule, produced during the interaction, substantially increases the calculated relative production rates of O2(b1Σ g + , v > 1). The obtained coefficients are used to calculate the O2(b1Σ g + , v= 1–4) relative populations at 110 km (T = 250 K) and 150 km (T = 500 K) altitudes of the polar ionosphere. The calculated populations have been compared with the results of the published measurements of the Atmospheric system band luminosity intensities, and satisfactory agreement has been obtained for low altitudes.  相似文献   

4.
The use of submersed macrophyte tissue δ 15N to quantify the level of WWTP effluent use in a highly urbanized and agricultural river was evaluated using several methods. Macrophytes, NH4 + and NO3 ? were collected by canoe along two 10 km reaches of river, upstream and downstream of two major municipal WWTPs over 3 years. NH4 + decreased in concentration while δ 15N–NH4 + increased as a function of distance downstream of both WWTPs, changing in one survey from 13 to 31 ‰ over 1 km. This increase is attributed to the combined effects of volatilization, nitrification and uptake. While NO 3 ? concentrations increased downstream of the WWTP over one of the survey reaches, δ 15N–NO 3 ? showed no prominent trend with distance at either. Macrophyte tissue δ 15N increased with distance downstream of both WWTPs, with a slope not significantly different from that of δ 15N–NH4 + suggesting that macrophytes incorporate effluent NH4 + as their main N source in those areas. However, mixing models suggest that towards the end of the reach, where source separation is distinct, macrophytes may utilize background NO 3 ? . Our study indicates the difficulty of deriving precise estimates of effluent use by macrophytes in a system where the δ 15N of the effluent changes rapidly. It also illustrates the utility of macrophytes in describing those changes where the effluent is too attenuated to allow for direct isotopic analysis.  相似文献   

5.
Concentrations of major ions in surface waters of the rivers of Khara-Murin and Snezhnaya are compared based on data of many-year observations carried out in the 1950s and 2000s. The concentrations of HCO 3 ? , Cl?, Ca2+, Mg2+, Na+ + K+ are shown to be stable. A considerable increase in SO 4 ?2 concentration was revealed.  相似文献   

6.
Presently available data on the reaction of SO2 with OH radicals (OH + SO2 + \(M\xrightarrow[{k_1 }]{}\) HSO3 +M) are critically reviewed in light of recent stratospheric sulfur budget calculations. These calculations impose that the net oxidation ratek of SO2 within the stratosphere should fall within the range 10?7≤k≤10?9, if the SO2 oxidation model for the stratospheric sulfate layer is assumed to be correct. The effective reaction rate constantk 1 * =k 1[M] at the stratospheric temperature is estimated as $$k_1^* = \frac{{(8.2 \pm 2.2) \times 10^{ - 13} \times [M]}}{{(0.79 \mp 0.34) \times 10^{ - 13} + [M]}}cm^3 /molecules sec$$ where [M] refers to the total number density (molecules/cm3). Using the above limiting values ofk 1 * , and the estimated OH density concentrations, the net oxidation rate is calculated as 3.6×10?7≤k≤1.3×10?8 at 17 km altitude. This indicates that the upper limit of thesek values exceeds the tolerable range imposed by the model by a factor of about four. Obviously the uncertainty of thek 1 * values and of the OH concentrations in the stratosphere is still too large to make definite conclusions on the validity of the SO2 model.  相似文献   

7.
Tsunamis are most destructive at near to regional distances, arriving within 20–30 min after a causative earthquake; effective early warning at these distances requires notification within 15 min or less. The size and impact of a tsunami also depend on sea floor displacement, which is related to the length, L, width, W, mean slip, D, and depth, z, of the earthquake rupture. Currently, the primary seismic discriminant for tsunami potential is the centroid-moment tensor magnitude, M w CMT , representing the product LWD and estimated via an indirect inversion procedure. However, the obtained M w CMT and the implied LWD value vary with rupture depth, earth model, and other factors, and are only available 20–30 min or more after an earthquake. The use of more direct discriminants for tsunami potential could avoid these problems and aid in effective early warning, especially for near to regional distances. Previously, we presented a direct procedure for rapid assessment of earthquake tsunami potential using two, simple measurements on P-wave seismograms—the predominant period on velocity records, T d , and the likelihood, T 50 Ex , that the high-frequency, apparent rupture-duration, T 0, exceeds 50–55 s. We have shown that T d and T 0 are related to the critical rupture parameters L, W, D, and z, and that either of the period–duration products T d T 0 or T d T 50 Ex gives more information on tsunami impact and size than M w CMT , M wp, and other currently used discriminants. These results imply that tsunami potential is not directly related to the product LWD from the “seismic” faulting model, as is assumed with the use of the M w CMT discriminant. Instead, information on rupture length, L, and depth, z, as provided by T d T 0 or T d T 50 Ex , can constrain well the tsunami potential of an earthquake. We introduce here special treatment of the signal around the S arrival at close stations, a modified, real-time, M wpd(RT) magnitude, and other procedures to enable early estimation of event parameters and tsunami discriminants. We show that with real-time data currently available in most regions of tsunami hazard, event locations, m b and M wp magnitudes, and the direct, period–duration discriminant, T d T 50 Ex can be determined within 5 min after an earthquake occurs, and T 0, T d T 0, and M wpd(RT) within approximately 10 min. This processing is implemented and running continuously in real-time within the Early-est earthquake monitor at INGV-Rome (http://early-est.rm.ingv.it). We also show that the difference m b  ? log10(T d T 0) forms a rapid discriminant for slow, tsunami earthquakes. The rapid availability of these measurements can aid in faster and more reliable tsunami early warning for near to regional distances.  相似文献   

8.
In the strip limestone mine in Guiding county, Guizhou Province the shear and frictionin situ tests of rock body were made for the three typical inclined weak bands C 3 1 /C 3 1 , C 3 1 /C 2 2 and C 2 2 /C 2 1 . The tests were made according to the second scheme of cuneate sample of the standards on rock mechanics test of Water Conservancy and Electricity Ministry. The changes of the resistivity in the weak band and the acoustic speed across the weak band were measured in the same time. The apparent resistivity data, obtained for 8 samples on 27 measure lines in 38 cycle tests, show that the apparent resistivity changes have rather obvious characters as follows: 1. At shear and friction stage, the change of the apparent resistivity accelerates after the yield point, and reaches the maximum of change rate and change amplitude near fracture point (except the lines with resistivity invariant); 2. On the same sample, the resistivity changes are different on the various lines and related to the location settled the lines, there are some “sensitive” location; 3. At the stage of preloading normal stress before shearing, the resistivity decreases on most lines, but on a few lines the resistivity does not changes; 4. After unloading shear stress, the resistivity could not recover completely and the hysteresis of resistiviity takes place on a few lines.  相似文献   

9.
The study aims to measure the hydrological behavior and nutrients dynamics of the springs located in different landscapes of Kosi basin, Indian central Himalaya. A total number of eight springs were considered for the present investigation, each landscape represented by one spring. The monitoring for hydrological measurement was conducted in January 1998 to December 1999, the interval between two successive measurements was 10 days, i.e., 240 hr (total 72 observations were made). Water quality measurement was done in three main seasons, i.e., winter (Jan.), summer (June) and monsoon (Aug.) of 1998 and 1999, and the average value for measured parameters were calculated. These samples were analyzed for pH, electrical conductivity, total dissolved solids, dissolve oxygen, Ca2?, Mg2?, Na?, Cl?, F?, NO 3 ? , and SO 4 2? . Hydrology of spring’s water showed that the reserve forest has a higher water retention capacity than the other landscapes, and the spring recharge capacity highly influenced by the settlements, open grazing, mismanaged agricultural and deforestation activities. The spring water chemistry shows that the springs located in forest and sparsely populated areas have lower EC, TDS, cationic and anionic concentration and are safe for drinking purposes, but those in irrigated land and densely populated areas feature higher EC, low dissolved oxygen concentration and higher NO 3 ? , which makes the water of these springs unsuitable for drinking. F concentration was higher in the springs located in the settlement area. In brief, the study indicates that the unmanaged drains, very poor and old pattern of sewage disposing system result in an increase in Na?, Cl?, F?, NO 3 ? , and SO 4 2? concentration as compared to the springs in agricultural and forested areas. All of the studied springs are badly managed which a is great threat for the longevity and quality of the water bodies, in particular, in Indian Central Himalayan region. This study suggests the ways of the constructional works, grazing. Forest resource extraction and agricultural activities in water bodies catchments area should also be controlled.  相似文献   

10.
The apparent equilibrium constant, K 1 ′ , for the first acidity constant of carbonic acid has been determined in a lake water of 1.6 mM ionic strength in the temperature interval 4–18°C. The experimental method used comprises pH measurements in situ (NBS scale) with a probe and an IR-method for the selective determination of [H2CO3] and [HCO 3 ? ] in water samples. In the temperature interval studied the results can be described by the equation logK 1 ′ =126.39?6320.81/T?19.5682 ln T and are in agreement with the values of K 1 ′ obtained by the empirical equation presented by Millero [15]. This experimental agreement justifies thermodynamic calculations in the carbonate system based on field data. Also the experimental method described can be used to evaluate the acid-base balance of organic rich natural waters.  相似文献   

11.
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12.
A mathematical model of the middle and high latitude ionosphere   总被引：5，自引：0，他引：5  
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13.
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14.
This review summarizes direct and indirect analytical methods for the detection and quantification of the reactive oxygen species (ROS): 1O2, O 2 ·? /HOO·, H2O2, HO·, and CO 3 ·? in aqueous solution. Each section briefly describes the chemical properties of a specific ROS followed by a table (organized alphabetically by detection method, i.e., absorbance, chemiluminescence, etc.) summarizing the nature of the observable (associated analytical signal) for each method, limit of detection, application notes, and reaction of the probe molecule with the particular ROS.  相似文献   

15.
In the present study, a digital waveform dataset of 216 local earthquakes recorded by the Egyptian National Seismic Network (ENSN) was used to estimate the attenuation of seismic wave energy in the greater Cairo region. The quality factor and the frequency dependence for Coda waves and S-waves were estimated and clarified. The Coda waves (Q c) and S-waves (Q d) quality factor were estimated by applying the single scattering model and Coda Normalization method, respectively, to bandpass-filtered seismograms of frequency bands centering at 1.5, 3, 6, 12, 18 and 24?Hz. Lapse time dependence was also studied for the area, with the Coda waves analyzed through four lapse time windows (10, 20, 30 and 40?s). The average quality factor as function of frequency is found to be Q c?=?35?±?9f 0.9±0.02 and Q d?=?10?±?2f 0.9±0.02 for Coda and S-waves, respectively. This behavior is usually correlated with the degree of tectonic complexity and the presence of heterogeneities at several scales. The variation of Q c with frequency and lapse time shows that the lithosphere becomes more homogeneous with depth. In fact, by using the Coda Normalization method we obtained low Q d values as expected for a heterogeneous and active zone. The intrinsic quality factor (Q i ?1 ) was separated from the scattering quality factor (Q s ?1 ) by applying the Multiple Lapse Time Domain Window Analysis (MLTWA) method under the assumption of multiple isotropic scattering with uniform distribution of scatters. The obtained results suggest that the contribution of the intrinsic attenuation (Q i ?1 ) prevails on the scattering attenuation (Q s ?1 ) at frequencies higher than 3?Hz.  相似文献   

16.
Unloaded natural rock masses are known to generate seismic signals (Green et al., 2006; Hainzl et al., 2006; Husen et al., 2007; Kraft et al., 2006). Following a 1,000 m3 mass failure into the Mediterranean Sea, centimeter-wide tensile cracks were observed to have developed on top of an unstable segment of the coastal cliff. Nanoseismic monitoring techniques (Wust-Bloch and Joswig, 2006; Joswig, 2008), which function as a seismic microscope for extremely weak seismic events, were applied to verify whether brittle failure is still generated within this unconsolidated sandstone mass and to determine whether it can be detected. Sixteen days after the initial mass failure, three small-aperture sparse arrays (Seismic Navigation Systems-SNS) were deployed on top of this 40-m high shoreline cliff. This paper analyzes dozens of spiky nanoseismic (?2.2 ≥ M L ≥ ?3.4) signals recorded over one night in continuous mode (at 200 Hz) at very short slant distances (3–67 m). Waveform characterization by sonogram analysis (Joswig, 2008) shows that these spiky signals are all short in duration (>0.5 s). Most of their signal energy is concentrated in the 10–75 Hz frequency range and the waveforms display high signal similarity. The detection threshold of the data set reaches M L ?3.4 at 15 m and M L ?2.7 at 67 m. The spatial distribution of source signals shows 3-D clustering within 10 m from the cliff edge. The time distribution of M L magnitude does not display any decay pattern of M L over time. This corroborates an unusual event decay over time (modified Omori’s law), whereby an initial quiet period is followed by regained activity, which then fades again. The polarization of maximal waveform amplitude was used to estimate spatial stress distribution. The orientation of ellipses displaying maximal signal energy is consistent with that of tensile cracks observed in the field and agrees with rock mechanics predictions. The M L– surface rupture length relationship displayed by our data fits a constant-slope extrapolation of empirical data collected by Wells and Coppersmith (1994) for normal fault features at much larger scale. Signal characterization and location as well as the absence of direct anthropogenic noise sources near the monitoring site, all indicate that these nanoseismic signals are generated by brittle failure within the top section of the cliff. The atypical event decay over time that was observed suggests that the cliff material is undergoing post-collapse bulk strain accommodation. This feasibility study demonstrates the potential of nanoseismic monitoring in rapidly detecting, locating and analyzing brittle failure generated within unconsolidated material before total collapse occurs.  相似文献   

17.
The accumulation of data sets of past tsunamis is the most basic but reliable way to prepare for future tsunamis because the frequency of tsunami occurrence and their magnitude can be estimated by historical records of tsunamis. Investigation of tsunami deposits preserved in geological layers is an effective measure to understand ancient tsunamis that occurred before historical records began. However, the areas containing tsunami deposits can be narrower than the area of tsunami inundation, thus resulting in underestimation of the magnitude of past tsunamis. A field survey was conducted after the 2010 Chile tsunami and 2011 Japan tsunami to investigate the chemical properties of the tsunami-inundated soil to examine the applicability of tsunami inundation surveys considering water-soluble salts in soil. The soil and tsunami deposits collected in the tsunami-inundated areas are rich in water-soluble ions (Na+, Mg2+, Cl?, Br? and SO 4 2? ) compared with the samples collected in the non-inundated areas. The analytical result that the ratios of Na+, Mg2+, Br? and SO 4 2? to Cl? are nearly the same in the tsunami deposits and in the tsunami-inundated soil suggests that the deposition of these ions resulting from the tsunami inundation does not depend on whether or not tsunami deposits exist. Discriminant analysis of the tsunami-inundated areas using the ion contents shows the high applicability of these ions to the detection of tsunami inundation during periods when the amount of rainfall is limited. To examine the applicability of this method to palaeotsunamis, the continuous monitoring of water-soluble ions in tsunami-inundated soil is needed as a future study.  相似文献   

18.
A modified formula of the cumulative frequency-magnitude relation has been formulated and tested in a previous paper by the authors of this study. Based on the modified relationship, the following reoccurrence formulas have been obtained.
  1. For the ‘T-years period’ larger earthquake magnitude,M T $$M_T = \frac{1}{{A_3 }}ln\frac{{A_2 }}{{(1/T) + A_1 }}.$$
  2. For the value of the maximum earthquake magnitude, which is exceeded with probabilityP inT-years period,M PT $$M_{PT} = \frac{{ln(A_2 .T)}}{{A_3 }} - \frac{{ln[A_1 .T - ln(1 - P)]}}{{A_3 }}.$$
  3. For the probability of occurrence of an earthquake of magnitudeM in aT-years period,P MT $$P_{MT} = 1 - \exp [ - T[ - A_1 + A_2 \exp ( - A_3 M)]].$$
The above formulas provide estimates of the probability of reoccurrence of the largest earthquake events which are significantly more realistic than those based on the Gutenberg-Richter relationships; at least for numerous tested earthquake samples from the major area of Greece.  相似文献   

19.
We estimate the corner frequencies of 20 crustal seismic events from mainshock–aftershock sequences in different tectonic environments (mainshocks 5.7 < M W < 7.6) using the well-established seismic coda ratio technique (Mayeda et al. in Geophys Res Lett 34:L11303, 2007; Mayeda and Malagnini in Geophys Res Lett, 2010), which provides optimal stability and does not require path or site corrections. For each sequence, we assumed the Brune source model and estimated all the events’ corner frequencies and associated apparent stresses following the MDAC spectral formulation of Walter and Taylor (A revised magnitude and distance amplitude correction (MDAC2) procedure for regional seismic discriminants, 2001), which allows for the possibility of non-self-similar source scaling. Within each sequence, we observe a systematic deviation from the self-similar \( M_{0} \propto \mathop f\nolimits_{\text{c}}^{ - 3} \) line, all data being rather compatible with \( M_{0} \propto \mathop f\nolimits_{\text{c}}^{ - (3 + \varepsilon )} \) , where ε > 0 (Kanamori and Rivera in Bull Seismol Soc Am 94:314–319, 2004). The deviation from a strict self-similar behavior within each earthquake sequence of our collection is indicated by a systematic increase in the estimated average static stress drop and apparent stress with increasing seismic moment (moment magnitude). Our favored physical interpretation for the increased apparent stress with earthquake size is a progressive frictional weakening for increasing seismic slip, in agreement with recent results obtained in laboratory experiments performed on state-of-the-art apparatuses at slip rates of the order of 1 m/s or larger. At smaller magnitudes (M W < 5.5), the overall data set is characterized by a variability in apparent stress of almost three orders of magnitude, mostly from the scatter observed in strike-slip sequences. Larger events (M W > 5.5) show much less variability: about one order of magnitude. It appears that the apparent stress (and static stress drop) does not grow indefinitely at larger magnitudes: for example, in the case of the Chi–Chi sequence (the best sampled sequence between M W 5 and 6.5), some roughly constant stress parameters characterize earthquakes larger than M W ~ 5.5. A representative fault slip for M W 5.5 is a few tens of centimeters (e.g., Ide and Takeo in J Geophys Res 102:27379–27391, 1997), which corresponds to the slip amount at which effective lubrication is observed, according to recent laboratory friction experiments performed at seismic slip velocities (V ~ 1 m/s) and normal stresses representative of crustal depths (Di Toro et al. in Nature in press, 2011, and references therein). If the observed deviation from self-similar scaling is explained in terms of an asymptotic increase in apparent stress (Malagnini et al. in Pure Appl Geophys, 2014, this volume), which is directly related to dynamic stress drop on the fault, one interpretation is that for a seismic slip of a few tens of centimeters (M W ~ 5.5) or larger, a fully lubricated frictional state may be asymptotically approached.  相似文献   

20.
Non-Maxwellian ion velocity distribution functions have been theoretically predicted and confirmed by observations, to occur at high latitudes. These distributions deviate from Maxwellian due to the combined effect of the E×B drift and ion-neutral collisions. The majority of previous literature, in which the effect of ion self-collisions was neglected, established a clear picture for the ion distribution under a wide range of conditions. At high altitudes and/or for solar maximum conditions, the ion-to-neutral density ratio increases and, hence, the role of ion self-collisions becomes appreciable. A Monte Carlo simulation was used to investigate the behavior of O+ ions that are E×B-drifting through a background of neutral O, with the effect of O+ (Coulomb) self-collisions included. Wide ranges of the ion-to-neutral density ratio n i /n n and the electrostatic field E were considered in order to investigate the change of ion behavior with solar cycle and with altitude. For low altitudes and/or solar minimum (n i /n n \leq10?5), the effect of self-collisions is negligible. For higher values of n i /n n , the effect of self-collisions becomes significant and, hence, the non-Maxwellian features of the O+ distribution are reduced. For example, the parallel temperature T i\Vert increases, the perpendicular temperature T i⊥ decreases, the temperature anisotropy approaches unity and the toroidal features of the ion distribution function become less pronounced. Also, as E increases, the ion-neutral collision rate increases, while the ion-ion collision rate decreases. Therefore, the effect of ion self-collisions is reduced. Finally, the Monte Carlo results were compared to those that used simplified collision models in order to assess their validity. In general, the simple collision models tend to be more accurate for low E and for high n i /n n .  相似文献   

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