Establishing and validation of a standard for oil content of bottom sediments in surface water bodies     

L. V. Mikhailova  E. A. Isachenko-Bome 《Water Resources》2012,39(5):564-575

Model experiments with oil-polluted bottom sediments and aquatic organisms (bacteria, protozoa, rooted plants, worms, maggots insects, mollusks, crustaceans, benthos-eating fish), whose life cycle is associated with the bed of water bodies, where used to establish the lethal, sublethal, and threshold concentrations, as well as the maximal allowable oil concentration in bottom sediments as a standard established basing on the response of most sensitive test-organisms. The established standard??0.02 g/kg absolutely dry bottom sediment??was validated in rivers of the Ob basin and approved as a regional standard for water bodies of Khanty-Mansi Autonomous Area (Yugra).  相似文献   

Extreme hydrological events in the Danube River basin over the last decades     

M. V. Mikhailova  V. N. Mikhailov  V. N. Morozov 《Water Resources》2012,39(2):161-179

The article discusses the considerable changes in hydrometeorological conditions that occurred in the Danube River basin over the period from the late XX century to the early XXI century. Mention is made of the air and water temperature rise, softening of ice conditions, and, above all, the noticeable increase in the river water runoff. Particular attention is given to the recent extreme hydrological events in the Danube River basin: the disastrous rainfall flood that occurred in August 2002, the extremely high spring-summer floods in 2006 and 2010, and the extraordinary low-flow period in summer 2003. The meteorological reasons for these events have been analyzed. Specific features in the development and transformation of flood waves along the Danube River are discussed in detail, including the impact of the Iron Gate-1 Reservoir on these processes.  相似文献   

The response of river mouths to large-scale variations in sea level and river runoff: Case study of rivers flowing into the Caspian Sea     

V. N. Mikhailov  D. V. Magritsky  V. I. Kravtsova  M. V. Mikhailova  M. V. Isupova 《Water Resources》2012,39(1):11-43

Regularities in the response of the mouths of major rivers, flowing into the Caspian Sea, to large-scale variations in its level and river water runoff and sediment yield are considered. Changes in the morphological structure and hydrological regime of the Volga, Terek, Sulak, Ural, and Kura mouths have been analyzed in both geological past and separately for three modern periods: a considerable drop in Caspian Sea level before 1978, its abrupt rise in 1978–1995, and a relative stabilization in the subsequent years. Specific features were identified in the hydrological-morphological processes in different mouths, caused by the differences in river sediment yields, and the slopes of delta surface and mouth nearshore beds. Some theoretical and methodological approaches were verified in the analysis and evaluation of the processes under consideration. The obtained results of studies of the mouths of rivers flowing into the Caspian Sea can be regarded as examples and analogues in the assessment of processes, which take place at the mouths of other Russian and world rivers at present and can take place in the future under anticipated natural and anthropogenic variations in sea level and river runoff.  相似文献   

Locations and magnitudes of earthquakes in Central Asia from seismic intensity data     

D. Bindi  S. Parolai  A. Gómez-Capera  M. Locati  Z. Kalmetyeva  N. Mikhailova 《Journal of Seismology》2014,18(1):1-21

We apply the Bakun and Wentworth (Bull Seism Soc Am 87:1502–1521, 1997) method to determine the location and magnitude of earthquakes occurred in Central Asia using MSK-64 intensity assignments. The attenuation model previously derived and validated by Bindi et al. (Geophys J Int, 2013) is used to analyse 21 earthquakes that occurred over the period 1885–1964, and the estimated locations and magnitudes are compared to values available in literature. Bootstrap analyses are performed to estimate the confidence intervals of the intensity magnitudes, as well as to quantify the location uncertainty. The analyses of seven significant earthquakes for the hazard assessment are presented in detail, including three large historical earthquakes that struck the northern Tien-Shan between the end of the nineteenth and the beginning of the twentieth centuries: the 1887, M 7.3 Verny, the 1889, M 8.3 Chilik and the 1911, M 8.2 Kemin earthquakes. Regarding the 1911, Kemin earthquake the magnitude values estimated from intensity data are lower (i.e. MI_LH?=?7.8 and MI_W?=?7.6 considering surface wave and moment magnitude, respectively) than the value M?=?8.2 listed in the considered catalog. These values are more in agreement with the value M _S?=?7.8 revised by Abe and Noguchi (Phys Earth Planet In, 33:1–11, 1983b) for the surface wave magnitude. For the Kemin earthquake, the distribution of the bootstrap solutions for the intensity centre reveal two minima, indicating that the distribution of intensity assignments do not constrain a unique solution. This is in agreement with the complex source rupture history of the Kemin earthquake, which involved several fault segments with different strike orientations, dipping angles and focal mechanisms (e.g. Delvaux et al. in Russ Geol Geophys 42:1167–1177, 2001; Arrowsmith et al. in Eos Trans Am Geophys Union 86(52), 2005). Two possible locations for the intensity centre are obtained. The first is located on the easternmost sub-faults (i.e. the Aksu and Chon-Aksu segments), where most of the seismic moment was released (Arrowsmith et al. in Eos Trans Am Geophys Union 86(52), 2005). The second location is located on the westernmost sub-faults (i.e. the Dzhil'-Aryk segment), close to the intensity centre location obtained for the 1938, M 6.9 Chu-Kemin earthquake (MI_LH?=?6.9 and MI_W?=?6.8).  相似文献   

Hydrological-morphological processes in the mouth area of the Orinoco (Venezuela)     

M. V. Mikhailova 《Water Resources》2010,37(2):160-171

The peculiarities of the hydrological regime of the Orinoco River and the coastal zone of the Atlantic Ocean that affect the hydrological-morphological processes in the mouth area of the Orinoco River are considered. The major features of the delta water regime, including its inundation, runoff distribution over the delta branches, water and sediment balance, and the processes of river and sea water mixing are described. Special attention is paid to the morphological processes at the Orinoco mouth (delta evolution and modern processes at its coastline).  相似文献   

Many-year variations in river delta structures     

M. V. Mikhailova 《Water Resources》2016,43(5):766-778

Data on several river deltas are used to analyze the regularities in their dynamics in the context of variations of water and sediment runoff, sea level, and hydroengineering activities in delta areas. The basis for this analysis includes the results of many-year studies of river deltas in Russia and the world. The specific features of the evolution of the structure and morphometry of bayhead deltas, forming in bays, lagoons, and estuaries are shown in the case of the Alikazgan delta in the Terek mouth area and the deltas of two watercourses in the Mississippi mouth area. Data on many-year variations of the morphometric characteristics of modern protruding deltas in open coastal zones are systematized, and the factors that have an effect on these changes are analyzed. The types of delta formation processes and the types of deltas are considered with regard to the factors involved. The majority of modern river deltas are found to slow down their progradation into seas under the effect of anthropogenic runoff decline; moreover, some deltas have started retreating and degrading.  相似文献   

Heterogeneities in the mantle transition zone from observations of P-to-SV converted waves     

L.P. Vinnik  R.A. Avetisjan  N.G. Mikhailova 《Physics of the Earth and Planetary Interiors》1983,33(3):149-163

The method of detection of P-to-SV converted waves from distant earthquakes (Vinnik, 1977) was applied to sets of long-period records from a few seismograph stations in Europe and the west of North America. The results obtained suggest that the converted phases related to the major boundaries in the mantle can be reliably detected and the depths of conversion evaluated with an accuracy of a few kilometres. The depth of the olivine-spinel transition is close to 400 km and no difference between the estimates for the north of Europe and the west of North America is found. The depth of the boundary separating the upper and lower mantle is close to 640 km, which is 30 km less than in the recent Earth-reference models. Fine S velocity stratification of this transition changes laterally from a high-gradient layer 50 km thick, terminated at the bottom by a sharp discontinuity, to a gradient layer 100 km or more thick without the discontinuity. A striking anomaly of the mantle transition zone is found in the Rio Grande rift area where a well pronounced boundary is found at 510 km depth.  相似文献   

Internal and External Water Exchange in Nontidal River Deltas     

Mikhailova  M. V.  Isupova  M. V. 《Water Resources》2019,46(6):825-831

Water Resources - The types and specific features of the internal and external water exchange in nontidal deltas are discussed. The results of hydraulic calculation of water exchange in the...  相似文献   

Effects of strong earthquakes in variations of electrical and meteorological parameters of the near-surface atmosphere in Kamchatka region     

S. E. Smirnov  G. A. Mikhailova  Yu. M. Mikhailov  O. V. Kapustina 《Geomagnetism and Aeronomy》2017,57(5):610-617

The diurnal variations in electrical (quasistatic electric field and electrical conductivity) and meteorological (temperature, pressure, relative humidity of the atmosphere, and wind speed) parameters, measured simultaneously before strong earthquakes in Kamchatka region (November 15, 2006, М = 8.3; January 13, 2007, М = 8.1; January 30, 2016, М = 7.2), are studied for the first time in detail. It is found that a successively anomalous increase in temperature, despite the negative regular trend in these winter months, was observed in the period of six–seven days before the occurrences of earthquakes. An anomalous temperature increase led to the formation of “winter thunderstorm” conditions in the near-surface atmosphere of Kamchatka region, which was manifested in the appearance of an anomalous, type 2 electrical signal, the amplification of and intensive variations in electrical conductivity, heavy precipitation (snow showers), high relative humidity of air, storm winds, and pressure changes. With the weak flow of natural heat radiation in this season, the observed dynamics of electric and meteorological processes can likely be explained by the appearance of an additional heat source of seismic nature.  相似文献