The predictive value of various indicators of sperm for male fertility

Introduction. DNA fragmentation of sperm is one of the possible causes of reduced fertility potential of men. However, a significant correlation between conventional semen parameters and sperm DNA fragmentation was not found. This fact determines the relevance of the study of the influence of various parameters of sperm on male fertility.Materials and methods. The study included 60 men, aged 26–36 years (median – 30 years) with idiopathic infertility and the level of DNA fragmentation of sperm is higher than 15 %. These men were treated with hyperbaric oxygen therapy, after 3 months in vitro fertilization performed partners of these men. DNA fragmentation of sperm cells was determined by TUNEL (upper limit of normal – 15 %). The level of reactive oxygen species (ROS) of the ejaculate were determined by chemiluminescence (upper limit of normal – 0.64 mV/s).Results. The frequency of pregnancy in vitro fertilization was following: 62.8 and 64.7 % (p > 0.05) for the total number sperm of spermatozoa < 38 × 106 /ejaculate and ≥ 39 × 106 /ejaculate, respectively; 63.3 and 63.6 % (p > 0.05) for mobility (a + b) of spermatozoa < 40 and ≥ 40 %, respectively; 58.3 and 64.6 % (p > 0.05) for normal forms of spermatozoa < 4 and ≥ 4 %, respectively; 67.3 and 20.0 % (p < 0.05) for the level of DNA fragmentation of sperm ≤ 15 and > 15 %, respectively; 64.9 and 33.3 % (p < 0.05) for the level of ROS in semen ≤ 0.64 and > 0.64 mV/s, respectively.Conclusion. The probability of pregnancy after in vitro fertilization significantly depends on the levels of sperm DNA fragmentation in the sperm and level of ROS in semen

CREATING THE KULTUK POLYGON FOR EARTHQUAKE PREDICTION: VARIATIONS OF (234U/238U) AND 87SR/86SR IN GROUNDWATER FROM ACTIVE FAULTS AT THE WESTERN SHORE OF LAKE BAIKAL

Introduction. Determinations of (234U/238U) in groundwater samples are used for monitoring current deformations in active faults (parentheses denote activity ratio units). The cyclic equilibrium of activity ratio 234U/238U≈≈(234U/238U)≈γ≈1 corresponds to the atomic ratio ≈5.47×10–5. This parameter may vary due to higher contents of 234U nuclide in groundwater as a result of rock deformation. This effect discovered by P.I. Chalov and V.V. Cherdyntsev was described in [Cherdyntsev, 1969, 1973; Chalov, 1975; Chalov et al., 1990; Faure, 1989]. In 1970s and 1980s, only quite laborious methods were available for measuring uranium isotopic ratios. Today it is possible to determine concentrations and isotopic ration of uranium by express analytical techniques using inductively coupled plasma mass spectrometry (ICP‐MS) [Halicz et al., 2000; Shen et al., 2002; Cizdziel et al., 2005; Chebykin et al., 2007]. Sets of samples canbe efficiently analysed by ICP‐MS, and regularly collected uranium isotope values can be systematized at a new quality level for the purposes of earthquake prediction. In this study of (234U/238U) in groundwater at the Kultuk polygon, we selected stations of the highest sensitivity, which can ensure proper monitoring of the tectonic activity of the Obruchev and Main Sayan faults. These two faults that limit the Sharyzhalgai block of the crystalline basement of the Siberian craton in the south are conjugated in the territory of the Kultuk polygon (Fig 1). Forty sets of samples taken from 27 June 2012 to 28 January 2014 were analysed, and data on 170 samples are discussed in this paper.Methods. Isotope compositions of uranium and strontium were determined by methods described in [Chebykin et al., 2007; Pin et al., 1992] with modifications. Analyses of uranium by ISP‐MS technique were performed using an Agilent 7500ce quadrapole mass spectrometer of the Ultramicroanalysis Collective Use Centre; analyses of strontium were done using a Finnigan MAT 262 mass spectrometer of the Baikal Analytical Centre for Collective Use. A natural uranium isotope standard (GSO 7521‐99, Ural Electrochemical Plant, Novouralsk, Russia) and a strontium isotope standard (NBS 987) were used for quality control of the measurements.Results. The Kultuk polygon occupies large valleys of the Kultuchnaya, Angasolka, Talaya rivers and small valleys of the Medlyanka and Vorotny streams. The erosion basis of these valleys corresponds to the surface of Lake Baikal. In the valleys, there are several testing sites, including Staraya Angasolka, Slyudyanka, Vorotny, and Medlyanka. In the Kultuchnaya river valley, there are two sites, Tigunchikha and Verbny. Another two sites, Shkolny and Zemlyanichny, are located on slopes where no permanent water streams are available (Fig. 2). Measured U concentrations and(234U/238U) in water from the sites of the Kultuk polygon are placed in Table 1.Analysis and discussion of results. In water from an active fault, (234U/238U) depends on current deformation. The higher is the strain that causes fracturing, the higher is (234U/238U). The isotope composition of Sr sufficiently depends on the chemical weathering of rocks. The primary composition may be preserved in central parts of rock minerals and is detectable after preliminary treatment of an altered rock by HCl [Rasskazov et al., 2012]. In general, isotoperatios of U and Sr in groundwater and surface water depend on the composition of host rocks, weathering, and alkalinity. Dissolved uranium migrates as uranyl‐ion (UO22+) characterised by its highest degree of oxidation (+6). Reduced forms of U(+4) are practically water‐insoluble. Therefore, an indirect assessment of oxidation‐reduction properties of the medium can be based on uranium concentrations. For the Kultuk polygon, surface water with low (234U/238U) is divided by uranium content into two groups, with anomalously low (below 0.009 mkg/l), and medium (~0.5 mkg/l) concentrations of uranium (components from the Medlyanka river and Kultuchnaya river, respectively). The U abundances reflect relatively reduced conditions in group 1 and more oxidized in group 2. The higher (234U/238U) in the surface water with intermediate concentrations of uranium (0.009–0.500 mkg/l) may indicate the admixture of a groundwater component (Fig. 3). Figure 4 shows relations between surface water and groundwater components in the Kultuk polygon in terms of U content. In Figure 5, the field of data points of U and Sr isotope ratios in groundwater from the Kultuk polygon is contoured by curved lines that meet with each other at compositions corresponding to the end members E (87Sr/86Sr=0.7205, 234U/238U=1.0) and NE (87Sr/86Sr=0.70534, 234U/238U=3.3). Uranium ratios of the former and the latter components show equilibrium and the most nonequilibrium compositions, respectively. The field is characteristic of water samples from the rocks of the southern suture zone of the Siberian craton. Shift of the data points of water from stations 26 and 1310 to the right of this data field (i.e. with relative increasing 87Sr/86Sr) is due to lateral transition from the rocks of the suture zone to the Archean rocks of the Sharyzhalgai block (Fig. 6). The isotope systematics of uranium and strontium in the strongly nonequilibrium uranium segment is supplemented by the systematics of uranium in (234U/238U) vs. 1/U diagram (Fig. 7). The U composition in water from station 40 reflects a combination of processes that take place at station 27 (i.e. in the central part of the deformation system) and at station 38 (i.e. at its periphery). Approximately equal contents of uranium at the three above‐mentioned stations may reflect similar oxidization levels of the medium. In the Southern Baikal basin, the Irkutsk Seismic Station recorded an earthquake of class 11.2 on 08 January 2013 [Map…, 2013]. The earthquake epicentre was located near Listvyanka settlement (51.85° N, 105°16 E), at a distance of ~100 km from Kultuk settlement eastward of the Obruchev fault. On 24 April 2013, an earthquake of class 10 took place near Kultuk settlement. Another seismic event occurred on 07 June 2013 (Fig. 8). During the monitoring period, nine maximums and ten minimums of (234U/238U) were recorded at station 9, i.e. nine full cycles can be identified (Table 2). At station 9, amplitudes of the cycles exceed the measurement error by a factor of 2 to 4. In Fig. 9, at the curve showing temporal variations of (234U/238U) in water from station 9, deviations from similar curves for stations 11 and 8 are not marked. Curves of temporal variations of (234U/238U) in water from stations 40 and 27 are shown in Figure 10. At the first station (diagram а), there were three time intervals of monitoring: (1) 12 April 2013 to 04 July 2013, (2) 04 July 2013 to 21 October 2013, and (3) 21 October 2013 to 17 January 2014. The initial and final intervals are similar and show an abrupt decline of the curve with a clearly manifested drop of (234U/238U) in the middle part, a minimum and subsequent rise of the curve. The time interval between the compared periods of observation lasted 5–6 months. This middle interval marked a rapid increase of the average values of (234U/238U) in the range from 2.34 to 2.47 activity units with the average rate of about 0.2 units per year. In the curve of station 27, there is also a downward segment with a drop, a minimum and subsequent rise of the curve, which is partly coincident in time with the initial segments for station 40. Correlation in time is revealed between the earthquakes that occurred in the Kultuk polygon and the drops in the curves for the above‐mentioned stations. Considering the shape of the final segment of the curve based on observations at station 40, it could be expected that the drop in the downward curve should have been associated with earthquakes. However, no earthquakes took place. In this regard, attention should be paid to the fact that a concurrent drop lacks in the curve for station 27. This suggests that an earthquake would happen only in a case of co‐seismic (234U/238U) drops at both stations. Seismic processes are controlled by triggers that provide the synchronization effect. Self‐organization processes may be the cause of its manifestation. Intervals of synchronization of oscillations (similar to foreshock activation) are indicators of the unstable state of a seismic region [Sobolev et al., 2005]. Similar information of the transition to the pre‐seismogenic state can be obtained by analysing variations of (234U/238U) in water from active faults. In the initial monitoring stage, the deformation system of the Kultuk polygon (stations 8, 9 and 11) developed slowly, 110–170 days per cycle. The first indicators of the pre‐seismogenic state in the polygon were observed as a coincidence of the minimums in the cycles of all the stations on 16 March 2013. The first seismic event took place on 24 April 2013, i.e. 39 days after all the maximums coincided. In the period of the pre‐seismogenic state, relatively short cycles were manifested. The second seismic event occurred on 07 June 2013. It was reflected by the coincidence of the minimums of short cycles at stations 8, 9 and 40 (Fig. 11). The entire monitoring period at the Kultuk polygon can be divided into two time intervals starting from (1) 10 July 2012, and (2) 07 August 2013. The first time interval includes the preparation and occurrence of seismic events of class 10 in the polygon. In the second time interval, the deformation system was further developed, and a new seismogenic state became possible. The time interval from 10 July 2013 to 07 August 2013 includes three stages starting from (1) 10 July 2012, (2) 10 January 2013, and (3) 12 April 2013 (Fig. 12). Higher strain values along the line from station 8 to station 9 were accompanied by the occurrence of deformation along the line from station 40 to station 47 (submeridional direction at 14°), which resulted in the synchronization of (234U/238U) at these stations (Fig. 13). At the background of the chaotic state of the monitoring system of the Kultuk polygon, it is possible to distinguish sequential self‐organization phases from а to г as evidenced by the azimuthal synchronization of the stations. The spatial development of the recorded processes was represented the sequential seismogenic activation of the western termination of the Obruchev fault (Fig. 14). From the analyses of temporal variations of U concentrations (Fig. 15), we infer that the dynamics of uranium ingress into water was different at stations 9 and 8. In the initial monitoring stage, the background extremely high values of (234U/238U) and concentrations of uranium were inconsistent at stations 9 and 8. Later on, at station 9, episodes of the high mobility of uranium from the deformation zone alternated with episodes of the high mobility of uranium from the oxidation zone. At station 8, in the period from 26 October 2012 to 04 July 2013, uranium impulses took place occasionally in the deformation zone, and a few were combined with earthquakes of class 9 or 10. From 07 August 2013, the above‐mentioned impulses were replaced by uranium impulses from the oxidation zone. At this stage, an anomalous ingress of uranium was recorded.Conclusion. To validate the system of monitoring stations in the Kultuk polygon for earthquake prediction, spatial variations of (234U/238U) both in groundwater and surface water were studied. On sites of the tectonically stable areas, it was found that components of the surface runoff had admixtures of ground water components from the nearsurface water sources. On sites located at active faults, surface runoff components had admixtures of groundwater components from the deformation zone and oxidation zone. On sites located at active faults whereat permanent water streams lacked, the components from the deformation zone contained admixture of near‐surface ground water. The Sr–U‐isotopic systematics of groundwater at the Kultuk polygon was validated. Stations with high (234U/238U) (2.0–3.3activity units) and low 87Sr/86Sr (0.705341–0.712927) were selected for monitoring that lasted from 27 June 2012 to 28 January 2014. It was observed that (234U/238U) fluctuated in time, the duration of cycles and amplitudes of (234U/238U) fluctuations were variable, and the cycles of (234U/238U) in water were synchronized in the lines of the monitoring stations in the sublatitudinal and submeridional direction at the time intervals when seismic shocks occurred at the Kultuk polygon. The basic scenario of (234U/238U) variations in groundwater, recorded in the Kultuk polygon during the monitoring session, was examined in connection with the seismogenic activation of the western termination of the Obruchev fault. The SSE termination of the Main Sayan fault did not reveal any evidence on current tectonic deformations. The scenario of the reactivating Obruchev fault can be used for prediction of potential earthquakes in the Southern Baikal basin

РАЗРАБОТКА КУЛТУКСКОГО СЕЙСМОПРОГНОСТИЧЕСКОГО ПОЛИГОНА: ВАРИАЦИИ (234U/238U) И 87SR/86SR В ПОДЗЕМНЫХ ВОДАХ ИЗ АКТИВНЫХ РАЗЛОМОВ ЗАПАДНОГО ПОБЕРЕЖЬЯ БАЙКАЛА

Introduction. Determinations of (234U/238U) in groundwater samples are used for monitoring current deformations in active faults (parentheses denote activity ratio units). The cyclic equilibrium of activity ratio 234U/238U≈≈(234U/238U)≈γ≈1 corresponds to the atomic ratio ≈5.47×10–5. This parameter may vary due to higher contents of 234U nuclide in groundwater as a result of rock deformation. This effect discovered by P.I. Chalov and V.V. Cherdyntsev was described in [Cherdyntsev, 1969, 1973; Chalov, 1975; Chalov et al., 1990; Faure, 1989]. In 1970s and 1980s, only quite laborious methods were available for measuring uranium isotopic ratios. Today it is possible to determine concentrations and isotopic ration of uranium by express analytical techniques using inductively coupled plasma mass spectrometry (ICP‐MS) [Halicz et al., 2000; Shen et al., 2002; Cizdziel et al., 2005; Chebykin et al., 2007]. Sets of samples canbe efficiently analysed by ICP‐MS, and regularly collected uranium isotope values can be systematized at a new quality level for the purposes of earthquake prediction. In this study of (234U/238U) in groundwater at the Kultuk polygon, we selected stations of the highest sensitivity, which can ensure proper monitoring of the tectonic activity of the Obruchev and Main Sayan faults. These two faults that limit the Sharyzhalgai block of the crystalline basement of the Siberian craton in the south are conjugated in the territory of the Kultuk polygon (Fig 1). Forty sets of samples taken from 27 June 2012 to 28 January 2014 were analysed, and data on 170 samples are discussed in this paper.Methods. Isotope compositions of uranium and strontium were determined by methods described in [Chebykin et al., 2007; Pin et al., 1992] with modifications. Analyses of uranium by ISP‐MS technique were performed using an Agilent 7500ce quadrapole mass spectrometer of the Ultramicroanalysis Collective Use Centre; analyses of strontium were done using a Finnigan MAT 262 mass spectrometer of the Baikal Analytical Centre for Collective Use. A natural uranium isotope standard (GSO 7521‐99, Ural Electrochemical Plant, Novouralsk, Russia) and a strontium isotope standard (NBS 987) were used for quality control of the measurements.Results. The Kultuk polygon occupies large valleys of the Kultuchnaya, Angasolka, Talaya rivers and small valleys of the Medlyanka and Vorotny streams. The erosion basis of these valleys corresponds to the surface of Lake Baikal. In the valleys, there are several testing sites, including Staraya Angasolka, Slyudyanka, Vorotny, and Medlyanka. In the Kultuchnaya river valley, there are two sites, Tigunchikha and Verbny. Another two sites, Shkolny and Zemlyanichny, are located on slopes where no permanent water streams are available (Fig. 2). Measured U concentrations and(234U/238U) in water from the sites of the Kultuk polygon are placed in Table 1.Analysis and discussion of results. In water from an active fault, (234U/238U) depends on current deformation. The higher is the strain that causes fracturing, the higher is (234U/238U). The isotope composition of Sr sufficiently depends on the chemical weathering of rocks. The primary composition may be preserved in central parts of rock minerals and is detectable after preliminary treatment of an altered rock by HCl [Rasskazov et al., 2012]. In general, isotoperatios of U and Sr in groundwater and surface water depend on the composition of host rocks, weathering, and alkalinity. Dissolved uranium migrates as uranyl‐ion (UO22+) characterised by its highest degree of oxidation (+6). Reduced forms of U(+4) are practically water‐insoluble. Therefore, an indirect assessment of oxidation‐reduction properties of the medium can be based on uranium concentrations. For the Kultuk polygon, surface water with low (234U/238U) is divided by uranium content into two groups, with anomalously low (below 0.009 mkg/l), and medium (~0.5 mkg/l) concentrations of uranium (components from the Medlyanka river and Kultuchnaya river, respectively). The U abundances reflect relatively reduced conditions in group 1 and more oxidized in group 2. The higher (234U/238U) in the surface water with intermediate concentrations of uranium (0.009–0.500 mkg/l) may indicate the admixture of a groundwater component (Fig. 3). Figure 4 shows relations between surface water and groundwater components in the Kultuk polygon in terms of U content. In Figure 5, the field of data points of U and Sr isotope ratios in groundwater from the Kultuk polygon is contoured by curved lines that meet with each other at compositions corresponding to the end members E (87Sr/86Sr=0.7205, 234U/238U=1.0) and NE (87Sr/86Sr=0.70534, 234U/238U=3.3). Uranium ratios of the former and the latter components show equilibrium and the most nonequilibrium compositions, respectively. The field is characteristic of water samples from the rocks of the southern suture zone of the Siberian craton. Shift of the data points of water from stations 26 and 1310 to the right of this data field (i.e. with relative increasing 87Sr/86Sr) is due to lateral transition from the rocks of the suture zone to the Archean rocks of the Sharyzhalgai block (Fig. 6). The isotope systematics of uranium and strontium in the strongly nonequilibrium uranium segment is supplemented by the systematics of uranium in (234U/238U) vs. 1/U diagram (Fig. 7). The U composition in water from station 40 reflects a combination of processes that take place at station 27 (i.e. in the central part of the deformation system) and at station 38 (i.e. at its periphery). Approximately equal contents of uranium at the three above‐mentioned stations may reflect similar oxidization levels of the medium. In the Southern Baikal basin, the Irkutsk Seismic Station recorded an earthquake of class 11.2 on 08 January 2013 [Map…, 2013]. The earthquake epicentre was located near Listvyanka settlement (51.85° N, 105°16 E), at a distance of ~100 km from Kultuk settlement eastward of the Obruchev fault. On 24 April 2013, an earthquake of class 10 took place near Kultuk settlement. Another seismic event occurred on 07 June 2013 (Fig. 8). During the monitoring period, nine maximums and ten minimums of (234U/238U) were recorded at station 9, i.e. nine full cycles can be identified (Table 2). At station 9, amplitudes of the cycles exceed the measurement error by a factor of 2 to 4. In Fig. 9, at the curve showing temporal variations of (234U/238U) in water from station 9, deviations from similar curves for stations 11 and 8 are not marked. Curves of temporal variations of (234U/238U) in water from stations 40 and 27 are shown in Figure 10. At the first station (diagram а), there were three time intervals of monitoring: (1) 12 April 2013 to 04 July 2013, (2) 04 July 2013 to 21 October 2013, and (3) 21 October 2013 to 17 January 2014. The initial and final intervals are similar and show an abrupt decline of the curve with a clearly manifested drop of (234U/238U) in the middle part, a minimum and subsequent rise of the curve. The time interval between the compared periods of observation lasted 5–6 months. This middle interval marked a rapid increase of the average values of (234U/238U) in the range from 2.34 to 2.47 activity units with the average rate of about 0.2 units per year. In the curve of station 27, there is also a downward segment with a drop, a minimum and subsequent rise of the curve, which is partly coincident in time with the initial segments for station 40. Correlation in time is revealed between the earthquakes that occurred in the Kultuk polygon and the drops in the curves for the above‐mentioned stations. Considering the shape of the final segment of the curve based on observations at station 40, it could be expected that the drop in the downward curve should have been associated with earthquakes. However, no earthquakes took place. In this regard, attention should be paid to the fact that a concurrent drop lacks in the curve for station 27. This suggests that an earthquake would happen only in a case of co‐seismic (234U/238U) drops at both stations. Seismic processes are controlled by triggers that provide the synchronization effect. Self‐organization processes may be the cause of its manifestation. Intervals of synchronization of oscillations (similar to foreshock activation) are indicators of the unstable state of a seismic region [Sobolev et al., 2005]. Similar information of the transition to the pre‐seismogenic state can be obtained by analysing variations of (234U/238U) in water from active faults. In the initial monitoring stage, the deformation system of the Kultuk polygon (stations 8, 9 and 11) developed slowly, 110–170 days per cycle. The first indicators of the pre‐seismogenic state in the polygon were observed as a coincidence of the minimums in the cycles of all the stations on 16 March 2013. The first seismic event took place on 24 April 2013, i.e. 39 days after all the maximums coincided. In the period of the pre‐seismogenic state, relatively short cycles were manifested. The second seismic event occurred on 07 June 2013. It was reflected by the coincidence of the minimums of short cycles at stations 8, 9 and 40 (Fig. 11). The entire monitoring period at the Kultuk polygon can be divided into two time intervals starting from (1) 10 July 2012, and (2) 07 August 2013. The first time interval includes the preparation and occurrence of seismic events of class 10 in the polygon. In the second time interval, the deformation system was further developed, and a new seismogenic state became possible. The time interval from 10 July 2013 to 07 August 2013 includes three stages starting from (1) 10 July 2012, (2) 10 January 2013, and (3) 12 April 2013 (Fig. 12). Higher strain values along the line from station 8 to station 9 were accompanied by the occurrence of deformation along the line from station 40 to station 47 (submeridional direction at 14°), which resulted in the synchronization of (234U/238U) at these stations (Fig. 13). At the background of the chaotic state of the monitoring system of the Kultuk polygon, it is possible to distinguish sequential self‐organization phases from а to г as evidenced by the azimuthal synchronization of the stations. The spatial development of the recorded processes was represented the sequential seismogenic activation of the western termination of the Obruchev fault (Fig. 14). From the analyses of temporal variations of U concentrations (Fig. 15), we infer that the dynamics of uranium ingress into water was different at stations 9 and 8. In the initial monitoring stage, the background extremely high values of (234U/238U) and concentrations of uranium were inconsistent at stations 9 and 8. Later on, at station 9, episodes of the high mobility of uranium from the deformation zone alternated with episodes of the high mobility of uranium from the oxidation zone. At station 8, in the period from 26 October 2012 to 04 July 2013, uranium impulses took place occasionally in the deformation zone, and a few were combined with earthquakes of class 9 or 10. From 07 August 2013, the above‐mentioned impulses were replaced by uranium impulses from the oxidation zone. At this stage, an anomalous ingress of uranium was recorded.Conclusion. To validate the system of monitoring stations in the Kultuk polygon for earthquake prediction, spatial variations of (234U/238U) both in groundwater and surface water were studied. On sites of the tectonically stable areas, it was found that components of the surface runoff had admixtures of ground water components from the nearsurface water sources. On sites located at active faults, surface runoff components had admixtures of groundwater components from the deformation zone and oxidation zone. On sites located at active faults whereat permanent water streams lacked, the components from the deformation zone contained admixture of near‐surface ground water. The Sr–U‐isotopic systematics of groundwater at the Kultuk polygon was validated. Stations with high (234U/238U) (2.0–3.3activity units) and low 87Sr/86Sr (0.705341–0.712927) were selected for monitoring that lasted from 27 June 2012 to 28 January 2014. It was observed that (234U/238U) fluctuated in time, the duration of cycles and amplitudes of (234U/238U) fluctuations were variable, and the cycles of (234U/238U) in water were synchronized in the lines of the monitoring stations in the sublatitudinal and submeridional direction at the time intervals when seismic shocks occurred at the Kultuk polygon. The basic scenario of (234U/238U) variations in groundwater, recorded in the Kultuk polygon during the monitoring session, was examined in connection with the seismogenic activation of the western termination of the Obruchev fault. The SSE termination of the Main Sayan fault did not reveal any evidence on current tectonic deformations. The scenario of the reactivating Obruchev fault can be used for prediction of potential earthquakes in the Southern Baikal basin.Введение. Для отслеживания текущих деформаций в зонах активных разломов перспективны определения (234U/238U) в подземных водах (скобки обозначают единицы активности). Циклическое равновесие отношения активностей 234U/238U≈(234U/238U)≈γ≈1 соответствует атомному отношению ≈5.47×10–5. Вариации этого параметра могут быть обусловлены эффектом Чалова–Чердынцева – обогащением подземных вод нуклидом 234U в результате деформаций пород [Cherdyntsev, 1969, 1973; Chalov, 1975; Chalov et al., 1990; Faure, 1989]. В 1970–1980‐х гг. использовались трудоемкие методы измерения изотопных отношений урана. В настоящее время для измерений концентраций и изотопных отношений урана разрабатываются экспрессные методики с использованием метода масс‐спектрометрии с индуктивно связанной плазмой (ИСП–МС) [Halicz et al., 2000; Shen et al., 2002; Cizdziel et al., 2005; Chebykin et al., 2007]. Этим методом могут анализироваться серии проб, поэтому проблема сейсмопрогностического значения урановой изотопной систематики подземных вод в свете режимных наблюдений может быть выведена на качественно новый уровень. Настоящая работа по измерениям (234U/238U) в подземных водах преследует цель – выбрать на Култукском полигоне наиболее чувствительные станции для наблюдений активности Обручевского и Главного Саянского разломов, ограничивающих с юга Шарыжалгайский выступ кристаллического фундамента Сибирского кратона и сочленяющихся между собой на этой территории (рис. 1). Использованы данные, полученные для 170 проб из сорока серий, отобранных в период с 27 июня 2012 г. до 28 января 2014 г.Методика. Для определения изотопного состава урана и стронция в природных водах использовали модифицированные методики [Chebykin et al., 2007; Pin et al., 1992]. Аналитические исследования урана проводили методом ИСП–МС на квадрупольном масс-спектрометре Agilent 7500ce в центре коллективного пользования «Ультрамикроанализ», аналитические исследования стронция – на масс‐спектрометре Finnigan MAT 262 Байкальского аналитического центра коллективного пользования. Для контроля качества измерений применяли стандартный образец изотопного состава природного урана ГСО 7521‐99 (Уральский электрохимический комбинат, г. Новоуральск) и стандартный образец изотопного состава стронция NBS 987.Результаты. Култукский полигон охватывает сравнительно крупные бассейны речек Култучная, Ангасолка и Талая, а также небольшие бассейны ручьев Медлянка и Воротный. Базису эрозии в этих бассейнах соответствует зеркало оз. Байкал. В бассейнах выделяются участки опробования: Старая Ангасолка, Слюдянка, Воротный, Медлянка, в бассейне р. Култучная – два участка, Тигунчиха и Вербный. Еще два участка, Школьный и Земляничный, находятся на склонах, лишенных постоянных водотоков (рис. 2). Результаты измерений концентраций U и (234U/238U) в водах участков Култукского полигона приведены в табл. 1.Анализ результатов и обсуждение. В воде активных разломов (234U/238U) зависит от текущих деформаций. Чем выше деформации, вызывающие образование трещин, тем выше (234U/238U). Изотопный состав Sr существенно зависит от химического выветривания породы. Его первичный состав может сохраниться в центральных частях минералов породы и выявляется посредством предварительной обработки пробы измененной породы раствором соляной кислоты [Rasskazov et al., 2012]. В целом изотопные отношения U и Sr в подземных и поверхностных водах меняются в зависимости от состава вмещающих пород, степени их выветривания и щелочности. Растворенный уран мигрирует в виде уранил‐иона UO22+, в котором он находится в своей высшей степени окисления (+6). Восстановленные формы U(+4) практически не растворимы в воде, поэтому по концентрации урана в воде можно делать косвенную оценку окислительно‐восстановительных свойств среды. Поверхностные воды Култукского полигона с низкими (234U/238U) разделяются на группу с аномально низкими концентрациями урана (менее 0.009 мкг/л, компонент р. Медлянка) и группу с умеренными концентрациями урана (~0.5 мкг/л, компонент р. Култучная). Состав урана первой группы отражает резко восстановительные условия, второй – более окислительные. Возрастание (234U/238U) в поверхностных водах с промежуточными концентрациями урана (0.009–0.5 мкг/л) может свидетельствовать о примеси компонента подземных вод (рис. 3). Рис. 4 иллюстрирует соотношения компонентов поверхностных и подземных вод Култукского полигона по составу урана. На рис. 5 поле фигуративных точек изотопных отношений U и Sr в водах Култукского полигона ограничивается кривыми линиями, сходящимися между собой в точках, соответствующих конечным компонентам E иNE. В первом уран находится в изотопном равновесии (equilibrium U, 87Sr/86Sr = 0.7205, (234U/238U)=1.0), во втором – имеет сильно неравновесный состав (nonequilibrium U, 87Sr/86Sr = 0.70534, (234U/238U)=3.3). Область этих точек характеризует воды из пород южной шовной зоны Сибирского кратона. Смещение фигуративных точек вод ст. 26 и 1310 правее этой области (т.е. с относительным обогащением радиогенным Sr) обусловлено латеральной сменой пород шовной зоны архейскими породами Шарыжалгайского блока Сибирского кратона (рис. 6). Изотопная систематика урана и стронция сегмента сильнонеравновесного U дополняется систематикой урана в координатах (234U/238U) – 1/U (рис. 7). Состав урана в водах ст. 40 отражает сочетание процессов, протекающих на ст. 27, в центре деформационной системы, и на ее периферии, на ст. 38. Приблизительно равные содержания U на всех трех станциях могут отражать близкую степень окисленности среды. По данным Иркутской сейсмической станции [Map…, 2013], в течение начального периода исследований вод в районе Южно‐Байкальской впадины признак активизации проявился 08.01.2013 г. в землетрясении класса 11.2 с эпицентром рядом с пос. Листвянка (51.85° с.ш., 105°16 в.д.), на удалении от пос. Култук на ~100 км к востоку вдоль Обручевского разлома. Затем, 24.04.2013 г., произошло землетрясение класса 10 в районе пос. Култук. Новая сейсмическая активизация имела место 07.06.2013 г. (рис. 8). За все время наблюдений на ст. 9 выделилось 9 максимумов и 10 минимумов (234U/238U), составляющих 9 полных циклов (табл. 2). Амплитуды циклов на этой станции превышают ошибку измерений в 2–4 раза. На рис. 9 приводится график временных вариаций (234U/238U) в водах ст. 9 без обозначения ошибок в сопоставлении с подобными графиками для ст. 11 и 8. На рис. 10 приводятся графики временных вариаций (234U/238U) в водах ст. 40 и 27. Временной интервал наблюдений на первой станции (диаграмма а) разделяется на три отрезка: 1) 12.04.–04.07.2013 г., 2) 04.07–21.10.2013 г. и 3) 21.10.2013–17.01.2014 г. Начальный и конечный отрезки сходны между собой по резкомуснижению кривой с четко выраженной ступенью (234U/238U) в средней части, минимумом и последующим поднятием кривой. Временной интервал между сопоставимыми частями этих отрезков составлял 5–6 месяцев. Промежуточный отрезок обозначил крутой рост средних значений (234U/238U) в диапазоне 2.34–2.47 ед. активности со средней скоростью около 0.2 ед./год. На ст. 27 также выделяется отрезок нисходящей кривой со ступенью, минимумом и восходящей кривой, частично совпадающий по времени с начальным отрезком ст. 40. Землетрясения Култукского полигона пришлись на согласующиеся во времени ступенчатые части кривых этих станций. По сходной конфигурации линии конечного отрезка наблюдений ст. 40 можно было бы предположить, что образование ступени на нисходящей кривой должно было также сопровождаться землетрясениями. Однако землетрясений не произошло. В связи с этим мы обращаем внимание на отсутствие одновременного проявления ступенчатой конфигурации на ст. 27. По‐видимому, для реализации сейсмического события косейсмическая ступень должна быть выражена на обеих станциях. Сейсмические процессы контролируются триггерами, обеспечивающими эффект синхронизации. Причиной его проявления могут быть процессы самоорганизации. Интервалы синхронизации колебаний, подобно форшоковой активизации, являются признаками неустойчивого состояния сейсмоактивной области [Sobolev et al., 2005]. Подобную информацию о переходе в предсейсмогенное состояние можно получить из анализа вариаций (234U/238U) в водах из активных разломов. В начальный интервал наблюдений деформационная система Култукского полигона (станции 8, 9 и 11) развивалась медленно, с периодичностью 110–170 дней/цикл. Первые признаки предсейсмогенного состояния на полигоне обозначились совмещением минимумов в циклах всех станций 16.03.2013 г. После общего совмещения минимумов через 39 дней произошло первое сейсмическое событие (24.04.2013 г.). В предсейсмогенном состоянии стали проявляться сравнительно короткие периоды циклов. Второе сейсмическое событие (07.06.2013 г.) отразилось в совмещении минимумов короткопериодных циклов станций 8, 9 и 40 (рис. 11). Время наблюдений на Култук