Performance of A Combination Process of UV/H2O2/Micro‐Aeration for Oxidation of Dichloroacetic Acid in Drinking Water

The decomposition of dichloroacetic acid (DCAA) in water using a UV/H₂O₂/micro‐aeration process was investigated in this paper. DCAA cannot be removed by UV radiation, H₂O₂ oxidation or micro‐aeration alone, while UV/H₂O₂/micro‐aeration combination processes have proved effective and can degrade this compound completely. With initial concentrations of about 110 μg/L, more than 95.1% of DCAA can be removed in 180 min under UV intensity of 1048.7 μW/cm², H₂O₂ dosage of 30 mg/L and micro‐aeration flow rate of 2 L/min. However, more than 30 μg/L of DCAA was left after 180 min by UV/H₂O₂ combination process without micro‐aeration with the same UV intensity and H₂O₂ dosage. The effects of applied UV radiation intensity, H₂O₂ dose, initial DCAA concentration and pH on the degradation of DCAA have been examined in this study. Degradation mechanisms of DCAA with hydroxyl radical oxidation have been discussed. The removal rate of DCAA was sensitive to operational parameters. There was a linear relationship between rate constant k and UV intensity and initial H₂O₂ concentration, which indicated that a higher removal capacity can be achieved by improvement of both factors. A newly found nitrogenous disinfection by‐product (N‐DBP)‐DCAcAm, which has the potential to form DCAA, was easier to remove than DCAA by UV/H₂O₂ and UV/H₂O₂/micro‐aeration processes. Finally, a preliminary cost comparison revealed that the UV/H₂O₂/micro‐aeration process was more cost‐effective than the UV/H₂O₂ process in the removal of DCAA from drinking water.     

曝气充氧对城市污染河道内源铵态氮释放的控制

以城市污染河道沉积物和上覆水为研究对象,利用模拟实验方法,探讨不同曝气充氧方式(水曝气EW、底泥曝气ES)对污染河道內源铵态氮(NH4+-N)释放的影响.研究结果发现:从间隙水和沉积物中NH4+-N的削减效果来看,底泥曝气均要优于水曝气;实验结束后,底泥曝气组沉积物与间隙水中NH4+-N含量分别减少63.39%和43.33%,水曝气组分别减少了7.54%和13.98%;从沉积物-水界面NH4+-N的扩散通量变化来看,水曝气组界面通量高于对照组,其变化规律与对照组相似;底泥曝气组沉积物-水界面NH4+-N扩散通量变化过程完全不同于其它两组,在整个试验周期内(除第5 d以外),底泥曝气组的通量低于水曝气组,在第15 d最低,为13.73 mg/(m2.d),仅为水曝气组和对照组的14.68%和19.93%,表明底泥曝气组沉积物NH4+-N的释放潜力低于水曝气组沉积物.     

A study on the characteristics of the information dimensionD 1 of the temporal and spatial distributions of earthquakes in an active fault zone

The research of the information dimension (D ₁) in an active fault zone considers the contribution of each seismic event to information and reflects the characteristics of the temporal and spatial distributions of earthquakes from a new point of view, avoiding some short-comings of the research about the capacity dimension (D ₀). The results of calculation show that the information dimension of the temporal distribution in Xianshuihe active fault zone before Luhuo large earthquake isD ₁=0.1051. It is a consult creterion of large earthquakes in future in the fault zone. The information dimensions of the temporal distribution of the earthquakes in Anninghe active fault zone are respectivelyD ₁(t _N)=0.1363 (for the north section) andD ₁(t _S)=0.06710 (for the south section). The information dimensions of the spatial distribution are respectivelyD ₁(K _N)=1.053 (for the north section) andD ₁(K _S)=0.7758 (for the south section). The north section and the south section belong to two self-similar systems with different information dimensions respectively. The extent of the self-organization of seismic activity in the south section is higher than that in the north section. This is helpful for us to judge the major dangerous section in the key region of the seismic monitoring. The research about the information dimension of the temporal and the spatial distributions of earthquakes is significant for the exploration of active fault zones and seismic prediction.     

Fracturing and hydrothermal alteration in normal fault zones

Large normal fault zones are characterized by intense fracturing and hydrothermal alteration. Displacement is localized in a slip zone of cataclasite, breccia and phyllonite surrounding corrugated and striated fault surfaces. Slip zone rock grades into fractured, but less comminuted and hydrothermally altered rock in the transition zone, which in turn grades abruptly into the wall rock. Fracturing and fluid flow is episodic, because permeability generated during earthquakes is destroyed by hydrothermal processes during the time between earthquakes.Fracture networks are described by a fracture fabric tensor (F). The permeability tensor (k) is used to estimate fluid transport properties if the trace of F is sufficiently large. Variations in elastic moduli and seismic velocities between fault zone and wall rock are estimated as a function of fracture density (). Fracturing decreases elastic moduli in the transition zone by 50–100% relative to the country rock, and similar or even greater changes presumably occur in the slip zone.P-andS-wave velocity decrease, andV _p /V _s increases in the fault zone relative to the wall rock. Fracture permeability is highly variable, ranging between 10^–13 m² and 10^–19 m² at depths near 10 km. Changes in permeability arise from variations in effective stress and fracture sealing and healing.Hydrothermal alteration of quartzo-feldspathic rock atT>300°C creates mica, chlorite, epidote and alters the quartz content. Alteration changes elastic moduli, but the changes are much less than those caused by fracturing.P-andS-wave velocities also decrease in the hydrothermally altered fault rock relative to the country rock, and there is a slight decrease inV _p /V _s , which partially offsets the increase inV _p /V _s caused by fracturing.Fracturing and hydrothermal alteration affect fault mechanics. Low modulus rock surrounding fault surfaces increases the probability of exceeding the critical slip distance required for the onset of unstable slip during rupture initiation. Boundaries between low modulus fault rock and higher modulus wall rock also act as rupture guides and enhance rupture acceleration to dynamic velocity. Hydrothermal alteration at temperatures in excess of 300°C weakens the deeper parts of the fault zone by producingphyllitic mineral assemblages. Sealing of fracture in time periods between large earthquakes generates pods of abnormally pressured fluid which may play a fundamental role in the initiation of large earthquakes.     

Variations in radon activity in the crustal fault zones: Spatial characteristics

The data of the profile gas emanation survey conducted on three spatial scales in separate regions of the Mongolia-Baikal seismic belt are generalized to establish the regularities of the spatially heterogeneous distribution of soil radon activity above the active faults in the Earth’s crust. It is shown that the shapes, sizes, and contrast of the near-fault radon anomalies are complicated by erosion and weathering; however, the critical role in their formation is played by the structural-geological controls, which determine the internal structure and recent activity of the fault zones. As a consequence, the cross-fault shape of the studied radon anomalies is vitally controlled by four structural situations, which correspond to the combinations of the structural type of the fault (localized/distributed) and the presence/absence of the fine filler material in the zone controlled by the fault. The cross-fault dimension of the emanation anomaly is commensurate or slightly larger than the width of the fault zone comprising all the fractures and joints associated with the formation of the main fault, which, due to the low permeability of the tectonites, is in most cases marked by the lowest concentration of soil radon. The contrast of the emanation anomalies, which we suggest to estimate in terms of a relative parameter K _Q , gravitates to certain levels of this parameter. This provides the basis for distinguishing five groups of the fault zones with low (K _Q ≤ 2), moderate (2 < K _Q ≤ 3), increased (3 < K _Q ≤ 5), high (5 < K _Q ≤ 10), and ultrahigh (K _Q > 10) radon activity. The previous studies show that for increasing the efficiency of the emanation survey in the fault zones, it is advisable to set up long profiles, reduce the measurement step in the vicinities of the main faults, specify the threshold of identifying the anomalies at the arithmetic mean level over the profile, and use the relative parameter K _Q for comparing and estimating the faults in terms of the intensity of their radon activity.     

A study on the characteristics of the information dimension D 1 of the temporal and spatial distributions of earthquakes in an active fault zone

The research of the information dimension (D ₁) in an active fault zone considers the contribution of each seismic event to information and reflects the characteristics of the temporal and spatial distributions of earthquakes from a new point of view, avoiding some short-comings of the research about the capacity dimension (D ₀). The results of calculation show that the information dimension of the temporal distribution in Xianshuihe active fault zone before Luhuo large earthquake isD ₁=0.1051. It is a consult creterion of large earthquakes in future in the fault zone. The information dimensions of the temporal distribution of the earthquakes in Anninghe active fault zone are respectivelyD ₁(t _N)=0.1363 (for the north section) andD ₁(t _S)=0.06710 (for the south section). The information dimensions of the spatial distribution are respectivelyD ₁(K _N)=1.053 (for the north section) andD ₁(K _S)=0.7758 (for the south section). The north section and the south section belong to two self-similar systems with different information dimensions respectively. The extent of the self-organization of seismic activity in the south section is higher than that in the north section. This is helpful for us to judge the major dangerous section in the key region of the seismic monitoring. The research about the information dimension of the temporal and the spatial distributions of earthquakes is significant for the exploration of active fault zones and seismic prediction. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 372–379, 1991. This paper is sponsored by the Chinese Joint Seismological Science Foundation. The English version is improved by Zhenwen An.     

Selection and scaling of earthquake records in assessment of structures in low-to-moderate seismicity zones

The behaviour of a building during an earthquake depends on many factors including the characteristics of the ground motion, the configuration and dynamic characteristics of the structure, the hysteretic behaviour of the structural components, the building's non-structural parts, and the local soil behaviour. When conducting seismic assessment studies, controlling the first factor involves selecting and scaling appropriate earthquake records. It is a common practice to scale the records to fit a target acceleration response S_a determined from a pre-determined spectrum or attenuation law. In doing so, two key-problems must be faced: (i) the value adopted for the “effective” period T₁,which lengthens as the structure enters the non-linear range, and (ii) the reliability of the reference value adopted for S_a(T₁). In this work, the influence of selecting appropriate values for these two parameters—T₁ and S_a(T₁)—on the response of the building is investigated from the study of two structures, of 4 and 8 stories. The study does not focus on evaluating a particular seismic code; rather, it uses a European attenuation model as the target spectrum. Non-linear dynamic response analyses are carried out to investigate the Collapse Prevention State of these structures subjected to records representative of a Performance-based Earthquake Engineering level characterized by 2% exceedence in 50 years with 2475 years of return time. The records are selected from a database of European earthquakes, and the failure of the structures is evaluated by statistical means. From the results of the analyses, it is proposed that in seismic assessment studies the reference period for scaling should be 1.1 times the fundamental period of the structure, and at least 30 records should be used to guarantee reliable results.     

Stress wave patterns and the size of the non-elastic zones of an explosive source

Summary The travel-time curves of characteristic moments of stress wave patterns were investigated. The arrival time of the onset of stress wavet ₀, of the maximum amplitudet ₁ and of the moment terminating the pressure part (the first half-wave) of this wavet ₂ were taken to be representative. These travel-time curves were used to determine the velocities of propagation of these moments (V ₀,V ₁ andV ₂) as functions of the distance from the source. According to their variations it is possible to appoint the size of the cavity created by the explosion and to determine the distance at which the elastic source surface of stress waves is to be found. The radius of the cavity is given by 1.5 times the distance at whichV ₁ separates fromV ₀. The elastic source surface of stress waves is defined by the distance from whichV ₀ is constant and at whichV ₁ andV ₂ have minimum values. These two distances determine the points at which the character of the stress wave pattern changes: from shock wave in gases, through shock wave in a solid medium to a seismic wave.Paper presented at the General Assembly of the European Seismological Commission, Luxembourg, Sept. 21–29, 1970.     

Elasticity of antigorite,seismic detection of serpentinites,and anisotropy in subduction zones

Serpentinization of the mantle wedge is an important process that influences the seismic and mechanical properties in subduction zones. Seismic detection of serpentines relies on the knowledge of elastic properties of serpentinites, which thus far has not been possible in the absence of single-crystal elastic properties of antigorite. The elastic constants of antigorite, the dominant serpentine at high-pressure in subduction zones, were measured using Brillouin spectroscopy under ambient conditions. In addition, antigorite lattice preferred orientations (LPO) were determined using an electron back-scattering diffraction (EBSD) technique. Isotropic aggregate velocities are significantly lower than those of peridotites to allow seismic detection of serpentinites from tomography. The isotropic V_P/V_S ratio is 1.76 in the Voigt–Reuss–Hill average, not very different from that of 1.73 in peridotite, but may vary between 1.70 and 1.86 between the Voigt and Reuss bonds. Antigorite and deformed serpentinites have a very high seismic anisotropy and remarkably low velocities along particular directions. V_P varies between 8.9 km s^? 1 and 5.6 km s^? 1 (46% anisotropy), and 8.3 km s^? 1 and 5.8 km s^? 1 (37%), and V_S between 5.1 km s^? 1 and 2.5 km s^? 1 (66%), and 4.7 km s^? 1 and 2.9 km s^? 1 (50%) for the single-crystal and aggregate, respectively. The V_P/V_S ratio and shear wave splitting also vary with orientation between 1.2 and 3.4, and 1.3 and 2.8 for the single-crystal and aggregate, respectively. Thus deformed serpentinites can present seismic velocities similar to peridotites for wave propagation parallel to the foliation or lower than crustal rocks for wave propagation perpendicular to the foliation. These properties can be used to detect serpentinite, quantify the amount of serpentinization, and to discuss relationships between seismic anisotropy and deformation in the mantle wedge. Regions of high V_P/V_S ratios and extremely low velocities in the mantle wedge of subduction zones (down to about 6 and 3 km.s^?1 for V_P and V_S, respectively) are difficult to explain without strong preferred orientation of serpentine. Local variations of anisotropy may result from kilometer-scale folding of serpentinites. Shear wave splittings up to 1–1.5 s can be explained with moderately thick (10–20 km) serpentinite bodies.     

MTBE in Drinking Water Production – Occurrence and Efficiency of Treatment Technologies

In Germany, the gasoline additive methyl tert‐butyl ether (MTBE) is almost constantly detected in measurable concentrations in surface waters and is not significantly removed during riverbank filtration. The removal of MTBE from water has been the focus of many studies that mostly were performed at high concentration levels and centred in understanding the mechanisms of elimination. In order to assess the performance of conventional and advanced water treatment technologies for MTBE removal in the low concentration range further studies were undertaken. Laboratory experiments included aeration, granulated activated carbon (GAC) adsorption, ozonation and advanced oxidation processes (AOP). The results show that the removal of MTBE by conventional technologies is not easily achieved. MTBE is only removed by aeration at high expense. Ozonation at neutral pH values did not prove to be effective in eliminating MTBE at all. The use of ozone/H₂O₂ (AOP) may lead to a partly elimination of MTBE. However, the ozone/H₂O₂ concentrations required for a complete removal of MTBE from natural waters is much higher than the ozone levels applied nowadays in waterworks. MTBE is only poorly adsorbed on activated carbon, thus GAC filtration is not efficient in eliminating MTBE. A comparison with real‐life data from German waterworks reveals that if MTBE is detected in the raw water it is most often found in the corresponding drinking water as well due to the poor removal efficiency of conventional treatment steps.     

城市湖泊不同水生植被区水体温室气体溶存浓度及其影响因素

为了解城市湖泊不同水生植被区水体温室气体的溶存浓度及其影响因素,于2015年4-11月按每月2次的频率采用顶空平衡法对聊城市铃铛湖典型植被区——菹草区、莲藕区和睡莲区表层水中CO₂、CH₄和N₂O的溶存浓度进行监测,计算水中温室气体的饱和度和排放通量,并测定水温（T）、pH、溶解氧（DO）、叶绿素a及营养盐浓度等理化指标,以探究水体环境因子对温室气体溶存浓度的影响.结果表明,铃铛湖各植被区水体温室气体均处于过饱和状态,是大气温室气体的"源";莲藕区CH₄浓度、饱和度和排放通量均显著高于菹草区,而各植被区N₂O和CO₂均无显著性差异;不同植被区湖水中DO、总氮（TN）、总磷（TP）和硝态氮（NO₃^--N）浓度具有显著差异,其中DO、TN和NO₃^--N浓度均表现为菹草区最高,莲藕区最低,而TP浓度则正好相反;各植被区温室气体浓度和水环境参数间的相关分析和多元回归分析的结果表明,水生植物可通过影响水体的理化性质对温室气体的产生和排放产生显著差异影响,在菹草区亚硝态氮（NO₂^--N）、NO₃^--N、T和DO是控制水体温室气体浓度的主要因子;睡莲区为TP和pH;莲藕区则为pH、NO₂^--N和DO.     

The geomagnetic field recorded in sediments of the Tuzla section (the Krasnodar Territory,Russia) over the time interval 120–70 ka

Petro-and paleomagnetic methods are applied to the study of the lower part of the Early Pleistocene Tuzla section on the Black Sea coast of the Taman Peninsula, This part of the section is composed of marine and lagoonal sediments deposited over the time interval 120–70 ka. The measured curves of the variation in the geomagnetic field inclination reveal an anomalous direction dated at ～110 ka that coincides with a similar anomalous direction in the Eltigen section (Ukraine) correlating with the Blake paleomagnetic event. The significant correlation between the time series NRM_0.015/SIRM_0.015 (Tuzla section) and the world composite Sint-800 curve indicates that the curve NRM_0.015/SIRM_0.015 in the interval 110–70 ka actually reflects the variation in the relative paleointensity of the geomagnetic field.     

Deep structure and tomographic imaging of strong earthquake source zones

This work generalizes the results of tomographic imaging performed by the authors for epicentral zones. Seismic events in North Africa (the M _w = 5.8 earthquake of 1985 near the town of Constantine), eastern Anatolia (the Erzincan M _w = 6.7 earthquake of 1992), the Lesser and Greater Caucasus (the 1988 Spitak M _w = 6.8 and the 1991 Racha M _w = 7.0 earthquakes), and northern Sakhalin (the 1995 Neftegorsk M _w = 7.1 earthquake) are examined. It is shown how various morphokinematic types of active faults differ in the resulting tomographic images at various depths. A classification of tomographic images of strong earthquake source zones is proposed in accordance with the rank of their generating faults. The sources of the Spitak, Racha, and Erzincan earthquakes are confined to large boundary faults separating tectonic zones. Lower velocity bands are revealed in the tomographic images, and low velocity “pockets” 1–2 km or somewhat more in width penetrating to a depth of up to 15 km are observed near the fault zones. The Constantine and Neftegorsk earthquakes were generated by faults of a lower rank. The source zones of these events are imaged tomographically as narrow gradient zones.     

Chemostratigraphy of the Ediacaran basinal setting on the Yangtze platform,South China: Oceanographic and diagenetic aspects of the carbon isotopic depth gradient

The Ediacaran Yangtze platform in South China, which represents depositional settings ranging from coastal to basinal, provides valuable information for understanding climate changes and animal evolution during the Ediacaran Period. Although the shallower settings have been investigated, research on the basinal sections has been limited. This has hampered efforts to establish stratigraphic correlations and understand the oceanographic setting of the Yangtze platform. In this paper, the chemostratigraphy of a basinal section at Fengtan, Hunan Province, is reported based on analyses of stable carbon isotope profiles in carbonates (δ¹³C_carb), organic matter (δ¹³C_org), total organic carbon, ⁸⁷Sr/⁸⁶Sr ratios, and Mn, Rb, and Sr concentrations. The basinal section of the Doushantuo Formation, which is represented at Fengtan, provides data supporting regional correlations and oceanography. Three intervals in the Doushantuo Formation are correlated with the Three Gorges: (i) a negative δ¹³C_carb anomaly with stable δ¹³C_org values and altered ⁸⁷Sr/⁸⁶Sr ratios in the lower section can be correlated to the boundary between Doushantuo Members 2 and 3 (Interval A); (ii) a relatively high δ¹³C_carb anomaly with unaltered ⁸⁷Sr/⁸⁶Sr ratios (up to 0.7086) in the middle section corresponding to the lower part of Doushantuo Member 3 (Interval B); and (iii) a negative δ¹³C_carb anomaly with lowered δ values in the upper section can be correlated to the long interval of negative δ¹³C_carb (Interval C). The Gaskiers glaciation is likely represented in Interval A, and Interval C corresponds to the Shuram excursion reported for other Ediacaran localities. Our correlations confirm the depth gradient of δ¹³C_carb in the Yangtze platform and imply that reductive conditions prevailed in the basinal section from the Early to Middle Ediacaran. Under such conditions, anaerobic degradation of organic carbon or methane perturbed the inorganic carbon isotopic compositions and was at least partly responsible for the depth gradient of δ¹³C_carb.     

Stochastic delineation of well capture zones

In this work, we describe a stochastic method for delineating well capture zones in randomly heterogeneous porous media. We use a moment equation (ME) approach to derive the time-dependent mean capture zones and their associated uncertainties. The mean capture zones are determined by reversely tracking the non-reactive particles released at a small circle around each pumping well. The uncertainty associated with the mean capture zones is calculated based on the particle displacement covariances for nonstationary flow fields. The flow statistics are obtained either by directly solving the flow moment equations derived with a first-order ME approach or from Monte Carlo simulations (MCS) of flow. The former constitutes a full ME approach, and the latter is a hybrid ME-MCS approach. This hybrid approach is invoked to examine the validity of the transport component of the stochastic method by ensuring that the ME and MC transport approaches have the same underlying flow statistics. We compared both the full ME and the hybrid ME-MCS results with those obtained with a full MCS approach. It has been found that the three approaches are in excellent agreement when the variability of hydrologic conductivity is small (_Y²=0.16). At a moderate variability (_Y²=0.5), the hybrid ME-MCS and the full MCS results are in excellent agreement whereas the results from the full ME approach deviate slightly from the full MCS results. This indicates that the (first-order) ME transport approach renders a good approximation at this level of variability and that the first-order ME flow approximation may not be sufficiently accurate at this variability in the case of divergent/convergent flow. The first-order ME flow approach may need to be corrected with higher-order terms even for moderate _Y² although the literature results reveal that the first-order ME flow approach is robust for uniform mean flow (i.e., giving accurate results even with _Y² as large as four).     

Variation of the magnetic properties in a basaltic dyke with concentric cooling zones

The effects of the variation of magnetic grain size on the magnetic properties of rocks have been studied throughout a reversely magnetized basaltic dyke with concentric cooling zones.Except in a few tachylites in which the magnetic mineral is a Ti-rich titanomagnetite, in the bulk of the dyke the magnetization is carried by almost pure magnetite grains. Although the percentage p of these magnetic oxides varies slightly, the large changes in the various magnetic parameters observed across the dyke are essentially attributable to large variations in the grain size of the magnetic particles.From the outer scoria region, where the magnetic grains are a mixture of single-domain (SD) and superparamagnetic (SP) grains, to the tachylite zone with finely crystallized basaltic glass containing interacting elongated SD particles, one observes an increase of both the ratio of the saturation remanent magnetization and the saturation induced magnetization J_rs/J_is, the bulk coercive force H_c, the median destructive field MDF, the intensity of the remanent magnetization J_r, and the Koenigsberger ratio Q. In the tachylites these parameters reach unusually high values, for subaerial basalts:

$\text{〈}\text{J}{}_{\mathrm{rs}}\text{J}{}_{\mathrm{is}}\text{〉 = 0.3, 〈H}{}_{\mathrm{c}}\text{〉 = 460 O}{}_{\mathrm{e}}\text{, 〈MDF〉 = 620 O}{}_{\mathrm{e}}\text{r.m.s., 〈J}{}_{\mathrm{r}}\text{〉 = 2.7 · 10}{}^{\mathrm{?2}}\text{e.m.u. cm}{}^{\mathrm{?3}}\text{〈Q〉 = 24}$

These parameters decrease in the basalt toward the centre of the dyke where pseudo-single-domain (pseudo-SD) particles coexist together with multidomain (MD) grains. The susceptibility remains approximately constant from the inner basalt to the tachylite, but increases in the scoria up to values 10 times higher owing to the presence of SP particles. The magnetic viscosity increases also drastically toward the margin of the dyke due to an increase of the fraction of the SD particles just above the superparamagnetic threshold.     

Characteristics of the seismic attenuation in two tectonically active zones of Southern Europe

The seismic energy attenuation in the frequency range of 1–18 Hz was studied in the two tectonically active zones of Irno Valley (Southern Italy) and Granada Basin (South-East Spain). Data were recorded by short period vertical components seismographs for low-magnitude local earthquakes. The method of coda waves, assuming singleS toS scattering approximation, was used to calculate the quality factorQ from the two data set. Results show a quality factor increasing with frequency, following the empirical lawQ=Q _o f ⁿ .Q _o andn are lower for the Irno Valley than for Granada. This result is interpreted in terms of different scattering environments present in the two investigated areas.     

Magnetostratigraphy of Upper Permian sediments in the southwestern slope of Pai-Khoi (Khei-Yaga River section): Evidence for the global Permian-Triassic crisis

The study of rock samples from the Upper Permian Khei-Yaga River section revealed an r-n-r-n-r magnetic polarity succession based on the prefolding characteristic component of natural remanent magnetization. With account for stratigraphic and previous magnetostratigraphic data on Lower Triassic rocks from the Khei-Yaga River section, the examined strata of the Pechora Group (Silova Formation) may be compared with magnetic zones R₁P₂u and N₁P₃t in the magnetostratigraphic scale of European Russia. The gap in the paleomagnetic record, which corresponds in the examined section to the interval of the mid-Severodvinian Stage to basal Induan Stage, Zone N₁T included, is estimated to be 10 Ma long. It is assumed that this hiatus represents one of the local signs of the global Permian-Triassic crisis.     

2004年以来长江中下游干流水体高锰酸盐指数时空变化分析

高锰酸盐指数是我国水环境质量评价和污染控制考核的重要指标,其浓度高低能反映水体受到有机物污染的严重程度.2003年三峡水库投入运行后,长江中下游干流水文情势发生了重大变化.为此,研究了长江中下游干流耗氧有机污染物的典型参数——高锰酸盐指数的时空变化特征.结果表明,长江中下游干流水体：2004年以来,高锰酸盐指数总体趋降,且目前已处于较低水平并趋于稳定;不同江段和水期高锰酸盐指数变化趋势不一致;耗氧有机污染物以溶解态为主,且溶解态所占比例沿程趋于降低,南津关、汉口、吴淞口下23 km断面溶解态占比中位值分别为0.862、0.734和0.598;可沉降颗粒物对水体中高锰酸盐指数浓度影响较低,尤其在研究河段上游段,悬浮颗粒中所含耗氧物质占总量比例中位值分别为0.138、0.266和0.402;上游江段水体同一监测断面不同测线和测点间高锰酸盐指数测定值差异不显著;河口段则存在显著差异,尤其是表层和底层之间;沿江城市江段近岸水域水体中耗氧物质污染程度较低,其澄清样中高锰酸盐指数均值在1.91～3.45 mg/L之间,仅局部城市江段和水期出现值高于6.0 mg/L的现象.     

Succession and global correlation of Late Tremadoc graptolite zones from South China

The Tremadocian is the first stage of the Ordovician System and is subdivided into two parts in general. The Upper Tremadocian, spanning a temporal interval of ca. 8 Ma, yields graptolite faunas crucial for biostratigraphic division and correlation in high resolution. Relatively complete successions of Upper Tremadoc graptolite zones have been proposed in Scandinavia, and North and South America. In South China, the coeval graptolite strata are widespread in deep water facies, but the successions of graptolite zones recognized so far are quite incomplete and thus very difficult to be correlated with those in other countries. In recent years, we have sampled bed by bed the Nanba section in the Yiyang area, Hunan Province and, below the Tetragraptus approximatus Zone, identified four Upper Tremadoc graptolite zones in descending order: the Hunnegraptus copiosus Zone, the Araneograptus murrayi Zone, the Aorograptus victoriae Zone and the Adelograptus tenellus Zone. To date, the Nanba section is the only section in China that presents a relatively complete and globally comparable succession of Upper Tremadoc graptolite zones. Therefore, this study not only confirms the existence of some Upper Tremadoc graptolite zones that were never found before in China, but also facilitates a highly resolved division and correlation for the Upper Tremadoc graptolite strata in China. Supported by National Natural Science Foundation of China (Grant No. 40472014)