Transient heterogeneity in an aquifer undergoing bioremediation of hydrocarbons

Localized, transient heterogeneity was studied in a sand aquifer undergoing benzene, toluene, ethylbenzene, and xylene bioremediation using a novel array of multilevel, in situ point velocity probes (PVPs). The experiment was conducted within a sheet-pile alleyway to maintain a constant average flow direction through time. The PVPs measured changes in groundwater velocity direction and magnitude at the centimeter scale, making them ideal to monitor small-scale changes in hydraulic conductivity (K). Velocities were shown to vary nonuniformly by up to a factor of 3 when a source of oxygen was established down-gradient of the petroleum spill. In spite of these local variations, the average groundwater velocity within the 7 m × 20 m sheet-piled test area only varied within ± 25%. The nonuniform nature of the velocity variations across the gate indicated that the changes were not due solely to seasonal hydraulic gradient fluctuations. At the conclusion of the experiment, microbial biomass levels in the aquifer sediments was approximately 1 order of magnitude higher in the oxygen-amended portion of the aquifer than at the edge of the plume or in locations up-gradient of the source. These data suggest that the transient velocities resulted, at least in part, from enhanced biological activity that caused transient heterogeneities in the porous medium.     

Influence of multiple stressors on the auto-remediation processes occurring in salt marshes

Due to increasing global population, salt marshes have been subjected to multiple stressors such as increasing nutrient loadings and historical contamination. In order to better understand how does the salt marsh plants auto-remediation capacity (phytoaccumulation of metals) is affected by cultural eutrophication, an experiment was performed under controlled conditions. Plants were exposure to equal metal concentrations (Zn, Cu, and Ni - micronutrients, and Cd - class B metal) simulating historical contamination and three different concentrations of nitrogen (nitrate) simulating steps of cultural eutrophication. According to our study, under the tested concentrations, cultural eutrophication does not seem to affect Zn, Cu and Ni phytoremediation of H. portulacoides, but the ecosystem service of Cd phytoremediation seems to be promoted. Nevertheless, Cd high toxicity and bioaccumulation should be taken into account, as well as the vulnerability of salt marsh ecosystems, whose reduction will have drastic consequences to the ecosystem health.     

Structural Traces of Secondary Faults (Fractures) along the Main Faults and Their Reliability as Kinematic Indicators

Secondary/minor structures occurring along the main fault surfaces are important indicators for judging the kinematic characteristics of faults. However, many factors can lead to the formation of these structures, which results in the difficulty for rapid judgment and application in the fields. A series of secondary faults/fractures developed due to the movement of main faults are the most important and widespread phenomena in the scope of brittle deformation. The morphology of the main fault surfaces is various, and former researchers mainly discussed the structures on the main even fault surfaces. However, the fluctuation of fault surfaces is the intrinsic character of the faults, and the intersection between the main fault and secondary faults/fractures can produce a series of kinematic indicators on the main fault surfaces. Based on previous studies and our observations, i.e. the structural traces of the P, R, R’, T and X shears/faults along the main faults, some indicators which are rarely reported previously, are described in the paper. Furthermore, their reliabilities are also discussed, and more practical and reliable criteria are brought forward. We suggest that the simple application of congruous and incongruous steps without knowing their exact origins should be abandoned in the fields, and several types of indicators along one fault surface should be checked with each other as much as possible. Meanwhile, the origins of some other arcuate indicators on the fault surfaces are also discussed, and new models are brought forward.     

A New Three–Dimensional Superstructure in Bafertisite

A new superstructure was found in bafertisite [(Ba0.98Na0.02)1.00(Fe1.71Mn0.26Mg0.01)1.98 TiO[(Si1.82Ti0.04Al0.03Cr0.01)1.90O7](OH1.40F0.53Cl0.03)1.96] from Donghai County, Jiangsu Province, China. The occurrence of the superstructure reflections were observed by single crystal diffraction using a SMAR APEX CCD. The a*, b*and c* axis directions revealed extra weak reflection spots of the superstructure. The apparent 2a, 2b and 2c superstructure is monoclinic with unit cell a＝10.6502(15)?, b＝13.7233(19)?, c＝21.6897(3)?, α＝90o, β＝94.698(3)o, γ＝90o,space group Cm,Z=16. If c* extra weak reflections are ignored, the secondary supercell gave a cell a＝10.6548(15)?, b＝13.7284(19)?, c＝11.6900(17)?, α＝90o, β＝112.322(28)o, γ＝90o,space group Cm,Z=8. The basic subcell was obtained by ignoring all extra weak reflection spots and gave: a＝5.3249(17)?, b＝6.8669(22)?, c＝10.8709(36)?, α＝90o, β＝94.740(62)o, γ＝90o,space P21/m,Z=2. The superstructure has been refined to R = 0.063 for 7805 [R(int) = 0.0266] unique reflections I>2δ(I). The structure consists of an octahedra (O) sheet sandwiched between two heteropolyhedral (H) sheets. These sheets consist of Ti–octahedra and twin tetrahedral disilicate groups [Si2O7]. The O sheet comprises (Fe,Mg)O4 octahedra. The large Ba cation is located in the interlayer area. The refined structure shows Fe, Mg are partly ordered. The shifting of the TiO6 octahedron and SiO4 tetrahedron sites in the sheet may be a consequence of the superstructure.     

Effects of residual chlorine on the mortality, grazing and respiration of Labidocera euchaeta (Copepoda)

In this study,the authors investigated the effects of residual chlorine on mortality,grazing and respiration of Labidocera euchaeta in laboratory.The grazing rate was evaluated by subtraction method of food concentration and respiration rate was measured using oxygen electrode.It was found that the lethal effect of residual chlorine on L.euchaeta increased with enhanced concentration and prolonged duration.The medium lethal concentration (LC 50 ) of chlorine for L.euchaeta in 24 h was about 0.58 mg/L and the safe concentration was about 0.21 mg/L.However,the grazing and respiration of L.euchaeta decreased by 32.6% and 18.9% when exposed to 0.2 mg/L residual chlorine for 4 h.It indicated that the physiological activities of zooplankton could be suppressed by the residual chlorine less than the safety concentration.Therefore,both survival and physiological activities of the organisms living in the thermal (nuclear) power plant discharging waters should be considered when carrying out the ecological risks assessment.     

The Effects of Assimilating Satellite Brightness Temperature and Bogus Data on the Simulation of Typhoon Kalmaegi (2008)

Observational and bogus satellite data are directly assimilated into the Weather Research and Forecasting (WRF) model in simulations of Typhoon Kalmaegi (2008). The data assimilation is performed using the Radiative Transfer for TIROS-N Operational Vertical Sounder (RTTOV) model and the three-dimensional variational data assimilation (3DVAR) technique, with satellite observations taken from the National Oceanic and Atmospheric Administration-16 (NOAA-16) Advanced TIROS Vertical Sounder (ATOVS) system composed of the High-resolution Infrared Radiation Sounder (HIRS), the Advanced Microwave Sounding Unit-A (AMSU-A), and the Advanced Microwave Sounding Unit-B (AMSU-B). Data assimilation experiments are initialized at three different times. Improvements in the numerical simulation of the typhoon are discussed in the context of wind, temperature, pressure, and geopotential fields. The results indicate that assimilation of satellite data can improve both the representation of the initial conditions and the subsequent simulation of the typhoon. Different satellite data have different impacts on the typhoon track. In these simulations, data from AMSU-A play a greater role in improving the simulation of the typhoon than data from AMSU-B or HIRS. Assimilation of satellite data significantly affects the simulation of the subtropical high and the steering of the typhoon by the environmental flow. The subtropical high is enhanced and extends westward in the data assimilation experiments. The background flow therefore steers the typhoon more westward, improving the simulated typhoon track. Although direct assimilation of satellite brightness temperature improves the simulated environmental conditions, it does not significantly improve the simulated intensity of the typhoon. By contrast, initializing the typhoon simulation using bogus data in tandem with satellite data improves not only the environmental conditions but also the simulated inner-core structure of the typhoon. Assimilation of both types of data therefore improves the simulation of both the typhoon track and the typhoon intensity. The results of these experiments offer new insight into improving numerical simulations of typhoons.     

Diagenetic Sequences Analysis of Fuyu Reservoir in

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｏｒｄｅｒｉｎｇｏｆｄｉａｇｅｎｅｔｉｃｅｖｅｎｔｓｉｓｏｎｅｏｆｔｈｅｍｏｓｔｉｍｐｏｒｔａｎｔｋｅｙｓｔｏｔｈｅｕｌｔｉｍａｔｅｉｎｔｅｒｐｒｅｔａｔｉｏｎｏｆｔｈｅｗａｙｓｉｎｗｈｉｃｈｔｈｅｇｅｏｌｏｇｉｃａｌａｎｄｇｅｏｃｈｅｍｉｃａｌｈｉｓｔｏｒｙｏｆａｓａｎｄｓｔｏｎｅａｆｆｅｃｔｅｄｉｔｓｃｏｍｐｏｓｉｔｉｏｎａｎｄｔｅｘｔｕｒｅ .Ｔｈｉｓａｒｔｉ ｃｌｅｇｉｖｅａｄｅｔａｉｌｄｅｓｃｒｉｐｔｉｏｎａｎｄｏｒｉｇｉｎｅｘｐｌａｎａｔｉｏｎｔｏｔｈｅａ…     

Formation of the CME Leading Edge Observed in the 2003 February 18 Event

This work investigates a typical coronal mass ejection (CME) observed on 2003 February 18, by various space and ground instruments, in white light, Ha, EUV and X-ray. The Ha and EUV images indicate that the CME started with the eruption of a long filament located near the solar northwest limb. The white light coronal images show that the CME initiated with the rarefaction of a region above the solar limb and followed by the formation of a bright arcade at the boundary of the rarefying region at height 0.46 R(?) above the solar surface. The rarefying process synchronized with the slow rising phase of the eruptive filament, and the CME leading edge was observed to form as the latter started to accelerate. The lower part of the filament brightened in Ha as the filament rose to a certain height and parts of the filament was visible in the GOES X-ray images during the rise. These brightenings imply that the filament may be heated by the magnetic reconnection below the filament in the early stage of the eruption. We suggest that a possible mechanism which leads to the formation of the CME leading edge and cavity is the magnetic reconnection which takes place below the filament after the filament has reached a certain height.     

Hub-and-Spoke System in Air Transportation and Its Implications to Regional Economic Development——A Case Study of United States

1 Introduction Over the past twenty years since the enactment of the Airline Deregulation Act, the major US domestic carriers have developed hub-and-spoke structures for their op- erations. These have been instrumental in helping to reduce the overall costs of air travel to the U.S. public and to increase the travel options that are available. This effect also means that the quantity and quality of air ser- vices vary quite considerably between cities in the United States. The pattern of a…