Groundwater management based on GIS techniques, chemical indicators and vulnerability to seawater intrusion modelling: application to the Mahdia–Ksour Essaf aquifer, Tunisia

In arid and semi-arid countries worldwide, conflicts between human development activities and conservation of groundwater resources are widespread and attract many public debates. This research aims to propose groundwater management alternatives for a coastal aquifer by studying its vulnerability and in particularly the risk of seawater intrusion. An additional objective is to propose some agricultural policies aimed to conserve groundwater resources in Mahdia and Ksour Essaf. Intensive groundwater mining, for irrigation and for water drinking, has caused an overexploitation of the water resources. In addition, the degradation of water quality, caused by septic tanks and intensive agricultural activities, has given rise to notable crucial state of the groundwater resources. With the aim of tackling the groundwater degradation problem, integration into a common platform of vulnerability assessment, seawater intrusion modelling and hydrochemical analysis is proposed. This platform can considerably reflect the water resources state in order to propose some solutions reducing the contamination of the Mahdia–Ksour Essaf aquifer. The groundwater management alternatives, proposed in this study, were prepared within a geographical information system.     

Scoring IDC SEL1 events for identifying misformed events

The International Data Center (IDC) produces several automatic seismic event lists followed by a reviewed event list as part of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty. For the time period from 2005 to 2011, on average, approximately 160 events per day were included in the first IDC automatic Standard Event List (SEL1). For the same time period, “only” 86 events per day were included in the IDC Reviewed Event Bulletin (REB). Several possible reasons may explain why an event included in SEL1 is excluded from the REB; for example: misassociation, namely, the association process generated an artificial event by associating information from stations that recorded several different events. Reducing the number of SEL1 events that are ultimately excluded from the REB would improve the automatic process relying on the SEL1 Bulletin and would reduce the workload of the analysts at the IDC. In this work, we present a scoring method that indicates the probability that an SEL1 event will “survive” the analysis process and be included in the REB. The method tries to imitate “good” analyst practice. Namely, based on the experience gained in analyzing information from a specific region with a seismic network, the analyst can decide if an event is a “real” event or not. The score was created for the International Monitoring System primary seismic stations based on the REB for the time period of 2005 to the beginning of 2011. The score is designed to indicate if the set of stations contributing/not contributing to the event is consistent with what is expected based on the analysis of past events that occurred in the same region. A byproduct of the analysis needed for the score is a statistical measure that assesses the typical contribution of a specific station to a specific region. This information can be useful in its own right, for example, to design subnetworks that will increase automatic processing efficiency.     

Filling Some Black Holes: Modeling the Connection Between Urbanization,Infrastructure, and Global Service Intensity

This empirical article combines insights from previous research on the level of knowledge-intensive service in metropolitan areas with the aim to develop an understanding of the spatial structure of the global service economy. We use a stepwise regression model with the Globalization and World Cities research network's measure of globalized service provisioning as the dependent variable and a range of variables focusing on population, infrastructure, urban primacy, and national regulation as independent variables. The discussion of the results focuses on model parameters as well as the meaning of outliers and is used to explore some avenues for future research.     

The H Lyman-α emission line from the upper atmosphere of Jupiter: Parametric radiative transfer study and comparison with data

This study uses the adding-doubling radiative transfer method in which we take into account the curvature effect of the planetary atmosphere in order to test the sensitivity of the jovian Ly-α emission line in relation to H column density, eddy diffusion coefficient, frequency redistribution function for photon scattering, temperature vertical profile, and an added hot atomic H layer on the top of the atmosphere. We also focus here on developing new diagnostic tools that will help us to obtain more confidently the underlying thermospheric structure of Jupiter. First, using the brightness distribution for specific wavelength bands as proposed by Ben Jaffel et al. [Ben Jaffel, L., Magnan, C., Vidal-Madjar, A., 1988. Astron. Astrophys. 204, 319-326], we show that the spatial thickness of the atomic H layer above the homopause level can be measured directly as the separation between the vertical positions of respectively the line core and line wing optical limbs. This thickness also constrains the [H] column and the value KH of the eddy diffusion coefficient at the homopause level at the disc location under consideration. We also propose to refine the value of KH and [H], respectively, at a specific planetary latitude, using the Q ratio of the limb peak brightness to the intensity from other regions over the planetary disc. Finally, the relationship between the disc brightness distribution from specific wavelength bands of the emission line and the temperature gradient in the thermosphere is demonstrated, thus providing an accurate tool to access this key information from high resolution observations. Quick, preliminary comparisons with some existing HTS/STIS data show the H layer thickness at auroral latitudes (∼1700 km) is much smaller than at equatorial latitudes (∼3900 km). These results strongly support the existence of a gradient in both H density and KH versus latitude, with higher values of KH at high latitudes and higher values of the H density at the equatorial regions. Such a small H layer thickness at auroral latitudes is consistent with a high mixing in the atmosphere that brings the hydrocarbons upwards, reducing consequently the column of hydrogen that scatters photons. These preliminary results show the strength of the proposed approach and open new horizons to use strong resonant emission lines at high resolution as a diagnostic for the state and structure of planetary upper atmospheres.     

Progress on the Front of Pulsating Subdwarf B Stars

We briefly review the recent advances that have been made on the front of pulsating subdwarf B (sdB) stars. The first family of sdB pulsators, the EC 14026 stars, was discovered a few years ago and consists of short-period (～100?200 s) p-mode variables. The second type of pulsating sdB’s consists of the PG 1716+426 stars, a group of variables showing long-period (～1 h) g-mode pulsations. The existence of the latter was first reported less than a year ago. While the two types of sdB pulsators differ markedly in their observational characteristics, we recently found a unifying property in the sense that the observed modes in these objects are excited through the same driving process, a classic kappa mechanism associated with the radiative levitation of iron in the stellar envelope.     

塔里木盆地东北部侏罗系烃源岩特征及初步评价

塔里木盆地是中国最大的含油气盆地,其东北部的侏罗系分布面积广、厚度大,主要发育一套煤系烃源岩.根据钻井及大量的实验测试等资料,研究了侏罗系煤系烃源岩的发育特征及其有机地球化学、有机岩石学特征,表明其有机质丰度较高,达到中等-好级别;有机质类型以Ⅲ型为主、Ⅱ型为辅;有机质热演化程度处于未成熟-低成熟阶段,部分地区可能达成熟阶段;烃源岩主要生烃显微组分为基质镜质体,少量孢子体、角质体和碎屑壳质体.综合分析表明,塔里木盆地侏罗系烃源岩具备一定的生烃条件和油气勘探前景.     

青藏高原春夏季对流层温度异常特征

利用NCEP/NCAR再分析资料,在揭示青藏高原对流层中上层(500~200hPa)温度变化特征的基础上,通过比较与同纬度地区对流层中上层温度的差异,从温度纬向偏差角度定义了一个高原热力指数(TDI),并分析了该指数在春夏季的多时间尺度变化特征。结果表明:1由春到夏,亚洲对流层中上层的暖中心经历了从西太平洋西进到大陆,并逐渐发展控制整个东亚地区,之后东退的过程。春季扰动温度暖中心由我国华南地区逐渐西移至高原南部,中心强度逐渐增大,夏季扰动中心稳定在青藏高原南部;2TDI的年变化曲线呈现出明显的单峰型特征,表明高原的热力作用从4月开始明显增强,并在7月达到最大,9月后又迅速减弱;3各月TDI的最高值、最低值和平均值均表现出夏季大冬季小的特征,夏季TDI变幅明显小于其他季节;4TDI具有明显的年际变化,但春(夏)季该指数存在一定(明显)的月际差异,且无明显的线性变化趋势。     

Investigating mid‐Ediacaran glaciation and final Gondwana amalgamation using coupled sedimentology and 40Ar/ 39Ar detrital muscovite provenance from the Paraguay Belt,Brazil

Understanding the evolution of the northern Paraguay Belt, Brazil, is critical in two current controversies: (i) the number, timing and significance of Ediacaran glaciations; and (ii) the timing of amalgamation of South American Gondwana. The Neoproterozoic Alto Paraguay Group forms much of the northern Paraguay Belt. The Serra Azul Formation, within this Group, contains unequivocal evidence for a glacial influence on sedimentation, including multi‐directional striations on sandstone clasts and striated, polished and bullet‐shaped mudstone clasts. However, the age of the Serra Azul Formation is not well‐constrained. The northern Paraguay Belt also formed after the traditionally accepted time for amalgamation of South American Gondwana. If the orogen represents closure of an ocean, then this traditional view is incorrect. A significant number of single grain ⁴⁰Ar/³⁹Ar detrital muscovite cooling ages (ca 120) from the Alto Paraguay Group are presented. The three youngest grains from the Serra Azul Formation yield a weighted mean age of 640 ± 15 Myr, providing a robust maximum depositional age for this formation. This age, when considered with other data, suggests that the Serra Azul Formation developed in a mid‐Ediacaran glaciation consistent with that expressed in the Gaskiers Formation of Newfoundland, Canada. Cryogenian ⁴⁰Ar/³⁹Ar detrital muscovite ages from the Alto Paraguay Group are hard to reconcile with the known geology of Amazonia and are interpreted as being sourced from the evolving orogen to the east – from an arc terrane, possibly the Goiás–Paranapanema Massif. Detrital muscovites in the upper part of the Alto Paraguay Group are as young as 544 ± 7 Myr, consistent with mounting evidence that indicates a Cambrian age for orogenesis within the Paraguay Belt during the final amalgamation of Gondwana. This article suggests that the data best support a model where ocean closure in the region continued until Ediacaran/Cambrian times, with final ocean closure represented by orogenesis in the Paraguay–Araguaia orogen.